US20130218250A1 - MRI-compatible implantable device - Google Patents
MRI-compatible implantable device Download PDFInfo
- Publication number
- US20130218250A1 US20130218250A1 US13/838,385 US201313838385A US2013218250A1 US 20130218250 A1 US20130218250 A1 US 20130218250A1 US 201313838385 A US201313838385 A US 201313838385A US 2013218250 A1 US2013218250 A1 US 2013218250A1
- Authority
- US
- United States
- Prior art keywords
- band stop
- filter
- stop filter
- implantable
- frequencies
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Images
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
- A61N1/00—Electrotherapy; Circuits therefor
- A61N1/02—Details
- A61N1/08—Arrangements or circuits for monitoring, protecting, controlling or indicating
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
- A61N1/00—Electrotherapy; Circuits therefor
- A61N1/18—Applying electric currents by contact electrodes
- A61N1/32—Applying electric currents by contact electrodes alternating or intermittent currents
- A61N1/36—Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
- A61N1/362—Heart stimulators
- A61N1/37—Monitoring; Protecting
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
- A61N1/00—Electrotherapy; Circuits therefor
- A61N1/18—Applying electric currents by contact electrodes
- A61N1/32—Applying electric currents by contact electrodes alternating or intermittent currents
- A61N1/36—Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
- A61N1/362—Heart stimulators
- A61N1/37—Monitoring; Protecting
- A61N1/3718—Monitoring of or protection against external electromagnetic fields or currents
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
- A61N1/00—Electrotherapy; Circuits therefor
- A61N1/18—Applying electric currents by contact electrodes
- A61N1/32—Applying electric currents by contact electrodes alternating or intermittent currents
- A61N1/36—Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
- A61N1/372—Arrangements in connection with the implantation of stimulators
- A61N1/375—Constructional arrangements, e.g. casings
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
- A61N1/00—Electrotherapy; Circuits therefor
- A61N1/18—Applying electric currents by contact electrodes
- A61N1/32—Applying electric currents by contact electrodes alternating or intermittent currents
- A61N1/36—Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
- A61N1/372—Arrangements in connection with the implantation of stimulators
- A61N1/375—Constructional arrangements, e.g. casings
- A61N1/37512—Pacemakers
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
- A61N1/00—Electrotherapy; Circuits therefor
- A61N1/02—Details
- A61N1/08—Arrangements or circuits for monitoring, protecting, controlling or indicating
- A61N1/086—Magnetic resonance imaging [MRI] compatible leads
Definitions
- a medical apparatus comprised of a parallel resonant frequency circuit activated by energy input.
- Magnetic resonance imaging has been developed as an imaging technique adapted to obtain both images of anatomical features of human patients as well as some aspects of the functional activities of biological tissue. These images have medical diagnostic value in determining the state of the health of the tissue examined.
- a patient in an MRI process a patient is typically aligned to place the portion of his anatomy to be examined in the imaging volume of the MRI apparatus.
- Such MRI apparatus typically comprises a primary magnet for supplying a constant magnetic field (B 0 ) which, by convention, is along the z-axis and is substantially homogeneous over the imaging volume and secondary magnets that can provide linear magnetic field gradients along each of three principal Cartesian axes in space (generally x, y, and z, or x 1 , x 2 and x 3 , respectively).
- a magnetic field gradient ( ⁇ B z / ⁇ X i ) refers to the variation of the field along the direction parallel to B o with respect to each of the three principal Cartesian axes, X i .
- the apparatus also comprises one or more RF (radiofrequency) coils which provide excitation and detection of the NMR signal.
- implantable devices such as implantable pulse generators (IPGs) and cardioverter/defibrillator/pacemakers (CDPs) are sensitive to a variety of forms of electromagnetic interference (EMI). These devices include sensing and logic systems that respond to low-level signals from the heart. Because the sensing systems and conductive elements of these implantable devices are responsive to changes in local electromagnetic fields, they are vulnerable to external sources of severe electromagnetic noise, and in particular to electromagnetic fields emitted during the magnetic resonance imaging (MRI) procedure. Thus, patients with implantable devices are generally advised not to undergo magnetic resonance imaging (MRI) procedures.
- MRI magnetic resonance imaging
- U.S. Pat. No. 5,217,010 (to Tsitlik et al.) describes the use of inductive and capacitive filter elements to protect internal circuitry.
- U.S. Pat. No. 5,968,083 (to Ciciarelli et al.) describes a device adapted to switch between low and high impedance modes of operation in response to EMI insult.
- U.S. Pat. No. 6,188,926 (to Vock) discloses a control unit for adjusting a cardiac pacing rate of a pacing unit to an interference backup rate when heart activity cannot be sensed due to EMI. The entire disclosure of each of these United States patents is hereby incorporated by reference into this specification.
- a medical device comprising a lead wherein the lead is in electrical communication with the device and a substrate, a control circuit that is responsive to a selected activation source, a resonant circuit that controls the flow of electrical current through a first circuit wherein said first circuit is comprised of the lead wherein the resonant circuit is controlled by the control circuit, and the resonant circuit is disposed between the device and the lead, and the lead serves as an antenna that is adapted to receive pulsed radio frequency fields from an electromagnetic source external to said device.
- FIG. 1 is sectional view showing a cross-section of one preferred implantable device of the invention
- FIGS. 2 a and 2 b are block diagrams showing the functional components the implantable device of FIG. 1 ;
- FIG. 3 is a schematic of a robust pacing circuit utilized in the device of FIG. 1 ;
- FIG. 4 is schematic illustrating a “cordwood” construction of the pacing circuitry of the device of FIG. 1 ;
- FIG. 5 is a schematic of a preferred process of the invention.
- FIG. 6A is a pulse depiction of a standard MRI device
- FIG. 6B is a pulse depiction of the optical emitter of the apparatus of this invention.
- FIG. 6C is a timing diagram of pulses produced by MRI device, showing its phase relationship to the energy produced by the optical emitter of FIG. 6B ;
- FIG. 6D is a pulse energy of input and output of a cardiac assist device of this invention, showing the phase relationships between said input and output;
- FIG. 7 is a schematic of one embodiment of the present invention.
- FIGS. 8A through 8D are schematics of various resonant frequency circuits which can be used in the device of FIG. 1 ;
- FIG. 9 is a depiction of one implantable device of the invention.
- FIG. 10 is a depiction of another implantable device of the invention.
- the first part of the specification discusses the utilization of a secondary backup medical device.
- the second part of this specification discloses a medical device comprising a lead wherein the lead is in electrical communication with the device and a substrate, a control circuit that is responsive to a selected activation source, a resonant circuit that controls the flow of electrical current through a first circuit wherein said first circuit is comprised of the lead wherein the resonant circuit is controlled by the control circuit, and the resonant circuit is disposed between the device and the lead, and the lead serves as an antenna that is adapted to receive pulsed radio frequency fields from an electromagnetic source external to said device.
- an implantable device that is resistant to electromagnetic interference comprising first and second modular components and an arrangement for communication between the first module and second modules.
- the first module performs physiologic functions and the second module is deactivated.
- the second module which is resistant to EMI insult, is activated and the first module is deactivated to further protect its components from EMI.
- an implantable device used to monitor and maintain at least one physiologic function, which is capable of operating in the presence of damaging electromagnetic interference.
- the implantable device includes primary and secondary modules, each independently protected from EMI damage via at least one shielding and/or filtering agent, and a non-electrical communication device for communicating in at least one direction between the primary and the secondary modules.
- the primary module in response to input from electrical sensing leads, activates the secondary module in a failsafe mode. In the failsafe mode, the secondary module carries out a function upon activation and in the presence of electromagnetic interference.
- the function performed by the implantable device is a cardiac assist function
- the implantable device is a cardiac assist device.
- FIG. 1 A cross-section diagram of an embodiment of the implantable device according to one embodiment of the present invention is shown in FIG. 1 .
- the body of the device 10 is shown in rectangular form for illustrative purposes only and may have a rounded shape when implanted in the body to avoid tissue damage due to sharp edges.
- the body of the implantable device 10 includes two modules, a primary module 20 and a secondary module 30 , which are hermetically sealed from each other.
- the primary module is a demand pacemaker (DDD) with PCD functionality.
- DDD demand pacemaker
- a demand (DDD) pacemaker denotes an implantable device that paces and senses both atrial and ventrical chambers of the heart and can either trigger or inhibit functions depending on detected parameters.
- the primary module 20 controls the various pacing, cardioversion and defibrillation operations of the implantable device 10 via electrical pacing lead 24 , and detects parameters indicating how the heart is functioning via electrical sensing lead 28 .
- Both the pacing leads and sensing leads are bipolar leads; these leads comprise means for connecting the cardiac assist device to a patient's heart (not shown), and they comprise means for furnishing electrical impulses from the cardiac assist device to the heart.
- the primary module 20 includes a circuitry portion 21 , which contains signal detection and logic circuitry for performing pacing and analysis functions and a battery portion 22 .
- the battery includes either no magnetic material or non-magnetic materials. It may be, for example, a lithium-iodine battery, or its chemical equivalent, e.g. It may have an anode of lithium or carbon and a cathode of iodine, carbon monofluoride, or of silver vanadium oxide, or sulfur dioxide, SOCl 2 or SO 2 Cl 2 .
- the circuitry portion 21 is separated from the battery portion by a non-magnetic and non-corrosive layer 23 which, as described below, can be made from titanium or from a carbon-composite material.
- the implantable device 10 also includes a secondary module 30 , which contains independent circuitry 31 , and battery 32 components also separated by a non-magnetic and non-corrosive layer 33 .
- the secondary module 30 is not activated when the primary module 20 operates, but is only switched on when the primary module malfunctions or detects a voltage induced by electromagnetic interference (EMI) that exceeds a certain level, such as, for example, 3 Volts.
- EMI electromagnetic interference
- the secondary module 30 acts as a backup VOO pacemaker (ventricle driven, with no ventricle-sensing input nor any ventricular triggering or inhibition), which is ventricle driven, with no ventricle-sensing input nor any ventricular triggering or inhibition.
- the secondary module 30 sends pacing signals via a unipolar electrical lead 34 to a ventricle chamber of the heart but does not receive any detected input signals.
- the secondary module 30 is supplied with power by a separate battery source 32 , which is also of a non-magnetic type, such as a lithium-iodine battery.
- Both the primary and secondary modules 20 , 30 are encased within shielding 16 that protect their respective circuitry components from external electromagnetic fields.
- the shielding 16 can be made from carbon-matrix composites with continuous carbon fiber filler which is particularly effective in EMI shielding, as discussed in “Electromagnetic interference shielding using continuous carbon-fiber carbon-matrix and polymer-matrix composites,” Luo, X., and Chung, D.D.L., in Composites: Part B (1999), and also suitable for injection molding to encase circuit components.
- the thickness of the shielding 16 varies from approximately 1 to 3 millimeters.
- the batteries of the primary and secondary modules 22 , 32 are also encased in separate shielding 16 made of similar materials.
- An optical window 40 made from glass or ceramic, which may be an infrared-transmissive window, is situated between the respective circuitry portions 21 and 31 of the primary and secondary modules 20 , 30 .
- the optical window 40 allows for communication to occur between the primary and secondary modules 20 and 30 .
- the window 40 is transparent to a range of frequencies of visible or infrared radiation.
- the thickness of the window has an optimal range of between 0.3 and 1.0 centimeter.
- the optical window 40 is bound with brazing to sealing fixtures 35 , 36 (also referred to as ferrules) that are welded to the respective modules in a manner that may correspond, for example, to that described in, for example, U.S. Pat. No. 5,902,326 to Lessar et al. The entire disclosure of this United States patent is hereby incorporated by reference into this specification.
- the entire implantable device 10 is coated with a non-magnetic, biocompatible layer 18 such as rolled titanium or flexible graphite.
- a non-magnetic, biocompatible layer 18 such as rolled titanium or flexible graphite.
- Flexible graphite has been shown to be a particularly effective shielding gasket material as discussed, for example, in Flexible Graphite for Gasketing, Adsorption, Electromagnetic Interference Shielding, Vibration Damping, Electrochemical Applications, and Stress Sensing, Chung, D. D. L., Journal of Mat. Eng. And Performance, Vol. 92 (2000), due to its resilience, chemical resistance and shielding properties.
- Graphite/polymer composites may also serve as layer 18 .
- FIG. 2 shows functional components of a dual-module implantable device 10 according to an embodiment of the present invention.
- the functional components of the primary module 20 include a power supply (from the battery 22 ), which supplies power along a main power and device communication bus 125 to the circuitry 21 .
- the circuitry 21 includes a processor 100 coupled to the main bus 125 , which can be implemented as a parallel processor, or as a microprocessor adapted to perform analog signal processing functions 102 in addition to error detection 104 and power reduction operations 106 .
- the processor 100 analyzes cardiac signals input from the sensing lead 28 and determines a QRS complex from the various properties of the input signals.
- the processor 100 determines from the analysis whether a detrimental condition exists, and directs a pacing circuit 140 to transmit corrective pulses to ameliorate the condition.
- the processor 100 is also configured to detect internal errors or circuitry malfunctions. As will be described further, when such errors are detected, the processor 100 initiates a shut down of the primary module 20 and sends a signal via optical window 40 that instructs module 30 to become activated. Furthermore, to preserve the life of the battery 22 for as long as possible, the processor 100 regulates the application of power to various circuit elements in order to reduce static power consumption, in a manner such as described, for example, in U.S. Pat. No. 5,916,237 to Schu; the entire disclosure of this United States patent is hereby incorporated by reference into this specification.
- the processor 100 is coupled to a memory unit 170 in which instructions and data are stored.
- the primary module circuitry 21 also includes an optical source unit 150 coupled to the main bus 125 .
- Optical source unit 150 can be any source of visible or infrared radiation that does not consume significant amounts of power, such as a light emitting diode (LED).
- LED light emitting diode
- the optical source 150 turns on and off with a specific well-defined frequency or remains continually on.
- the optical source unit 150 is arranged in relation to the optical window 40 so that radiation emitted from the source unit 150 penetrates through the optical window 40 into the secondary module 30 .
- Both the processor 100 and the optical source unit 150 are situated downstream from a power-down switch 118 .
- the primary module circuitry 21 also includes an optical sensor unit 160 similarly placed in relation to the optical window 40 , in this case, so that it can receive radiation emitted from sources within the secondary module 30 .
- the optical sensor unit 160 preferably is a low-power photodetector sensitive to infrared or visible radiation of a certain wavelength range, preferably from about 400 to 800 nanometers.
- the optical sensor unit 160 is coupled to the main bus 125 upstream from the power-down switch 118 , so that it remains connected to the power supply 22 via the main bus 125 and therefore remains functional, even when the power-down switch 118 is opened.
- a telemetry unit 180 is also situated upstream from the power-down switch 118 so it also can function when the power-down switch 118 is opened.
- the telemetry unit 180 may be, for example, a subcutaneous near-infrared signal transmitter, such as described in U.S. Pat. No. 6,192,261 to Gratton et al., that radiates through body tissues and can communicate with a near-by remote programming device equipped with an infrared receiver, for example, during an examination at a medical facility; the entire disclosure of this United States patent is hereby incorporated by reference into this specification.
- the telemetry unit may use low-power high-frequency radio signals in the Bluetooth® range to communicate with nearby Bluetooth-enabled network devices. In either case, the telemetry unit 180 can communicate information such as the condition of the heart, the remaining life of the implantable device batteries, and whether the primary module 20 is inoperative.
- the processor 100 is coupled to pacing lead 24 and sensing lead 28 via respective comparators 110 and 115 .
- the comparator 110 compares voltage on the input lead 28 with a threshold voltage, set to, for example 3 Volts. If the input voltage exceeds the threshold voltage, the comparator 110 sends a signal to the processor 100 .
- the comparator 115 is reverse biased, so that it compares voltages caused by external fields, rather than the output pulse signal on the pacing lead 24 , to the threshold voltage, also set to, for example, 3 Volts. If the external voltage appearing on the pacing lead exceeds the threshold voltage, the comparator 115 sends a signal to the processor 100 .
- a switch (not shown) is thrown to redirect lead signal through capacitive and inductive elements 114 , which filter signals on the pacing 24 and sensing 28 leads in a way known in the art before they reach the circuitry 21 of the primary module 20 .
- the processor 100 Upon receiving the threshold signal from either comparators 110 or 115 , the processor 100 sends a power-down signal to open the switch 118 . Additionally, the processor 100 may send a power-down signal to open the switch 118 in response to detection of internal errors or malfunctions.
- U.S. Pat. No. 5,653,735 describes, for example, one way by which error detection module 104 can detect malfunctions in primary module 20 not caused by EMI; the entire disclosure of this United States patent is hereby incorporated by reference into this specification.
- the primary module circuitry components downstream from the switch are disconnected from the power supply 22 and no longer operate.
- the primary module 20 stops transmitting pacing pulses to the heart and the optical source unit 150 stops radiating through the optical window 40 .
- the telemetry unit 180 and the optical sensor unit 160 of the primary module 20 continue operating.
- the optical detector 260 of the secondary module 30 When the optical source unit 150 of the primary module 20 stops emitting radiation, this event is detected by the optical detector 260 of the secondary module 30 , which is adapted to detect an absence of radiation of either a certain frequency or for a defined period of time, for example, two seconds. Upon detection, the optical detector 260 transmits a power-up signal to switch 218 , which closes and connects the secondary module circuitry 31 to the secondary power supply 32 . In this manner, the secondary module 30 is activated when the primary module 20 is deactivated.
- the secondary module circuitry 31 includes an oscillator stage 230 , an amplifier stage 240 and a counter 245 .
- FIG. 3 shows an exploded view of the oscillator 230 and amplifier 240 stages, which are comprised of robust electrical components, such as bipolar transistors, that are not easily disturbed by electromagnetic insult.
- the oscillator 230 includes bipolar transistors 321 and 322 which are coupled in an emitter feedback arrangement.
- the RC circuit 310 comprised of resistor 311 and capacitor 312 sets the fixed repetition rate of the oscillator 230 .
- a shaping RC circuit 340 modifies the shape of a pulse that triggers the ventricle tissues in the heart (shown as 400 ).
- This secondary module circuitry 31 generates an electrical pulse that stimulates the heart tissues via a lead 34 extending from the secondary module 30 , whereby it produces ventricular contraction at a fixed rate.
- the return path for the pulse signal is through lead 34 from the body tissues 400 to the secondary module 30 . Since the pacing lead 34 can conduct electromagnetic interference, a reverse biased comparator 280 switches the conducting path to capacitive and inductive filtering elements 290 when a threshold voltage is reached. This adds an extra layer of protection to the secondary module circuitry 31 .
- the secondary module 30 only performs basic pacing operations and does not perform diagnostic functions, if the primary module 20 shuts down in response to temporary electromagnetic interference, it is important to reactivate the primary module 20 (and deactivate the secondary module 30 ) when the implantable device 10 is no longer threatened by the electromagnetic interference. For example, since MRI procedures generally last approximately half an hour, the primary module 20 should only be deactivated for a half an hour plus an additional amount as a tolerance factor, for example.
- the secondary module circuitry 31 includes a counter element 245 coupled to the oscillator element 230 , that counts oscillator transitions. Once the secondary module is turned on, the counter element 245 increments and can trigger a reset function to turn the primary module 20 back on when it reaches a specific count after a pre-defined length of time.
- the counter 245 triggers an optical source 250 to transmit radiation through the optical window 40 to the primary module 20 in which the radiation is detected by optical sensor unit 160 .
- this radiation may be a single pulse lasting for one second.
- the optical sensor unit 160 sends a trigger signal to close the power-down switch 118 and turn the primary module 20 back on.
- the processor 100 of the primary module 20 detects that it is connected to the power supply 22 , it runs diagnostic tests in a power-on-reset (POR) mode, such as described, for example, in U.S. Pat. No.
- the processor 100 sends a trigger to the pacing unit 140 to begin operation and simultaneously sends a transmission signal to the optical source unit 150 , whereupon the optical source unit 150 turns on or begins to pulse according to its pre-set frequency.
- the optical detector 260 of the secondary unit detects that the optical source unit 150 of the primary unit is on, and in response, triggers the switch 218 to open, deactivating the secondary module circuitry 31 .
- the circuitry components 31 may be arranged, according to one embodiment of the secondary module circuitry 31 , in a “cordwood” design such as is shown in FIG. 4 .
- a “cordwood” design such as is shown in FIG. 4 .
- all components are laid side by side on a teflon block 415 , to avoid adherence, and a thin layer of mixed epoxy is laid onto the circuit components, which are aligned so as to minimize the wiring between the various components which reduces extraneous induced EMI pickup.
- the circuit 410 is removed from the teflon block and the components are wired as illustrated in FIG. 4 .
- the resistor and capacitor components 425 are shown hand-wired with very short leads, which reduce electrical pickup signals from an MRI in progress that might disturb the operation of the pacemaker circuitry.
- the secondary module circuitry 31 comprises a custom designed integrated circuit (IC) fabricated, with the active semiconductors, resistors, capacitors and the connecting wires part of the IC.
- IC integrated circuit
- MRI has been developed as an imaging modality used to obtain images of anatomical features of human patients as well as some aspects of the functional activity of biological tissue.
- the images have medical diagnostic value in determining the state of health of the tissue examined.
- the patient is aligned to place the portion of the anatomy to be examined in the imaging volume of a MRI apparatus.
- the apparatus typically comprises a primary magnet for supplying a constant magnetic field (B 0 ) which by convention is along the z-axis and is substantially homogeneous over the imaging volume and secondary magnets that can provide linear magnetic field gradients along each of three principal Cartesian axes in space (generally x, y, and z, or x 1 , x 2 and x 3 , respectively).
- a magnetic field gradient ( ⁇ B z / ⁇ X i ) refers to the variation of the field along the direction parallel to Bo with respect to each of the three principal Cartesian axes, X i .
- the apparatus also comprises one or more RF (radio frequency) coils which provide excitation and detection of the NMR signal.
- ⁇ is the gyromagnetic ratio (approximately 42.6 megahertz [MHz] per Tesla for hydrogen)
- B 0 is the static magnetic field magnitude.
- the resonant frequency at 1.5 Tesla for hydrogen in clinical scanners is approximately 63.9 megahertz. Therefore, in the range of 0.5 to 14.1 Tesla, the resonant frequency range will be 21.3 megahertz to 651 megahertz. Clinical MRI almost exclusively images utilizing the resonance of hydrogen, therefore the value for ⁇ of 42.6 megahertz per Tesla is standard.
- timing circuitry 441 within the MRI Instrumentation hardware activates the gradient coils of the MRI scanner while substantially simultaneously activating a trigger voltage (see step 444 ). Thereafter, generally within a period of 3 microseconds, the timing circuitry 441 also activates the transmission of radio frequency coil pulses (see step 446 ).
- timing circuits known to those skilled in the art as MRI timing circuitry 441 .
- FIG. 8 of U.S. Pat. No. 4,379,262 (“Nuclear magnetic resonance systems”)
- the control block shown at element 25 of such FIG. 8 provides the basic control input for the apparatus. This may simply be an operator control panel at which the operator selects the next operation required or may be a microprocessor holding a predetermined control pattern but will generally be a combination of those two.
- the control 25 supplies instructions to a sequence controller 26 .
- circuits 27 comprise a system clock and appropriate counters and gates. The entire disclosure of this United States patent is hereby incorporated by reference into this specification.
- Timing circuits of the type disclosed in U.S. Pat. No. 4,379,262 are well known and are adapted to control any sequence of operations which is known in advance. These circuits can readily be adapted to a chosen examination procedure.
- the field control 16 gates the field probe output from amplifier 17 with timing signals from 14 and takes a count in counter 28 which is in fact the measured field.
- the measured field is compared in a subtractor 30 with the precalculated field (demand setting) from a store such as a read only memory 31 .
- the consequent error signal is digitised in unit 32 to be applied to coil 12 via a power amplifier, thereby bringing the field to the required value.
- the NMR apparatus 40 is first caused to operate with a GR gradient in the manner previously disclosed, and the resonance signals thus provided are demodulated in demodulators 43 and 44 at frequency f o from a reference oscillator 45 .
- demodulation is into in-phase and quadrature components, the reference for demodulator 44 being shifted by 90° in circuits 46 .
- the trigger voltage 444 activated by the timing circuitry 441 will be applied to a specified diode (see step 447 ), thereby preferably forming a parallel-resonant circuit that is functional only when the resonant condition is met (see FIGS. 8A through 8D for some suitable resonant circuits which utilize such a diode; also see steps 448 and 449 of FIG. 5 ).
- this trigger voltage 444 provides means for furnishing electrical impulses to either an optical emitter (not shown in FIG. 5 ) and/or for directly activating a diode (not shown).
- parallel-resonant circuits have very high impedances at or near the resonant frequency of the circuit and essentially perform as open switches at such resonant frequencies.
- the parallel resonant circuit becomes functional (see step 448 )
- it prevents current at or near the resonant frequency from passing through it.
- this parallel-resonant circuit is interconnected between a cardiac assist device circuit and cardiac leads and is functional, it will effectively open the circuitry of the cardiac assist device, totally inhibiting current induced by the radio frequency fields of the MRI system from flowing to the device or via the leads to the heart (see step 450 ).
- the functional resonant circuit prevents the occurrence of deleterious effects on the cardiac assist device and the heating of the electrodes placed in the cardiac tissue.
- the parallel resonant circuit which is activated provides means for ceasing the furnishing of electrical impulses from a cardiac assist device to a patient's heart; when alternating currents are supplied which deviate from frequency at which resonance occurs in the parallel resonant circuit, current is allowed to flow to the device, the amount of flow depending upon the deviation from the resonant frequency. Consequently, when the parallel circuit is not activated (at frequencies more or less than the resonant frequency), it acts as a closed switch, and there is provided means for furnishing the electrical impulses to the heart.
- the amount of current which will be allowed to flow at frequencies other than the resonant frequency may be adjusted by adjusting the “Q” of the circuit which, in turn, depends upon, e.g., the resistance in the circuit.
- the timing circuitry signals the MRI gradient field pulses and the trigger voltage off
- the circuitry of the cardiac assist device is activated because the parallel-resonant circuit ceases to exist.
- the pulsed radio frequency is no longer being produced, there is no danger to the pacemaker circuit and the patient within whom such circuit is disposed.
- FIGS. 6A , 6 B, 6 C, and 6 D illustrate one preferred series of phase relationships which preferably are produced by the timing circuit of the MRI device.
- the activation of the “slice select” (SS) gradient 460 occurs immediately prior to the application of the radio frequency (RF) pulse 462 .
- the gradient and RF coils activated utilizing the standard pulse sequence in FIG. 6A is of the type magnetic field gradient and RF coils described hereinabove.
- FIGS. 6B , 6 C and 6 D A simplified depiction of the timing relationship between the RF coil activation, the triggering of the optical emitter (OE) and the output of the cardiac assist device is shown in FIGS. 6B , 6 C and 6 D respectively, which illustrate the timing of one embodiment of the present invention.
- the units of the axis in FIGS. 6A through 6D are relative and can take on many different values.
- a wide variety of timing sequences are possible depending upon the choice of pulse sequence and type of cardiac assist device. This embodiment of the invention may be applied to any number of time sequences similar to FIGS. 6B , 6 C and 6 D.
- the triggering of activation for the optical emitter (OE) 460 precedes the triggering of the activation of the radio frequency (RF) coils of the MRI scanner 468 .
- radio frequency fields are generated whose concentration is at a maximum within the core of the coils. These fields interact with and are “received by” all materials with which it contacted.
- a cardiac assist device within a patient will be contacted and affected by such R.F. fields.
- the R.F. fields may trigger the cardiac assist device and cause rapid pacing when, in fact, such is not required by the patient.
- the R.F. fields often induce a voltage within the cardiac assist device which is so substantial that it often destroys the device.
- the term “receiving pulsed radio frequency fields” includes any device which is in any manner affected by the pulsed radio frequency fields.
- the cardiac assist device might not contain a formal antenna for receiving the pulsed radio frequency fields, it still contains means for receiving such pulsed radio frequency fields in that one or more of its components interact with such fields.
- the leads of the cardiac assist device often act as antennae.
- a multitude of waveforms may be applied for the MRI sequence.
- cardiac assist devices CADs
- the timing description shown in FIG. 6D is only one example of a ventricular VOO pacemaker pulsing waveform.
- the initiation of any pulse (for example, pulse 470 in FIG. 6D ) from the VOO cardiac assist device (CAD) will not occur during a radio frequency pulse derived from the RF transmit coils of the MRI scanner.
- the duration of this pulse will not overlap or occur during an RF pulse derived from the RF transmit coils of the MRI scanner.
- U.S. Pat. No. 6,163,724 (“Microprocessor capture detection circuit and method”) discloses means for auto-capture detection in a variety of pacing and sensing modes.
- this patent discloses a software programmable (device means such as a microprocessor) that discriminates between evoked response signals and post-pace polarization signals sensed by an implantable medical device.
- the polarity of the positive or negative change in voltage in respect of time (or dv/dt) of the waveform incident on the lead electrodes is monitored during a short period of time immediately following a paced event.
- the post-pace polarization signal exhibits a relatively constant polarity during the capture detect window, that the evoked response signal may cause the polarity of post-pace polarization signal to reverse during the capture detect window, that the sign of the post-pace polarization polarity, either positive or negative, is determined by the design of the specific output circuitry.
- the evoked response signal may reverse the polarity of the sensed signal in either case, from positive to negative or from negative to positive, during the time window of interest.
- U.S. Pat. No. 6,169,921 (“Autocapture determination for an implantable cardioverter defibrillator”) discloses a cardiac pacing/defibrillation system that enhances the ability of a cardiac pacer to automatically detect whether a pacing stimulus results in heart capture or contraction.
- the cardiac pacing/defibrillation system of this patent includes a pacing circuit that attenuates polarization voltages or “afterpotential” which develop at the heart tissue/electrode interface following the delivery of a stimulus to the heart tissue, which thereby allows the pacing electrodes to be utilized to sense an evoked response to the pacing stimulus.
- the cardiac pacing/defibrillation system of this patent may utilize the ventricular coil electrode and superior vena cava coil electrode to sense an evoked response, thereby eliminating the necessity for an additional ventricular lead for sensing an evoked response.
- the device of this patent allows accurate detection of an evoked response of the heart, to thereby determine whether each pacing stimulus results in capture.
- the entire disclosure of this United States patent is hereby incorporated by reference into this specification.
- a parallel resonant circuit is activated.
- Some suitable resonant circuits which may be used in the process of this invention are depicted in FIGS. 8A , 8 B, 8 C, and 8 D.
- a cardiac assist device comprising means for connecting said cardiac assist device to a heart, means for furnishing electrical impulses from said cardiac assist device to said heart, means for ceasing the furnishing of said electrical impulses to said heart, means for receiving pulsed radio frequency fields, and means for receiving optical signals.
- the device contains a control circuit comprised of a parallel resonant frequency circuit activated by optical input.
- radio frequency (RF) energy of a specified frequency
- RF radio frequency
- the “Q” (quality factor) of the parallel resonant circuit may be varied, thus varying the amount of current which is allowed to flow at specified frequencies off of the resonant frequency.
- FIGS. 8A through 8D are disclosed in U.S. Pat. No. 6,144,205 of Steven Souza et al. The entire disclosure of this United States patent is hereby incorporated by reference into this specification.
- FIG. 8A corresponds to FIG. 2 of the patent
- FIG. 8B corresponds to FIG. 4 of the patent
- FIG. 8C corresponds to FIG. 5 of the patent
- FIG. 8D corresponds to FIG. 6 of the patent.
- FIG. 8A depicts one embodiment where a series resonant circuit 500 comprises an inductance 502 with capacitances 504 and 506 .
- Inductance 508 , capacitance 504 and PIN diode 510 form a blocking resonant loop coupled through capacitance 504 to the cardiac assist device.
- PIN diodes are preferably utilized because of their high on/off conductance ratio.
- a dc trigger voltage (see step 444 of FIG. 5 ) is applied to the terminals 512 and 514 from an external source via an electrical lead, such as a lead from a trigger device adapted to produce such voltage when initiated from a separate source, such as the timing circuitry in an MRI scanner.
- the terminals 512 and 514 also serve as the receiving means of the radio frequency energy of specified frequency of the transmit receiver of the MRI scanner.
- the direct current is applied to terminals 512 and 514 , and where the bias is such that it produces a forward current through diode 510 , the inductance 508 forms a parallel-resonant condition with the capacitance 504 . This condition results in the loss of conduction through the entire circuit 500 hence disabling and opening the circuit.
- the direct current 511 applied to PIN diode 510 is applied from an external source via an electrical lead, such a lead from a trigger device adapted to produce such current when initiated by a dc trigger voltage from a separate source, such as the timing circuitry in an MRI scanner.
- a trigger device adapted to produce such current when initiated by a dc trigger voltage from a separate source, such as the timing circuitry in an MRI scanner.
- the diodes 534 , 542 , 544 , 574 , and 576 in FIGS. 8B , 8 C and 8 D will be optically controlled photodiodes.
- the parallel resonant circuit switch disclosed in U.S. Pat. No. 5,055,810 (“Ultra-High speed light activated microwave switch/modulation using photoreactive effect”); the entire disclosure of this United States patent is hereby incorporated by reference into this specification.
- Disclosed in this United States patent is a resonant circuit switch that is controllable via a photodiode.
- the fabrication of the photodiode illustrated in this patent utilizes the reactance of the photodiode instead of the standard use of the resistance. This results in a drastic increase in the switching speeds of the entire resonant switch.
- the circuit 520 comprises an inductance 522 connected to form a resonant circuit 527 with a pair of series connected capacitances 524 and 526 with an intermediate node 528 between the capacitances.
- the resonant circuit 527 is tuned to the Larmor frequency of the substance being examined by MRI, (e.g., human tissue).
- the dc trigger voltage can be linked through an electrical lead to terminal 529 to the intermediate node 528 via an inductor 530 or other reactive electrical device.
- the other pole of the dc trigger voltage can be linked through an electrical lead to terminal 531 to a node 532 between the second capacitance 532 and inductance 522 .
- a photosensitive semiconductor device such as a photodiode 534 , is connected to the dc trigger voltage without regard to diode polarity.
- the photosensitive device could comprise a PIN-type photodiode, a phototransistor, a photodarlington transistor pair, a light-activated SCR or a photo-FET.
- the device of this invention is comprised of means for receiving an energy input and, in response thereto, for activating the parallel resonant circuit described above.
- One form of energy which will activate the parallel resonant is photonic energy, and a switching device incorporating such photonic energy will be described in the remainder of this specification.
- a transmitted optical signal via a fiber optic cable 520 may be positioned on or near the skin surface 424 (see FIG. 7 ) of a patient to illuminate the active surface of photodiode 534 .
- the photodiode 534 may be placed within a feed-through assembly 422 , as is known to those skilled in the art of designing and constructing capacitive feed-through assemblies in cardiac assist devices.
- One may connect the cardiac leads (not shown) to the cardiac assist device 400 .
- optical radiation is transmitted through the skin a patient.
- a photodector may be disposed beneath the skin, substantially anywhere in the living organism. It is preferred not to have to transmit the light through highly absorbent body tissue, such as a liver, or through bone. However, subcutaneous placement of the photodetector(s) beneath one or more skin layers is relatively efficient.
- the optical emitter 418 responds by producing a light beam which is sent through the optical fiber 420 .
- This light beam illuminates the photodiode 534 in the circuit 520 , hereby rendering the photodiode conductive.
- This causes the blocking loop 537 (see FIG. 8B ) formed by the photodiode 534 , input inductor 530 , and the second capacitance 526 to be parallel resonant at the Larmor frequency.
- the blocking loop 537 is coupled to the resonant circuit 527 .
- This blocking loop parallel resonance substantially nulls the response of the resonant circuit 527 at the Larmor frequency, thereby preventing current from flowing from the electrical leads to the cardiac assist device 400 during RF transmission of an MRI procedure.
- the optical emitter 418 does not produce illumination of the photodiode 534 so that the blocking loop 537 does not form a complete parallel resonant circuit and has no effect on the resonant circuit 527 .
- blocking loop 537 also presents a high impedance between the cardiac leads and the resonant circuit 527 electrically isolates the two components during the transmission of the RF pulses. Thus any signal induced in the circuit 520 , due to the intense transmit fields, will be attenuated before reaching the electronics of the cardiac assist device 400 .
- the device depicted in FIG. 5 of U.S. Pat. No. 6,144,205 may be utilized in the apparatus of this invention.
- the device of such FIG. 5 is similar to the device of FIG. 4 of the patent but has been modified with the addition of a semiconductor switch 188 in parallel with the photosensitive device 190 , but with the opposite polarity (i.e. An anti-parallel connection with photosensitive device 190 ).
- the normal forward current between terminals 191 and 192 through semiconductor switch 188 is opposite that of normal forward current between terminals 191 and 192 through photodiode 190 .
- Semiconductor switch 188 may, for example, be a PIN type diode, transistor, FET or SCR.
- the current produced by the photodiode or other type of photosensitive device 190 when illuminated, will flow through and partially turn on semiconductor switch 188 thereby reducing the net RF impedance between terminals 191 and 192 .
- This will reduce the on-state impedance in blocking loop 194 , increasing the degree to which the parallel resonance of blocking loop 194 nulls the response of resonant circuit 195 comprising inductance 196 and two capacitances 197 and 198 .
- the entire disclosure of this United States patent is hereby incorporated by reference into this specification.
- the semiconductor switch 188 may also be a photodiode or other type of photosensitive device. In this case, best operation will be obtained if provision is made to adequately illuminate both photosensitive devices 190 and 188 in order to render those devices conductive.
- FIG. 6 of U.S. Pat. No. 6,144,205 illustrates an alternative third embodiment 354 of the optical technique for disabling an RF antenna.
- This embodiment has a parallel resonant blocking loop 201 , comprised of photosensitive semiconductor switch 214 , inductor 212 , and capacitance 204 rather than capacitance 206 corresponding to capacitances 174 and 198 in FIGS. 4 and 5 of such patent, respectively, and optionally semiconductor switch 216 .
- This can be done because there is no need to provide an electrically conducting path to photosensitive semiconductor device 214 as is the case for PIN diode 20 in FIG. 2 of this patent.
- Device 214 may be connected without regard to diode polarity, and may be a photodiode, a PIN-type photodiode, a phototransistor, a photodarlington transistor pair, a light-activated SCR or a photo-FET. If semiconductor switch 216 is omitted the circuit operation is identical to that of the first embodiment in FIG. 4 of this patent, while offering an additional option for physical placement of the components of blocking loop 201 .
- the circuit of FIG. 6 of this patent offers the further advantage that photosensitive semiconductor switch 214 and inductance 212 are not in the signal path between the resonant circuit 208 and the signal cable 158 connected to terminals 218 and 219 , and therefore do not attenuate the received signal in receive mode.
- the modifications of the second embodiment of the patent shown in FIG. 5 thereof may be applied to the circuit of FIG. 6 of the patent. This will reduce the on state impedance in blocking loop 201 , increasing the degree to which the parallel resonance of blocking loop nulls the response of resonant circuit 208 .
- the anti-parallel semiconductor switch 216 may also be a photodiode or other type of photosensitive device or any semiconductor activated by photodiode 214 .
- a circuit as shown in FIGS. 8A through 8D may be placed within a feed-through assembly within the path of the leads immediately adjacent to the pacing electrode of the cardiac assist device.
- a capacitive filter is mounted at the inboard side of a device housing, with capacitive filter electrode plate sets coupled respectively to the housing and the terminal pin by an electrically conductive combination of adhesive, brazing and soldering.
- multiple capacitive filters are provided in an array within a common base structure, where each capacitive filter is associated with a respective terminal pin.
- the cardiac assist device 400 will not shut down when the open circuit is established.
- An open circuit at the lead will be recognized by the cardiac assist device processor as a specific event defined within ROM 170 (see FIG. 2 ).
- the cardiac assist device processor 100 (see FIG. 2 ) will not respond to this event definition and remain in astatic state until the parallel-resonance circuit is triggered off and the closed circuit is reestablished between the cardiac leads 24 and 28 (see FIG. 2 ) and the cardiac assist device 400 .
- the parallel-resonant circuit on the secondary module 30 there will be no requirement for signaling from the open circuit due to the fact that there is no sensing capability of the VOO secondary module 30 . Referring again to FIG.
- the cardiac assist device 10 of this invention will be remotely signaled to open the connection between both the sensing lead 28 and the pacing lead 24 of the device and the primary module 20 .
- a feed-through assembly 602 and 604 (see FIG. 9 ) connects leads 24 and 28 , respectively, wherein such feed-through assembly contains the resonant circuit(s) of FIGS. 8A and/or 8 B and/or 8 C and/or 8 D, as described hereinabove.
- the secondary module 30 may also contain the same mechanism remotely signaled to open a connection between the pacing lead 34 and the secondary module 30 via feed-through assembly 608 .
- an inductor/capacitor/diode (RLC) radio frequency detection circuit for the detection of the frequency specific RF signal is utilized.
- RLC inductor/capacitor/diode
- One of the resonant circuits shown in FIGS. 8A through 8D can be placed at the output end of the sensing lead and at one input into the processor 100 .
- One may use any number of combinations of an RLC resonant circuit to serve the same function as the ones depicted in these Figures.
- additional components described in FIG. 1 have been omitted from FIGS. 9 and 10 but not from the actual specification, unless otherwise noted.
- the remote signal may be in the form of a radio frequency field (RF) from a magnetic resonance imaging (MRI) scanner.
- RF radio frequency field
- MRI magnetic resonance imaging
- the secondary module will be omitted and the remote signaling derived from the scanner will influence only a resonant circuit switch from values for the capacitor and inductors within this type of circuit are required such that a high Q value of resonance is acquired within the circuit.
- the device is a surgical device. It is desirable to utilize MRI to guide various surgical processes. When the surgical device is electrically operated, the MRI field prohibits the use of the device. A number of attempts have been made to solve this problem. Reference may be had, for example, to U.S. Pat. No. 6,418,337 to Torchia (MRI Guided Hyperthermia Surgery); U.S. Pat. No. 6,516,211 to Acker (MRI-Guided Therapeutic Unit and Methods); U.S. Pat. No. 6,544,041 to Damadian (Simulator for Surgical Procedure); U.S. Pat. No. 6,574,497 to Pacetti (MRI Medical Device Markers Utilizing Fluorine-19), U.S. Pat. No.
- the device is a catheter.
- the substrate the device in communication with is a biological lumen, such as an artery or vein.
- a coil is disposed within the catheter.
- the biological lumen is a urogenital canal.
- the biological lumen is an esophagus.
Landscapes
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Public Health (AREA)
- Veterinary Medicine (AREA)
- Radiology & Medical Imaging (AREA)
- Biomedical Technology (AREA)
- Animal Behavior & Ethology (AREA)
- General Health & Medical Sciences (AREA)
- Engineering & Computer Science (AREA)
- Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
- Heart & Thoracic Surgery (AREA)
- Cardiology (AREA)
- Biophysics (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Electrotherapy Devices (AREA)
- Neurology (AREA)
Abstract
A medical device containing a device for connecting the medical device to a substrate, for furnishing electrical impulses from the medical device to the substrate, for ceasing the furnishing of electrical impulses to the substrate, for receiving pulsed radio frequency fields, for transmitting and receiving optical signals, and for protecting the substrate and the medical device from currents induced by the pulsed radio frequency fields. The medical device contains a control circuit comprised of a parallel resonant frequency circuit.
Description
- This application is a continuation of applicant's co-pending patent application U.S. Ser. No. 10/946,026, filed on Sep. 21, 2004, which in turn is a continuation-in-part of U.S. Ser. No. 09/921,066, filed on Aug. 2, 2001 (now U.S. Pat. No. 6,925,328), which in turn is a continuation-in-part of U.S. Ser. No. 09/839,286, filed on Apr. 20, 2001 (now U.S. Pat. No. 6,795,730). Priority for U.S. Ser. No. 09/839,286 is based upon provisional patent application U.S. Ser. No. 60/198,631, filed on Apr. 20, 2000.
- A medical apparatus comprised of a parallel resonant frequency circuit activated by energy input.
- Magnetic resonance imaging (MRI) has been developed as an imaging technique adapted to obtain both images of anatomical features of human patients as well as some aspects of the functional activities of biological tissue. These images have medical diagnostic value in determining the state of the health of the tissue examined.
- Thus, e.g., as is disclosed in U.S. Pat. No. 6,144,205 (the entire disclosure of which is hereby incorporated by reference into this specification), in an MRI process a patient is typically aligned to place the portion of his anatomy to be examined in the imaging volume of the MRI apparatus. Such MRI apparatus typically comprises a primary magnet for supplying a constant magnetic field (B0) which, by convention, is along the z-axis and is substantially homogeneous over the imaging volume and secondary magnets that can provide linear magnetic field gradients along each of three principal Cartesian axes in space (generally x, y, and z, or x1, x2 and x3, respectively). A magnetic field gradient (ΔBz/ΔXi) refers to the variation of the field along the direction parallel to Bo with respect to each of the three principal Cartesian axes, Xi. The apparatus also comprises one or more RF (radiofrequency) coils which provide excitation and detection of the NMR signal.
- The use of the MRI process with patients who have implanted medical devices, such as pacemakers often presents problems. As is known to those skilled in the art, implantable devices (such as implantable pulse generators (IPGs) and cardioverter/defibrillator/pacemakers (CDPs) are sensitive to a variety of forms of electromagnetic interference (EMI). These devices include sensing and logic systems that respond to low-level signals from the heart. Because the sensing systems and conductive elements of these implantable devices are responsive to changes in local electromagnetic fields, they are vulnerable to external sources of severe electromagnetic noise, and in particular to electromagnetic fields emitted during the magnetic resonance imaging (MRI) procedure. Thus, patients with implantable devices are generally advised not to undergo magnetic resonance imaging (MRI) procedures.
- Attempts have been made to protect implantable devices from MRI fields. Thus, for example, U.S. Pat. No. 5,217,010 (to Tsitlik et al.) describes the use of inductive and capacitive filter elements to protect internal circuitry. U.S. Pat. No. 5,968,083 (to Ciciarelli et al.) describes a device adapted to switch between low and high impedance modes of operation in response to EMI insult. U.S. Pat. No. 6,188,926 (to Vock) discloses a control unit for adjusting a cardiac pacing rate of a pacing unit to an interference backup rate when heart activity cannot be sensed due to EMI. The entire disclosure of each of these United States patents is hereby incorporated by reference into this specification.
- However, the “solutions” presented by these prior art patents are not entirely adequate. The techniques they describe do not provide a fail-safe system when the protective circuitry or the backup modes of the implantable device fail to protect the implantable device from malfunction due to exposure to electromagnetic fields.
- It is an object of this invention to provide a device that will cease furnishing power to a medical device at specified intervals while an individual is undergoing an MRI procedure.
- It is another object of this invention to provide a means for furnishing power to a medical device while protecting it from damage induced by certain radio frequency fields.
- A medical device comprising a lead wherein the lead is in electrical communication with the device and a substrate, a control circuit that is responsive to a selected activation source, a resonant circuit that controls the flow of electrical current through a first circuit wherein said first circuit is comprised of the lead wherein the resonant circuit is controlled by the control circuit, and the resonant circuit is disposed between the device and the lead, and the lead serves as an antenna that is adapted to receive pulsed radio frequency fields from an electromagnetic source external to said device.
- The invention will be described by reference to the following drawings, in which like numerals refer to like elements, and in which:
-
FIG. 1 is sectional view showing a cross-section of one preferred implantable device of the invention; -
FIGS. 2 a and 2 b are block diagrams showing the functional components the implantable device ofFIG. 1 ; -
FIG. 3 is a schematic of a robust pacing circuit utilized in the device ofFIG. 1 ; -
FIG. 4 is schematic illustrating a “cordwood” construction of the pacing circuitry of the device ofFIG. 1 ; -
FIG. 5 is a schematic of a preferred process of the invention; -
FIG. 6A is a pulse depiction of a standard MRI device; -
FIG. 6B is a pulse depiction of the optical emitter of the apparatus of this invention; -
FIG. 6C is a timing diagram of pulses produced by MRI device, showing its phase relationship to the energy produced by the optical emitter ofFIG. 6B ; -
FIG. 6D is a pulse energy of input and output of a cardiac assist device of this invention, showing the phase relationships between said input and output; -
FIG. 7 is a schematic of one embodiment of the present invention. -
FIGS. 8A through 8D are schematics of various resonant frequency circuits which can be used in the device ofFIG. 1 ; -
FIG. 9 is a depiction of one implantable device of the invention; and -
FIG. 10 is a depiction of another implantable device of the invention. - The present invention will be described in connection with a preferred embodiment, however, it will be understood that there is no intent to limit the invention to the embodiment described. On the contrary, the intent is to cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.
- This specification is presented in two parts. The first part of the specification discusses the utilization of a secondary backup medical device. The second part of this specification discloses a medical device comprising a lead wherein the lead is in electrical communication with the device and a substrate, a control circuit that is responsive to a selected activation source, a resonant circuit that controls the flow of electrical current through a first circuit wherein said first circuit is comprised of the lead wherein the resonant circuit is controlled by the control circuit, and the resonant circuit is disposed between the device and the lead, and the lead serves as an antenna that is adapted to receive pulsed radio frequency fields from an electromagnetic source external to said device.
- In one embodiment of the present invention, there is provided an implantable device that is resistant to electromagnetic interference comprising first and second modular components and an arrangement for communication between the first module and second modules. During a normal operating mode, the first module performs physiologic functions and the second module is deactivated. When electromagnetic interference is detected, the second module, which is resistant to EMI insult, is activated and the first module is deactivated to further protect its components from EMI.
- There is also provided, in another embodiment, an implantable device used to monitor and maintain at least one physiologic function, which is capable of operating in the presence of damaging electromagnetic interference. The implantable device includes primary and secondary modules, each independently protected from EMI damage via at least one shielding and/or filtering agent, and a non-electrical communication device for communicating in at least one direction between the primary and the secondary modules. The primary module, in response to input from electrical sensing leads, activates the secondary module in a failsafe mode. In the failsafe mode, the secondary module carries out a function upon activation and in the presence of electromagnetic interference.
- In one embodiment, the function performed by the implantable device is a cardiac assist function, and the implantable device is a cardiac assist device.
- A cross-section diagram of an embodiment of the implantable device according to one embodiment of the present invention is shown in
FIG. 1 . The body of thedevice 10 is shown in rectangular form for illustrative purposes only and may have a rounded shape when implanted in the body to avoid tissue damage due to sharp edges. The body of theimplantable device 10 includes two modules, aprimary module 20 and asecondary module 30, which are hermetically sealed from each other. As will be described further below, according to an embodiment of the present invention, the primary module is a demand pacemaker (DDD) with PCD functionality. As is known in the art, a demand (DDD) pacemaker denotes an implantable device that paces and senses both atrial and ventrical chambers of the heart and can either trigger or inhibit functions depending on detected parameters. During normal operation, theprimary module 20 controls the various pacing, cardioversion and defibrillation operations of theimplantable device 10 viaelectrical pacing lead 24, and detects parameters indicating how the heart is functioning viaelectrical sensing lead 28. Both the pacing leads and sensing leads are bipolar leads; these leads comprise means for connecting the cardiac assist device to a patient's heart (not shown), and they comprise means for furnishing electrical impulses from the cardiac assist device to the heart. - The
primary module 20 includes acircuitry portion 21, which contains signal detection and logic circuitry for performing pacing and analysis functions and abattery portion 22. The battery includes either no magnetic material or non-magnetic materials. It may be, for example, a lithium-iodine battery, or its chemical equivalent, e.g. It may have an anode of lithium or carbon and a cathode of iodine, carbon monofluoride, or of silver vanadium oxide, or sulfur dioxide, SOCl2 or SO2Cl2. Thecircuitry portion 21 is separated from the battery portion by a non-magnetic andnon-corrosive layer 23 which, as described below, can be made from titanium or from a carbon-composite material. - The
implantable device 10 also includes asecondary module 30, which containsindependent circuitry 31, andbattery 32 components also separated by a non-magnetic andnon-corrosive layer 33. Thesecondary module 30 is not activated when theprimary module 20 operates, but is only switched on when the primary module malfunctions or detects a voltage induced by electromagnetic interference (EMI) that exceeds a certain level, such as, for example, 3 Volts. During such an occurrence, thesecondary module 30 acts as a backup VOO pacemaker (ventricle driven, with no ventricle-sensing input nor any ventricular triggering or inhibition), which is ventricle driven, with no ventricle-sensing input nor any ventricular triggering or inhibition. Thesecondary module 30 sends pacing signals via a unipolarelectrical lead 34 to a ventricle chamber of the heart but does not receive any detected input signals. In accordance with its backup function, thesecondary module 30 is supplied with power by aseparate battery source 32, which is also of a non-magnetic type, such as a lithium-iodine battery. - Both the primary and
secondary modules secondary modules - An
optical window 40, made from glass or ceramic, which may be an infrared-transmissive window, is situated between therespective circuitry portions secondary modules optical window 40 allows for communication to occur between the primary andsecondary modules window 40 is transparent to a range of frequencies of visible or infrared radiation. The thickness of the window has an optimal range of between 0.3 and 1.0 centimeter. To maintain a hermetic seal between themodules optical window 40 is bound with brazing to sealingfixtures 35, 36 (also referred to as ferrules) that are welded to the respective modules in a manner that may correspond, for example, to that described in, for example, U.S. Pat. No. 5,902,326 to Lessar et al. The entire disclosure of this United States patent is hereby incorporated by reference into this specification. - To further protect the
implantable device 10 from external electromagnetic fields, the entireimplantable device 10, including the electrical leads 24, 28, 34, is coated with a non-magnetic,biocompatible layer 18 such as rolled titanium or flexible graphite. Flexible graphite has been shown to be a particularly effective shielding gasket material as discussed, for example, in Flexible Graphite for Gasketing, Adsorption, Electromagnetic Interference Shielding, Vibration Damping, Electrochemical Applications, and Stress Sensing, Chung, D. D. L., Journal of Mat. Eng. And Performance, Vol. 92 (2000), due to its resilience, chemical resistance and shielding properties. Graphite/polymer composites may also serve aslayer 18. With both the inner 16 and outer 18 shielding layers in place, only the ends of the electrical leads 24, 28, 34, that are in direct contact with substrate remain vulnerable to electromagnetic fields. Since the ends of the leads must be exposed in order to deliver electrical current to the substrate or detect electrical impulses, electromagnetic interference can propagate through the ends of the leads to the circuitry of the primary andsecondary modules -
FIG. 2 shows functional components of a dual-moduleimplantable device 10 according to an embodiment of the present invention. As shown, the functional components of theprimary module 20 include a power supply (from the battery 22), which supplies power along a main power anddevice communication bus 125 to thecircuitry 21. Thecircuitry 21 includes aprocessor 100 coupled to themain bus 125, which can be implemented as a parallel processor, or as a microprocessor adapted to perform analog signal processing functions 102 in addition toerror detection 104 and power reduction operations 106. In the analog-processing mode 102, theprocessor 100 analyzes cardiac signals input from thesensing lead 28 and determines a QRS complex from the various properties of the input signals. Theprocessor 100 determines from the analysis whether a detrimental condition exists, and directs apacing circuit 140 to transmit corrective pulses to ameliorate the condition. - The
processor 100 is also configured to detect internal errors or circuitry malfunctions. As will be described further, when such errors are detected, theprocessor 100 initiates a shut down of theprimary module 20 and sends a signal viaoptical window 40 that instructsmodule 30 to become activated. Furthermore, to preserve the life of thebattery 22 for as long as possible, theprocessor 100 regulates the application of power to various circuit elements in order to reduce static power consumption, in a manner such as described, for example, in U.S. Pat. No. 5,916,237 to Schu; the entire disclosure of this United States patent is hereby incorporated by reference into this specification. Theprocessor 100 is coupled to amemory unit 170 in which instructions and data are stored. - The
primary module circuitry 21 also includes anoptical source unit 150 coupled to themain bus 125.Optical source unit 150 can be any source of visible or infrared radiation that does not consume significant amounts of power, such as a light emitting diode (LED). During normal operation of the primary module, theoptical source 150, according to various implementations known in the art, turns on and off with a specific well-defined frequency or remains continually on. Theoptical source unit 150 is arranged in relation to theoptical window 40 so that radiation emitted from thesource unit 150 penetrates through theoptical window 40 into thesecondary module 30. Both theprocessor 100 and theoptical source unit 150 are situated downstream from a power-down switch 118. - The
primary module circuitry 21 also includes anoptical sensor unit 160 similarly placed in relation to theoptical window 40, in this case, so that it can receive radiation emitted from sources within thesecondary module 30. Theoptical sensor unit 160 preferably is a low-power photodetector sensitive to infrared or visible radiation of a certain wavelength range, preferably from about 400 to 800 nanometers. Theoptical sensor unit 160 is coupled to themain bus 125 upstream from the power-down switch 118, so that it remains connected to thepower supply 22 via themain bus 125 and therefore remains functional, even when the power-down switch 118 is opened. - Similarly, a
telemetry unit 180 is also situated upstream from the power-down switch 118 so it also can function when the power-down switch 118 is opened. Thetelemetry unit 180 may be, for example, a subcutaneous near-infrared signal transmitter, such as described in U.S. Pat. No. 6,192,261 to Gratton et al., that radiates through body tissues and can communicate with a near-by remote programming device equipped with an infrared receiver, for example, during an examination at a medical facility; the entire disclosure of this United States patent is hereby incorporated by reference into this specification. In another implementation, the telemetry unit may use low-power high-frequency radio signals in the Bluetooth® range to communicate with nearby Bluetooth-enabled network devices. In either case, thetelemetry unit 180 can communicate information such as the condition of the heart, the remaining life of the implantable device batteries, and whether theprimary module 20 is inoperative. - The
processor 100 is coupled to pacinglead 24 andsensing lead 28 viarespective comparators comparator 110 compares voltage on theinput lead 28 with a threshold voltage, set to, for example 3 Volts. If the input voltage exceeds the threshold voltage, thecomparator 110 sends a signal to theprocessor 100. Thecomparator 115 is reverse biased, so that it compares voltages caused by external fields, rather than the output pulse signal on thepacing lead 24, to the threshold voltage, also set to, for example, 3 Volts. If the external voltage appearing on the pacing lead exceeds the threshold voltage, thecomparator 115 sends a signal to theprocessor 100. - When a voltage exceeds the threshold, this indicates that external EMI fields, which may be caused by an MRI device, are present, and that normal operation of the primary module is to cease. To protect the
primary module 20, from excessive voltage signals, a switch (not shown) is thrown to redirect lead signal through capacitive andinductive elements 114, which filter signals on the pacing 24 andsensing 28 leads in a way known in the art before they reach thecircuitry 21 of theprimary module 20. Upon receiving the threshold signal from eithercomparators processor 100 sends a power-down signal to open theswitch 118. Additionally, theprocessor 100 may send a power-down signal to open theswitch 118 in response to detection of internal errors or malfunctions. U.S. Pat. No. 5,653,735 describes, for example, one way by whicherror detection module 104 can detect malfunctions inprimary module 20 not caused by EMI; the entire disclosure of this United States patent is hereby incorporated by reference into this specification. - When the power-
down switch 118 is opened, the primary module circuitry components downstream from the switch are disconnected from thepower supply 22 and no longer operate. In particular, theprimary module 20 stops transmitting pacing pulses to the heart and theoptical source unit 150 stops radiating through theoptical window 40. As noted above, thetelemetry unit 180 and theoptical sensor unit 160 of theprimary module 20 continue operating. - When the
optical source unit 150 of theprimary module 20 stops emitting radiation, this event is detected by the optical detector 260 of thesecondary module 30, which is adapted to detect an absence of radiation of either a certain frequency or for a defined period of time, for example, two seconds. Upon detection, the optical detector 260 transmits a power-up signal to switch 218, which closes and connects thesecondary module circuitry 31 to thesecondary power supply 32. In this manner, thesecondary module 30 is activated when theprimary module 20 is deactivated. - The
secondary module circuitry 31 includes anoscillator stage 230, anamplifier stage 240 and acounter 245.FIG. 3 shows an exploded view of theoscillator 230 andamplifier 240 stages, which are comprised of robust electrical components, such as bipolar transistors, that are not easily disturbed by electromagnetic insult. Theoscillator 230 includesbipolar transistors RC circuit 310 comprised ofresistor 311 andcapacitor 312 sets the fixed repetition rate of theoscillator 230. Once thesecondary module 30 is turned on, a pulse is produced and sent on to anamplifier stage 240 comprisingbipolar transistor 323. A shapingRC circuit 340, comprising capacitor 341 and resistor 342, modifies the shape of a pulse that triggers the ventricle tissues in the heart (shown as 400). Thissecondary module circuitry 31 generates an electrical pulse that stimulates the heart tissues via alead 34 extending from thesecondary module 30, whereby it produces ventricular contraction at a fixed rate. The return path for the pulse signal is throughlead 34 from thebody tissues 400 to thesecondary module 30. Since thepacing lead 34 can conduct electromagnetic interference, a reversebiased comparator 280 switches the conducting path to capacitive andinductive filtering elements 290 when a threshold voltage is reached. This adds an extra layer of protection to thesecondary module circuitry 31. - Because the
secondary module 30 only performs basic pacing operations and does not perform diagnostic functions, if theprimary module 20 shuts down in response to temporary electromagnetic interference, it is important to reactivate the primary module 20 (and deactivate the secondary module 30) when theimplantable device 10 is no longer threatened by the electromagnetic interference. For example, since MRI procedures generally last approximately half an hour, theprimary module 20 should only be deactivated for a half an hour plus an additional amount as a tolerance factor, for example. - To keep track of the length of time the
secondary module 30 is operating, thesecondary module circuitry 31 includes acounter element 245 coupled to theoscillator element 230, that counts oscillator transitions. Once the secondary module is turned on, thecounter element 245 increments and can trigger a reset function to turn theprimary module 20 back on when it reaches a specific count after a pre-defined length of time. - In one embodiment, the
counter 245 triggers anoptical source 250 to transmit radiation through theoptical window 40 to theprimary module 20 in which the radiation is detected byoptical sensor unit 160. For example, this radiation may be a single pulse lasting for one second. In response to detection of radiation, theoptical sensor unit 160 sends a trigger signal to close the power-down switch 118 and turn theprimary module 20 back on. When theprocessor 100 of theprimary module 20 detects that it is connected to thepower supply 22, it runs diagnostic tests in a power-on-reset (POR) mode, such as described, for example, in U.S. Pat. No. 6,016,448 to Busackero et al., wherein initial conditions of the heart are determined and stored inmemory unit 170; the entire disclosure of this patent is hereby incorporated by reference into this specification. During this mode, theprocessor 100 also runs internal error checks, so that if the original power-down was caused by internal malfunction, and the cause of the malfunction has not been corrected, the secondary module is not deactivated. - If the internal error checks indicate that the
primary module circuitry 21 can support the PCD cardiac assist functions properly, theprocessor 100 sends a trigger to thepacing unit 140 to begin operation and simultaneously sends a transmission signal to theoptical source unit 150, whereupon theoptical source unit 150 turns on or begins to pulse according to its pre-set frequency. The optical detector 260 of the secondary unit then detects that theoptical source unit 150 of the primary unit is on, and in response, triggers theswitch 218 to open, deactivating thesecondary module circuitry 31. - To further improve the EMI resistance of the
secondary module 30, thecircuitry components 31 may be arranged, according to one embodiment of thesecondary module circuitry 31, in a “cordwood” design such as is shown inFIG. 4 . As illustrated, in this arrangement all components are laid side by side on ateflon block 415, to avoid adherence, and a thin layer of mixed epoxy is laid onto the circuit components, which are aligned so as to minimize the wiring between the various components which reduces extraneous induced EMI pickup. When the epoxy has cured, thecircuit 410 is removed from the teflon block and the components are wired as illustrated inFIG. 4 . The resistor andcapacitor components 425 are shown hand-wired with very short leads, which reduce electrical pickup signals from an MRI in progress that might disturb the operation of the pacemaker circuitry. - In another embodiment, the
secondary module circuitry 31 comprises a custom designed integrated circuit (IC) fabricated, with the active semiconductors, resistors, capacitors and the connecting wires part of the IC. A monolithic IC of this type is described, for example, in U.S. Pat. No. 5,649,965 to Pons et al. The entire disclosure of this patent is hereby incorporated by reference into this specification. - MRI has been developed as an imaging modality used to obtain images of anatomical features of human patients as well as some aspects of the functional activity of biological tissue. The images have medical diagnostic value in determining the state of health of the tissue examined. To obtain images, typically, the patient is aligned to place the portion of the anatomy to be examined in the imaging volume of a MRI apparatus. The apparatus typically comprises a primary magnet for supplying a constant magnetic field (B0) which by convention is along the z-axis and is substantially homogeneous over the imaging volume and secondary magnets that can provide linear magnetic field gradients along each of three principal Cartesian axes in space (generally x, y, and z, or x1, x2 and x3, respectively). A magnetic field gradient (ΔBz/ΔXi) refers to the variation of the field along the direction parallel to Bo with respect to each of the three principal Cartesian axes, Xi. The apparatus also comprises one or more RF (radio frequency) coils which provide excitation and detection of the NMR signal.
- As is known to those skilled in the art of MRI scanner design, there is a requirement to isolate the RF receive coil from the RF transmit coil. One method to accomplish this is the utilization of a parallel resonant circuit tuned to the Larmor frequency of the MRI system. The Larmor frequency of the MRI system is dependent upon the static magnetic field magnitude. The majority of clinical scanners in use today use a 1.5 Tesla superconducting magnet. There are a variety of static magnetic field magnitudes, which are used in research environments and in the future may be utilized clinically. Through the Larmor relationship it is known that
-
ω=γB0 - where ω is in radians per second (=2π times the frequency), γ is the gyromagnetic ratio (approximately 42.6 megahertz [MHz] per Tesla for hydrogen) and B0 is the static magnetic field magnitude. The resonant frequency at 1.5 Tesla for hydrogen in clinical scanners is approximately 63.9 megahertz. Therefore, in the range of 0.5 to 14.1 Tesla, the resonant frequency range will be 21.3 megahertz to 651 megahertz. Clinical MRI almost exclusively images utilizing the resonance of hydrogen, therefore the value for γ of 42.6 megahertz per Tesla is standard.
- One preferred process of the instant invention is presented in
FIG. 5 . Referring toFIG. 5 , and instep 440 thereof,timing circuitry 441 within the MRI Instrumentation hardware activates the gradient coils of the MRI scanner while substantially simultaneously activating a trigger voltage (see step 444). Thereafter, generally within a period of 3 microseconds, thetiming circuitry 441 also activates the transmission of radio frequency coil pulses (see step 446). - One may use timing circuits known to those skilled in the art as
MRI timing circuitry 441. Thus, e.g., referring toFIG. 8 of U.S. Pat. No. 4,379,262 (“Nuclear magnetic resonance systems”), there is disclosed a detailed timing and control arrangement 14. The control block shown at element 25 of suchFIG. 8 provides the basic control input for the apparatus. This may simply be an operator control panel at which the operator selects the next operation required or may be a microprocessor holding a predetermined control pattern but will generally be a combination of those two. The control 25 supplies instructions to a sequence controller 26. This holds, in read-only memory, a predetermined bit pattern array representing instruction pulses for each of the output lines for each instruction and provides these pulses at timing intervals from timing circuits 27 in response to instructions from 25. Circuits 27 comprise a system clock and appropriate counters and gates. The entire disclosure of this United States patent is hereby incorporated by reference into this specification. - Timing circuits of the type disclosed in U.S. Pat. No. 4,379,262 are well known and are adapted to control any sequence of operations which is known in advance. These circuits can readily be adapted to a chosen examination procedure.
- Referring again to U.S. Pat. No. 4,379,262 and to
FIG. 9 thereof, it will be seen that thefield control 16 gates the field probe output from amplifier 17 with timing signals from 14 and takes a count incounter 28 which is in fact the measured field. Held in a staticiser 29, the measured field is compared in asubtractor 30 with the precalculated field (demand setting) from a store such as a read onlymemory 31. The consequent error signal is digitised inunit 32 to be applied to coil 12 via a power amplifier, thereby bringing the field to the required value. The entire disclosure of this United States patent is hereby incorporated by reference into specification. - By way of further illustration, suitable MRI instrumentation timing circuitry is disclosed in U.S. Pat. No. 4,333,053 (“Imaging systems”), the entire disclosure of which is hereby incorporated by reference into this specification. Referring to U.S. Pat. No. 4,333,053 and to
FIG. 11 thereof, it will be seen that a block diagrammatic circuit for implementing a standard MRI procedure is illustrated. The NMR apparatus (see, e.g.,FIG. 1 of U.S. Pat. No. 4,333,053) is indicated aselement 40. Element 41, is a timing control unit which cooperates with the NMR apparatus and serves to control the timing of the various operations. It will be appreciated that the operation follows a well defined and predetermined sequence. The times for particular operations are therefore held in stores incorporated in unit 41; and, in response to signals from a system clock 42, timing signals are transmitted to the respective parts of the system. In practice, this, as with many other units, may be incorporated in a digital processor which can control the operation as well as processing the final signals. - Referring again to U.S. Pat. No. 4,333,053, the
NMR apparatus 40 is first caused to operate with a GR gradient in the manner previously disclosed, and the resonance signals thus provided are demodulated in demodulators 43 and 44 at frequency fo from areference oscillator 45. To preserve phase information, demodulation is into in-phase and quadrature components, the reference for demodulator 44 being shifted by 90° in circuits 46. - Referring again to
FIG. 5 of the instant specification, thetrigger voltage 444 activated by thetiming circuitry 441 will be applied to a specified diode (see step 447), thereby preferably forming a parallel-resonant circuit that is functional only when the resonant condition is met (seeFIGS. 8A through 8D for some suitable resonant circuits which utilize such a diode; also seesteps 448 and 449 ofFIG. 5 ). As will be apparent, thistrigger voltage 444 provides means for furnishing electrical impulses to either an optical emitter (not shown inFIG. 5 ) and/or for directly activating a diode (not shown). - As is known to those skilled in the art, parallel-resonant circuits have very high impedances at or near the resonant frequency of the circuit and essentially perform as open switches at such resonant frequencies. When the parallel resonant circuit becomes functional (see step 448), it then prevents current at or near the resonant frequency from passing through it. Thus, when this parallel-resonant circuit is interconnected between a cardiac assist device circuit and cardiac leads and is functional, it will effectively open the circuitry of the cardiac assist device, totally inhibiting current induced by the radio frequency fields of the MRI system from flowing to the device or via the leads to the heart (see step 450). Therefore, the functional resonant circuit prevents the occurrence of deleterious effects on the cardiac assist device and the heating of the electrodes placed in the cardiac tissue. Thus, in the device of this application, the parallel resonant circuit which is activated provides means for ceasing the furnishing of electrical impulses from a cardiac assist device to a patient's heart; when alternating currents are supplied which deviate from frequency at which resonance occurs in the parallel resonant circuit, current is allowed to flow to the device, the amount of flow depending upon the deviation from the resonant frequency. Consequently, when the parallel circuit is not activated (at frequencies more or less than the resonant frequency), it acts as a closed switch, and there is provided means for furnishing the electrical impulses to the heart.
- As will be apparent to those skilled in the art, the amount of current which will be allowed to flow at frequencies other than the resonant frequency may be adjusted by adjusting the “Q” of the circuit which, in turn, depends upon, e.g., the resistance in the circuit.
- When the timing circuitry signals the MRI gradient field pulses and the trigger voltage off, the circuitry of the cardiac assist device is activated because the parallel-resonant circuit ceases to exist. However, since, in this event, the pulsed radio frequency is no longer being produced, there is no danger to the pacemaker circuit and the patient within whom such circuit is disposed.
-
FIGS. 6A , 6B, 6C, and 6D illustrate one preferred series of phase relationships which preferably are produced by the timing circuit of the MRI device. - Referring to
FIG. 6A , the activation of the “slice select” (SS)gradient 460 occurs immediately prior to the application of the radio frequency (RF)pulse 462. The gradient and RF coils activated utilizing the standard pulse sequence inFIG. 6A is of the type magnetic field gradient and RF coils described hereinabove. - A simplified depiction of the timing relationship between the RF coil activation, the triggering of the optical emitter (OE) and the output of the cardiac assist device is shown in
FIGS. 6B , 6C and 6D respectively, which illustrate the timing of one embodiment of the present invention. The units of the axis inFIGS. 6A through 6D are relative and can take on many different values. A wide variety of timing sequences are possible depending upon the choice of pulse sequence and type of cardiac assist device. This embodiment of the invention may be applied to any number of time sequences similar toFIGS. 6B , 6C and 6D. - Referring again to
FIGS. 6B , 6C, and 6D, the triggering of activation for the optical emitter (OE) 460 precedes the triggering of the activation of the radio frequency (RF) coils of theMRI scanner 468. - Once the radio frequency coils of the MRI scanner are activated, radio frequency fields are generated whose concentration is at a maximum within the core of the coils. These fields interact with and are “received by” all materials with which it contacted. A cardiac assist device within a patient will be contacted and affected by such R.F. fields. The R.F. fields may trigger the cardiac assist device and cause rapid pacing when, in fact, such is not required by the patient.
- Alternatively, or additionally, the R.F. fields often induce a voltage within the cardiac assist device which is so substantial that it often destroys the device.
- As used in the specification, the term “receiving pulsed radio frequency fields” includes any device which is in any manner affected by the pulsed radio frequency fields. Thus, even though the cardiac assist device might not contain a formal antenna for receiving the pulsed radio frequency fields, it still contains means for receiving such pulsed radio frequency fields in that one or more of its components interact with such fields. Without wishing to be bound to any particular theory, applicants believe that the leads of the cardiac assist device often act as antennae.
- A multitude of waveforms may be applied for the MRI sequence. There are also a variety of cardiac assist devices (CADs) providing different pulsing and sensing capabilities. The timing description shown in
FIG. 6D is only one example of a ventricular VOO pacemaker pulsing waveform. The initiation of any pulse (for example,pulse 470 inFIG. 6D ) from the VOO cardiac assist device (CAD) will not occur during a radio frequency pulse derived from the RF transmit coils of the MRI scanner. The duration of this pulse will not overlap or occur during an RF pulse derived from the RF transmit coils of the MRI scanner. - By way of illustration and not limitation, an example of one complex scenario for the sensing and pacing steps is described in U.S. Pat. No. 4,800,883 (“Apparatus for generating multiphasic defibrillation pulse waveform”), the entire disclosure of which is hereby incorporated by reference into this specification.
- By way of further illustration, U.S. Pat. No. 6,163,724 (“Microprocessor capture detection circuit and method”) discloses means for auto-capture detection in a variety of pacing and sensing modes. Thus, e.g., this patent discloses a software programmable (device means such as a microprocessor) that discriminates between evoked response signals and post-pace polarization signals sensed by an implantable medical device. The polarity of the positive or negative change in voltage in respect of time (or dv/dt) of the waveform incident on the lead electrodes is monitored during a short period of time immediately following a paced event. The patent also discloses that the post-pace polarization signal exhibits a relatively constant polarity during the capture detect window, that the evoked response signal may cause the polarity of post-pace polarization signal to reverse during the capture detect window, that the sign of the post-pace polarization polarity, either positive or negative, is determined by the design of the specific output circuitry. In the device of this patent, the evoked response signal may reverse the polarity of the sensed signal in either case, from positive to negative or from negative to positive, during the time window of interest. In another embodiment of the patent, and when the magnitude of the post-pace polarization is so great that the evoked response does not reverse the polarity of the waveform, discrimination of the evoked response is achieved by noting an acceleration (or increasing magnitude of dv/dt) in the sensed signal or waveform. The entire disclosure of this United States patent is hereby incorporated by reference into this specification.
- By way of further illustration, U.S. Pat. No. 6,169,921 (“Autocapture determination for an implantable cardioverter defibrillator”) discloses a cardiac pacing/defibrillation system that enhances the ability of a cardiac pacer to automatically detect whether a pacing stimulus results in heart capture or contraction. The cardiac pacing/defibrillation system of this patent includes a pacing circuit that attenuates polarization voltages or “afterpotential” which develop at the heart tissue/electrode interface following the delivery of a stimulus to the heart tissue, which thereby allows the pacing electrodes to be utilized to sense an evoked response to the pacing stimulus. The cardiac pacing/defibrillation system of this patent may utilize the ventricular coil electrode and superior vena cava coil electrode to sense an evoked response, thereby eliminating the necessity for an additional ventricular lead for sensing an evoked response. The device of this patent allows accurate detection of an evoked response of the heart, to thereby determine whether each pacing stimulus results in capture. The entire disclosure of this United States patent is hereby incorporated by reference into this specification.
- In
step 446 ofFIG. 5 , a parallel resonant circuit is activated. Some suitable resonant circuits which may be used in the process of this invention are depicted inFIGS. 8A , 8B, 8C, and 8D. In one embodiment of the invention, there is provided a cardiac assist device comprising means for connecting said cardiac assist device to a heart, means for furnishing electrical impulses from said cardiac assist device to said heart, means for ceasing the furnishing of said electrical impulses to said heart, means for receiving pulsed radio frequency fields, and means for receiving optical signals. The device contains a control circuit comprised of a parallel resonant frequency circuit activated by optical input. - Referring again to
FIGS. 8A , 8B, 8C, and 8D, radio frequency (RF) energy, of a specified frequency, will cause a resonant circuit to be activated, resulting in a high impedance block of induced current. This high impedance will essentially cause a disconnect between the cardiac leads and the primary and/or secondary module of the device, thereby inhibiting deleterious current to the leads and the modules. When one of the resonant circuits depicted inFIGS. 8A through 8D is not induced, the circuits will simply conduct current between the cardiac assist device and the heart. By choosing the appropriate circuit components, one may choose a “Q” which will provide the desired current flow, or lack thereof, at specified frequencies. At resonance it is a requirement that -
- where the units of f are in hertz, L are in henries, and C are in farads.
- In one embodiment, by the use of a variable resistor (not shown), the “Q” (quality factor) of the parallel resonant circuit may be varied, thus varying the amount of current which is allowed to flow at specified frequencies off of the resonant frequency.
- The circuits depicted in
FIGS. 8A through 8D are disclosed in U.S. Pat. No. 6,144,205 of Steven Souza et al. The entire disclosure of this United States patent is hereby incorporated by reference into this specification.FIG. 8A corresponds toFIG. 2 of the patent,FIG. 8B corresponds toFIG. 4 of the patent,FIG. 8C corresponds toFIG. 5 of the patent, andFIG. 8D corresponds toFIG. 6 of the patent. This patent claims an antenna assembly for a magnetic resonance imaging system that produces images of a substance, said antenna assembly comprising: a resonant circuit having a first inductance and being tuned to resonate at a Larmor frequency specified herein; a reactive electrical device; a photosensitive first semiconductor switch selectively connecting the reactive electrical device to the resonant circuit, wherein impingement of any optical energy on the photosensitive first semiconductor switch alters connection of the reactive electrical device to the resonant circuit thereby substantially nulling the response of resonant circuit at the Larmor frequency; and a receive coil control coupled to illuminate the photosensitive first semiconductor switch. - The Figures of Untied States patent 6,144,205 disclose resonant circuits having a first inductance and being tuned to resonate at a Larmor frequency.
FIG. 8A depicts one embodiment where a seriesresonant circuit 500 comprises aninductance 502 withcapacitances Inductance 508,capacitance 504 andPIN diode 510 form a blocking resonant loop coupled throughcapacitance 504 to the cardiac assist device. As is known to those skilled in the art, PIN diodes are preferably utilized because of their high on/off conductance ratio. - A dc trigger voltage (see
step 444 ofFIG. 5 ) is applied to theterminals terminals terminals diode 510, theinductance 508 forms a parallel-resonant condition with thecapacitance 504. This condition results in the loss of conduction through theentire circuit 500 hence disabling and opening the circuit. - In one preferred embodiment, the direct current 511 applied to
PIN diode 510 is applied from an external source via an electrical lead, such a lead from a trigger device adapted to produce such current when initiated by a dc trigger voltage from a separate source, such as the timing circuitry in an MRI scanner. When the direct current 511 is not applied to thePIN diode 510, the circuit is open (disabled). - In one preferred embodiment, the
diodes FIGS. 8B , 8C and 8D will be optically controlled photodiodes. One may use conventional resonant circuits activated by optical switches. Thus, e.g., one may use the parallel resonant circuit switch disclosed in U.S. Pat. No. 5,055,810 (“Ultra-High speed light activated microwave switch/modulation using photoreactive effect”); the entire disclosure of this United States patent is hereby incorporated by reference into this specification. Disclosed in this United States patent is a resonant circuit switch that is controllable via a photodiode. The fabrication of the photodiode illustrated in this patent utilizes the reactance of the photodiode instead of the standard use of the resistance. This results in a drastic increase in the switching speeds of the entire resonant switch. - Referring again to
FIG. 8B , thecircuit 520 comprises aninductance 522 connected to form aresonant circuit 527 with a pair of series connectedcapacitances intermediate node 528 between the capacitances. Theresonant circuit 527 is tuned to the Larmor frequency of the substance being examined by MRI, (e.g., human tissue). In one embodiment the dc trigger voltage can be linked through an electrical lead to terminal 529 to theintermediate node 528 via aninductor 530 or other reactive electrical device. The other pole of the dc trigger voltage can be linked through an electrical lead to terminal 531 to anode 532 between thesecond capacitance 532 andinductance 522. A photosensitive semiconductor device, such as aphotodiode 534, is connected to the dc trigger voltage without regard to diode polarity. Alternatively, the photosensitive device could comprise a PIN-type photodiode, a phototransistor, a photodarlington transistor pair, a light-activated SCR or a photo-FET. - The device of this invention is comprised of means for receiving an energy input and, in response thereto, for activating the parallel resonant circuit described above. One form of energy which will activate the parallel resonant is photonic energy, and a switching device incorporating such photonic energy will be described in the remainder of this specification. Alternatively, or additionally, one may use other forms of energy to activate the parallel resonant circuit. Thus, for example, one may utilize a direct current voltage supplied by the MRI scanner and/or another apparatus to activate, e.g., a diode (such as, e.g., a pin diode).
- Referring to both
FIGS. 7 and 8B , as in one preferred embodiment of the invention, a transmitted optical signal via a fiber optic cable 520 (seeFIG. 8B ) may be positioned on or near the skin surface 424 (seeFIG. 7 ) of a patient to illuminate the active surface ofphotodiode 534. Thephotodiode 534 may be placed within a feed-throughassembly 422, as is known to those skilled in the art of designing and constructing capacitive feed-through assemblies in cardiac assist devices. One may connect the cardiac leads (not shown) to thecardiac assist device 400. - In one embodiment, optical radiation is transmitted through the skin a patient. In one aspect of this embodiment, one may use near infrared light in the range of from about 700 to about 900 nanometers and, preferably, from about 750 to about 850 nanometers. It is often preferred to use optical radiation of from about 775 to about 825 nanometers; it is known that radiation of about 800 nanometers efficiently is transmitted through the skin of human beings.
- As will be apparent, a photodector may be disposed beneath the skin, substantially anywhere in the living organism. It is preferred not to have to transmit the light through highly absorbent body tissue, such as a liver, or through bone. However, subcutaneous placement of the photodetector(s) beneath one or more skin layers is relatively efficient.
- Referring again to
FIG. 7 , when the signal online 429 indicates that the MRI system gradient coils are active 440/444, theoptical emitter 418 responds by producing a light beam which is sent through theoptical fiber 420. This light beam illuminates thephotodiode 534 in thecircuit 520, hereby rendering the photodiode conductive. This causes the blocking loop 537 (seeFIG. 8B ) formed by thephotodiode 534,input inductor 530, and thesecond capacitance 526 to be parallel resonant at the Larmor frequency. The blockingloop 537 is coupled to theresonant circuit 527. This blocking loop parallel resonance substantially nulls the response of theresonant circuit 527 at the Larmor frequency, thereby preventing current from flowing from the electrical leads to thecardiac assist device 400 during RF transmission of an MRI procedure. During the receive mode, theoptical emitter 418 does not produce illumination of thephotodiode 534 so that the blockingloop 537 does not form a complete parallel resonant circuit and has no effect on theresonant circuit 527. When resonant at the Larmor frequency, blockingloop 537 also presents a high impedance between the cardiac leads and theresonant circuit 527 electrically isolates the two components during the transmission of the RF pulses. Thus any signal induced in thecircuit 520, due to the intense transmit fields, will be attenuated before reaching the electronics of thecardiac assist device 400. - In one embodiment, the device depicted in
FIG. 5 of U.S. Pat. No. 6,144,205 may be utilized in the apparatus of this invention. Referring to suchFIG. 5 , and to embodiment 254, the device of suchFIG. 5 is similar to the device ofFIG. 4 of the patent but has been modified with the addition of a semiconductor switch 188 in parallel with the photosensitive device 190, but with the opposite polarity (i.e. An anti-parallel connection with photosensitive device 190). In such a configuration, the normal forward current between terminals 191 and 192 through semiconductor switch 188 is opposite that of normal forward current between terminals 191 and 192 through photodiode 190. Semiconductor switch 188 may, for example, be a PIN type diode, transistor, FET or SCR. The current produced by the photodiode or other type of photosensitive device 190, when illuminated, will flow through and partially turn on semiconductor switch 188 thereby reducing the net RF impedance between terminals 191 and 192. This will reduce the on-state impedance in blocking loop 194, increasing the degree to which the parallel resonance of blocking loop 194 nulls the response of resonant circuit 195 comprising inductance 196 and two capacitances 197 and 198. The entire disclosure of this United States patent is hereby incorporated by reference into this specification. - As a variation of the aforementioned embodiment, and referring again to U.S. Pat. No. 6,144,205, the semiconductor switch 188 may also be a photodiode or other type of photosensitive device. In this case, best operation will be obtained if provision is made to adequately illuminate both photosensitive devices 190 and 188 in order to render those devices conductive.
-
FIG. 6 of U.S. Pat. No. 6,144,205 illustrates an alternative third embodiment 354 of the optical technique for disabling an RF antenna. This embodiment has a parallel resonant blocking loop 201, comprised of photosensitive semiconductor switch 214, inductor 212, and capacitance 204 rather than capacitance 206 corresponding to capacitances 174 and 198 inFIGS. 4 and 5 of such patent, respectively, and optionally semiconductor switch 216. This can be done because there is no need to provide an electrically conducting path to photosensitive semiconductor device 214 as is the case forPIN diode 20 inFIG. 2 of this patent. Device 214 may be connected without regard to diode polarity, and may be a photodiode, a PIN-type photodiode, a phototransistor, a photodarlington transistor pair, a light-activated SCR or a photo-FET. If semiconductor switch 216 is omitted the circuit operation is identical to that of the first embodiment inFIG. 4 of this patent, while offering an additional option for physical placement of the components of blocking loop 201. The circuit ofFIG. 6 of this patent offers the further advantage that photosensitive semiconductor switch 214 and inductance 212 are not in the signal path between the resonant circuit 208 and the signal cable 158 connected toterminals 218 and 219, and therefore do not attenuate the received signal in receive mode. - As a variation of the third embodiment of this patent, the modifications of the second embodiment of the patent shown in
FIG. 5 thereof (that is, the addition of a semiconductor switch 216 anti-parallel with the photosensitive semiconductor device 214) may be applied to the circuit ofFIG. 6 of the patent. This will reduce the on state impedance in blocking loop 201, increasing the degree to which the parallel resonance of blocking loop nulls the response of resonant circuit 208. As a further variation of this third embodiment, the anti-parallel semiconductor switch 216 may also be a photodiode or other type of photosensitive device or any semiconductor activated by photodiode 214. - In another embodiment, a circuit as shown in
FIGS. 8A through 8D may be placed within a feed-through assembly within the path of the leads immediately adjacent to the pacing electrode of the cardiac assist device. - Thus, e.g., one may use the device depicted in U.S. Pat. No. 6,031,710, the entire disclosure of which is hereby incorporated by reference into this specification. This patent discloses a capacitive filter feed-through assembly and method of making the same for shielding an implantable medical device, such as a pacemaker or a defibrillator, from electromagnetic interference or noise. A ferrule is adapted for mounting onto a conductive device housing by welding, soldering, brazing or gluing, and supports a terminal pin for feed-through passage to a housing interior. A capacitive filter is mounted at the inboard side of a device housing, with capacitive filter electrode plate sets coupled respectively to the housing and the terminal pin by an electrically conductive combination of adhesive, brazing and soldering. In one embodiment of the invention of this patent, multiple capacitive filters are provided in an array within a common base structure, where each capacitive filter is associated with a respective terminal pin.
- Referring again to
FIG. 7 , and in one embodiment thereof, thecardiac assist device 400 will not shut down when the open circuit is established. An open circuit at the lead will be recognized by the cardiac assist device processor as a specific event defined within ROM 170 (seeFIG. 2 ). The cardiac assist device processor 100 (seeFIG. 2 ) will not respond to this event definition and remain in astatic state until the parallel-resonance circuit is triggered off and the closed circuit is reestablished between the cardiac leads 24 and 28 (seeFIG. 2 ) and thecardiac assist device 400. For the embodiment utilizing the parallel-resonant circuit on thesecondary module 30 there will be no requirement for signaling from the open circuit due to the fact that there is no sensing capability of the VOOsecondary module 30. Referring again toFIG. 1 andFIGS. 9 , in one embodiment of the present invention, thecardiac assist device 10 of this invention will be remotely signaled to open the connection between both thesensing lead 28 and thepacing lead 24 of the device and theprimary module 20. A feed-throughassembly 602 and 604 (seeFIG. 9 ) connects leads 24 and 28, respectively, wherein such feed-through assembly contains the resonant circuit(s) ofFIGS. 8A and/or 8B and/or 8C and/or 8D, as described hereinabove. - Referring to
FIG. 10 , thesecondary module 30 may also contain the same mechanism remotely signaled to open a connection between the pacinglead 34 and thesecondary module 30 via feed-throughassembly 608. In one additional embodiment, an inductor/capacitor/diode (RLC) radio frequency detection circuit for the detection of the frequency specific RF signal is utilized. One of the resonant circuits shown inFIGS. 8A through 8D can be placed at the output end of the sensing lead and at one input into theprocessor 100. One may use any number of combinations of an RLC resonant circuit to serve the same function as the ones depicted in these Figures. For the purpose of simplicity of representation, additional components described inFIG. 1 have been omitted fromFIGS. 9 and 10 but not from the actual specification, unless otherwise noted. The remote signal may be in the form of a radio frequency field (RF) from a magnetic resonance imaging (MRI) scanner. - The use of the resonant circuits of
FIGS. 8A through 8D as described in the present invention dictates that the EMI shielding 18 specified in this specification not be utilized on the lead portion of the device specified herein. - In another separate embodiment the secondary module will be omitted and the remote signaling derived from the scanner will influence only a resonant circuit switch from values for the capacitor and inductors within this type of circuit are required such that a high Q value of resonance is acquired within the circuit.
- The foregoing description was primarily drawn to cardiac assist devices. One skilled in the art would likewise envision alternative embodiments which employed medical devices other than cardiac assist devices. These devices would be connected to substrates other than a heart.
- In one embodiment, the device is a surgical device. It is desirable to utilize MRI to guide various surgical processes. When the surgical device is electrically operated, the MRI field prohibits the use of the device. A number of attempts have been made to solve this problem. Reference may be had, for example, to U.S. Pat. No. 6,418,337 to Torchia (MRI Guided Hyperthermia Surgery); U.S. Pat. No. 6,516,211 to Acker (MRI-Guided Therapeutic Unit and Methods); U.S. Pat. No. 6,544,041 to Damadian (Simulator for Surgical Procedure); U.S. Pat. No. 6,574,497 to Pacetti (MRI Medical Device Markers Utilizing Fluorine-19), U.S. Pat. No. 6,606,513 to Lardo (Magnetic Resonance Imaging Transseptal Needle Antenna); U.S. Pat. No. 6,618,620 to Freundlich (Apparatus for Controlling Thermal Dosing in a Thermal Treatment System); U.S. Pat. No. 6,675,037 to Tsekos (MRI-Guided Interventional Mammary Procedures); U.S. Pat. No. 6,712,844 to Pacetti (MRI Compatible Stent); United States applications 20030199754 to Hibner (Method for Using an MRI Compatible Biopsy Device with Detachable Probe); 2003/0111142 to Horton (Bulk Metallic Glass Medical Instruments, Implants, and Methods of Using Same); and the like. As would be apparent to one skilled in the art, the teachings of this application may easily be adapted for use with the above-mentioned surgical devices. The content of each of the aforementioned patents and patent applications is hereby incorporated by reference into this specification.
- In one embodiment, the device is a catheter. In one such embodiment, the substrate the device is in communication with is a biological lumen, such as an artery or vein. In another such embodiment, a coil is disposed within the catheter. In another such embodiment, the biological lumen is a urogenital canal. In yet another such embodiment, the biological lumen is an esophagus.
- The foregoing description was primarily directed to a preferred embodiment of the invention. Although some attention was given to various alternatives within the scope of the invention, it is anticipated that one skilled in the art will likely realize additional alternatives that are now apparent from disclosure of embodiments of the invention. For example, the invention may be used to disable a transmit antenna rather than a receive antenna, and may be used in systems other than MRI systems where similar functionality is desirable. Accordingly, the scope of the invention should be determined from the following claims and not limited by the above disclosure.
Claims (91)
1-40. (canceled)
41. A band stop filter for an implantable lead wire of an active implantable medical device, which comprises:
a) a lead wire having a length extending between and to a proximal end and a distal end; and
b) at least one band stop filter comprising a capacitor in parallel with an inductor,
said parallel capacitor and inductor combination placed in series with the lead wire somewhere along the length between and to the proximal end and the distal end of the lead wire
wherein values of capacitance and inductance have been selected such that the band stop filter is resonant at a selected frequency
and further wherein the overall Q of the band stop filter is selected to balance impedance at the selected frequency verses frequency band width characteristics.
42. The band stop filter of claim 41 , wherein the Q of the inductor is relatively high and the Q of the capacitor is relatively low to select the overall Q of the band stop filter.
43. The band stop filter of claim 42 , wherein the inductor has a relatively low resistive loss; and wherein the capacitor has a relatively high equivalent series resistance.
44. The band stop filter of claim 43 , wherein the overall Q of the band stop filter is selected to attenuate current flow through the lead wire along a range of selected frequencies.
45. The band stop filter of claim 44 , wherein the range of selected frequencies includes a plurality of MRI pulsed frequencies.
46. The band stop filter of claim 44 , wherein the range of selected frequencies includes an MRI pulsed frequency.
47. The band stop filter of claim 41 , wherein the band stop filter is disposed adjacent to a distal tip of the lead wire.
48. The band stop filter of claim 41 , wherein the band stop filter is disposed adjacent an electrode.
49. The band stop filter of claim 47 or 48 , wherein the band stop filter is connected into a tip electrode.
50. The band stop filter of claim 47 or 48 , wherein the band stop filter is connected into at least one of a TIP electrode and a RING electrode.
51. A band stop filter for a medical diagnostic or therapeutic device comprising:
an active implantable medical device and
an implantable lead wire having a length extending therefrom between and to a proximal end and a distal end and adapted to be in contact with biological cells, the band stop filter comprising:
at least one band stop filter associated with the lead wire, for attenuating current flow through the lead wire at a selected frequency,
wherein the band stop filter comprises a capacitor in parallel with an inductor,
said parallel capacitor and inductor placed in series with the lead wire somewhere along the length between and to the proximal end and the distal end of the lead wire;
wherein values of capacitance and inductance are selected such that the band stop filter is resonant at the selected frequency.
52. The band stop filter of claim 51 , wherein the Q of the inductor is relatively high and the Q of the capacitor is relatively low to select the overall Q of the band stop filter.
53. The band stop filter of claim 52 , wherein the inductor has a relatively low resistive loss.
54. The band stop filter of claim 52 , wherein the capacitor has a relatively high equivalent series resistance.
55. The band stop filter of claim 52 , wherein the overall Q of the band stop filter is selected to attenuate current flow through the lead wire along a range of selected frequencies.
56. The band stop filter of claim 55 , wherein the range of selected frequencies includes a plurality of MRI pulsed frequencies.
57. The band stop filter of claim 55 , wherein the range of selected frequencies includes an MRI pulsed frequency.
58. The band stop filter of claim 51 , wherein the band stop filter is disposed adjacent to the distal tip of the implantable lead wire.
59. The band stop filter of claim 51 , wherein the band stop filter is disposed adjacent an electrode.
60. The band stop filter of claim 58 or 59 , wherein the band stop filter is connected into a tip electrode.
61. The band stop filter of claim 58 or 59 , wherein the band stop filter is connected into at least one of a TIP electrode and a RING electrode.
62. The band stop filter of claim 60 , wherein the overall Q of the band stop filter is selected to attenuate current flow through the implantable lead wire along a range of selected frequencies.
63. The band stop filter of claim 51 , wherein the implantable medical device is selected from the group consisting of cardiac pacemakers and implantable cardioverter defibrillators.
64. The band stop filter of claim 51 , wherein the implantable medical device is selected from the group consisting of implantable pulse generators, cardioverter/defibrillator/pacemakers and pacemakers.
65. The band stop filter of claim 51 , wherein the implantable medical device is selected from the group consisting of neurostimulators, cardiac pacemakers, gastric stimulators and implantable cardioverter defibrillators.
66. The band stop filter of claim 51 , wherein the implantable medical device is selected from the group consisting of implantable pulse generators, cardioverter/defibrillator/pacemakers, pacemakers, neurological stimulators and gastrointestinal stimulators.
67. The band stop filter of claim 51 , wherein the overall Q of the band stop filter is selected to balance impedance at the selected frequency verses frequency band width characteristics.
68. The band stop filter of claim 51 , wherein the overall Q of the band stop filter is selected to balance a desired current flow verses specified frequencies.
69. The band stop filter of claim 51 , wherein the Q of the band stop filter is selected to provide a desired current flow at specified frequencies.
70. A band stop filter for an implantable lead wire of an active implantable medical device, which comprises:
a) lead wires each having a length extending between and to a proximal end and a distal end; and
b) at least one band stop filter comprising a capacitor and an inductor to provide a parallel-resonant circuit,
said capacitor and inductor placed in the path of the lead wires somewhere along their length between and to the proximal ends and the distal ends of the lead wires
wherein values of capacitance and inductance have been selected such that the band stop filter is resonant at a selected frequency
and further wherein the overall Q of the band stop filter is selected to balance impedance at the selected frequency verses frequency band width characteristics.
71. The band stop filter of claim 70 , wherein the Q of the inductor is relatively high and the Q of the capacitor is relatively low to select the overall Q of the band stop filter.
72. The band stop filter of claim 71 , wherein the inductor has a relatively low resistive loss; and wherein the capacitor has a relatively high equivalent series resistance.
73. The band stop filter of claim 72 , wherein the overall Q of the band stop filter is selected to attenuate current flow through the lead wires along a range of selected frequencies.
74. The band stop filter of claim 73 , wherein the range of selected frequencies includes a plurality of MRI pulsed frequencies.
75. The band stop filter of claim 73 , wherein the range of selected frequencies includes an MRI pulsed frequency.
76. The band stop filter of claim 70 , wherein the band stop filter is disposed adjacent to a distal tip of a lead wire.
77. The band stop filter of claim 70 , wherein the band stop filter is disposed within the path of the leads adjacent an electrode.
78. The band stop filter of claim 76 or 77 , wherein the band stop filter is connected into a tip electrode.
79. The band stop filter of claim 76 or 77 , wherein the band stop filter is connected into at least one of a TIP electrode and a RING electrode.
80. A band stop filter for a medical diagnostic or therapeutic device comprising
an active implantable medical device and
implantable lead wires each having a length extending therefrom between and to a proximal end and a distal end and adapted to be in contact with biological cells, the band stop filter comprising:
at least one band stop filter associated with the lead wires, for attenuating current flow through the lead wires at a selected frequency,
wherein the band stop filter comprises a capacitor and an inductor to provide a parallel-resonant circuit,
said capacitor and inductor placed in the path of the lead wires somewhere along their length between and to the proximal ends and the distal ends of the lead wires
wherein values of capacitance and inductance are selected such that the band stop filter is resonant at the selected frequency.
81. The band stop filter of claim 80 , wherein the Q of the inductor is relatively high and the Q of the capacitor is relatively low to select the overall Q of the band stop filter.
82. The band stop filter of claim 81 , wherein the inductor has a relatively low resistive loss.
83. The band stop filter of claim 81 , wherein the capacitor has a relatively high equivalent series resistance.
84. The band stop filter of claim 81 , wherein the overall Q of the band stop filter is selected to attenuate current flow through the lead wire along a range of selected frequencies.
85. The band stop filter of claim 84 , wherein the range of selected frequencies includes a plurality of MRI pulsed frequencies.
86. The band stop filter of claim 84 , wherein the range of selected frequencies includes an MRI pulsed frequency.
87. The band stop filter of claim 80 , wherein the band stop filter is disposed adjacent to the distal tip of an implantable lead wire.
88. The band stop filter of claim 80 , wherein the band stop filter is disposed within the path of the leads adjacent an electrode
89. The band stop filter of claim 87 or 88 , wherein the band stop filter is connected into a tip electrode.
90. The band stop filter of claim 87 or 88 , wherein the band stop filter is connected into at least one of a TIP electrode and a RING electrode.
91. The band stop filter of claim 89 , wherein the overall Q of the band stop filter is selected to attenuate current flow through the implantable lead wire along a range of selected frequencies.
92. The band stop filter of claim 80 , wherein the implantable medical device is selected from the group consisting of cardiac pacemakers and implantable cardioverter defibrillators.
93. The band stop filter of claim 80 , wherein the implantable medical device is selected from the group consisting of implantable pulse generators, cardioverter/defibrillator/pacemakers and pacemakers.
94. The band stop filter of claim 80 , wherein the implantable medical device is selected from the group consisting of neurostimulators, cardiac pacemakers, gastric stimulators and implantable cardioverter defibrillators.
95. The band stop filter of claim 80 , wherein the implantable medical device is selected from the group consisting of implantable pulse generators, cardioverter/defibrillator/pacemakers, pacemakers, neurological stimulators and gastrointestinal stimulators.
96. The band stop filter of claim 80 , wherein the overall Q of the band stop filter is selected to balance impedance at the selected frequency verses frequency band width characteristics.
97. The band stop filter of claim 80 , wherein the overall Q of the band stop filter is selected to balance a desired current flow verses specified frequencies.
98. The band stop filter of claim 80 , wherein the Q of the band stop filter is selected to provide a desired current flow at specified frequencies.
99. A filter for implantable lead wires of an active implantable medical device, which comprises:
lead wires each having a length extending between and to a proximal end and a distal end; and
at least one filter comprising a parallel-resonant circuit including a capacitor and an inductor,
said parallel-resonant circuit placed within the path of the leads;
wherein values of capacitance and inductance have been selected such that the filter is resonant at a selected frequency;
and further wherein the Q of the filter is selected to provide the desired current flow, or lack thereof, at specified frequencies.
100. The filter of claim 99 , wherein the Q of the inductor is relatively high and the Q of the capacitor is relatively low to select the overall Q of the filter.
101. The filter of claim 100 , wherein the inductor has a relatively low resistive loss; and wherein the capacitor has a relatively high equivalent series resistance.
102. The filter of claim 101 , wherein the overall Q of the filter is selected to attenuate current flow through the lead wires along a range of selected frequencies.
103. The filter of claim 102 , wherein the range of selected frequencies includes a plurality of MRI pulsed frequencies.
104. The filter of claim 102 , wherein the range of selected frequencies includes an MRI pulsed frequency.
105. The filter of claim 99 , wherein the filter is disposed adjacent to a distal tip of a lead wire.
106. The filter of claim 99 , wherein the filter is disposed within the path of the leads adjacent an electrode.
107. The filter of claim 105 or 106 , wherein the filter is connected into a tip electrode.
108. The filter of claim 105 or 106 , wherein the filter is connected into at least one of a TIP electrode and a RING electrode.
109. A filter for a medical diagnostic or therapeutic device comprising
an active implantable medical device and
implantable lead wires each having a length extending therefrom between and to a proximal end and a distal end and adapted to be in contact with biological cells, the filter comprising:
at least one filter associated with the lead wires, for attenuating current flow through the lead wires at a selected frequency,
wherein the filter comprises a parallel-resonant circuit including a capacitor and an inductor,
said parallel-resonant circuit placed within the path of the lead wires;
wherein values of capacitance and inductance are selected such that the filter is resonant at the selected frequency.
110. The filter of claim 109 , wherein the Q of the inductor is relatively high and the Q of the capacitor is relatively low to select the overall Q of the filter.
111. The filter of claim 110 , wherein the inductor has a relatively low resistive loss.
112. The filter of claim 110 , wherein the capacitor has a relatively high equivalent series resistance.
113. The filter of claim 110 , wherein the overall Q of the filter is selected to attenuate current flow through the lead wires along a range of selected frequencies.
114. The filter of claim 113 , wherein the range of selected frequencies includes a plurality of MRI pulsed frequencies.
115. The filter of claim 113 , wherein the range of selected frequencies includes an MRI pulsed frequency.
116. The filter of claim 109 , wherein the filter is disposed adjacent to the distal tip of an implantable lead wire.
117. The filter of claim 109 , wherein the filter is disposed within the path of the leads adjacent an electrode.
118. The filter of claim 116 or 117 , wherein the filter is connected into a tip electrode.
119. The filter of claim 116 or 117 , wherein the filter is connected into at least one of a TIP electrode and a RING electrode.
120. The filter of claim 118 , wherein the overall Q of the filter is selected to attenuate current flow through an implantable lead wire along a range of selected frequencies.
121. The filter of claim 109 , wherein the implantable medical device is selected from the group consisting of cardiac pacemakers and implantable cardioverter defibrillators.
122. The filter of claim 109 , wherein the implantable medical device is selected from the group consisting of implantable pulse generators, cardioverter/defibrillator/pacemakers and pacemakers.
123. The filter of claim 109 , wherein the implantable medical device is selected from the group consisting of neurostimulators, cardiac pacemakers, gastric stimulators and implantable cardioverter defibrillators.
124. The filter of claim 109 , wherein the implantable medical device is selected from the group consisting of implantable pulse generators, cardioverter/defibrillator/pacemakers, pacemakers, neurological stimulators and gastrointestinal stimulators.
125. The filter of claim 109 , wherein the overall Q of the filter is selected to balance impedance at the selected frequency verses frequency band width characteristics.
126. The filter of claim 109 , wherein the overall Q of the filter is selected to balance a desired current flow verses specified frequencies.
127. The filter of claim 109 , wherein the Q of the filter is selected to provide a desired current flow at specified frequencies.
128. The band stop filter of claim 61 , wherein the overall Q of the band stop filter is selected to attenuate current flow through the implantable lead wire along a range of selected frequencies.
129. The band stop filter of claim 90 , wherein the overall Q of the band stop filter is selected to attenuate current flow through an implantable lead wire along a range of selected frequencies.
130. The filter of claim 119 , wherein the overall Q of the filter is selected to attenuate current flow through an implantable lead wire along a range of selected frequencies.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US13/838,385 US20130218250A1 (en) | 2000-04-20 | 2013-03-15 | MRI-compatible implantable device |
Applications Claiming Priority (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US19863100P | 2000-04-20 | 2000-04-20 | |
US09/839,286 US6795730B2 (en) | 2000-04-20 | 2001-04-20 | MRI-resistant implantable device |
US09/921,066 US6925328B2 (en) | 2000-04-20 | 2001-08-02 | MRI-compatible implantable device |
US10/946,026 US8527046B2 (en) | 2000-04-20 | 2004-09-21 | MRI-compatible implantable device |
US13/838,385 US20130218250A1 (en) | 2000-04-20 | 2013-03-15 | MRI-compatible implantable device |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/946,026 Continuation US8527046B2 (en) | 2000-04-20 | 2004-09-21 | MRI-compatible implantable device |
Publications (1)
Publication Number | Publication Date |
---|---|
US20130218250A1 true US20130218250A1 (en) | 2013-08-22 |
Family
ID=46302878
Family Applications (3)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/946,026 Expired - Fee Related US8527046B2 (en) | 2000-04-20 | 2004-09-21 | MRI-compatible implantable device |
US13/408,933 Abandoned US20120158080A1 (en) | 2000-04-20 | 2012-02-29 | Mri-compatible implantable device |
US13/838,385 Abandoned US20130218250A1 (en) | 2000-04-20 | 2013-03-15 | MRI-compatible implantable device |
Family Applications Before (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/946,026 Expired - Fee Related US8527046B2 (en) | 2000-04-20 | 2004-09-21 | MRI-compatible implantable device |
US13/408,933 Abandoned US20120158080A1 (en) | 2000-04-20 | 2012-02-29 | Mri-compatible implantable device |
Country Status (1)
Country | Link |
---|---|
US (3) | US8527046B2 (en) |
Families Citing this family (70)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6893772B2 (en) * | 1993-11-19 | 2005-05-17 | Medtronic, Inc. | Current collector for lithium electrode |
US20070168005A1 (en) * | 2001-02-20 | 2007-07-19 | Biophan Technologies, Inc. | Medical device with an electrically conductive anti-antenna member |
US20050283167A1 (en) * | 2003-08-25 | 2005-12-22 | Biophan Technologies, Inc. | Medical device with an electrically conductive anti-antenna member |
US6829509B1 (en) * | 2001-02-20 | 2004-12-07 | Biophan Technologies, Inc. | Electromagnetic interference immune tissue invasive system |
US6949929B2 (en) * | 2003-06-24 | 2005-09-27 | Biophan Technologies, Inc. | Magnetic resonance imaging interference immune device |
US20070168006A1 (en) * | 2001-02-20 | 2007-07-19 | Biophan Technologies, Inc. | Medical device with an electrically conductive anti-antenna member |
US20050283214A1 (en) * | 2003-08-25 | 2005-12-22 | Biophan Technologies, Inc. | Medical device with an electrically conductive anti-antenna member |
US20070173911A1 (en) * | 2001-02-20 | 2007-07-26 | Biophan Technologies, Inc. | Medical device with an electrically conductive anti-antenna member |
US20050288753A1 (en) * | 2003-08-25 | 2005-12-29 | Biophan Technologies, Inc. | Medical device with an electrically conductive anti-antenna member |
US7388378B2 (en) * | 2003-06-24 | 2008-06-17 | Medtronic, Inc. | Magnetic resonance imaging interference immune device |
US7839146B2 (en) | 2003-06-24 | 2010-11-23 | Medtronic, Inc. | Magnetic resonance imaging interference immune device |
US7242981B2 (en) * | 2003-06-30 | 2007-07-10 | Codman Neuro Sciences Sárl | System and method for controlling an implantable medical device subject to magnetic field or radio frequency exposure |
US20050050042A1 (en) * | 2003-08-20 | 2005-03-03 | Marvin Elder | Natural language database querying |
US20050283213A1 (en) * | 2003-08-25 | 2005-12-22 | Biophan Technologies, Inc. | Medical device with an electrically conductive anti-antenna member |
US20050049482A1 (en) * | 2003-08-25 | 2005-03-03 | Biophan Technologies, Inc. | Electromagnetic radiation transparent device and method of making thereof |
US20050288757A1 (en) * | 2003-08-25 | 2005-12-29 | Biophan Technologies, Inc. | Medical device with an electrically conductive anti-antenna member |
US20050288751A1 (en) * | 2003-08-25 | 2005-12-29 | Biophan Technologies, Inc. | Medical device with an electrically conductive anti-antenna member |
US20050288756A1 (en) * | 2003-08-25 | 2005-12-29 | Biophan Technologies, Inc. | Medical device with an electrically conductive anti-antenna member |
US20050288752A1 (en) * | 2003-08-25 | 2005-12-29 | Biophan Technologies, Inc. | Medical device with an electrically conductive anti-antenna member |
US20050288754A1 (en) * | 2003-08-25 | 2005-12-29 | Biophan Technologies, Inc. | Medical device with an electrically conductive anti-antenna member |
US20050288755A1 (en) * | 2003-08-25 | 2005-12-29 | Biophan Technologies, Inc. | Medical device with an electrically conductive anti-antenna member |
US8868212B2 (en) * | 2003-08-25 | 2014-10-21 | Medtronic, Inc. | Medical device with an electrically conductive anti-antenna member |
US7824408B2 (en) | 2004-08-05 | 2010-11-02 | Tyco Healthcare Group, Lp | Methods and apparatus for coagulating and/or constricting hollow anatomical structures |
WO2006023700A2 (en) * | 2004-08-20 | 2006-03-02 | Biophan Technologies, Inc. | Magnetic resonance imaging interference immune device |
US8014867B2 (en) | 2004-12-17 | 2011-09-06 | Cardiac Pacemakers, Inc. | MRI operation modes for implantable medical devices |
US7369898B1 (en) * | 2004-12-22 | 2008-05-06 | Pacesetter, Inc. | System and method for responding to pulsed gradient magnetic fields using an implantable medical device |
US7625372B2 (en) | 2005-02-23 | 2009-12-01 | Vnus Medical Technologies, Inc. | Methods and apparatus for coagulating and/or constricting hollow anatomical structures |
US20070010741A1 (en) * | 2005-05-19 | 2007-01-11 | Biophan Technologies, Inc. | Electromagnetic resonant circuit sleeve for implantable medical device |
US8255054B2 (en) * | 2005-11-04 | 2012-08-28 | Kenergy, Inc. | MRI compatible implanted electronic medical device |
US8233985B2 (en) * | 2005-11-04 | 2012-07-31 | Kenergy, Inc. | MRI compatible implanted electronic medical device with power and data communication capability |
US20070178383A1 (en) * | 2006-01-31 | 2007-08-02 | Viavattine Joseph J | Current collector |
EP1998847B1 (en) * | 2006-03-24 | 2013-02-13 | Medtronic, Inc. | Implantable medical device |
US9037257B2 (en) * | 2006-04-07 | 2015-05-19 | Medtronic, Inc. | Resonance tuning module for implantable devices and leads |
EP2067501A3 (en) * | 2006-04-07 | 2011-12-21 | Medtronic, Inc. | Resonance circuit for implantable devices and leads |
US20080103543A1 (en) * | 2006-10-31 | 2008-05-01 | Medtronic, Inc. | Implantable medical device with titanium alloy housing |
US8768486B2 (en) | 2006-12-11 | 2014-07-01 | Medtronic, Inc. | Medical leads with frequency independent magnetic resonance imaging protection |
WO2008077037A2 (en) * | 2006-12-18 | 2008-06-26 | Ergin Atalar | Mri compatible implantable devices |
WO2009042545A2 (en) * | 2007-09-24 | 2009-04-02 | Boston Scientific Limited | Mri phase visualization of interventional devices |
US8032228B2 (en) * | 2007-12-06 | 2011-10-04 | Cardiac Pacemakers, Inc. | Method and apparatus for disconnecting the tip electrode during MRI |
US8086321B2 (en) | 2007-12-06 | 2011-12-27 | Cardiac Pacemakers, Inc. | Selectively connecting the tip electrode during therapy for MRI shielding |
US8571661B2 (en) | 2008-10-02 | 2013-10-29 | Cardiac Pacemakers, Inc. | Implantable medical device responsive to MRI induced capture threshold changes |
EP2398553B1 (en) | 2009-02-19 | 2015-07-22 | Cardiac Pacemakers, Inc. | Systems for providing arrhythmia therapy in mri environments |
WO2011014465A2 (en) * | 2009-07-31 | 2011-02-03 | Proteus Biomedical, Inc. | Lead for use in rf field |
US8565869B2 (en) * | 2009-09-24 | 2013-10-22 | Chong Il Lee | Device and system to improve the safety of an electrical stimulating device in an electromagnetic radiation environment |
WO2011071597A1 (en) | 2009-12-08 | 2011-06-16 | Cardiac Pacemakers, Inc. | Implantable medical device with automatic tachycardia detection and control in mri environments |
EP2338564B1 (en) * | 2009-12-22 | 2013-03-27 | BIOTRONIK CRM Patent AG | MRI optocoupler |
US9616246B2 (en) * | 2010-01-04 | 2017-04-11 | Covidien Lp | Apparatus and methods for treating hollow anatomical structures |
US9008788B2 (en) * | 2010-02-10 | 2015-04-14 | Medtronic, Inc. | Enablement and/or disablement of an exposure mode of an implantable medical device |
CA2793103C (en) | 2010-03-26 | 2015-04-28 | Boston Scientific Neuromodulation Corporation | Method for controlled shutdown of an implantable medical device |
US20130110203A1 (en) * | 2011-10-27 | 2013-05-02 | Boston Scientific Neuromodulation Corporation | Managing a Multi-function Coil in an Implantable Medical Device Using an Optical Switch |
US9369001B2 (en) | 2013-05-16 | 2016-06-14 | Delphi Technologies, Inc. | Magnetic field detection apparatus for a wireless power transfer system |
US9492671B2 (en) | 2014-05-06 | 2016-11-15 | Medtronic, Inc. | Acoustically triggered therapy delivery |
US9999774B2 (en) * | 2014-05-06 | 2018-06-19 | Medtronic, Inc. | Optical trigger for therapy delivery |
US9669224B2 (en) | 2014-05-06 | 2017-06-06 | Medtronic, Inc. | Triggered pacing system |
KR102323206B1 (en) | 2014-08-13 | 2021-11-08 | 삼성전자주식회사 | The method and apparatus for filtering magnetic field induced in the coil of magnetic resonance imaging system |
WO2018031714A1 (en) | 2016-08-11 | 2018-02-15 | Foundry Innovation & Research 1, Ltd. | Systems and methods for patient fluid management |
WO2016131020A1 (en) | 2015-02-12 | 2016-08-18 | Foundry Innovation & Research 1, Ltd. | Implantable devices and related methods for heart failure monitoring |
US11367947B2 (en) * | 2015-03-16 | 2022-06-21 | St. Jude Medical International Holding S.á r.l. | Field concentrating antennas for magnetic position sensors |
WO2017024051A1 (en) | 2015-08-03 | 2017-02-09 | Foundry Innovation & Research 1, Ltd. | Devices and methods for measurement of vena cava dimensions, pressure, and oxygen saturation |
US9974949B2 (en) | 2015-10-16 | 2018-05-22 | Cyberonics, Inc. | MRI-safe implantable lead assembly |
US10286209B2 (en) | 2016-04-29 | 2019-05-14 | Medtronic, Inc. | Methods and implantable medical devices for automatic entry to an exposure mode of operation upon exposure to a magnetic disturbance |
EP3454935A2 (en) | 2016-05-11 | 2019-03-20 | Inspire Medical Systems, Inc. | Attenuation arrangement for implantable medical device |
US11701018B2 (en) | 2016-08-11 | 2023-07-18 | Foundry Innovation & Research 1, Ltd. | Wireless resonant circuit and variable inductance vascular monitoring implants and anchoring structures therefore |
US11206992B2 (en) | 2016-08-11 | 2021-12-28 | Foundry Innovation & Research 1, Ltd. | Wireless resonant circuit and variable inductance vascular monitoring implants and anchoring structures therefore |
JP7241405B2 (en) | 2016-11-29 | 2023-03-17 | ファウンドリー イノベーション アンド リサーチ 1,リミテッド | Wireless resonant circuit and variable inductance vascular implant for monitoring vascular and fluid status in patients, and systems and methods utilizing same |
WO2018220143A1 (en) | 2017-05-31 | 2018-12-06 | Foundry Innovation And Research 1, Ltd | Implantable ultrasonic vascular sensor |
EP3629921A1 (en) | 2017-05-31 | 2020-04-08 | Foundry Innovation & Research 1, Ltd. | Implantable sensors for vascular monitoring |
US20200046420A1 (en) | 2018-08-08 | 2020-02-13 | Biosense Webster (Israel) Ltd. | Contact force sensor comprising tuned amplifiers |
CN113944618B (en) * | 2020-07-16 | 2023-02-17 | 西门子(深圳)磁共振有限公司 | Helium compressor monitoring system, method and magnetic resonance imaging equipment |
CN116801941A (en) * | 2020-11-10 | 2023-09-22 | 赛纳吉亚医疗公司 | Active implantable medical device including an optically active trigger |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20030050557A1 (en) * | 1998-11-04 | 2003-03-13 | Susil Robert C. | Systems and methods for magnetic-resonance-guided interventional procedures |
US6539253B2 (en) * | 2000-08-26 | 2003-03-25 | Medtronic, Inc. | Implantable medical device incorporating integrated circuit notch filters |
US20070288058A1 (en) * | 2001-04-13 | 2007-12-13 | Greatbatch Ltd. | Band stop filter employing a capacitor and an inductor tank circuit to enhance mri compatibility of active implantable medical devices |
Family Cites Families (297)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3057356A (en) | 1960-07-22 | 1962-10-09 | Wilson Greatbatch Inc | Medical cardiac pacemaker |
US3478746A (en) | 1965-05-12 | 1969-11-18 | Medtronic Inc | Cardiac implantable demand pacemaker |
US3669095A (en) | 1966-08-25 | 1972-06-13 | Tokyo Shibaura Electric Co | Catheter-type semi-conductor radiation detector for insertion into a human body |
US3508167A (en) | 1968-06-28 | 1970-04-21 | Mennen Greatbatch Electronics | Pulse generator |
US3654537A (en) | 1970-04-29 | 1972-04-04 | Westinghouse Electric Corp | High efficiency power supply for charging capacitors in steps |
US3686958A (en) | 1971-02-22 | 1972-08-29 | Ladd Res Ind | Fiber optic pressure detector |
US3718142A (en) | 1971-04-23 | 1973-02-27 | Medtronic Inc | Electrically shielded, gas-permeable implantable electro-medical apparatus |
US3789667A (en) | 1972-02-14 | 1974-02-05 | Ladd Res Ind Inc | Fiber optic pressure detector |
US3825015A (en) | 1972-12-14 | 1974-07-23 | American Optical Corp | Single catheter for atrial and ventricular stimulation |
GB1505130A (en) | 1974-05-07 | 1978-03-22 | Seiko Instr & Electronics | Systems for detecting information in an artificial cardiac pacemaker |
US4038990A (en) | 1975-11-19 | 1977-08-02 | Medtronic, Inc. | Cautery protection circuit for a heart pacemaker |
US3968802A (en) | 1975-01-24 | 1976-07-13 | Medtronic, Inc. | Cautery protection circuit for a heart pacemaker |
US4012641A (en) | 1975-12-05 | 1977-03-15 | The United States Of America As Represented By The Secretary Of The Navy | Portable pulsed signal generator |
US4071032A (en) | 1976-01-29 | 1978-01-31 | Pacesetter Systems Inc. | Implantable living tissue stimulators |
US4091818A (en) | 1976-08-03 | 1978-05-30 | Research Corporation | Cardiac pacing apparatus with electromagnetic interference protection |
JPS5382980A (en) | 1976-12-28 | 1978-07-21 | Agency Of Ind Science & Technol | Distribution type information transmission unit by multi point electric stimulas |
US4200110A (en) | 1977-11-28 | 1980-04-29 | United States Of America | Fiber optic pH probe |
US4333053A (en) | 1979-03-13 | 1982-06-01 | Emi Limited | Imaging systems |
US4210029A (en) | 1979-05-04 | 1980-07-01 | Lad Research Industries, Inc. | Differential fiber optic differential pressure sensor |
US4379262A (en) | 1979-08-10 | 1983-04-05 | Picker International Limited | Nuclear magnetic resonance systems |
JPS56106663A (en) | 1980-01-31 | 1981-08-25 | Tokyo Shibaura Electric Co | Transmitting medium for energy to organism buried device |
US4325382A (en) | 1980-05-15 | 1982-04-20 | Memorial Hospital For Cancer And Allied Diseases | Process and apparatus for the real time adaptive filtering of catheter pressure measurements |
US4341221A (en) | 1980-10-07 | 1982-07-27 | Medtronic, Inc. | Shielded recording electrode system |
CA1176091A (en) | 1981-06-17 | 1984-10-16 | Charles D. Knipe | Optical cable |
US4491768A (en) | 1981-11-04 | 1985-01-01 | Eaton Corporation | Pulse width modulation inverter with battery charger |
US4450408A (en) | 1981-12-11 | 1984-05-22 | General Electric Company | Low loss wide band front end for NMR receiver |
US4476870A (en) | 1982-03-30 | 1984-10-16 | The United States Of America As Represented By The Department Of Health And Human Services | Fiber optic PO.sbsb.2 probe |
JPS59103644A (en) | 1982-12-07 | 1984-06-15 | オリンパス光学工業株式会社 | Endoscope photographing apparatus |
US4934785A (en) | 1983-08-29 | 1990-06-19 | American Telephone And Telegraph Company | Optical fiber connector |
DE3430625A1 (en) | 1984-08-20 | 1986-02-27 | Siemens AG, 1000 Berlin und 8000 München | DEVICE FOR THE CORE SPIN TOMOGRAPHY |
US4727874A (en) | 1984-09-10 | 1988-03-01 | C. R. Bard, Inc. | Electrosurgical generator with high-frequency pulse width modulated feedback power control |
US4611127A (en) | 1984-09-20 | 1986-09-09 | Telectronics N.V. | Electronic sensor for static magnetic field |
US4545381A (en) | 1984-10-01 | 1985-10-08 | Cordis Corporation | Adapter for converting a metal encapsulated implantable cardiac pacer to an externally worn cardiac pacer |
JPS61197336A (en) | 1985-02-28 | 1986-09-01 | Ricoh Co Ltd | Copying machine |
US5209233A (en) * | 1985-08-09 | 1993-05-11 | Picker International, Inc. | Temperature sensing and control system for cardiac monitoring electrodes |
US4677471A (en) | 1985-08-16 | 1987-06-30 | Olympus Optical Co., Ltd. | Endoscope |
JPS6252443A (en) | 1985-08-30 | 1987-03-07 | Toshiba Corp | Probe tuning circuit of mr apparatus |
EP0236562B2 (en) | 1985-12-11 | 2006-06-07 | Telectronics N.V. | Apparatus for cardiac pacing with detection of cardiac evoked potentials |
US4800883A (en) | 1986-04-02 | 1989-01-31 | Intermedics, Inc. | Apparatus for generating multiphasic defibrillation pulse waveform |
US4719159A (en) | 1986-05-19 | 1988-01-12 | Eastman Kodak Company | Sealed lithium battery |
US4784461A (en) | 1986-11-04 | 1988-11-15 | Northern Telecom Limited | Optical cable with improved strength |
US5055810A (en) | 1986-12-31 | 1991-10-08 | Hughes Aircraft Company | Ultra-high speed light activated microwave switch/modulation using photoreactive effect |
JPS63270024A (en) | 1987-04-27 | 1988-11-08 | Olympus Optical Co Ltd | Electronic endoscopic apparatus |
US4903701A (en) | 1987-06-05 | 1990-02-27 | Medtronic, Inc. | Oxygen sensing pacemaker |
DE3880910D1 (en) | 1987-07-27 | 1993-06-17 | Siemens Ag | CATHETER FOR IMPLANTATION IN THE HEART WITH A BUILT-IN MEASURING PROBE. |
US4827906A (en) | 1987-08-31 | 1989-05-09 | Heineman Medical Research Center | Apparatus and method for activating a pump in response to optical signals from a pacemaker |
US4827934A (en) | 1987-10-27 | 1989-05-09 | Siemens-Pacesetter, Inc. | Sensing margin detectors for implantable electromedical devices |
US5010888A (en) | 1988-03-25 | 1991-04-30 | Arzco Medical Electronics, Inc. | Method and apparatus for detection of posterior ischemia |
US4880004A (en) | 1988-06-07 | 1989-11-14 | Intermedics, Inc. | Implantable cardiac stimulator with automatic gain control and bandpass filtering in feedback loop |
JP2671016B2 (en) | 1988-07-08 | 1997-10-29 | サージカル・レーザー・テクノロジーズ・インコーポレイテッド | Laser treatment device for narrow path in living tissue |
DE3831809A1 (en) | 1988-09-19 | 1990-03-22 | Funke Hermann | DEVICE DETERMINED AT LEAST PARTLY IN THE LIVING BODY |
US4911525A (en) | 1988-10-05 | 1990-03-27 | Hicks John W | Optical communication cable |
US5089697A (en) | 1989-01-11 | 1992-02-18 | Prohaska Otto J | Fiber optic sensing device including pressure detection and human implantable construction |
US5226210A (en) | 1989-01-23 | 1993-07-13 | Minnesota Mining And Manufacturing Company | Method of forming metal fiber mat/polymer composite |
US4991590A (en) | 1989-01-30 | 1991-02-12 | Martin Goffman Associates | Fiber optic intravascular blood pressure transducer |
US5348010A (en) | 1989-02-24 | 1994-09-20 | Medrea, Inc., Pennsylvania Corp., Pa. | Intracavity probe and interface device for MRI imaging and spectroscopy |
US4930521A (en) | 1989-03-17 | 1990-06-05 | Metzger William T | Variable stiffness esophageal catheter |
US5240004A (en) | 1989-04-28 | 1993-08-31 | Thomas Jefferson University | Intravascular, ultrasonic imaging catheters and methods for making same |
US5061680A (en) | 1989-07-31 | 1991-10-29 | Biomagnetic Technologies, Inc. | Superconducting biomagnetometer with remote pickup coil |
US5158932A (en) | 1989-07-31 | 1992-10-27 | Biomagnetic Technologies, Inc. | Superconducting biomagnetometer with inductively coupled pickup coil |
US5570671A (en) | 1989-09-18 | 1996-11-05 | The Research Foundation Of State University Of New York | Method for positioning esophageal catheter for determining pressures associated with the left atrium |
US4987897A (en) | 1989-09-18 | 1991-01-29 | Medtronic, Inc. | Body bus medical device communication system |
RU1785710C (en) | 1989-10-06 | 1993-01-07 | Vremennyj Nauchnyj Kollektiv O | Microwave resonant therapeutic device |
US5178149A (en) | 1989-11-06 | 1993-01-12 | Michael Imburgia | Transesophageal probe having simultaneous pacing and echocardiographic capability, and method of diagnosing heart disease using same |
US5985129A (en) | 1989-12-14 | 1999-11-16 | The Regents Of The University Of California | Method for increasing the service life of an implantable sensor |
US5108369A (en) | 1990-03-15 | 1992-04-28 | Diagnostic Devices Group, Limited | Dual-diameter multifunction catheter |
US5154387A (en) | 1990-05-31 | 1992-10-13 | Syncromed Corporation | Method and apparatus for esophageal pacing |
US5387232A (en) | 1990-05-31 | 1995-02-07 | Synchrotech Medical Corporation | Method and apparatus for esophageal pacing |
US5168871A (en) | 1990-11-09 | 1992-12-08 | Medtronic, Inc. | Method and apparatus for processing quasi-transient telemetry signals in noisy environments |
AU645848B2 (en) | 1991-01-15 | 1994-01-27 | Pacesetter Ab | A system and method for post-processing intracardiac signals |
DE4104359A1 (en) | 1991-02-13 | 1992-08-20 | Implex Gmbh | CHARGING SYSTEM FOR IMPLANTABLE HOERHILFEN AND TINNITUS MASKERS |
US6134003A (en) | 1991-04-29 | 2000-10-17 | Massachusetts Institute Of Technology | Method and apparatus for performing optical measurements using a fiber optic imaging guidewire, catheter or endoscope |
AU635172B2 (en) | 1991-05-13 | 1993-03-11 | Nippon Telegraph & Telephone Corporation | Multifiber optical connector plug with low reflection and low insertion loss |
US5217010A (en) | 1991-05-28 | 1993-06-08 | The Johns Hopkins University | Ecg amplifier and cardiac pacemaker for use during magnetic resonance imaging |
US5267564A (en) | 1991-06-14 | 1993-12-07 | Siemens Pacesetter, Inc. | Pacemaker lead for sensing a physiologic parameter of the body |
US5951596A (en) | 1991-07-01 | 1999-09-14 | Laser Biotherapy Inc | Biological tissue stimulation by optical energy |
US5217009A (en) | 1991-07-10 | 1993-06-08 | Kronberg James W | Compact biomedical pulsed signal generator for bone tissue stimulation |
US5869412A (en) | 1991-08-22 | 1999-02-09 | Minnesota Mining & Manufacturing Co. | Metal fibermat/polymer composite |
EP0534782A1 (en) | 1991-09-26 | 1993-03-31 | Medtronic, Inc. | Implantable medical device enclosure |
US5464014A (en) | 1991-10-03 | 1995-11-07 | Sugan Company Limited | Display device for bioelectrical and biophysical phenomena |
US5243979A (en) | 1991-11-15 | 1993-09-14 | Medtronic, Inc. | Method and apparatus for implementing activity sensing in a pulse generator |
DE69230153T2 (en) | 1991-11-18 | 2000-03-09 | Sumitomo Electric Industries | Device for plugging together optical connectors with applicator for liquid for index adjustment |
US5830209A (en) | 1992-02-05 | 1998-11-03 | Angeion Corporation | Multi-fiber laser catheter |
US5681575A (en) | 1992-05-19 | 1997-10-28 | Westaim Technologies Inc. | Anti-microbial coating for medical devices |
US5324310A (en) | 1992-07-01 | 1994-06-28 | Medtronic, Inc. | Cardiac pacemaker with auto-capture function |
US5265602A (en) | 1992-07-13 | 1993-11-30 | Medtronic, Inc. | Ring-to-ring cardiac electrogram pacemaker |
US5435308A (en) | 1992-07-16 | 1995-07-25 | Abbott Laboratories | Multi-purpose multi-parameter cardiac catheter |
WO1994004083A1 (en) | 1992-08-26 | 1994-03-03 | Advanced Interventional Systems | Optical catheter with stranded fibers |
DE69316018T2 (en) | 1992-09-18 | 1998-04-16 | Otsuka Pharma Co Ltd | CARBOSTYRILE DERIVATIVES AS AN ANTIARRHYTMICS |
GB2272306B (en) | 1992-11-09 | 1996-11-20 | Fujitsu Ltd | Coupling of optical parts using a refractive index imaging material |
EP0597463A3 (en) | 1992-11-13 | 1996-11-06 | Dornier Med Systems Inc | Thermotherapiesonde. |
US5330512A (en) | 1992-12-28 | 1994-07-19 | Cardiac Pacemakers, Inc. | Electrode charge-neutral sensing of evoked ECG |
US5387229A (en) | 1993-01-21 | 1995-02-07 | Pacesetter, Inc. | Multi-sensor cardiac pacemaker with sensor event recording capability |
FR2704131B1 (en) | 1993-04-22 | 1995-06-30 | Odam | Sensor device for electrocardiogram. |
KR100269825B1 (en) | 1993-04-30 | 2000-10-16 | 미야즈 준이찌로 | Optical connector and method thereof |
US5420954A (en) | 1993-05-24 | 1995-05-30 | Photonics Research Incorporated | Parallel optical interconnect |
SE9301855D0 (en) | 1993-06-01 | 1993-06-01 | Siemens-Elema Ab | MEDICAL SYSTEM |
US6052613A (en) | 1993-06-18 | 2000-04-18 | Terumo Cardiovascular Systems Corporation | Blood pressure transducer |
US5370668A (en) | 1993-06-22 | 1994-12-06 | Medtronic, Inc. | Fault-tolerant elective replacement indication for implantable medical device |
US5523534A (en) | 1993-06-28 | 1996-06-04 | Vital Connections, Inc. | Shielded carbon lead for medical electrodes |
US5571088A (en) | 1993-07-01 | 1996-11-05 | Boston Scientific Corporation | Ablation catheters |
US6277107B1 (en) | 1993-08-13 | 2001-08-21 | Daig Corporation | Guiding introducer for introducing medical devices into the coronary sinus and process for using same |
US5410413A (en) | 1993-08-18 | 1995-04-25 | Petrometrix Ltd. | Optical head probe using a gradient index lens and optical fibers |
US5917625A (en) | 1993-09-09 | 1999-06-29 | Kabushiki Kaisha Toshiba | High resolution optical multiplexing and demultiplexing device in optical communication system |
US5626618A (en) | 1993-09-24 | 1997-05-06 | The Ohio State University | Mechanical adjunct to cardiopulmonary resuscitation (CPR), and an electrical adjunct to defibrillation countershock, cardiac pacing, and cardiac monitoring |
US5435316A (en) | 1993-10-07 | 1995-07-25 | Medtronic, Inc. | Low amplitude pacing artifact detection amplifier circuit with driven right leg for filtering high frequency noise caused by multiple noise sources |
FR2710848B1 (en) | 1993-10-08 | 1995-12-01 | Ela Medical Sa | Implantable defibrillator with optically isolated shock generator. |
JP3236716B2 (en) | 1993-10-15 | 2001-12-10 | 富士写真光機株式会社 | Shield structure of electronic endoscope device |
US5492118A (en) | 1993-12-16 | 1996-02-20 | Board Of Trustees Of The University Of Illinois | Determining material concentrations in tissues |
SE513183C2 (en) | 1994-03-18 | 2000-07-24 | Ericsson Telefon Ab L M | Process for producing an optocomponent and nested optocomponent |
US5453838A (en) | 1994-06-17 | 1995-09-26 | Ceram Optec Industries, Inc. | Sensing system with a multi-channel fiber optic bundle sensitive probe |
US5445151A (en) | 1994-06-23 | 1995-08-29 | General Electric Company | Method for blood flow acceleration and velocity measurement using MR catheters |
US5716386A (en) | 1994-06-27 | 1998-02-10 | The Ohio State University | Non-invasive aortic impingement and core and cerebral temperature manipulation |
US5601611A (en) | 1994-08-05 | 1997-02-11 | Ventritex, Inc. | Optical blood flow measurement apparatus and method and implantable defibrillator incorporating same |
US5601615A (en) | 1994-08-16 | 1997-02-11 | Medtronic, Inc. | Atrial and ventricular capture detection and threshold-seeking pacemaker |
DE4431703C2 (en) | 1994-09-06 | 1997-01-30 | Itt Ind Gmbh Deutsche | Magnetic field sensor with Hall element |
GB2293248B (en) | 1994-09-07 | 1998-02-18 | Northern Telecom Ltd | Providing optical coupling between optical components |
SE9403188D0 (en) | 1994-09-22 | 1994-09-22 | Siemens Elema Ab | Magnetic field detector on a medical implant |
US6036654A (en) | 1994-09-23 | 2000-03-14 | Baxter International Inc. | Multi-lumen, multi-parameter catheter |
US5827997A (en) | 1994-09-30 | 1998-10-27 | Chung; Deborah D. L. | Metal filaments for electromagnetic interference shielding |
AU3299995A (en) | 1994-10-04 | 1996-04-18 | Medtronic, Inc. | Protective feedthrough |
US5520190A (en) | 1994-10-31 | 1996-05-28 | Ventritex, Inc. | Cardiac blood flow sensor and method |
US5582170A (en) | 1994-12-01 | 1996-12-10 | University Of Massachusetts Medical Center | Fiber optic sensor for in vivo measurement of nitric oxide |
FR2728799B1 (en) | 1994-12-30 | 1997-03-28 | Ela Medical Sa | ACTIVE IMPLANTABLE DEVICE, IN PARTICULAR STIMULATOR OR CARDIAC DEFIBRILLATOR, PROVIDED WITH MEANS OF PROTECTION AGAINST ELECTROMAGNETIC DISTURBANCES OF EXTERNAL ORIGIN |
US5836895A (en) | 1995-01-09 | 1998-11-17 | Arzco Medical Systems, Inc. | Esophageal catheter with gauge |
US5603697A (en) | 1995-02-14 | 1997-02-18 | Fidus Medical Technology Corporation | Steering mechanism for catheters and methods for making same |
US5699801A (en) | 1995-06-01 | 1997-12-23 | The Johns Hopkins University | Method of internal magnetic resonance imaging and spectroscopic analysis and associated apparatus |
US5749910A (en) | 1995-06-07 | 1998-05-12 | Angeion Corporation | Shield for implantable cardioverter defibrillator |
US5697958A (en) | 1995-06-07 | 1997-12-16 | Intermedics, Inc. | Electromagnetic noise detector for implantable medical devices |
US5814090A (en) | 1995-06-07 | 1998-09-29 | Angeion Corporation | Implantable medical device having heat-shrink conforming shield |
US5653735A (en) | 1995-06-28 | 1997-08-05 | Pacesetter, Inc. | Implantable cardiac stimulation device having an improved backup mode of operation and method thereof |
US5723856A (en) | 1995-08-01 | 1998-03-03 | California Institute Of Technology | Opto-electronic oscillator having a positive feedback with an open loop gain greater than one |
JPH0949947A (en) | 1995-08-10 | 1997-02-18 | Hitachi Ltd | Optical module |
US6166806A (en) | 1995-09-29 | 2000-12-26 | Tjin; Swee Chuan | Fiber optic catheter for accurate flow measurements |
US5882108A (en) | 1995-10-12 | 1999-03-16 | Valeo Sylvania L.L.C. | Lighting with EMI shielding |
US5774501A (en) | 1995-10-24 | 1998-06-30 | Halpern, Deceased; Peter H. | High speed multilevel symbol telemetry system for cardiac pacemakers |
US5738105A (en) | 1995-10-24 | 1998-04-14 | Angeion Corporation | Method and apparatus for sensing R-waves using both near field and far field sensing simultaneously |
US5620476A (en) | 1995-11-13 | 1997-04-15 | Pacesetter, Inc. | Implantable medical device having shielded and filtered feedthrough assembly and methods for making such assembly |
US5733247A (en) | 1995-12-20 | 1998-03-31 | Hewlett-Packard Company | MR compatible patient monitor |
US5679026A (en) | 1995-12-21 | 1997-10-21 | Ventritex, Inc. | Header adapter for an implantable cardiac stimulation device |
US5868664A (en) | 1996-02-23 | 1999-02-09 | Envision Medical Corporation | Electrically isolated sterilizable endoscopic video camera head |
US5776167A (en) | 1996-02-27 | 1998-07-07 | Pacesetter, Inc. | System and method for alleviating the effects of pacemaker crosstalk |
SE9601155D0 (en) | 1996-03-26 | 1996-03-26 | Pacesetter Ab | Device for active implant |
CA2220770C (en) | 1996-03-28 | 2004-08-17 | Medtronic, Inc. | Detection of pressure waves transmitted through catheter/lead body |
US5973779A (en) | 1996-03-29 | 1999-10-26 | Ansari; Rafat R. | Fiber-optic imaging probe |
US5776168A (en) | 1996-04-03 | 1998-07-07 | Medtronic, Inc. | EGM recording system for implantable medical device |
US5782880A (en) | 1996-04-23 | 1998-07-21 | Medtronic, Inc. | Low energy pacing pulse waveform for implantable pacemaker |
US6263229B1 (en) | 1998-11-13 | 2001-07-17 | Johns Hopkins University School Of Medicine | Miniature magnetic resonance catheter coils and related methods |
US5928145A (en) | 1996-04-25 | 1999-07-27 | The Johns Hopkins University | Method of magnetic resonance imaging and spectroscopic analysis and associated apparatus employing a loopless antenna |
US6006134A (en) | 1998-04-30 | 1999-12-21 | Medtronic, Inc. | Method and device for electronically controlling the beating of a heart using venous electrical stimulation of nerve fibers |
US6005191A (en) | 1996-05-02 | 1999-12-21 | Parker-Hannifin Corporation | Heat-shrinkable jacket for EMI shielding |
US5817130A (en) | 1996-05-03 | 1998-10-06 | Sulzer Intermedics Inc. | Implantable cardiac cardioverter/defibrillator with EMI suppression filter with independent ground connection |
US5611016A (en) | 1996-06-07 | 1997-03-11 | Lucent Technologies Inc. | Dispersion-balanced optical cable |
EP0864102B1 (en) | 1996-09-02 | 2005-09-21 | Philips Electronics N.V. | Invasive device for use in a magnetic resonance imaging apparatus |
US5730134A (en) | 1996-09-09 | 1998-03-24 | General Electric Company | System to monitor temperature near an invasive device during magnetic resonance procedures |
US5963034A (en) | 1996-09-19 | 1999-10-05 | Ramar Corporation | Electro-optic electromagnetic field sensor system with optical bias adjustment |
US5755742A (en) | 1996-11-05 | 1998-05-26 | Medtronic, Inc. | Cardioversion/defibrillation lead impedance measurement system |
US6119031A (en) | 1996-11-21 | 2000-09-12 | Boston Scientific Corporation | Miniature spectrometer |
US5755739A (en) | 1996-12-04 | 1998-05-26 | Medtronic, Inc. | Adaptive and morphological system for discriminating P-waves and R-waves inside the human body |
DE69736826T2 (en) | 1996-12-05 | 2007-05-16 | Philips Medical Systems (Cleveland), Inc., Cleveland | Radio frequency coils for nuclear resonance |
US5814089A (en) | 1996-12-18 | 1998-09-29 | Medtronic, Inc. | Leadless multisite implantable stimulus and diagnostic system |
US5814087A (en) | 1996-12-18 | 1998-09-29 | Medtronic, Inc. | Rate responsive pacemaker adapted to adjust lower rate limit according to monitored patient blood temperature |
US5999857A (en) | 1996-12-18 | 1999-12-07 | Medtronic, Inc. | Implantable device telemetry system and method |
US5865839A (en) | 1996-12-30 | 1999-02-02 | Doorish; John F. | Artificial retina |
US5895980A (en) | 1996-12-30 | 1999-04-20 | Medical Pacing Concepts, Ltd. | Shielded pacemaker enclosure |
US6055455A (en) | 1997-01-06 | 2000-04-25 | Cardiac Pacemakers, Inc. | Filtered feedthrough for an implantable medical device |
FR2758221B1 (en) | 1997-01-07 | 1999-03-26 | Ela Medical Sa | DEVICE FOR FILTERING HEART ACTIVITY SIGNALS |
JP3515305B2 (en) | 1997-01-16 | 2004-04-05 | 株式会社フジクラ | Optical connector |
US5982961A (en) | 1997-01-21 | 1999-11-09 | Molecular Optoelectronics Corporation | Organic crystal compound optical waveguide and methods for its fabrication |
NL1005068C2 (en) | 1997-01-23 | 1998-07-27 | Ct Rrn Academisch Ziekenhuis U | Catheter system and a catheter forming part thereof. |
US5928569A (en) | 1997-02-26 | 1999-07-27 | Specialty Silicone Products, Inc. | Substantially uniform moldable blends of silver particulate and organopolysiloxane |
US5919135A (en) | 1997-02-28 | 1999-07-06 | Lemelson; Jerome | System and method for treating cellular disorders in a living being |
US5766227A (en) | 1997-03-04 | 1998-06-16 | Nappholz; Tibor A. | EMI detection in an implantable pacemaker and the like |
US5817133A (en) | 1997-03-04 | 1998-10-06 | Medtronic, Inc. | Pacemaker with morphological filtering of sensed cardiac signals |
US6067472A (en) | 1997-03-12 | 2000-05-23 | Medtronic, Inc. | Pacemaker system and method with improved evoked response and repolarization signal detection |
US6266563B1 (en) | 1997-03-14 | 2001-07-24 | Uab Research Foundation | Method and apparatus for treating cardiac arrhythmia |
US5772604A (en) | 1997-03-14 | 1998-06-30 | Emory University | Method, system and apparatus for determining prognosis in atrial fibrillation |
US6275730B1 (en) | 1997-03-14 | 2001-08-14 | Uab Research Foundation | Method and apparatus for treating cardiac arrythmia |
US6173203B1 (en) | 1997-04-08 | 2001-01-09 | Survivalink Corpration | Circuit mounting system for automated external defibrillator circuits |
US5808730A (en) | 1997-04-08 | 1998-09-15 | Ceramoptec Industries Inc. | Fiber optic displacement sensor |
US6056415A (en) | 1997-04-11 | 2000-05-02 | Minrad Inc. | Penlight having low magnetic susceptibility |
US6036639A (en) | 1997-04-11 | 2000-03-14 | Minrad Inc. | Laryngoscope having low magnetic susceptibility and method of assembling |
US5752977A (en) | 1997-04-15 | 1998-05-19 | Medtronic, Inc. | Efficient high data rate telemetry format for implanted medical device |
US5873898A (en) | 1997-04-29 | 1999-02-23 | Medtronic, Inc. | Microprocessor capture detection circuit and method |
US6198972B1 (en) | 1997-04-30 | 2001-03-06 | Medtronic, Inc. | Control of externally induced current in implantable medical devices |
US5817136A (en) | 1997-05-02 | 1998-10-06 | Pacesetter, Inc. | Rate-responsive pacemaker with minute volume determination and EMI protection |
US6278057B1 (en) | 1997-05-02 | 2001-08-21 | General Science And Technology Corp. | Medical devices incorporating at least one element made from a plurality of twisted and drawn wires at least one of the wires being a nickel-titanium alloy wire |
US5870272A (en) | 1997-05-06 | 1999-02-09 | Medtronic Inc. | Capacitive filter feedthrough for implantable medical device |
US5827195A (en) | 1997-05-09 | 1998-10-27 | Cambridge Heart, Inc. | Electrocardiogram noise reduction using multi-dimensional filtering |
US6026316A (en) | 1997-05-15 | 2000-02-15 | Regents Of The University Of Minnesota | Method and apparatus for use with MR imaging |
US6128522A (en) | 1997-05-23 | 2000-10-03 | Transurgical, Inc. | MRI-guided therapeutic unit and methods |
US5940554A (en) | 1997-05-23 | 1999-08-17 | Lightwave Link, Inc. | Fiber optic coupling apparatus and method |
ES2129361B1 (en) | 1997-05-28 | 1999-12-16 | Univ Madrid Politecnica | PHOTOVOLTAIC TELEALIMENTATION SYSTEM THROUGH FIBER OPTICS FOR IMPLANTABLE MEDICAL DEVICES. |
US6090473A (en) | 1997-06-24 | 2000-07-18 | Bridgestone Corporation | Electromagnetic-wave shielding and light transmitting plate |
WO1999000057A1 (en) | 1997-06-27 | 1999-01-07 | Michigan Instruments, Inc. | Non-invasive aortic impingement |
US5987995A (en) | 1997-07-17 | 1999-11-23 | Sentec Corporation | Fiber optic pressure catheter |
US6056721A (en) | 1997-08-08 | 2000-05-02 | Sunscope International, Inc. | Balloon catheter and method |
US6076003A (en) | 1998-05-01 | 2000-06-13 | R.Z. Comparative Diagnostics Ltd. | Electrocardiography electrodes holder and monitoring set |
US6049736A (en) | 1997-09-03 | 2000-04-11 | Medtronic, Inc. | Implantable medical device with electrode lead having improved surface characteristics |
US6144866A (en) | 1998-10-30 | 2000-11-07 | Medtronic, Inc. | Multiple sensor assembly for medical electric lead |
US5902326A (en) | 1997-09-03 | 1999-05-11 | Medtronic, Inc. | Optical window for implantable medical devices |
US6052614A (en) | 1997-09-12 | 2000-04-18 | Magnetic Resonance Equipment Corp. | Electrocardiograph sensor and sensor control system for use with magnetic resonance imaging machines |
US6011994A (en) | 1997-09-24 | 2000-01-04 | Equitech Intl' Corporation | Multipurpose biomedical pulsed signal generator |
US5967977A (en) | 1997-10-03 | 1999-10-19 | Medtronic, Inc. | Transesophageal medical lead |
GB2330202A (en) | 1997-10-07 | 1999-04-14 | Marconi Gec Ltd | Flexible MRI antenna for intra-cavity use |
US5891171A (en) | 1997-10-22 | 1999-04-06 | Pacesetter Incorporated | Apparatus with noise classification in an implantable cardiac device by using an amplifier with a variable threshold |
US5897577A (en) | 1997-11-07 | 1999-04-27 | Medtronic, Inc. | Pacing lead impedance monitoring circuit and method |
US5968083A (en) | 1997-11-12 | 1999-10-19 | Pacesetter, Inc. | Active overload detection and protection circuit for implantable cardiac therapy devices |
US5928270A (en) | 1997-12-02 | 1999-07-27 | Cardiocommand, Inc. | Method and apparatus for incremental cardioversion or defibrillation |
SE9704520D0 (en) | 1997-12-04 | 1997-12-04 | Pacesetter Ab | Pacemaker |
US6013376A (en) | 1997-12-09 | 2000-01-11 | 3M Innovative Properties Company | Metal fibermat/polymer composite |
US5946086A (en) | 1997-12-10 | 1999-08-31 | Northern Telecom Limited | Optical mean power controller with provisionable output levels |
US6016477A (en) | 1997-12-18 | 2000-01-18 | International Business Machines Corporation | Method and apparatus for identifying applicable business rules |
US6091744A (en) | 1998-01-14 | 2000-07-18 | Hewlett-Packard Company | Wavelength selectable source for wavelength division multiplexed applications |
US5963690A (en) | 1998-01-20 | 1999-10-05 | Cheng; Yu-Feng | Optical fiber connector |
US5978710A (en) | 1998-01-23 | 1999-11-02 | Sulzer Intermedics Inc. | Implantable cardiac stimulator with safe noise mode |
EP1051109A4 (en) | 1998-01-26 | 2005-03-09 | Scimed Life Systems Inc | Catheter assembly with distal end inductive coupler and embedded transmission line |
US6258087B1 (en) | 1998-02-19 | 2001-07-10 | Curon Medical, Inc. | Expandable electrode assemblies for forming lesions to treat dysfunction in sphincters and adjoining tissue regions |
US5999853A (en) | 1998-03-02 | 1999-12-07 | Vitatron Medical, B.V. | Dual chamber pacemaker with single pass lead and with bipolar and unipolar signal processing capability |
US5973906A (en) | 1998-03-17 | 1999-10-26 | Maxwell Energy Products, Inc. | Chip capacitors and chip capacitor electromagnetic interference filters |
US5871509A (en) | 1998-04-02 | 1999-02-16 | Pacesetter Ab | Method and apparatus to remove data outliers, produced by external disturbance, in internally measured signals in an implantable cardiac stimulator |
US6256541B1 (en) | 1998-04-17 | 2001-07-03 | Cardiac Pacemakers, Inc. | Endocardial lead having defibrillation and sensing electrodes with septal anchoring |
US6023641A (en) | 1998-04-29 | 2000-02-08 | Medtronic, Inc. | Power consumption reduction in medical devices employing multiple digital signal processors |
US6091987A (en) | 1998-04-29 | 2000-07-18 | Medtronic, Inc. | Power consumption reduction in medical devices by employing different supply voltages |
US6070102A (en) | 1998-04-29 | 2000-05-30 | Medtronic, Inc. | Audible sound confirmation of programming an implantable medical device |
US6082367A (en) | 1998-04-29 | 2000-07-04 | Medtronic, Inc. | Audible sound communication from an implantable medical device |
US5916237A (en) | 1998-04-30 | 1999-06-29 | Medtronic, Inc. | Power control apparatus and method for a body implantable medical device |
US6270831B2 (en) | 1998-04-30 | 2001-08-07 | Medquest Products, Inc. | Method and apparatus for providing a conductive, amorphous non-stick coating |
US6090728A (en) | 1998-05-01 | 2000-07-18 | 3M Innovative Properties Company | EMI shielding enclosures |
US6266555B1 (en) | 1998-05-07 | 2001-07-24 | Medtronic, Inc. | Single complex electrogram display having a sensing threshold for an implantable medical device |
US5957857A (en) | 1998-05-07 | 1999-09-28 | Cardiac Pacemakers, Inc. | Apparatus and method for automatic sensing threshold determination in cardiac pacemakers |
US6066096A (en) | 1998-05-08 | 2000-05-23 | Duke University | Imaging probes and catheters for volumetric intraluminal ultrasound imaging and related systems |
US6118910A (en) | 1998-05-19 | 2000-09-12 | Agilent Technologies, Inc. | Method of aligning optical fibers to a multi-port optical assembly |
US6134478A (en) | 1998-06-05 | 2000-10-17 | Intermedics Inc. | Method for making cardiac leads with zone insulated electrodes |
US6029086A (en) | 1998-06-15 | 2000-02-22 | Cardiac Pacemakers, Inc. | Automatic threshold sensitivity adjustment for cardiac rhythm management devices |
US6275732B1 (en) | 1998-06-17 | 2001-08-14 | Cardiac Pacemakers, Inc. | Multiple stage morphology-based system detecting ventricular tachycardia and supraventricular tachycardia |
US6080829A (en) | 1998-06-24 | 2000-06-27 | Medtronic, Inc. | Silalkylenesiloxane copolymer materials and methods for their preparation |
FR2780290B1 (en) | 1998-06-26 | 2000-09-22 | Ela Medical Sa | ACTIVE IMPLANTABLE MEDICAL DEVICE SERVED AS A CARDIAC STIMULATOR, DEFIBRILLATOR AND / OR CARDIOVERTER, ESPECIALLY OF THE MULTI-SITE TYPE |
US6148222A (en) | 1998-07-10 | 2000-11-14 | Cardiocommand, Inc. | Esophageal catheters and method of use |
DE19833350C1 (en) | 1998-07-24 | 2000-03-09 | Bruker Analytik Gmbh | Sampling head used for taking NMR measurements includes a series condenser between high frequency line and measurement coil |
US6163724A (en) | 1998-09-18 | 2000-12-19 | Medtronic, Inc. | Microprocessor capture detection circuit and method |
US6029087A (en) | 1998-09-22 | 2000-02-22 | Vitatron Medical, B.V. | Cardiac pacing system with improved physiological event classification based on DSP |
JP2000102137A (en) | 1998-09-22 | 2000-04-07 | Sumitomo Wiring Syst Ltd | Optical cable, laying method thereof and wiring system using the same |
US6129745A (en) | 1998-10-23 | 2000-10-10 | Medtronic, Inc. | Medical device for automatic diagnosis of undersensing by timing |
US6016448A (en) | 1998-10-27 | 2000-01-18 | Medtronic, Inc. | Multilevel ERI for implantable medical devices |
US9061139B2 (en) * | 1998-11-04 | 2015-06-23 | Greatbatch Ltd. | Implantable lead with a band stop filter having a capacitor in parallel with an inductor embedded in a dielectric body |
US6701176B1 (en) * | 1998-11-04 | 2004-03-02 | Johns Hopkins University School Of Medicine | Magnetic-resonance-guided imaging, electrophysiology, and ablation |
US6144205A (en) | 1998-11-19 | 2000-11-07 | General Electric Company | Optical control of radio frequency antennae in a magnetic resonance imaging system |
US6052623A (en) | 1998-11-30 | 2000-04-18 | Medtronic, Inc. | Feedthrough assembly for implantable medical devices and methods for providing same |
US6278897B1 (en) | 1998-12-03 | 2001-08-21 | Medtronic, Inc | Medical electrical lead and introducer system |
US6148229A (en) | 1998-12-07 | 2000-11-14 | Medrad, Inc. | System and method for compensating for motion artifacts in a strong magnetic field |
US6169921B1 (en) | 1998-12-08 | 2001-01-02 | Cardiac Pacemakers, Inc. | Autocapture determination for an implantable cardioverter defibrillator |
US6275734B1 (en) | 1998-12-30 | 2001-08-14 | Pacesetter, Inc. | Efficient generation of sensing signals in an implantable medical device such as a pacemaker or ICD |
US6149313A (en) | 1998-12-31 | 2000-11-21 | Siecor Operations, Llc | Gender selectable fiber optic connector and associated fabrication method |
US6317633B1 (en) | 1999-01-19 | 2001-11-13 | Medtronic, Inc. | Implantable lead functional status monitor and method |
US6259954B1 (en) | 1999-02-18 | 2001-07-10 | Intermedics Inc. | Endocardial difibrillation lead with strain-relief coil connection |
US6256537B1 (en) | 1999-03-17 | 2001-07-03 | Medtronic, Inc. | Pacemaker system with inhibition of AV node for rate regulation during atrial fibrillation |
US6263242B1 (en) | 1999-03-25 | 2001-07-17 | Impulse Dynamics N.V. | Apparatus and method for timing the delivery of non-excitatory ETC signals to a heart |
US6223083B1 (en) | 1999-04-16 | 2001-04-24 | Medtronic, Inc. | Receiver employing digital filtering for use with an implantable medical device |
US6240317B1 (en) | 1999-04-30 | 2001-05-29 | Medtronic, Inc. | Telemetry system for implantable medical devices |
US6146415A (en) | 1999-05-07 | 2000-11-14 | Advanced Cardiovascular Systems, Inc. | Stent delivery system |
US6266566B1 (en) | 1999-05-21 | 2001-07-24 | Medtronic, Inc. | Waveform normalization in a medical device |
US6270457B1 (en) | 1999-06-03 | 2001-08-07 | Cardiac Intelligence Corp. | System and method for automated collection and analysis of regularly retrieved patient information for remote patient care |
US6142678A (en) | 1999-06-15 | 2000-11-07 | Jds Uniphase Inc. | Optical coupling |
US6278894B1 (en) | 1999-06-21 | 2001-08-21 | Cardiac Pacemakers, Inc. | Multi-site impedance sensor using coronary sinus/vein electrodes |
US6274265B1 (en) | 1999-07-21 | 2001-08-14 | Medtronic, Inc. | Method and system for evaluating an electrochemical cell for use with an implantable medical device |
US6272380B1 (en) | 1999-08-19 | 2001-08-07 | Medtronic, Inc. | Apparatus for treating atrial tachy arrhythmias with synchronized shocks |
US6208899B1 (en) | 1999-09-15 | 2001-03-27 | Pacesetter, Inc. | Implantable cardioversion device with automatic filter control |
US6675037B1 (en) | 1999-09-29 | 2004-01-06 | Regents Of The University Of Minnesota | MRI-guided interventional mammary procedures |
US6272377B1 (en) | 1999-10-01 | 2001-08-07 | Cardiac Pacemakers, Inc. | Cardiac rhythm management system with arrhythmia prediction and prevention |
US6544041B1 (en) | 1999-10-06 | 2003-04-08 | Fonar Corporation | Simulator for surgical procedures |
US6230060B1 (en) | 1999-10-22 | 2001-05-08 | Daniel D. Mawhinney | Single integrated structural unit for catheter incorporating a microwave antenna |
US6367984B1 (en) | 1999-11-10 | 2002-04-09 | Lucent Technologies, Inc. | Optical fiber adapter |
US6277078B1 (en) | 1999-11-19 | 2001-08-21 | Remon Medical Technologies, Ltd. | System and method for monitoring a parameter associated with the performance of a heart |
CA2398967A1 (en) | 2000-02-01 | 2001-08-09 | Albert C. Lardo | Magnetic resonance imaging transseptal needle antenna |
CA2403822A1 (en) | 2000-03-31 | 2001-10-11 | Surgi-Vision, Inc. | Systems for evaluating the urethra and the periurethral tissues |
US6925328B2 (en) * | 2000-04-20 | 2005-08-02 | Biophan Technologies, Inc. | MRI-compatible implantable device |
WO2001080940A1 (en) | 2000-04-20 | 2001-11-01 | Greatbio Technologies, Inc. | Mri-resistant implantable device |
US6418337B1 (en) | 2000-06-15 | 2002-07-09 | Autolitt Inc. | MRI guided hyperthermia surgery |
US6254632B1 (en) | 2000-09-28 | 2001-07-03 | Advanced Cardiovascular Systems, Inc. | Implantable medical device having protruding surface structures for drug delivery and cover attachment |
US6618620B1 (en) | 2000-11-28 | 2003-09-09 | Txsonics Ltd. | Apparatus for controlling thermal dosing in an thermal treatment system |
US6574497B1 (en) | 2000-12-22 | 2003-06-03 | Advanced Cardiovascular Systems, Inc. | MRI medical device markers utilizing fluorine-19 |
US20020116028A1 (en) | 2001-02-20 | 2002-08-22 | Wilson Greatbatch | MRI-compatible pacemaker with pulse carrying photonic catheter providing VOO functionality |
US20020162605A1 (en) | 2001-03-05 | 2002-11-07 | Horton Joseph A. | Bulk metallic glass medical instruments, implants, and methods of using same |
US20070088416A1 (en) | 2001-04-13 | 2007-04-19 | Surgi-Vision, Inc. | Mri compatible medical leads |
US7787958B2 (en) * | 2001-04-13 | 2010-08-31 | Greatbatch Ltd. | RFID detection and identification system for implantable medical lead systems |
US7899551B2 (en) * | 2001-04-13 | 2011-03-01 | Greatbatch Ltd. | Medical lead system utilizing electromagnetic bandstop filters |
US6712844B2 (en) | 2001-06-06 | 2004-03-30 | Advanced Cardiovascular Systems, Inc. | MRI compatible stent |
US6871091B2 (en) | 2001-10-31 | 2005-03-22 | Medtronic, Inc. | Apparatus and method for shunting induced currents in an electrical lead |
US6944489B2 (en) | 2001-10-31 | 2005-09-13 | Medtronic, Inc. | Method and apparatus for shunting induced currents in an electrical lead |
US7050855B2 (en) | 2002-01-29 | 2006-05-23 | Medtronic, Inc. | Medical implantable system for reducing magnetic resonance effects |
US6985775B2 (en) | 2002-01-29 | 2006-01-10 | Medtronic, Inc. | Method and apparatus for shunting induced currents in an electrical lead |
US20030144720A1 (en) | 2002-01-29 | 2003-07-31 | Villaseca Eduardo H. | Electromagnetic trap for a lead |
US7769426B2 (en) | 2002-04-23 | 2010-08-03 | Ethicon Endo-Surgery, Inc. | Method for using an MRI compatible biopsy device with detachable probe |
US20050288752A1 (en) | 2003-08-25 | 2005-12-29 | Biophan Technologies, Inc. | Medical device with an electrically conductive anti-antenna member |
US20050288751A1 (en) | 2003-08-25 | 2005-12-29 | Biophan Technologies, Inc. | Medical device with an electrically conductive anti-antenna member |
JP4734951B2 (en) * | 2005-02-18 | 2011-07-27 | 株式会社日立製作所 | Presence management server and system |
-
2004
- 2004-09-21 US US10/946,026 patent/US8527046B2/en not_active Expired - Fee Related
-
2012
- 2012-02-29 US US13/408,933 patent/US20120158080A1/en not_active Abandoned
-
2013
- 2013-03-15 US US13/838,385 patent/US20130218250A1/en not_active Abandoned
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20030050557A1 (en) * | 1998-11-04 | 2003-03-13 | Susil Robert C. | Systems and methods for magnetic-resonance-guided interventional procedures |
US6539253B2 (en) * | 2000-08-26 | 2003-03-25 | Medtronic, Inc. | Implantable medical device incorporating integrated circuit notch filters |
US20070288058A1 (en) * | 2001-04-13 | 2007-12-13 | Greatbatch Ltd. | Band stop filter employing a capacitor and an inductor tank circuit to enhance mri compatibility of active implantable medical devices |
Also Published As
Publication number | Publication date |
---|---|
US8527046B2 (en) | 2013-09-03 |
US20120158080A1 (en) | 2012-06-21 |
US20050043761A1 (en) | 2005-02-24 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US8527046B2 (en) | MRI-compatible implantable device | |
US6925328B2 (en) | MRI-compatible implantable device | |
US6795730B2 (en) | MRI-resistant implantable device | |
EP2136877B1 (en) | Mri compatible implantable medical devices | |
US7013174B2 (en) | Electromagnetic interference immune tissue invasive system | |
US6829509B1 (en) | Electromagnetic interference immune tissue invasive system | |
US9345882B2 (en) | Implantable medical device voltage divider circuit for mitigating electromagnetic interference | |
US20110112599A1 (en) | Mri signal filtering for implantable medical device | |
Stevenson et al. | Issues and design solutions associated with performing MRI scans on patients with active implantable medical devices |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |