JP5155311B2 - Ultrasonic transmitting / receiving transducer housed in header of implantable medical device - Google Patents

Description

  The present invention relates to a transducer that, when used in combination with an implantable medical device, performs wireless communication between the implantable medical device and a remote sensor implanted in the body or other implantable medical device. It is. More particularly, the present invention relates to a transducer disposed within a header of an implantable medical device.

  This application claims the priority of provisional application 60 / 820,062 filed on July 21, 2006, and is claimed in US patent application Ser. No. 11 / 212,176, filed August 26, 2005. The continuation-in-part applications are hereby incorporated by reference in their entirety by reference to both of these applications.

  Implantable medical devices are often used to treat various conditions. Examples of implantable medical devices include drug administration devices, analgesic devices, and devices for treating cardiac arrhythmias. An example of an implantable medical device used to treat cardiac arrhythmias is a cardiac pacemaker, which typically treats a bradycardia (ie, an abnormally slow heart beat) by being implanted in the patient's body. To do. The pacemaker includes a pulse generator and a plurality of leads that form an electrical connection between the pulse generator and the heart. An implantable cardioverter defibrillator (ICD) is used to treat tachycardia (ie, abnormally fast heart beats). The ICD also includes a pulse generator and a plurality of leads that supply electrical energy to the heart. A pulse generator typically includes a housing that houses a battery and electrical circuitry, and a header that connects leads to the pulse generator.

  Implantable medical devices are also useful for the treatment of heart failure. Cardiac resynchronization therapy (CRT), commonly referred to as biventricular pacing, is a new treatment for heart failure that stimulates both the right and left ventricles to improve blood flow efficiency and heart rate. Increase the amount. The treatment of heart failure and cardiac arrhythmias can be improved by using chronically implanted sensors. For example, it would be useful if a pressure sensor could be placed in the vasculature because diastolic pressure could be a significant predictor of decompensation progression in heart failure patients. The pressure sensor can also be used as part of a pacing therapy or a defibrillation therapy. By communicating between the implantable medical device and the long-term implantable sensor, the sensor data can be downloaded by the clinician or the sensor data can be used to change the treatment performed on the implantable medical device. it can. Accordingly, there is a need for an implantable medical device that includes a transducer that communicates with a long-term implantable sensor.

  The present invention according to one embodiment is an implantable medical device adapted to be implanted in a body tissue. The implantable medical device includes a housing and a header connected to the housing. The cavity is disposed in the header. An ultrasound transducer adapted to transmit ultrasound at a propagation frequency is disposed within the cavity, and a coupling surface is disposed between the ultrasound transducer and the body tissue and is acoustically coupled to the body tissue.

  According to another embodiment, the present invention is an implantable medical device implanted in a body tissue. The implantable medical device includes a housing and a header connected to the housing. The cavity is located in the header and the means for transmitting the ultrasonic signal is located in the cavity. The coupling surface is disposed between the means for transmitting the ultrasonic signal and the body tissue and is acoustically coupled to the body tissue.

  The invention according to yet another embodiment is an implantable medical device that is implanted in a body tissue. The implantable medical device includes a housing, a header connected to the housing, and a tab connected to the housing. A cavity is disposed in the tub, and an ultrasound transducer adapted to transmit ultrasound at a propagation frequency is disposed in the cavity. The coupling surface is disposed between the ultrasonic transducer and the body tissue and is acoustically coupled to the body tissue.

  While multiple embodiments are disclosed, it will be apparent to those skilled in the art from the following detailed description that further embodiments of the present invention exist, and in the following detailed description, Illustrative embodiments of the invention are shown and described. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not as restrictive on the present invention.

1 is a cross-sectional perspective view of an implantable medical device according to one embodiment of the present invention. 1 shows a front view of an implantable medical device having an ultrasonic transducer disposed in a header according to one embodiment of the present invention. FIG. FIG. 3 illustrates a cross-sectional view of one embodiment of the implantable medical device of FIG. Figure 3 shows a cross-sectional view of another embodiment of the implantable medical device of Figure 2; FIG. 3 shows a perspective view of one embodiment of the ultrasonic transducer of FIG. 2. FIG. 6 shows a front view of yet another embodiment of an implantable medical device according to the present invention. FIG. 6 shows a front view of yet another embodiment of an implantable medical device according to the present invention. 1 shows a block diagram of an implantable medical device according to the present invention. FIG. 3 is a flowchart illustrating an exemplary method of using the implantable medical device of FIG. 2 for transmitting an ultrasound signal. FIG. 3 is a flowchart illustrating an exemplary method of using the implantable medical device of FIG. 2 to receive an ultrasound signal.

While the invention is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and are described in detail below. However, it is not intended that the invention be limited to the specific embodiments described. On the contrary, the invention is intended to cover all modifications, equivalents, and alternatives as falling within the scope of the invention as defined by the appended claims.

  FIG. 1 is a perspective view of an implantable medical device (IMD) 10. The IMD 10 includes a pulse generator 12 and a cardiac lead 14. Lead 14 functions to transmit electrical signals between heart 16 and pulse generator 12. The proximal end 18 of the lead 14 is connected to the pulse generator 12 and the distal end 20 is connected to the heart 16. The lead 14 includes a lead body 17 that extends from the lead proximal end 18 to the lead distal end 20.

  The heart 16 includes a right atrium 22, a right ventricle 24, and a pulmonary artery 26. The tricuspid valve 28 is located between the right atrium 22 and the right ventricle 24 and controls blood flow from the right atrium 22 to the right ventricle 24. The pulmonary valve 30 is located between the right ventricle 24 and the pulmonary artery 26 and controls blood flow from the right ventricle 24 to the pulmonary artery 26. The heart 16 further includes a left atrium 32, a left ventricle 34, and an aorta 36. The mitral valve 38 is located between the left atrium 32 and the left ventricle 34 and controls blood flow from the left atrium 32 to the left ventricle 34. The aortic valve 40 is located between the left ventricle 34 and the aorta 36 and controls blood flow from the left ventricle 34 to the aorta 36. In the illustrated embodiment, the IMD 10 includes a single lead 14, while in other embodiments, the IMD 10 includes a plurality of leads 14. For example, the IMD 10 includes a first lead 14 adapted to transmit an electrical signal between the pulse generator 12 and the left ventricle 34, and an electrical signal between the pulse generator 12 and the right ventricle 24. And a second lead 14 adapted to transmit.

  In the embodiment shown in FIG. 1, a spiral electrode 42 penetrates the endocardium 43 of the right ventricle 24 and is implanted in the myocardium 44 of the heart 16. When arranged as described above, the electrodes 42 can be used to detect electrical activity of the heart 16 or to apply stimulation pulses to the right ventricle 24. In other embodiments, the cardiac lead 14 of the present invention can be implanted in any other portion of the heart 16, as is known in the art. For example, lead 14 can be implanted in right atrium 22, right ventricle 24, pulmonary artery 26, left ventricle 34, or in a coronary vein. In one embodiment, the IMD 10 includes a plurality of electrodes 42 that are arranged to detect electrical activity and / or perform treatment on the left and right sides of the heart 16 or on both sides of the heart 16. Is done. In one embodiment, the lead 14 can be an epicardial lead, in which case the electrode 42 penetrates the epicardium 45. Although the IMD 10 shown in FIG. 1 is a cardiac pacemaker, in other embodiments, the IMD 10 can include any other medical device suitable for implantation in the body.

  As shown in FIG. 1, the remote control instrument 46 is placed in the pulmonary artery 26. Alternatively, the instrument 46 can be placed in the right ventricle 24, the aorta 36, or any other location within the heart 16 or vascular system, or near the heart 16 or vascular system. Can be arranged. The instrument 46 can comprise a pressure sensor, or alternatively can comprise a volume sensor, or can detect any other cardiac parameter such as systolic or diastolic blood pressure, or a blood pressure gradient. A derivative of such cardiac parameters can be calculated. In other embodiments, the instrument 46 can be placed at any location in the body that is adapted to detect the desired biological parameter. For example, the instrument 46 can be used to detect or monitor other biological functions such as glucose concentration. The instrument 46 shown in FIG. 1 may be a remote pressure sensor used to detect pressure in the pulmonary artery 26. The detected pressure can be used to predict decompensation in heart failure patients or to optimize pacing or defibrillation therapy. An example of a remote pressure sensor 46 adapted to measure pressure is disclosed in US Pat. No. 6,764,446 by Wolinsky et al.

  FIG. 2 shows a front view of one embodiment of the pulse generator 12 of FIG. As shown in FIG. 2, the pulse generator 12 includes a housing 48 and a header 50. The housing 48 includes a control circuit 52. The header 50 includes a connector 51 that is connected to the lead wire 14 or the lead wire group 14. The ultrasonic transducer 54 is disposed in the header 50, and the header 50 is connected to the control circuit 52 via an electrical feedthrough 55. In one embodiment, the ultrasonic transducer 54 transmits and receives ultrasonic signals having a frequency greater than about 20 kilohertz. In another embodiment, the ultrasonic transducer 54 transmits and receives ultrasonic signals having a frequency of about 40 kilohertz. The ultrasonic transducer 54 shown in FIG. 2 has a circular shape, but can alternatively have any other shape such as a square, rectangle, triangle, or irregular shape. The ultrasonic transducer 54 can include any piezoelectric material. In one embodiment, the ultrasonic transducer 54 can include a polyvinylidene difluoride (PVDF) material. One ultrasonic transducer composed of PVDF material is disclosed in US Patent Application Publication No. 2002/0036446 by Toda et al., Which is hereby incorporated by reference in its entirety. Incorporated in the description. In another embodiment, the ultrasonic transducer 54 can include a lead zirconate titanate (PZT) material. One ultrasonic transducer composed of PZT material is disclosed in US Patent Application Publication No. 2002/0027400 by Toda, which is hereby incorporated by reference in its entirety. Embedded in the book. Alternatively, the ultrasonic transducer 54 can include a capacitive micromachined ultrasonic transducer (cMUT) or any other transducer known in the art.

  A cross-sectional view of one embodiment of the implantable medical device 10 is shown in FIG. In the embodiment shown in FIG. 3, the ultrasonic transducer 54 includes a PVDF transducer. A cavity 56 is disposed in the header 50. A ceramic substrate or silicon substrate 58 is disposed upright from the rear wall 60 of the cavity 56. Substrate 58 includes an opening 62 and PVDF material 64 is disposed over and covers opening 62. The PVDF material 64 can be adhered to the substrate 58 using an epoxy or a medical adhesive. In one embodiment, the PVDF material 64 can constitute a bimorph structure having two PVDF material layers. Cavity 56 can be filled with water, oil, ultrasonic gel, or any other medium or material adapted to transmit ultrasonic waves. In one embodiment, the cavity 56 can be filled with any biocompatible material adapted to transmit ultrasound.

  A binding surface 66 is disposed over and covers the cavity 56. In one embodiment, the binding surface 66 includes any surface that has the property of propagating ultrasonic pressure between the medium of the cavity 56 and the body tissue. In one embodiment, the binding surface 66 can include a thin titanium diaphragm. In other embodiments, the binding surface 66 comprises any biocompatible material having a dimension that provides the ability to propagate ultrasonic pressure between the medium of the cavity 56 and the body tissue. An example of PVDF material adapted for use in ultrasonic transducers is Measurement Specialties, Inc., located at 950 Forge Avenue, 19403 Norristown, Pennsylvania, USA. Can be obtained from

  FIG. 4 shows another embodiment of the implantable medical device of FIG. In this embodiment, ultrasonic transducer 54 includes PZT material 68. A cavity 56 is disposed within the header 50 and is covered by a binding surface 66. PZT material 68 is connected to bonding surface 66. The PZT material 68 can be adhered to the bonding surface 66 using epoxy or any medical adhesive. Cavity 56 can be filled with air, nitrogen, or any other gas. Alternatively, the cavity 56 can be a vacuum. In the embodiment shown in FIG. 4, the coupling surface 66 includes a resonant surface that resonates at the ultrasonic propagation frequency. In one embodiment, this frequency is greater than 20 kilohertz. In another embodiment, this frequency is about 40 kilohertz.

  Another structure of the ultrasonic transducer 54 is shown in FIG. In this embodiment, the ultrasonic transducer 54 is disposed inside the package 70. The package 70 can be inserted into a cavity 56 disposed in the header 50. The package 70 can include titanium or any other suitable material. A binding surface 66 is disposed over the package 70. The ultrasonic transducer 54 structure within the package 70 can include the structures discussed with respect to FIGS. 3 and 4, or can include any other ultrasonic transducer structure known in the art. The package 70 has a cylindrical shape in FIG. 5, but can have any shape adapted to just fit the shape of the ultrasonic transducer 54.

  FIG. 6 shows another embodiment of the implantable medical device 10 of the present invention. In this embodiment, a plurality of ultrasonic transducers 54 are disposed in the header 50. The ultrasonic transducer 54 can include the ultrasonic transducers discussed with respect to FIGS. 3, 4, or any combination of FIGS. The plurality of ultrasonic transducers 54 can also include cMUT transducers or other types of ultrasonic transducers known in the art. The ultrasonic transducer 54 can be disposed on multiple surfaces of the header 50. Although six circular ultrasonic transducers 54 are shown in FIG. 6, any number of transducers of any shape can be used. If desired, the ultrasonic transducer 54 can include a package 70. With such a configuration, since the ultrasonic transducers 54 can operate in parallel, the resonance characteristics and the amplification characteristics are improved.

  FIG. 7 shows a front view of yet another embodiment of the implantable medical device 10. In this embodiment, the ultrasonic transducer 54 is disposed within the tab 72, which is attached to the housing 48 and connected to the control circuit via a feedthrough 74. Tab 72 may include the same material used in header 50. In one embodiment, tab 72 includes Tecothane. Alternatively, the tab 72 can comprise any biocompatible material, such as titanium, and can be welded to or attached to the housing 48. Tab 72 can include a plurality of ultrasonic transducers 54. The IMD 10 can include a plurality of tabs 72. The ultrasonic transducer 54 can be placed in the header 50, in the tab or tab group 72, or in the header 50 and in the tab or tab group 72. The ultrasonic transducer 54 can include any combination of PZT transducers, PVDF transducers, cMUT transducers, or any other transducer known in the art.

  FIG. 8 schematically shows the implantable medical device 10. As shown, the pulse generator 12 includes a housing 48 and a header 50. The housing 48 includes a control circuit 52, a memory 80, a battery 82, a receiver 84, and a transmitter 86. Ultrasonic transducer 54 is disposed within header 50 and is electrically connected to transmitter 86 and receiver 84. The transmitter 86, the receiver 84, and the memory 80 are connected to the control circuit 52. The control circuit 52 is supplied with power from the battery 82.

  FIG. 9 is a flowchart illustrating an exemplary method 200 for transmitting an ultrasound signal using the implantable medical device 10 of FIG. The control circuit 52 instructs the transmitter 86 to apply an AC voltage of propagation frequency to the ultrasonic transducer 54 (block 210). This voltage causes the ultrasonic transducer 54 to deform periodically at the propagation frequency (block 220). This periodic deformation causes the coupling surface 66 to vibrate at the propagation frequency so that the ultrasound signal passes through the tissue at the propagation frequency (block 230). In one embodiment, the ultrasonic transducer 54 includes PVDF material 64 and the coupling surface 66 includes a diaphragm, and the reciprocation of the diaphragm propagates ultrasonic waves from the PVDF material 64 to external tissue. In another embodiment, ultrasonic transducer 54 includes PZT material 58 and coupling surface 66 includes a resonant surface that resonates at the propagation frequency.

  FIG. 10 is a flowchart illustrating an exemplary method 300 for receiving an ultrasound signal using the implantable medical device of FIG. By irradiating the coupling surface 66 with an ultrasonic signal, the coupling surface vibrates at the propagation frequency (block 310). In one embodiment, the ultrasonic transducer 54 includes PVDF material 64 and the coupling surface 66 includes a diaphragm, and the reciprocation of the diaphragm propagates ultrasonic waves from external tissue to the PVDF material 64. In another embodiment, ultrasonic transducer 54 includes PZT material 58 and coupling surface 66 includes a resonant surface that resonates at the propagation frequency. As the coupling surface 66 vibrates, the ultrasonic transducer 54 is periodically deformed (block 320). This periodic deformation causes a voltage or current change to occur at the propagation frequency in the ultrasonic transducer 54, which is detected by the receiver 84 and processed by the control circuit 52 (block 330). In the manner shown in FIGS. 9 and 10, the ultrasonic transducer 54 can be used to transmit signals from the implantable medical device 10 to the remote sensor 46 and receive signals from the remote sensor 46.

  Although the present invention has been described with respect to implantable medical devices such as pacemakers and defibrillators, the present invention can be applied to insulin pumps, neurostimulators, drug delivery systems, pain management systems, heart rate sensors or lung sound sensors. It can be adapted for use in any other implantable medical device or in any other implantable medical device. Teleoperated instrument 46 is adapted to perform therapy or to monitor biological function, data transmission via pressure sensor, glucose concentration monitor, lung sound sensor, volume sensor, satellite Can include any type of long-term implantable device or remote sensor, such as a pacing device or any other remotely operated detector or therapeutic device, and detects a desired biological parameter Or can be placed at any site in the body that is suitable for treatment. Multiple remote controls 46 can be implanted anywhere in the body and in wireless communication with each other and with the IMD 10.

  Various changes and additions can be made to the exemplary embodiments discussed without departing from the scope of the present invention. For example, although the embodiments described above have been described with respect to particular features, the scope of the invention includes embodiments having different combinations of features and implementations that do not include all of the described features. Includes form. Accordingly, the scope of the invention includes all such alternatives, modifications, and variations as if they fall within the scope of the claims, including all equivalents of the claims.

Claims (9)

An implantable medical device that is implanted in a body tissue,
A housing and a header connected to the housing;
A cavity disposed in the header;
A package having a wall disposed within the cavity and forming a binding surface comprising a diaphragm;
Wherein arranged in the packaging body, and an ultrasonic transducer adapted to transmit ultrasound propagation frequencies, said ultrasonic transducer comprising a polyvinylidene difluoride (PVDF) material,
A control circuit configured to communicate with a remote device by driving the transducer at the propagation frequency and processing a signal received from the transducer;
The diaphragm, the disposed between the ultrasonic transducer and the body tissue, the diaphragm has a resonant frequency of greater than 20 kilohertz, said diaphragm body tissues and Ru are acoustically coupled, planting Ekomi medical device . The ultrasonic transducer further comprises a substrate disposed adjacent to a back wall of the cavity, the cavity is filled with an acoustic energy transfer medium, the substrate includes an opening, and the PVDF material covers the opening. The implantable medical device according to claim 1, wherein The plurality of cavities disposed within said header, ultrasonic transducer is disposed within each cavity, a diaphragm is disposed between each ultrasonic transducer and the body tissue, and Ru is body tissue and the acoustic coupling, claim The implantable medical device according to 1. 4. The implantable medical device according to claim 3 , wherein the header includes a plurality of surfaces, and at least two of the surfaces are provided with cavities. The package is constructed to fit exactly into the cavity, the implantable medical device of claim 1, wherein.   The implantable medical device according to claim 1, wherein a schematic shape of the ultrasonic transducer is circular.   The implantable medical device of claim 1, wherein the propagation frequency is about 40 kilohertz. The ultrasonic transducer is configured to receive the ultrasonic wave propagation frequency, implantable medical device of claim 1, wherein.   The implantable medical device of claim 1, comprising a pulse generator.

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