US20090093731A1 - Cardiac rhythm management system with noise detector - Google Patents

Cardiac rhythm management system with noise detector Download PDF

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US20090093731A1
US20090093731A1 US12333008 US33300808A US2009093731A1 US 20090093731 A1 US20090093731 A1 US 20090093731A1 US 12333008 US12333008 US 12333008 US 33300808 A US33300808 A US 33300808A US 2009093731 A1 US2009093731 A1 US 2009093731A1
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signal
cardiac
sample
noise
threshold
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Surekha Palreddy
Carlos Ricci
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Surekha Palreddy
Carlos Ricci
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    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61NELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N1/00Electrotherapy; Circuits therefor
    • A61N1/18Applying electric currents by contact electrodes
    • A61N1/32Applying electric currents by contact electrodes alternating or intermittent currents
    • A61N1/36Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
    • A61N1/362Heart stimulators
    • A61N1/37Monitoring; Protecting
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61NELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N1/00Electrotherapy; Circuits therefor
    • A61N1/18Applying electric currents by contact electrodes
    • A61N1/32Applying electric currents by contact electrodes alternating or intermittent currents
    • A61N1/36Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
    • A61N1/362Heart stimulators
    • A61N1/37Monitoring; Protecting
    • A61N1/3718Monitoring of or protection against external electromagnetic fields or currents
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10STECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S128/00Surgery
    • Y10S128/901Suppression of noise in electric signal

Abstract

A system, method, or device determines whether noise is present on a sampled and/or digitized sensed intrinsic cardiac signal based on a moving count of turning/inflection points of the signal. If noise is detected, the manner in which the cardiac signal is acquired, or the manner in which the device operates in response to the acquired cardiac signal (or both) is altered to reduce the risk of erroneously detecting noise as a heart depolarization and, therefore, inappropriately triggering or withholding therapy.

Description

    CROSS-REFERENCE TO RELATED APPLICATION(S)
  • [0001]
    This application is a division of U.S. patent application Ser. No. 11/110,490, filed on Apr. 20, 2005, which is a division of U.S. patent application Ser. No. 10/046,650, filed on Oct. 29, 2001, now issued as U.S. Pat. No. 6,892,092, the specifications of which are incorporated by reference herein.
  • TECHNICAL FIELD
  • [0002]
    This document relates generally to cardiac rhythm management systems, devices, and methods, and particularly, but not by way of limitation, to a cardiac rhythm management system with a noise detector that reduces the likelihood that noise on a cardiac signal is erroneously sensed as a cardiac depolarization.
  • BACKGROUND
  • [0003]
    When functioning properly, the human heart maintains its own intrinsic rhythm. Its sinoatrial node generates intrinsic electrical cardiac signals that depolarize the atria, causing atrial heart contractions. Its atrioventricular node then passes the intrinsic cardiac signal to depolarize the ventricles, causing ventricular heart contractions. These intrinsic cardiac signals can be sensed on a surface electrocardiogram (ECG) obtained from electrodes placed on the patient's skin, or from electrodes implanted within the patient's body. The surface ECG waveform, for example, includes artifacts associated with atrial depolarizations (“P-waves”) and those associated with ventricular depolarizations (“QRS complexes”).
  • [0004]
    A normal heart is capable of pumping adequate blood throughout the body's circulatory system. However, some people have irregular cardiac rhythms, referred to as cardiac arrhythmias. Moreover, some patients have poorly spatially-coordinated heart contractions. In either case, diminished blood circulation may result. For such patients, a cardiac rhythm management system may be used to improve the rhythm and/or spatial coordination of heart contractions. Such systems are often implanted in the patient and deliver therapy to the heart.
  • [0005]
    Cardiac rhythm management systems include, among other things, pacemakers, also referred to as pacers. Pacers deliver timed sequences of low energy electrical stimuli, called pace pulses, to the heart, such as via an intravascular leadwire or catheter (referred to as a “lead”) having one or more electrodes disposed in or about the heart. Heart contractions are initiated in response to such pace pulses (this is referred to as “capturing” the heart). By properly timing the delivery of pace pulses, the heart can be induced to contract in proper rhythm, greatly improving its efficiency as a pump. Pacers are often used to treat patients with bradyarrhythmias, that is, hearts that beat too slowly, or irregularly. Such pacers may also coordinate atrial and ventricular contractions to improve pumping efficiency. Cardiac rhythm management systems also include cardiac resynchronization therapy (CRT) devices for coordinating the spatial nature of heart depolarizations for improving pumping efficiency. For example, a CRT device may deliver appropriately timed pace pulses to different locations of the same heart chamber to better coordinate the contraction of that heart chamber, or the CRT device may deliver appropriately timed pace pulses to different heart chambers to improve the manner in which these different heart chambers contract together.
  • [0006]
    Cardiac rhythm management systems also include defibrillators that are capable of delivering higher energy electrical stimuli to the heart. Such defibrillators include cardioverters, which synchronize the delivery of such stimuli to portions of sensed intrinsic heart activity signals. Defibrillators are often used to treat patients with tachyarrhythmias, that is, hearts that beat too quickly. Such too-fast heart rhythms also cause diminished blood circulation because the heart isn't allowed sufficient time to fill with blood before contracting to expel the blood. Such pumping by the heart is inefficient. A defibrillator is capable of delivering a high energy electrical stimulus that is sometimes referred to as a defibrillation countershock, also referred to simply as a “shock.” The countershock interrupts the tachyarrhythmia, allowing the heart to reestablish a normal rhythm for the efficient pumping of blood. In addition to pacers, CRT devices, and defibrillators, cardiac rhythm management systems also include devices that combine these functions, as well as monitors, drug delivery devices, and any other implantable or external systems or devices for diagnosing or treating the heart.
  • [0007]
    One problem faced by cardiac rhythm management devices is in detecting the atrial and/or ventricular depolarizations in the intrinsic electrical cardiac signals, since the delivery of therapy to the heart is typically based at least in part on the timing and/or morphology of such detected depolarizations. To detect a depolarization event, the cardiac signal may be amplified, filtered, and/or level-detected (e.g., to determine whether an artifact exceeds a particular threshold level associated with an atrial or ventricular depolarization). Depolarization detection is complicated, however, by the fact that the intrinsic cardiac signals may include noise unrelated to the heart depolarization. The noise may arise from a variety of sources, including, among other things: myopotentials associated with skeletal muscle contractions; a loose or fractured leadwire providing intermittent contact between the device and the heart; or, electromagnetic interference from AC power provided to nearby electrical equipment (e.g., 60 Hertz), from nearby switching power supplies, from a nearby electrosurgical tool, from communication equipment, or from electronic surveillance equipment. Noise erroneously detected as a heart depolarization may inappropriately inhibit bradyarrhythmia pacing therapy or cardiac resynchronization therapy, or may inappropriately trigger tachyarrhythmia shock therapy. For these reasons, the present inventor has recognized a need for detecting the presence of such noise, and using this information in such a way that the occurrence of such consequences can be reduced or avoided altogether.
  • SUMMARY
  • [0008]
    This document discusses, among other things, a system, method, or device that determines whether noise is present on a sampled and/or digitized sensed intrinsic cardiac signal based on a moving count of turning/inflection points of the signal. If noise is detected, the manner in which the cardiac signal is acquired, or the manner in which the device operates in response to the acquired cardiac signal (or both) is altered to reduce the risk of erroneously detecting noise as a heart depolarization and, therefore, inappropriately triggering or withholding therapy.
  • [0009]
    In one example, this document discusses a method of determining whether a sampled cardiac signal is noisy. The method includes determining whether an evaluation sample of the cardiac signal is a turning point with respect to previous and subsequent samples. A number of the turning points is counted over a predetermined plurality of cardiac samples. A window that includes the predetermined plurality of cardiac samples is deemed to be noisy if the number of turning points exceeds a threshold value.
  • [0010]
    In another example, this document discusses a system. The system includes a first electrode associated with a heart. A cardiac signal detector is coupled to the first electrode. The cardiac signal detector includes a detector output providing a sampled cardiac signal. A signal processor circuit determines, over a predetermined plurality of cardiac signal samples, whether an evaluation sample of the cardiac signal is a turning point with respect to previous and subsequent samples. The signal processor circuit deems a portion of the cardiac signal to be noisy if a number of turning points exceeds a threshold value for the predetermined plurality of cardiac signal samples. Other aspects of the invention will be apparent on reading the following detailed description of the invention and viewing the drawings that form a part thereof.
  • BRIEF DESCRIPTION OF THE DRAWINGS
  • [0011]
    In the drawings, which are offered by way of example, and not by way of limitation, and which are not necessarily drawn to scale, like numerals describe substantially similar components throughout the several views. Like numerals having different letter suffixes represent different instances of substantially similar components.
  • [0012]
    FIG. 1 is a block diagram illustrating generally portions of a cardiac rhythm management system and portions of an environment in which it is used.
  • [0013]
    FIG. 2 is a graph illustrating generally a relatively noise-free cardiac signal.
  • [0014]
    FIG. 3 is a graph illustrating generally a relatively noisy cardiac signal.
  • [0015]
    FIG. 4 is a flow chart illustrating generally one example of a noise detection technique.
  • [0016]
    FIG. 5 is a signal graph of a sampled cardiac signal, illustrating generally one technique for determining whether an evaluation sample is a turning/inflection point.
  • [0017]
    FIG. 6 is a signal graph of the sampled cardiac signal of FIG. 5, illustrating, among other things, that the turning/inflection point evaluation may be performed at a different frequency from that at which the cardiac signal was sampled.
  • [0018]
    FIG. 7 is a block diagram illustrating generally, by way of example, but not by way of limitation, several possible operational adjustments that may be performed in response to a noisy cardiac signal.
  • [0019]
    FIG. 8 is a block diagram illustrating an alternative example of a system including a second FIFO counter for performing the noise detection technique illustrated in the flow chart of FIG. 9.
  • [0020]
    FIG. 9 is a flow chart illustrating generally another example of a noise detection technique.
  • [0021]
    FIG. 10 is a schematic/block diagram illustrating generally one example of a turning point detector for operating upon an analog acquired cardiac signal x(t) and providing an indication of whether a particular sample of the acquired cardiac signal x(t) represents a turning point in the acquired cardiac signal x(t).
  • [0022]
    FIG. 11 is a schematic/block diagram illustrating generally another example of a turning point detector for operating upon an analog acquired cardiac signal x(t) and providing an indication of whether a particular sample of the acquired cardiac signal x(t) represents a turning point in the acquired cardiac signal x(t).
  • DETAILED DESCRIPTION
  • [0023]
    In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that the embodiments may be combined, or that other embodiments may be utilized and that structural, logical and electrical changes may be made without departing from the spirit and scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims and their equivalents.
  • [0024]
    FIG. 1 is a block diagram illustrating generally portions of a cardiac rhythm management system 100 and portions of an environment in which it is used. In this example, system 100 includes a cardiac rhythm management device 102 coupled to a heart 104 by one or more electrodes associated with heart 104, such as for sensing intrinsic cardiac signals and/or for delivering energy or other therapy to heart 104. System 100 also includes a programmer or other remote interface 106, which is wirelessly or otherwise communicatively coupled to a telemetry circuit 108 or other communication circuit in device 102. Device 102 includes a pacer, a defibrillator, a cardiac resynchronization therapy (CRT) device, a monitor, a device that combines more than one of these functions, or any other implantable or external device for diagnosing and/or treating the heart. In one example, device 102 is sized and shaped for being pectorally or abdominally implanted in a human patient. The electrode(s) coupling device 102 to heart 104 may include an intravascular electrode, an intracardiac electrode, an epicardial electrode, or a housing or a header electrode located on a housing of device 102 or a header attached thereto, or any combination of the above. In some configurations, such as where portion(s) of device 102 are external to the patient, the electrode(s) coupling device 102 to heart 104 may include a skin surface electrode external to the patient. The electrodes may be associated with the heart for bipolar (i.e., two electrodes that are relatively close together) or for unipolar (i.e., two electrodes that are farther apart) signal sensing or therapy energy delivery (e.g., pacing pulse or shocks).
  • [0025]
    In the example of FIG. 1, device 102 includes a cardiac signal detector 110 having an input coupled to heart 104 by electrodes associated with heart 104 in a suitable manner for sensing an intrinsic cardiac signal. Detector 110 need not actually extract heart depolarizations from the sensed intrinsic cardiac signal; such functions may be performed elsewhere in device 102. Detector 110 typically includes a sense amplifier for acquiring and amplifying the cardiac signal. Detector 110 may also include one or more continuous-time and/or discrete time (e.g., switched-capacitor) filter circuits, such as for selectively emphasizing the desired heart depolarization information relative to other acquired signal content. Detector 110 may also include an analog-to-digital converter (ADC) to convert continuous-time and/or discrete time samples into numerical representations of those samples. Detector 110 may also include one or more digital filters (or other digital signal processing circuitry) following the ADC, such as for selectively emphasizing the desired heart depolarization information relative to other acquired signal content. Detector 110 also includes an output providing a periodically sampled data cardiac signal x(n) to a cardiac signal processor module 112 of controller 114. Controller 114 is capable of sequencing through various control states such as, for example, by using a digital microprocessor having executable instructions stored in an associated instruction memory circuit, a microsequencer, or a state machine. In operation, by executing these instructions, controller 114 provides the functionality of cardiac signal processor module 112, as well as providing control signals to cardiac signal detector 110 and an energy output circuit 118. In one example, cardiac signal processor module 112 includes a first-in-first-out (FIFO) memory and counter 115 and a noise flag 116 (such as, for example, a bit in a register) to assist in the noise detection technique discussed herein. Energy output circuit 118 provides pacing or resynchronization pulses, defibrillation shocks, or other appropriate cardiac therapy to heart 104. Device 102 also includes a battery or other power source 120.
  • [0026]
    FIG. 2 is a graph illustrating generally a relatively noise-free cardiac signal 200 obtained from electrodes associated with heart 104. FIG. 3 is a graph illustrating generally a relatively noisy cardiac signal 300 similarly obtained from electrodes associated with heart 104. In the example of FIG. 3, the additional noise may make the underlying heart chamber depolarizations difficult to detect, since the noise may include frequencies within the passband of the depolarizations and may, therefore, erroneously be level-detected as an actual heart depolarization.
  • [0027]
    FIG. 4 is a flow chart illustrating generally one example of a noise detection technique performed by cardiac signal processor 112 on the sampled cardiac signal x(n) that is output by cardiac signal detector 110. At 400, FIFO counter 115 and noise flag 116 are initialized. In one example, FIFO counter 115 includes an N-bit shift register, which is initialized at 400 to all zeros, and also includes an associated counter that outputs a sum of the number of ones in the N-bit shift register. Noise flag 116 is also initialized to zero, indicating that noise has not yet been detected as being present on the cardiac signal x(n). At 402, a cardiac signal sample is obtained. At 404, a previously-obtained evaluation sample is considered as to whether it represents a turning point (also referred to as an inflection point), with respect to a cardiac signal sample previous to the evaluation sample, and with respect to a cardiac signal sample subsequent to the evaluation sample. If, at 404, the evaluation sample is deemed a turning point, then at 406, a logic “1” is shifted into the N-bit FIFO shift register, the earliest-stored bit in the shift register is discarded, and FIFO counter 115 is then updated to represent the new sum of the number of ones in the N-bit shift register. Otherwise, where the evaluation sample is not deemed a turning point, then at 408 a logic “0” is shifted into the N-bit shift register, the earliest stored bit in the shift register is discarded, and FIFO counter 115 is updated to represent the new sum of the number of ones in the N-bit shift register. After 406 or 408, at 410, the sum of the ones in the N-bit shift register provided by FIFO counter 115 is compared to a predetermined threshold value. If the sum exceeds the predetermined threshold value, then at 412 the noise flag is set to indicate that noise is present on the sampled cardiac signal x(n) obtained from cardiac signal detector 110. Otherwise, where the sum does not exceed the predetermined threshold value, then at 414 the noise flag is cleared to indicate that noise is not present on the sampled cardiac signal x(n) obtained from cardiac signal detector 110. After 412 or 414, at 416, the noise flag is evaluated to determine whether noise is present on the sampled cardiac signal x(n), as indicated by the noise flag being set. If the cardiac signal is noisy, then, at 418, one or more noise adjustment parameters and/or techniques is applied to the cardiac signal detection by cardiac signal detector 110 or to the response of device 102 to the acquired cardiac signal. Otherwise, where the cardiac signal is not noisy, then, at 420, one or more default parameters and/or techniques is applied to the cardiac signal detection by cardiac signal detector 110 or to the response of device 102 to the acquired cardiac signal. After 418 or 420, at 422, another cardiac signal sample is obtained by cardiac signal processor 112, so that another evaluation sample can be considered to determine whether the evaluation sample is a turning or inflection point, at 404. Additionally, device 102 may optionally communicate the state of the noise flag to an external programmer or other remote user interface 106 via telemetry circuit 108. Therefore, FIG. 4 illustrates, among other things, that a significant proportion of turning or inflection points in the sampled cardiac signal may indicate the presence of noise, which indication, in turn, may be used to modify the way in which the cardiac signal is obtained so as to reduce the likelihood that noise deflections are erroneously interpreted as heart depolarizations.
  • [0028]
    In the example FIG. 4, the counter may alternatively be compared to a multi-valued threshold, such as for providing hysteresis. In one such example, the threshold includes two distinct values: a majority threshold value and a quorum threshold value. The majority threshold value typically exceeds the quorum threshold value. At 400, the threshold is set to the higher majority value. At 412, upon setting the noise flag, the threshold is then set to the lower quorum value. At 414, upon clearing the noise flag, the threshold is then set to the higher majority value. In operation, once the counter exceeds the majority value, the threshold is then decreased to the quorum value. This effectively adds hysteresis to reduce or avoid chatter around the quorum threshold value.
  • [0029]
    FIG. 5 is a signal graph of a sampled cardiac signal 500, illustrating generally one technique for determining (such as performed at 404 of FIG. 4) whether an evaluation sample 502 is a turning or inflection point. In this example, the presence of noise is determined from: the evaluation sample 502, x(i); a previous sample 504, such as immediately preceding sample x(i−1); and a subsequent sample 506, such as immediately succeeding sample x(i+1). In this example, using the three samples, x(i), x(i−1), and x(i+1), the following equation is evaluated:
  • [0000]

    TP=sign{x(i)-x(i−1)}*sign{x(i+1)-x(i)}  (1)
  • [0000]
    Equation 1 illustrates taking the sign of a first difference x(i)-x(i−1). A negative sign represents a negative-going signal excursion between the i sample and the (i−1) sample. A positive sign represents a positive-going signal excursion therebetween. Equation 1 also illustrates taking the sign of a second difference x(i+1)-x(i). A negative sign represents a negative going signal excursion between the (i+1) sample and the i sample. A positive sign represents a positive-going signal excursion therebetween. Thus, the product of the signs of the first and second differences, TP, will be −1 whenever the signal excursions on either side of the evaluation sample x(i) differ in direction or sense of their slopes, in which case the evaluation sample x(i) represents a turning/inflection point. Evaluation of the three samples then is shifted rightward on the signal illustration of FIG. 5, such as when another cardiac signal sample is obtained at 422 of FIG. 4, so that the number of turning/inflection points in a sliding window preceding the evaluation sample x(i) can be counted and compared to a threshold to determine whether a sufficient number of turning points has been detected to deem the cardiac signal to be noisy.
  • [0030]
    In the above example, choice of the x(i), x(i−1), and x(i+1) samples is simply a matter of convenience for ease of illustration of the above turning point noise detection technique. In particular, this example is not intended to imply a noncausal system. The above-discussed technique (or the other techniques discussed in this document) also applies to any other choice of sequential samples such as, for example, x(i), x(i−1), and x(i−2), or alternatively, x(i−1), x(i−2), and x(i−3), etc.
  • [0031]
    In a slightly modified example, a threshold requirement is added to the above technique for determining whether an evaluation sample 502 is a turning or inflection point. The threshold determines a noise floor below which the noise detection is substantially no longer sensitive. In one such example, a TP is evaluated according to Equation 1, but if |x(i)-x(i−1)|<TH1, or if |x(i+1)−x(i)|<TH2, then TP is set to a value different from −1 (e.g., set to 1) to indicate that evaluation sample 502 is not a turning point. TH1, and TH2 may take on the same, or different, threshold values. In one example, TH1=TH2=2 counts of an 8-bit A/D converter signal representing the sampled cardiac signal x(n). This suppresses excessive sensitivity to noise occurring at or beneath the level of 1 least significant bit (LSB). A similar threshold requirement may also be imposed on the other turning point evaluation techniques discussed in this document.
  • [0032]
    In one example, TP is a binary-valued signal that is high (“1”) if the evaluation sample 502 is a turning point, and low (“0”) otherwise. In another example, TP is a tri-state signal that is “-1” if the evaluation sample 502 is an inflection point, “0” if the slopes on either side of evaluation sample 502 are too small to determine whether evaluation sample 502 is an inflection point, and “1” if the slopes on either side of evaluation sample 502 are the same sign, such that evaluation sample 502 is not a turning point.
  • [0033]
    FIG. 6 is a signal graph of the sampled cardiac signal 500 of FIG. 5, illustrating that the turning/inflection point evaluation need not be performed at the same frequency at which the cardiac signal was sampled. In the example of FIG. 6, the turning/inflection point determination is based on the evaluation sample 502, x(i); a previous sample 504, such as preceding sample x(i−2); and a subsequent sample 506, such as succeeding sample x(i+2). Thus, Equation 1 can be expressed more generally as:
  • [0000]

    TP=sign{x(i)-x(i−K1)}*sign{x(i+K2)−x(i)}  (2)
  • [0000]
    where K1 and K2 are integer offset constants which may, but need not, be the same value. Moreover, the turning point evaluation may be carried out repeatedly over different subsampling frequencies of the frequency at which the cardiac signal was sampled. In such a technique, a vector of TP values corresponding to the different subsampling frequencies may provide useful information about the frequency content of the noise, or may allow the noise detection to be tailored to noise having a particular frequency content. In one example, this is accomplished by varying K between different values, and, at the different values of K: (1) determining, for each sample, TP=sign{x(i)-x(i−K)}*sign{x(i+K)−x(i)}, in which x(i) is the ith sample of the sampled cardiac signal x(n), and in which K is an integer offset, and in which TP=−1 is used as at least one factor indicating that x(i) is a turning point; and (2) deeming the cardiac signal to be noisy if a number of turning points occurring during a fixed number of samples preceding x(i) exceeds a threshold value.
  • [0034]
    FIG. 7 is a block diagram illustrating generally, by way of example, but not by way of limitation, several possible operational adjustments that may be performed by device 102 at 418 of FIG. 4 in response to noise flag 116 being set as determined at 416 of FIG. 4. In one example, at 418A, a sense amplifier gain in cardiac signal detector 110 is adjusted (e.g., decreased) when noise is present to avoid erroneously detecting the noise as a heart depolarization. For example, in a switched-capacitor sense amplifier, controller 114 provides a control signal to cardiac signal detector 110 to use different gain-setting switched-capacitors. This noise-dependent gain adjustment effectively uses noise detection as input to an automatic gain control (AGC) feedback system. In an alternative example, at 418B, a frequency selectivity characteristic of the sense amplifier or other cardiac signal filter is adjusted when cardiac signal noise is present to increase the selectivity to the heart depolarization frequencies of interest and more aggressively discriminate against noise at nearby higher or lower frequencies. Alternatively, at 418C, a sensitivity is adjusted (e.g., decreased) in the presence of cardiac signal noise. This may be accomplished, for example, by raising a level-detector threshold for heart depolarizations. Alternatively, at 418D, a sensing electrode configuration is adjusted. For example, where first and second pairs of bipolar sensing electrodes are associated with the same heart chamber, and the first pair of sensing electrodes yields a noisy signal, cardiac signal detector 110 may be decoupled from the first pair of sensing electrodes and coupled instead to the second pair of sensing electrodes in order to try to obtain a less noisy signal. This may be effective, for example, for noise resulting from a fractured lead or other poor connection between the first pair of sensing electrodes and cardiac signal detector 110. In other examples, the sensing electrode configuration may be switched from unipolar sensing to bipolar sensing or vice-versa. In an alternative example, at 418E, noise present on a first electrode pair, for example, may trigger corroboration of heart depolarization detection with an independent second sensing channel that is coupled to a second heart electrode pair. In this example, a heart depolarization detected at the first electrode pair by a first cardiac signal detector would require verification as also having been detected at the second electrode pair by a second cardiac signal detector, thereby reducing the system's susceptibility to erroneously detecting noise as a heart depolarization and thereby inappropriately triggering or withholding therapy to heart 104.
  • [0035]
    The above noise detection techniques were tested on data acquired from a human heart from electrodes configured for bipolar sensing. The resulting intrinsic cardiac signal was amplified by a high input impedance continuous-time amplifier and a switched-capacitor discrete-time sense amplifier. Filtering was performed to remove frequencies outside of the range of about 20 Hz to about 130 Hz. The resulting sampled cardiac signal was provided at a sampling frequency of about 200 Hz. The above-described noise detection technique was used in which the turning/inflection points were determined from an evaluation sample, an immediately preceding sample, and an immediately succeeding sample. A moving window (e.g., FIFO shift-register length) of N=10 samples was used. A threshold value of 4 turning/inflection points in the N=10 samples was taken to indicate the presence of noise on the cardiac signal. The results showed good discrimination between the cardiac signal noise and a true fine ventricular fibrillation waveform, which should be sensed as true ventricular heart depolarizations rather than noise.
  • [0036]
    FIG. 8 is a block diagram illustrating an alternative example of a system 100 in which device 102 includes a second FIFO counter 800 for performing the noise detection technique illustrated in the flow chart of FIG. 9. In FIG. 9, which shares certain similarities with FIG. 4, first FIFO counter 115, a second FIFO counter 800, and noise flag 116 are initialized. In one example, first FIFO counter 115 includes an N-bit shift register, which is initialized at 400 to all zeros, and also includes an associated first counter that outputs a sum of the number of ones in the N-bit shift register. In this example, second FIFO counter 800 includes an M-bit shift register, which is initialized at 400 to all zeros, and also includes an associated second counter that outputs a sum of the number of ones in the M-bit shift register. Noise flag 116 is also initialized to zero, indicating that noise has not yet been detected as being present on the cardiac signal x(n).
  • [0037]
    At 402, a cardiac signal sample is obtained. At 404, a previously-obtained evaluation sample is considered as to whether it represents a turning point (also referred to as an inflection point), with respect to a cardiac signal sample previous to the evaluation sample, and with respect to a cardiac signal sample subsequent to the evaluation sample. If, at 404, the evaluation sample is deemed a turning point, then at 406, a logic “1” is shifted into the N-bit first FIFO shift register, the earliest-stored bit in the shift register is discarded, and first FIFO counter 115 is then updated to represent the new sum of the number of ones in the N-bit shift register. Otherwise, where the evaluation sample is not deemed a turning point, then at 408 a logic “0” is shifted into the N-bit shift register, the earliest stored bit in the shift register is discarded, and first FIFO counter 115 is updated to represent the new sum of the number of ones in the N-bit shift register.
  • [0038]
    After 406 or 408, at 410, the sum of the ones in the N-bit shift register provided by first FIFO counter 115 is compared to a first predetermined threshold value. If the sum exceeds the predetermined threshold value, then at 900 a logic “1” is shifted into the M-bit second FIFO shift register, the earliest-stored bit in the shift register is discarded, and second FIFO counter 800 is then updated to represent the new sum of the number of ones in the M-bit shift register. Otherwise, where the evaluation sample is not deemed a turning point, then at 905 a logic “0” is shifted into the M-bit shift register, the earliest stored bit in the shift register is discarded, and second FIFO counter 800 is updated to represent the new sum of the number of ones in the M-bit shift register. After 900 or 905, at 910, the sum of the ones in the M-bit shift register provided by second FIFO counter 800 is compared to a second predetermined threshold value, which may be different than the first predetermined threshold value. If the sum exceeds the second predetermined threshold value, then at 412 the noise flag is set to indicate that noise is present on the sampled cardiac signal x(n) obtained from cardiac signal detector 110. Otherwise, where the sum does not exceed the predetermined threshold value, then at 414 the noise flag is cleared to indicate that noise is not present on the sampled cardiac signal x(n) obtained from cardiac signal detector 110.
  • [0039]
    After 412 or 414, at 416, the noise flag is evaluated to determine whether noise is present on the sampled cardiac signal x(n), as indicated by the noise flag being set. If the cardiac signal is noisy, then, at 418, one or more noise adjustment parameters and/or techniques is applied to the cardiac signal detection by cardiac signal detector 110 or to the response of device 102 to the acquired cardiac signal. Otherwise, where the cardiac signal is not noisy, then, at 420, one or more default parameters and/or techniques is applied to the cardiac signal detection by cardiac signal detector 110 or to the response of device 102 to the acquired cardiac signal. After 418 or 420, at 422, another cardiac signal sample is obtained by cardiac signal processor 112, so that another evaluation sample can be considered to determine whether the evaluation sample is a turning or inflection point, at 404. Additionally, device 102 may optionally communicate the state of the noise flag to an external programmer or other remote user interface 106 via telemetry circuit 108. Therefore, FIG. 9 illustrates, among other things, an example in which the output of the N-bit shift register indicates whether a particular “window” is noisy, and the output of the M-bit shift register indicates whether a predetermined number of “windows” is noisy, such that the signal should be deemed noisy. FIGS. 4 and 9 illustrate the process of cascading additional windows, together with corresponding counters and thresholds. This process can be extended to cascading any number of additional windows, as needed.
  • [0040]
    As discussed above with respect to FIG. 4, the first and second counters may alternatively be compared to respective multi-valued thresholds, such as for providing hysteresis. In one such example, each of the first and second thresholds includes two distinct values: a majority threshold value and a quorum threshold value. The majority threshold value typically exceeds its corresponding quorum threshold value. At 400, the first threshold is set to its higher majority value, and the second threshold is likewise set to its higher majority value. At 900, if the first counter exceeds the first threshold, the first threshold is then set to its lower quorum value. At 905, if the first counter does not exceed the first threshold, then the first threshold is then set to the higher majority value. At 412, upon setting the noise flag, the second threshold is then set to its lower quorum value. At 414, upon clearing the noise flag, the second threshold is then set to its higher majority value. In operation, once each counter exceeds its majority value, its threshold is then decreased to its quorum value. This effectively adds hysteresis to reduce or avoid chatter around the respective quorum threshold values.
  • [0041]
    FIG. 10 is a schematic/block diagram illustrating generally one example of a turning point detector 1000, suitable for being included within cardiac signal detector 110, for operating upon an analog acquired cardiac signal x(t) at input node 1002 and providing an indication TP at output node 1004 of whether a particular sample of the acquired cardiac signal x(t) represents a turning point in the acquired cardiac signal x(t). In the example of FIG. 10, the acquired continuous time cardiac signal x(t) is input to a first sample-and-hold (S/H) circuit 1006, to create a delayed sample x(t-T1) output at node 1008. This, in turn is input to a second S/H 1010, to create a further delayed sample x(t-T2) at node 1012. The appropriate delay is obtained by clocking S/H circuits 1006 and 1010 by one or more appropriately timed clock signals, such as CL1 and CL2 received at clocking input nodes 1014 and 1016 of S/H 1006 and S/H 1010, respectively.
  • [0042]
    The samples x(t), x(t-T1), and x(t-T2) are received at inputs of differential amplifiers/buffers 1018A-B, which may provide gain greater than one, unity gain, or attenuation, as appropriate. In this example, x(t-T1) is received at a negative input of amplifier 1018A and at a positive input of amplifier 1018B, x(t) is received at a positive input of amplifier 1018A, and x(t-T2) is received at a negative input of amplifier 1018B. Amplifier 1018A provides an output representing the difference [x(t)-x(t-T1)] at node 1020A to first and second comparators 1022A-B. Amplifier 1018B provides an output representing the difference [x(t-T1)-x(t-T2)] at node 1020B to third and fourth comparators 1022C-D.
  • [0043]
    Each of comparators 1022A-D also receive a reference voltage input. For example, comparator 1022A receives at node 1024A a reference voltage VT1, comparator 1022B receives at node 1024B a reference voltage VT2, comparator 1022C receives at node 1024C a reference voltage VT3, and comparator 1022D receives at node 1024D a reference voltage VT4, In this example, VT1, VT3 are slightly negative voltages, and VT2, VT4 are slightly positive voltages.
  • [0044]
    In this example, comparator 1022A outputs a binary-valued signal Y1 at node 1026A that is high when the difference [x(t)-x(t-T1)]>VT1 and low otherwise, comparator 1022B outputs a binary-valued signal Y2 at node 1026B that is high when the difference [x(t)-x(t-T1)]>VT2 and low otherwise, comparator 1022C outputs a binary-valued signal Y3 at node 1026C that is high when the difference [x(t-T)-x(t-T2)]>VT3 and low otherwise, and comparator 1022D outputs a binary-valued signal Y4 at node 1026D that is high when the difference [x(t-T1)-x(t-T2)]>VT4 and low otherwise.
  • [0045]
    The signals Y1, Y2, Y3, and Y4 are input to digital logic circuit 1028, which outputs the binary valued signal TP at node 1004 that is high when x(t-T1) represents a turning point with respect to x(t) and x(t-T2). In one example, logic circuit 1028 is configured to implement functionality based on a double-bit signal S1, comprised of signals Y1 and Y2, and another double-bit signal S2, comprised of signals Y3 and Y4. The signal S1 includes information about the slope of the difference [x(t)-x(t-T1)], and the signal S2 includes information about the slope of the difference [x(t-T1)-x(t-T2)], as described more particularly below in Tables 1 and 2.
  • [0000]
    TABLE 1
    Definition of S1
    S1 Y2 = 0 (Low) Y2 = 1 (High)
    Y1 = 0 (Low) A D
    Y1 = 1 (High) B C
  • [0000]
    TABLE 2
    Definition of S2
    S2 Y4 = 0 (Low) Y4 = 1 (High)
    Y3 = 0 (Low) A D
    Y3 = 1 (High) B C
  • [0046]
    In Tables 1 and 2, A represents a negative slope, B represents a small absolute slope, C represents a positive slope, and D is not a valid state. The digital logic for providing the output TP is defined by Table 3. As seen in Table 3, TP is high when the difference [x(t)-x(t-T1)] represents a negative slope and the difference [x(t-T1)-x(t-T2)] represents a positive slope, or vice-versa, and is low otherwise (the “X” notation refers to invalid states, which may be considered as “don't care” for the purposes of logical minimization for realization of the logic circuit).
  • [0000]
    TABLE 3
    Definition of TP
    TP S2 = A S2 = B S2 = C S2 = D
    S1 = A 0 0 1 X
    S1 = B 0 0 0 X
    S1 = C 1 0 0 X
    S1 = D X X X X
  • [0047]
    Although the configuration of comparators 1022A-D in FIG. 10 effectively implements a window comparator that will not yield a turning point if the slopes of either the difference [x(t)-x(t-T1)] or the difference [x(t-T1)-x(t-T2)] is of small magnitude, such a threshold requirement on the slopes is not required. For example, FIG. 11 is a schematic/block diagram illustrating generally an example in which these differences are each compared to 0V, by respective comparators 1100A-B. The respective comparator outputs at nodes 1105A-B are input to an exclusive-OR (XOR) gate 1110. XOR gate 1110 outputs TP, which is high when the sign of the difference [x(t)-x(t-T1)] is different from that of the difference [x(t-T1)-x(t-T2)].
  • [0048]
    It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-discussed embodiments may be used in combination with each other. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.”

Claims (21)

  1. 1. A device for association with a heart using at least one electrode, the device comprising:
    a cardiac signal detector, configured to be coupled to the first electrode, and including a detector output providing a cardiac signal;
    a signal processor circuit, configured to declare whether at least a portion of the cardiac signal is deemed noisy; and
    wherein, when the cardiac signal is deemed noisy, the cardiac signal detector is then reconfigured to be coupled to a different second electrode for detecting depolarizations, and wherein the cardiac signal detector includes independent first and second sensing channels that are respectively coupled to the first and second electrodes for independently sensing a depolarization at each of the first and second electrodes to corroborate depolarizations sensed at the first electrode using corresponding depolarizations independently sensed at the second electrode.
  2. 2. The device of claim 1, in which the detector output provides a sampled cardiac signal, and in which the signal processor is configured to determine over a predetermined plurality of cardiac signal samples, whether an evaluation sample of the cardiac signal is a turning point with respect to previous and subsequent samples, and to deem a portion of the cardiac signal to be noisy if a number of turning points exceeds a threshold value for the predetermined plurality of cardiac signal samples, and wherein, if the cardiac signal is deemed noisy, the cardiac signal detector is additionally coupled to the different second electrode for detecting depolarizations.
  3. 3. The device of claim 2, in which the signal processor operates to determine first and second directions of the cardiac signal preceding and following the evaluation sample, respectively, and to deem the evaluation sample to be a turning point if the first direction is different from the second direction and each of the first and second directions manifest a slope of a magnitude that exceeds a corresponding first and second threshold value before deeming the evaluation sample to be a turning point.
  4. 4. The device of claim 2, wherein, if the cardiac signal is deemed noisy, the cardiac signal detector is additionally coupled to a different second electrode for detecting depolarizations, and in which the signal processor operates to repeat at different frequencies the determination of whether the evaluation sample is a turning point.
  5. 5. The device of claim 2, in which the previous sample is taken at a first predetermined number of periodic samples away from the evaluation sample and the subsequent sample is taken at a second predetermined number of periodic samples away from the evaluation sample.
  6. 6. The device of claim 5, in which the signal processor operates to vary the first and second predetermined numbers.
  7. 7. The device of claim 2, in which the previous and subsequent samples respectively immediately precede and succeed the evaluation sample.
  8. 8. The device of claim 2, in which the threshold value includes a majority threshold value and a quorum threshold value.
  9. 9. The device of claim 2, in which the signal processor circuit includes:
    a difference circuit, coupled to the detector output to receive the sampled cardiac signal, and providing a first difference between an evaluation sample and a preceding sample and a second difference between a succeeding sample and the evaluation sample;
    a comparator, receiving at least one of the first and second differences for comparison to at least one threshold value, the comparator providing a comparator output indicative of the comparison; and
    a logic circuit, having an input coupled to the comparator output, and providing an output indicative of whether the evaluation sample represents a turning point with respect to the preceding and succeeding samples.
  10. 10. The device of claim 2, in which, if the cardiac signal is deemed noisy, the cardiac signal detector is coupled to the second electrode instead of the first electrode.
  11. 11. The device of claim 2, in which, if the cardiac signal is deemed noisy, the cardiac signal detector is coupled to the second electrode in addition to the first electrode to corroborate depolarizations sensed using the first electrode.
  12. 12. The device of claim 2, in which the signal processor is configured for determining, for each sample, TP=sign{x(i)-x(i−K)}*sign{x(i+K)-x(i)}, in which x(i) is the ith sample of the sampled cardiac signal x(n), and in which K is an integer offset, and in which TP=−1 is used as at least one factor indicating that x(i) is a turning point, and the signal processor is also configured for deeming the cardiac signal to be noisy if a number of turning points occurring during a fixed number of samples preceding x(i) exceeds a threshold value, in which the threshold value includes a majority threshold value and a quorum threshold value.
  13. 13. The device of claim 12, in which if |x(i)-x(i−K)| is less than a first threshold or |x(i+K)-x(i)| is less than a second threshold, then x(i) is deemed to be not a turning point.
  14. 14. A system including the device of claim 1, and further including the first electrode, and in which the first electrode includes at least one of an intravascular electrode, an intracardiac electrode, an epicardial electrode, a housing electrode, a header electrode, and a skin surface electrode.
  15. 15. A system including the device of claim 1, and further including a user interface, remote from and communicatively coupled to the signal processor to receive an indication of whether the portion of the cardiac signal is deemed noisy.
  16. 16. A device for association with a heart using at least one electrode, the device comprising:
    a cardiac signal detector coupled to the first electrode, and including a detector output providing a cardiac signal;
    means for determining whether a portion of the cardiac signal is deemed noisy; and
    wherein, if the cardiac signal is deemed noisy, the cardiac signal detector is coupled to a different second electrode for detecting depolarizations and wherein the cardiac signal detector includes independent first and second sensing channels that are respectively coupled to the first and second electrodes for independently sensing a depolarization at each of the first and second electrodes to corroborate depolarizations sensed at the first electrode using corresponding depolarizations independently sensed at the second electrode.
  17. 17. The device of claim 16, in which, if the cardiac signal is deemed noisy, the cardiac signal detector is coupled to the second electrode instead of the first electrode.
  18. 18. The device of claim 16, in which, if the cardiac signal is deemed noisy, the cardiac signal detector is coupled to the second electrode in addition to the first electrode to corroborate depolarizations sensed using the first electrode.
  19. 19. A device for association with a heart using at least one electrode, the device comprising:
    a cardiac signal detector coupled to the first electrode, and including a detector output providing a cardiac signal;
    a signal processor circuit configured to determine whether at least a portion of the cardiac signal is deemed to be noisy; and
    wherein, if the cardiac signal is deemed noisy, the cardiac signal detector is decoupled from the first electrode and instead coupled to a different second electrode for detecting depolarizations.
  20. 20. The device of claim 19, wherein the cardiac signal detector is configured to provide a sampled cardiac signal, wherein the signal processor circuit is configured to determine, over a predetermined plurality of cardiac signal samples, whether an evaluation sample of the cardiac signal is a turning point with respect to previous and subsequent samples, and to deem a portion of the cardiac signal to be noisy if a number of turning points exceeds a threshold value for the predetermined plurality of cardiac signal samples, and wherein the signal processor operates to determine first and second directions of the cardiac signal preceding and following the evaluation sample, respectively, and to deem the evaluation sample to be a turning point if the first direction is different from the second direction and each of the first and second directions manifest a slope of a magnitude that exceeds a corresponding first and second threshold value before deeming the evaluation sample to be a turning point.
  21. 21. The device of claim 20, in which the threshold value includes a first threshold value and a second threshold value, wherein the first threshold value is of larger magnitude than the second threshold value.
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Cited By (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070135722A1 (en) * 2002-08-06 2007-06-14 Yayun Lin Systems and methods for detecting or validating signals in the presence of noise
US20070276445A1 (en) * 2006-05-26 2007-11-29 Cameron Health, Inc. Systems and methods for sensing vector selection in an implantable medical device
US20070276452A1 (en) * 2006-05-26 2007-11-29 Cameron Health, Inc. Implantable medical device systems having initialization functions and methods of operation
US20070276447A1 (en) * 2006-05-26 2007-11-29 Cameron Health, Inc. Implantable medical devices and programmers adapted for sensing vector selection
US20080172100A1 (en) * 2007-01-16 2008-07-17 Cameron Health, Inc. Systems and methods for sensing vector selection in an implantable medical device using a polynomial approach
US20080188901A1 (en) * 2007-02-07 2008-08-07 Cameron Health, Inc. Sensing vector selection in a cardiac stimulus device with postural assessment
US20080275521A1 (en) * 2003-07-28 2008-11-06 Cameron Health, Inc. Vector Switching in an Implantable Cardiac Stimulus System
US20090054796A1 (en) * 2007-08-23 2009-02-26 Cameron Health, Inc. Patient Screening Tools for Implantable Cardiac Stimulus Systems
US20100094369A1 (en) * 2008-03-07 2010-04-15 Cameron Health, Inc. Methods and Devices for Accurately Classifying Cardiac Activity
US20110098775A1 (en) * 2009-10-27 2011-04-28 Cameron Health, Inc. Adaptive Waveform Appraisal in an Implantable Cardiac System
US20110172729A1 (en) * 2010-01-12 2011-07-14 Sweeney Robert J Use of significant point methodology to prevent inappropriate therapy
US8160687B2 (en) 2008-05-07 2012-04-17 Cameron Health, Inc. Methods and devices for accurately classifying cardiac activity
US8265737B2 (en) 2009-10-27 2012-09-11 Cameron Health, Inc. Methods and devices for identifying overdetection of cardiac signals
US8494630B2 (en) 2008-01-18 2013-07-23 Cameron Health, Inc. Data manipulation following delivery of a cardiac stimulus in an implantable cardiac stimulus device
US8548573B2 (en) 2010-01-18 2013-10-01 Cameron Health, Inc. Dynamically filtered beat detection in an implantable cardiac device
US8565878B2 (en) 2008-03-07 2013-10-22 Cameron Health, Inc. Accurate cardiac event detection in an implantable cardiac stimulus device
US8712523B2 (en) 2008-12-12 2014-04-29 Cameron Health Inc. Implantable defibrillator systems and methods with mitigations for saturation avoidance and accommodation
US8744556B2 (en) 2011-02-04 2014-06-03 Cardiac Pacemakers, Inc. Noise detection in implantable medical devices
US9149637B2 (en) 2009-06-29 2015-10-06 Cameron Health, Inc. Adaptive confirmation of treatable arrhythmia in implantable cardiac stimulus devices
US9149645B2 (en) 2013-03-11 2015-10-06 Cameron Health, Inc. Methods and devices implementing dual criteria for arrhythmia detection
US9554714B2 (en) 2014-08-14 2017-01-31 Cameron Health Inc. Use of detection profiles in an implantable medical device
US9579065B2 (en) 2013-03-12 2017-02-28 Cameron Health Inc. Cardiac signal vector selection with monophasic and biphasic shape consideration

Families Citing this family (35)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050101878A1 (en) * 2001-04-18 2005-05-12 Daly Christopher N. Method and apparatus for measurement of evoked neural response
US6892092B2 (en) * 2001-10-29 2005-05-10 Cardiac Pacemakers, Inc. Cardiac rhythm management system with noise detector utilizing a hysteresis providing threshold
US6917830B2 (en) * 2001-10-29 2005-07-12 Cardiac Pacemakers, Inc. Method and system for noise measurement in an implantable cardiac device
US7392085B2 (en) * 2001-11-21 2008-06-24 Cameron Health, Inc. Multiple electrode vectors for implantable cardiac treatment devices
WO2004021885A1 (en) * 2002-09-04 2004-03-18 Cochlear Limited Method and apparatus for measurement of evoked neural response
US7248921B2 (en) 2003-06-02 2007-07-24 Cameron Health, Inc. Method and devices for performing cardiac waveform appraisal
US8190268B2 (en) * 2004-06-15 2012-05-29 Cochlear Limited Automatic measurement of an evoked neural response concurrent with an indication of a psychophysics reaction
JP5548336B2 (en) 2004-06-15 2014-07-16 コクレア リミテッドCochlear Limited Automatic determination of the evoked neural response threshold
US20060173498A1 (en) * 2005-01-31 2006-08-03 Isabelle Banville Communication between an external defibrillator and an implantable medical device
DE102005027438B4 (en) * 2005-06-14 2011-12-22 Siemens Ag A process for the ECG triggering a measurement sequence a magnetic resonance apparatus
US7381188B1 (en) * 2005-07-19 2008-06-03 Pacesetter, Inc. System and method for processing and storing signal information in an implantable cardiac device
US8116867B2 (en) * 2005-08-04 2012-02-14 Cameron Health, Inc. Methods and devices for tachyarrhythmia sensing and high-pass filter bypass
US7693574B2 (en) 2005-08-31 2010-04-06 Cardiac Pacemakers, Inc. System and method for discriminating high frequency electromagnetic interference from cardiac events
US7801617B2 (en) 2005-10-31 2010-09-21 Cochlear Limited Automatic measurement of neural response concurrent with psychophysics measurement of stimulating device recipient
US20080004663A1 (en) * 2005-12-22 2008-01-03 Medtronic Emergency Response Systems, Inc. Defibrillator with implantable medical device detection
US8046063B2 (en) 2006-02-28 2011-10-25 Medtronic, Inc. Implantable medical device with adaptive operation
US7769452B2 (en) * 2006-03-29 2010-08-03 Medtronic, Inc. Method and apparatus for detecting arrhythmias in a medical device
FR2901147A1 (en) * 2006-05-18 2007-11-23 Ela Medical Soc Par Actions Si Medical device active implantable pacemaker, resynchronization, cardioversion and / or defibrillation, comprising lead fracture detection means
FR2901146A1 (en) * 2006-05-18 2007-11-23 Ela Medical Soc Par Actions Si Medical device active implantable pacemaker, resynchronization, cardioversion and / or defibrillation, comprising means for detection of ventricular noise artifacts
US20080058880A1 (en) * 2006-09-01 2008-03-06 Jaeho Kim System and method for pacing
US8014851B2 (en) * 2006-09-26 2011-09-06 Cameron Health, Inc. Signal analysis in implantable cardiac treatment devices
US7920919B1 (en) 2006-11-06 2011-04-05 Pacesetter, Inc. Morphology based motion detection for sensors sensitive to motion induced noise
US7725187B1 (en) 2006-11-06 2010-05-25 Pacesetter, Inc. Motion detection for sensors sensitive to motion induced noise
US20080228093A1 (en) * 2007-03-13 2008-09-18 Yanting Dong Systems and methods for enhancing cardiac signal features used in morphology discrimination
US7932696B2 (en) 2007-05-14 2011-04-26 Boston Scientific Neuromodulation Corporation Charger alignment indicator with adjustable threshold
US8244349B2 (en) * 2008-02-02 2012-08-14 Cameron Health, Inc. Adaptive shock delivery in an implantable cardiac stimulus device
JP2012510343A (en) * 2008-12-02 2012-05-10 プロテウス バイオメディカル インコーポレイテッド Selection of the optimum driving frequency in electrical tomography
JP5680634B2 (en) * 2009-06-15 2015-03-04 カーディアック ペースメイカーズ, インコーポレイテッド System and method for managing noise in implantable medical devices
US20110106191A1 (en) * 2009-10-30 2011-05-05 Medtronic, Inc. Implantable medical device noise mode
US9026198B2 (en) 2010-07-13 2015-05-05 Biotronik Se & Co. Kg Method and device for noise detection in physiological signals
US8983606B2 (en) 2010-10-29 2015-03-17 Medtronic, Inc. Enhanced sensing by an implantable medical device in the presence of an interfering signal from an external source
US8744578B2 (en) 2010-10-29 2014-06-03 Medtronic, Inc. Staged sensing adjustments by an implantable medical device in the presence of interfering signals
US8761717B1 (en) 2012-08-07 2014-06-24 Brian K. Buchheit Safety feature to disable an electronic device when a wireless implantable medical device (IMD) is proximate
US9440088B2 (en) 2012-12-06 2016-09-13 Cardiac Pacemakers, Inc. Implanted lead analysis system and method
US9533165B1 (en) 2015-08-19 2017-01-03 Medtronic, Inc. Detection of medical electrical lead issues and therapy control

Citations (60)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4432362A (en) * 1980-05-27 1984-02-21 Cordis Corporation Atrial-based, atrial-ventricular sequential cardiac pacer
US4589420A (en) * 1984-07-13 1986-05-20 Spacelabs Inc. Method and apparatus for ECG rhythm analysis
US4679144A (en) * 1984-08-21 1987-07-07 Q-Med, Inc. Cardiac signal real time monitor and method of analysis
US4779617A (en) * 1986-10-06 1988-10-25 Telectronics N.V. Pacemaker noise rejection system
US4913146A (en) * 1987-10-13 1990-04-03 Telectronics Pacing Systems Inc. Cardiac sense amplifier with pattern recognition capabilities
US4960123A (en) * 1988-03-21 1990-10-02 Telectronics N.V. Differentiating between arrhythmia and noise in an arrhythmia control system
US5010887A (en) * 1989-11-17 1991-04-30 Siemens-Pacesetter, Inc. Noise discrimination in implantable pacemakers
US5095902A (en) * 1989-08-28 1992-03-17 Siemens Aktiengesellschaft Implantable medical stimulation system optionally operable in a bipolar or a unipolar mode
US5188117A (en) * 1991-10-25 1993-02-23 Telectronics Pacing Systems, Inc. Notch filter noise rejection system in a cardiac control device
US5209237A (en) * 1990-04-12 1993-05-11 Felix Rosenthal Method and apparatus for detecting a signal from a noisy environment and fetal heartbeat obtaining method
US5270124A (en) * 1989-06-30 1993-12-14 The Broken Hill Proprietary Co., Ltd. Composite roll
US5388578A (en) * 1992-01-14 1995-02-14 Incontrol, Inc. Electrode system for use with an implantable cardiac patient monitor
US5492128A (en) * 1991-11-01 1996-02-20 Telectronics Pacing Systems, Inc. Intracardiac electrogram sensing in an arrhythmia control system
US5522857A (en) * 1994-09-20 1996-06-04 Vitatron Medical, B.V. Pacemaker with improved detection of and response to noise
US5562713A (en) * 1995-01-18 1996-10-08 Pacesetter, Inc. Bidirectional telemetry apparatus and method for implantable device
US5564430A (en) * 1993-11-17 1996-10-15 Ela Medical S.A. Automatic control of the sensing threshold for monitoring cardiac rhythm in a implantable device
US5573550A (en) * 1995-04-28 1996-11-12 Pacesetter, Inc. Implantable stimulation device having a low noise, low power, precision amplifier for amplifying cardiac signals
US5591214A (en) * 1995-11-20 1997-01-07 Telectronics Pacing Systems, Inc. Pacemaker with automatic blanking period function
US5613495A (en) * 1991-12-26 1997-03-25 Instromedix, Inc. High functional density cardiac monitoring system for captured windowed ECG data
US5647379A (en) * 1994-11-22 1997-07-15 Ventritex, Inc. Correlator based electromagnetic interference responsive control system useful in medical devices
US5697958A (en) * 1995-06-07 1997-12-16 Intermedics, Inc. Electromagnetic noise detector for implantable medical devices
US5702425A (en) * 1996-08-13 1997-12-30 Pacesetter, Inc. Apparatus and method of noise classification in an implantable cardiac device
US5702427A (en) * 1996-03-28 1997-12-30 Medtronic, Inc. Verification of capture using pressure waves transmitted through a pacing lead
US5709215A (en) * 1995-09-06 1998-01-20 Angeion Corporation R-wave detection method for implantable cardioverter defibrillators
US5755738A (en) * 1997-04-22 1998-05-26 Cardiac Pacemakers, Inc. Automatic sensing level adjustment for implantable cardiac rhythm management devices
US5766227A (en) * 1997-03-04 1998-06-16 Nappholz; Tibor A. EMI detection in an implantable pacemaker and the like
US5776168A (en) * 1996-04-03 1998-07-07 Medtronic, Inc. EGM recording system for implantable medical device
US5778881A (en) * 1996-12-04 1998-07-14 Medtronic, Inc. Method and apparatus for discriminating P and R waves
US5782876A (en) * 1996-04-15 1998-07-21 Medtronic, Inc. Method and apparatus using windows and an index value for identifying cardic arrhythmias
US5792212A (en) * 1997-03-07 1998-08-11 Medtronic, Inc. Nerve evoked potential measurement system using chaotic sequences for noise rejection
US5817135A (en) * 1997-05-02 1998-10-06 Pacesetter, Inc. Rate-responsive pacemaker with noise-rejecting minute volume determination
US5861008A (en) * 1997-02-10 1999-01-19 Pacesetter Ab Heart stimulating device with stimulation energy responsive to detected noise
US5867361A (en) * 1997-05-06 1999-02-02 Medtronic Inc. Adhesively-bonded capacitive filter feedthrough for implantable medical device
US5865749A (en) * 1996-11-07 1999-02-02 Data Sciences International, Inc. Blood flow meter apparatus and method of use
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
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
US5897575A (en) * 1997-10-24 1999-04-27 Pacesetter, Inc. Arrhythmia classification system with reliability indication that allows for low quality input signals in pacemakers
US5957857A (en) * 1998-05-07 1999-09-28 Cardiac Pacemakers, Inc. Apparatus and method for automatic sensing threshold determination in cardiac pacemakers
US5978710A (en) * 1998-01-23 1999-11-02 Sulzer Intermedics Inc. Implantable cardiac stimulator with safe noise mode
US5999848A (en) * 1997-09-12 1999-12-07 Alfred E. Mann Foundation Daisy chainable sensors and stimulators for implantation in living tissue
US6029086A (en) * 1998-06-15 2000-02-22 Cardiac Pacemakers, Inc. Automatic threshold sensitivity adjustment for cardiac rhythm management devices
US6068589A (en) * 1996-02-15 2000-05-30 Neukermans; Armand P. Biocompatible fully implantable hearing aid transducers
US6070097A (en) * 1998-12-30 2000-05-30 General Electric Company Method for generating a gating signal for cardiac MRI
US6112119A (en) * 1997-10-27 2000-08-29 Medtronic, Inc. Method for automatically adjusting the sensitivity of cardiac sense amplifiers
US6195585B1 (en) * 1998-06-26 2001-02-27 Advanced Bionics Corporation Remote monitoring of implantable cochlear stimulator
US6201993B1 (en) * 1998-12-09 2001-03-13 Medtronic, Inc. Medical device telemetry receiver having improved noise discrimination
US6208900B1 (en) * 1996-03-28 2001-03-27 Medtronic, Inc. Method and apparatus for rate-responsive cardiac pacing using header mounted pressure wave transducer
US6223083B1 (en) * 1999-04-16 2001-04-24 Medtronic, Inc. Receiver employing digital filtering for use with an implantable medical device
US6230059B1 (en) * 1999-03-17 2001-05-08 Medtronic, Inc. Implantable monitor
US6236882B1 (en) * 1999-07-14 2001-05-22 Medtronic, Inc. Noise rejection for monitoring ECG's
US6272381B1 (en) * 1988-03-25 2001-08-07 Pacesetter, Inc. Rate-responsive pacemaker with closed-loop control
US6282446B1 (en) * 1999-08-20 2001-08-28 Cardiac Pacemakers, Inc. Automatic shock lead gain adjuster
US6321115B1 (en) * 1999-12-03 2001-11-20 Pacesetter, Inc. Noise detection system and method for use in an implantable medical device
US6421554B1 (en) * 1998-12-31 2002-07-16 Samsung Electronics Co., Ltd. Method and device for detecting fault of lead in electrocardiogram system
US6505071B1 (en) * 1999-12-15 2003-01-07 Cardiac Pacemakers, Inc. Cardiac management device with capability of noise detection in automatic capture verification
US20030082713A1 (en) * 1999-12-10 2003-05-01 Rutter Andrew James Monitoring oligonucleotide binding processes using chemiluminescence quenching
US20040030256A1 (en) * 2002-08-06 2004-02-12 Yayun Lin Cardiac rhythm management systems and methods for detecting or validating cardiac beats in the presence of noise
US20040106957A1 (en) * 2001-10-29 2004-06-03 Surekha Palreddy Method and system for noise measurement in an implantable cardiac device
US6892092B2 (en) * 2001-10-29 2005-05-10 Cardiac Pacemakers, Inc. Cardiac rhythm management system with noise detector utilizing a hysteresis providing threshold
US7233827B1 (en) * 2000-09-05 2007-06-19 Pacesetter, Inc. Implantable cardiac stimulation device with automatic evoked response sensing electrode configuration selection and method

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE59209140D1 (en) 1992-07-31 1998-02-19 Pacesetter Ab An apparatus for detecting cardiac events
CA2110934A1 (en) 1992-12-11 1994-06-12 Robert L. Foldes Human cns receptors of the nmda-r1 family
US5817130A (en) * 1996-05-03 1998-10-06 Sulzer Intermedics Inc. Implantable cardiac cardioverter/defibrillator with EMI suppression filter with independent ground connection
DE69826213T2 (en) 1997-11-24 2006-03-02 St. Jude Medical Ab System for the detection of cardiac events for a pacemaker

Patent Citations (69)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4432362A (en) * 1980-05-27 1984-02-21 Cordis Corporation Atrial-based, atrial-ventricular sequential cardiac pacer
US4589420A (en) * 1984-07-13 1986-05-20 Spacelabs Inc. Method and apparatus for ECG rhythm analysis
US4679144A (en) * 1984-08-21 1987-07-07 Q-Med, Inc. Cardiac signal real time monitor and method of analysis
US4779617A (en) * 1986-10-06 1988-10-25 Telectronics N.V. Pacemaker noise rejection system
US4913146A (en) * 1987-10-13 1990-04-03 Telectronics Pacing Systems Inc. Cardiac sense amplifier with pattern recognition capabilities
US4960123A (en) * 1988-03-21 1990-10-02 Telectronics N.V. Differentiating between arrhythmia and noise in an arrhythmia control system
US6272381B1 (en) * 1988-03-25 2001-08-07 Pacesetter, Inc. Rate-responsive pacemaker with closed-loop control
US5270124A (en) * 1989-06-30 1993-12-14 The Broken Hill Proprietary Co., Ltd. Composite roll
US5095902A (en) * 1989-08-28 1992-03-17 Siemens Aktiengesellschaft Implantable medical stimulation system optionally operable in a bipolar or a unipolar mode
US5010887A (en) * 1989-11-17 1991-04-30 Siemens-Pacesetter, Inc. Noise discrimination in implantable pacemakers
US5209237A (en) * 1990-04-12 1993-05-11 Felix Rosenthal Method and apparatus for detecting a signal from a noisy environment and fetal heartbeat obtaining method
US5188117A (en) * 1991-10-25 1993-02-23 Telectronics Pacing Systems, Inc. Notch filter noise rejection system in a cardiac control device
US5492128A (en) * 1991-11-01 1996-02-20 Telectronics Pacing Systems, Inc. Intracardiac electrogram sensing in an arrhythmia control system
US5613495A (en) * 1991-12-26 1997-03-25 Instromedix, Inc. High functional density cardiac monitoring system for captured windowed ECG data
US5388578A (en) * 1992-01-14 1995-02-14 Incontrol, Inc. Electrode system for use with an implantable cardiac patient monitor
US5564430A (en) * 1993-11-17 1996-10-15 Ela Medical S.A. Automatic control of the sensing threshold for monitoring cardiac rhythm in a implantable device
US5522857A (en) * 1994-09-20 1996-06-04 Vitatron Medical, B.V. Pacemaker with improved detection of and response to noise
US5647379A (en) * 1994-11-22 1997-07-15 Ventritex, Inc. Correlator based electromagnetic interference responsive control system useful in medical devices
US5562713A (en) * 1995-01-18 1996-10-08 Pacesetter, Inc. Bidirectional telemetry apparatus and method for implantable device
US5573550A (en) * 1995-04-28 1996-11-12 Pacesetter, Inc. Implantable stimulation device having a low noise, low power, precision amplifier for amplifying cardiac signals
US5697958A (en) * 1995-06-07 1997-12-16 Intermedics, Inc. Electromagnetic noise detector for implantable medical devices
US5709215A (en) * 1995-09-06 1998-01-20 Angeion Corporation R-wave detection method for implantable cardioverter defibrillators
US5591214A (en) * 1995-11-20 1997-01-07 Telectronics Pacing Systems, Inc. Pacemaker with automatic blanking period function
US6068589A (en) * 1996-02-15 2000-05-30 Neukermans; Armand P. Biocompatible fully implantable hearing aid transducers
US5702427A (en) * 1996-03-28 1997-12-30 Medtronic, Inc. Verification of capture using pressure waves transmitted through a pacing lead
US6208900B1 (en) * 1996-03-28 2001-03-27 Medtronic, Inc. Method and apparatus for rate-responsive cardiac pacing using header mounted pressure wave transducer
US5776168A (en) * 1996-04-03 1998-07-07 Medtronic, Inc. EGM recording system for implantable medical device
US5782876A (en) * 1996-04-15 1998-07-21 Medtronic, Inc. Method and apparatus using windows and an index value for identifying cardic arrhythmias
US5702425A (en) * 1996-08-13 1997-12-30 Pacesetter, Inc. Apparatus and method of noise classification in an implantable cardiac device
US6063034A (en) * 1996-11-07 2000-05-16 Data Sciences International, Inc. Blood flow meter apparatus and method of use
US5865749A (en) * 1996-11-07 1999-02-02 Data Sciences International, Inc. Blood flow meter apparatus and method of use
US5778881A (en) * 1996-12-04 1998-07-14 Medtronic, Inc. Method and apparatus for discriminating P and R waves
US5861008A (en) * 1997-02-10 1999-01-19 Pacesetter Ab Heart stimulating device with stimulation energy responsive to detected noise
US5766227A (en) * 1997-03-04 1998-06-16 Nappholz; Tibor A. EMI detection in an implantable pacemaker and the like
US5792212A (en) * 1997-03-07 1998-08-11 Medtronic, Inc. Nerve evoked potential measurement system using chaotic sequences for noise rejection
US5755738A (en) * 1997-04-22 1998-05-26 Cardiac Pacemakers, Inc. Automatic sensing level adjustment for implantable cardiac rhythm management devices
US5817135A (en) * 1997-05-02 1998-10-06 Pacesetter, Inc. Rate-responsive pacemaker with noise-rejecting minute volume determination
US5867361A (en) * 1997-05-06 1999-02-02 Medtronic Inc. Adhesively-bonded capacitive filter feedthrough for implantable medical device
US6031710A (en) * 1997-05-06 2000-02-29 Medtronic, Inc. Adhesively- and solder-bonded capacitive filter feedthrough for implantable medical devices
US5870272A (en) * 1997-05-06 1999-02-09 Medtronic Inc. Capacitive filter feedthrough for implantable medical device
US5999848A (en) * 1997-09-12 1999-12-07 Alfred E. Mann Foundation Daisy chainable sensors and stimulators for implantation in living tissue
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
US5897575A (en) * 1997-10-24 1999-04-27 Pacesetter, Inc. Arrhythmia classification system with reliability indication that allows for low quality input signals in pacemakers
US6112119A (en) * 1997-10-27 2000-08-29 Medtronic, Inc. Method for automatically adjusting the sensitivity of cardiac sense amplifiers
US5978710A (en) * 1998-01-23 1999-11-02 Sulzer Intermedics Inc. Implantable cardiac stimulator with safe noise mode
US6198968B1 (en) * 1998-01-23 2001-03-06 Intermedics Inc. Implantable cardiac stimulator with safe noise mode
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
US5957857A (en) * 1998-05-07 1999-09-28 Cardiac Pacemakers, Inc. Apparatus and method for automatic sensing threshold determination in cardiac pacemakers
US6029086A (en) * 1998-06-15 2000-02-22 Cardiac Pacemakers, Inc. Automatic threshold sensitivity adjustment for cardiac rhythm management devices
US6195585B1 (en) * 1998-06-26 2001-02-27 Advanced Bionics Corporation Remote monitoring of implantable cochlear stimulator
US6201993B1 (en) * 1998-12-09 2001-03-13 Medtronic, Inc. Medical device telemetry receiver having improved noise discrimination
US6070097A (en) * 1998-12-30 2000-05-30 General Electric Company Method for generating a gating signal for cardiac MRI
US6421554B1 (en) * 1998-12-31 2002-07-16 Samsung Electronics Co., Ltd. Method and device for detecting fault of lead in electrocardiogram system
US6230059B1 (en) * 1999-03-17 2001-05-08 Medtronic, Inc. Implantable monitor
US6223083B1 (en) * 1999-04-16 2001-04-24 Medtronic, Inc. Receiver employing digital filtering for use with an implantable medical device
US6236882B1 (en) * 1999-07-14 2001-05-22 Medtronic, Inc. Noise rejection for monitoring ECG's
US6282446B1 (en) * 1999-08-20 2001-08-28 Cardiac Pacemakers, Inc. Automatic shock lead gain adjuster
US6321115B1 (en) * 1999-12-03 2001-11-20 Pacesetter, Inc. Noise detection system and method for use in an implantable medical device
US20030082713A1 (en) * 1999-12-10 2003-05-01 Rutter Andrew James Monitoring oligonucleotide binding processes using chemiluminescence quenching
US6505071B1 (en) * 1999-12-15 2003-01-07 Cardiac Pacemakers, Inc. Cardiac management device with capability of noise detection in automatic capture verification
US7233827B1 (en) * 2000-09-05 2007-06-19 Pacesetter, Inc. Implantable cardiac stimulation device with automatic evoked response sensing electrode configuration selection and method
US6892092B2 (en) * 2001-10-29 2005-05-10 Cardiac Pacemakers, Inc. Cardiac rhythm management system with noise detector utilizing a hysteresis providing threshold
US6917830B2 (en) * 2001-10-29 2005-07-12 Cardiac Pacemakers, Inc. Method and system for noise measurement in an implantable cardiac device
US20050192504A1 (en) * 2001-10-29 2005-09-01 Cardiac Pacemakers, Inc. Cardiac rhythm management system with noise detector
US20040106957A1 (en) * 2001-10-29 2004-06-03 Surekha Palreddy Method and system for noise measurement in an implantable cardiac device
US7467009B2 (en) * 2001-10-29 2008-12-16 Cardiac Pacemakers, Inc. Cardiac rhythm management system with noise detector
US20040030256A1 (en) * 2002-08-06 2004-02-12 Yayun Lin Cardiac rhythm management systems and methods for detecting or validating cardiac beats in the presence of noise
US7215993B2 (en) * 2002-08-06 2007-05-08 Cardiac Pacemakers, Inc. Cardiac rhythm management systems and methods for detecting or validating cardiac beats in the presence of noise
US20070135722A1 (en) * 2002-08-06 2007-06-14 Yayun Lin Systems and methods for detecting or validating signals in the presence of noise

Cited By (58)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8078272B2 (en) 2002-08-06 2011-12-13 Cardiac Pacemakers, Inc. Systems and methods for detecting or validating signals in the presence of noise
US20070135722A1 (en) * 2002-08-06 2007-06-14 Yayun Lin Systems and methods for detecting or validating signals in the presence of noise
US9764152B2 (en) 2003-07-28 2017-09-19 Cameron Health, Inc. Multiple electrode vectors for implantable cardiac treatment devices
US8825157B2 (en) 2003-07-28 2014-09-02 Cameron Health, Inc. Vector switching in an implantable cardiac stimulus system
US9345899B2 (en) 2003-07-28 2016-05-24 Cameron Health, Inc. Vector switching in an implantable cardiac stimulus system
US20080275521A1 (en) * 2003-07-28 2008-11-06 Cameron Health, Inc. Vector Switching in an Implantable Cardiac Stimulus System
US9364677B2 (en) 2006-05-26 2016-06-14 Cameron Health, Inc. Systems and methods for sensing vector selection in an implantable medical device
US20070276447A1 (en) * 2006-05-26 2007-11-29 Cameron Health, Inc. Implantable medical devices and programmers adapted for sensing vector selection
US20070276452A1 (en) * 2006-05-26 2007-11-29 Cameron Health, Inc. Implantable medical device systems having initialization functions and methods of operation
US8965530B2 (en) 2006-05-26 2015-02-24 Cameron Health, Inc. Implantable cardiac devices and methods using an x/y counter
US8788023B2 (en) 2006-05-26 2014-07-22 Cameron Health, Inc. Systems and methods for sensing vector selection in an implantable medical device
US20070276445A1 (en) * 2006-05-26 2007-11-29 Cameron Health, Inc. Systems and methods for sensing vector selection in an implantable medical device
US9744366B2 (en) 2006-05-26 2017-08-29 Cameron Health, Inc. Sensing vector selection in a cardiac stimulus device with postural assessment
US9357969B2 (en) 2006-05-26 2016-06-07 Cameron Health, Inc. Sensing vector selection in a cardiac stimulus device with postural assessment
US7783340B2 (en) 2007-01-16 2010-08-24 Cameron Health, Inc. Systems and methods for sensing vector selection in an implantable medical device using a polynomial approach
US20080172100A1 (en) * 2007-01-16 2008-07-17 Cameron Health, Inc. Systems and methods for sensing vector selection in an implantable medical device using a polynomial approach
US8781602B2 (en) 2007-02-07 2014-07-15 Cameron Health, Inc. Sensing vector selection in a cardiac stimulus device with postural assessment
US20080188901A1 (en) * 2007-02-07 2008-08-07 Cameron Health, Inc. Sensing vector selection in a cardiac stimulus device with postural assessment
US8200341B2 (en) 2007-02-07 2012-06-12 Cameron Health, Inc. Sensing vector selection in a cardiac stimulus device with postural assessment
US20090054796A1 (en) * 2007-08-23 2009-02-26 Cameron Health, Inc. Patient Screening Tools for Implantable Cardiac Stimulus Systems
US9380955B2 (en) 2007-08-23 2016-07-05 Cameron Health, Inc. Patient screening tools for implantable cardiac stimulus systems
US8079959B2 (en) 2007-08-23 2011-12-20 Cameron Health, Inc. Patient screening tools for implantable cardiac stimulus systems
US8494630B2 (en) 2008-01-18 2013-07-23 Cameron Health, Inc. Data manipulation following delivery of a cardiac stimulus in an implantable cardiac stimulus device
US9242112B2 (en) 2008-01-18 2016-01-26 Cameron Health, Inc. Data manipulation following delivery of a cardiac stimulus in an implantable cardiac stimulus device
US8700152B2 (en) 2008-01-18 2014-04-15 Cameron Health, Inc. Data manipulation following delivery of a cardiac stimulus in an implantable cardiac stimulus device
US9878172B2 (en) 2008-03-07 2018-01-30 Cameron Health, Inc. Methods and devices for accurately classifying cardiac activity
US8626280B2 (en) 2008-03-07 2014-01-07 Cameron Health, Inc. Methods and devices for accurately classifying cardiac activity
US8588896B2 (en) 2008-03-07 2013-11-19 Cameron Health, Inc. Methods and devices for accurately classifying cardiac activity
US8565878B2 (en) 2008-03-07 2013-10-22 Cameron Health, Inc. Accurate cardiac event detection in an implantable cardiac stimulus device
US8265749B2 (en) 2008-03-07 2012-09-11 Cameron Health, Inc. Methods and devices for accurately classifying cardiac activity
US8160686B2 (en) 2008-03-07 2012-04-17 Cameron Health, Inc. Methods and devices for accurately classifying cardiac activity
US9802056B2 (en) 2008-03-07 2017-10-31 Cameron Health, Inc. Accurate cardiac event detection in an implantable cardiac stimulus device
US20100094369A1 (en) * 2008-03-07 2010-04-15 Cameron Health, Inc. Methods and Devices for Accurately Classifying Cardiac Activity
US9162074B2 (en) 2008-03-07 2015-10-20 Cameron Health, Inc. Methods and devices for accurately classifying cardiac activity
US8929977B2 (en) 2008-03-07 2015-01-06 Cameron Health, Inc. Methods and devices for accurately classifying cardiac activity
US9339662B2 (en) 2008-03-07 2016-05-17 Cameron Health, Inc. Methods and devices for accurately classifying cardiac activity
US8600489B2 (en) 2008-05-07 2013-12-03 Cameron Health, Inc. Methods and devices for accurately classifying cardiac activity
US8160687B2 (en) 2008-05-07 2012-04-17 Cameron Health, Inc. Methods and devices for accurately classifying cardiac activity
US8880161B2 (en) 2008-05-07 2014-11-04 Cameron Health, Inc. Methods and devices for accurately classifying cardiac activity
US9763619B2 (en) 2008-05-07 2017-09-19 Cameron Health, Inc. Methods and devices for accurately classifying cardiac activity
US9265432B2 (en) 2008-05-07 2016-02-23 Cameron Health, Inc. Methods and devices for accurately classifying cardiac activity
US9079035B2 (en) 2008-12-12 2015-07-14 Cameron Health, Inc. Electrode spacing in a subcutaneous implantable cardiac stimulus device
US8712523B2 (en) 2008-12-12 2014-04-29 Cameron Health Inc. Implantable defibrillator systems and methods with mitigations for saturation avoidance and accommodation
US9636514B2 (en) 2009-06-29 2017-05-02 Cameron Health, Inc. Adaptive confirmation of treatable arrhythmia in implantable cardiac stimulus devices
US9149637B2 (en) 2009-06-29 2015-10-06 Cameron Health, Inc. Adaptive confirmation of treatable arrhythmia in implantable cardiac stimulus devices
US8265737B2 (en) 2009-10-27 2012-09-11 Cameron Health, Inc. Methods and devices for identifying overdetection of cardiac signals
US8744555B2 (en) 2009-10-27 2014-06-03 Cameron Health, Inc. Adaptive waveform appraisal in an implantable cardiac system
US8965491B2 (en) 2009-10-27 2015-02-24 Cameron Health, Inc. Adaptive waveform appraisal in an implantable cardiac system
US20110098775A1 (en) * 2009-10-27 2011-04-28 Cameron Health, Inc. Adaptive Waveform Appraisal in an Implantable Cardiac System
US20110172729A1 (en) * 2010-01-12 2011-07-14 Sweeney Robert J Use of significant point methodology to prevent inappropriate therapy
US8521276B2 (en) 2010-01-12 2013-08-27 Cardiac Pacemakers, Inc. Use of significant point methodology to prevent inappropriate therapy
US8548573B2 (en) 2010-01-18 2013-10-01 Cameron Health, Inc. Dynamically filtered beat detection in an implantable cardiac device
US8744556B2 (en) 2011-02-04 2014-06-03 Cardiac Pacemakers, Inc. Noise detection in implantable medical devices
US9421390B2 (en) 2013-03-11 2016-08-23 Cameron Health Inc. Methods and devices implementing dual criteria for arrhythmia detection
US9149645B2 (en) 2013-03-11 2015-10-06 Cameron Health, Inc. Methods and devices implementing dual criteria for arrhythmia detection
US9844678B2 (en) 2013-03-11 2017-12-19 Cameron Health, Inc. Methods and devices implementing dual criteria for arrhythmia detection
US9579065B2 (en) 2013-03-12 2017-02-28 Cameron Health Inc. Cardiac signal vector selection with monophasic and biphasic shape consideration
US9554714B2 (en) 2014-08-14 2017-01-31 Cameron Health Inc. Use of detection profiles in an implantable medical device

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