DUAL-USE SENSOR FOR RATE RESPONSIVE PACING AND HEART SOUND MONITORING

• US 20080015652A1
• Filed: 07/16/2007
• Published: 01/17/2008
• Est. Priority Date: 11/06/2003
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Maile, Keith, Siejko, Krzysztof
• Granted Patent: US 7,844,334 B2
• Time in Patent Office: Days
• US Class Current: 607/17
• CPC Class Codes: A61N 1/36542 controlled by body motion, e.g. acceleration
• CPC Class Codes: A61N 1/36585 controlled by two or more physical parameters

Abstract

An implantable medical device includes a dual-use sensor such as a single accelerometer that senses an acceleration signal. A sensor processing circuit processes the acceleration signal to produce an activity level signal and a heart sound signal. The implantable medical device provides for rate responsive pacing in which at least one pacing parameter, such as the pacing interval, is dynamically adjusted based on the physical activity level. The implantable medical device also uses the heart sounds for pacing control purposes or transmits a heart sound signal to an external system for pacing control and/or diagnostic purposes.

Claims

1. An implantable medical device, comprising:

a sensing circuit configured to sense at least one electrogram;

a pacing circuit configured to deliver pacing pulses;

a dual-use sensor configured to sense a signal indicative of physical activities and heart sounds;

a sensor processing circuit configured to produce an activity level signal and a heart sound using the sensed signal, the activity level signal indicative of a level of the physical activities, the heart sound signal indicative of the heart sounds, the sensor processing circuit including;

a first set of cutoff frequencies suitable for producing the activity level signal;

a first gain suitable for producing the activity level signal;

a second set of cutoff frequencies suitable for producing the heart sound signal; and

a second gain suitable for producing the heart sound signal;

an implant controller coupled to the sensing circuit, the pacing circuit, and the sensor processing circuit, the controller configured to control the delivery of the pacing pulses using the activity level signal and the heart sound signal; and

an implantable housing encapsulating at least the sensing circuit, the pacing circuit, the sensor processing circuit, and the controller.

2. The device of claim 1, wherein the dual-use sensor is a single integrated circuit accelerometer.

3. The device of claim 1, wherein the sensor processing circuit is configured to produce the activity level signal during a first time period and the heart sound signal during a second time period, wherein the first time period and the second time period do not overlap.

4. The device of claim 3, wherein the implant controller comprises a sensor processing circuit programming module configured to program the sensor processing circuit for producing the activity level signal using the first set of cutoff frequencies and the first gain during a first time period and producing the heart sound signal using the second set of cutoff frequencies and the second gain during a second time period.

5. The device of claim 4, wherein the sensor processing circuit comprises:

a band-pass filter having programmable cutoff frequencies; and

an amplifier having a programmable gain,

wherein the programmable cutoff frequencies and the programmable gain are adjustable after implantation of the implantable medical device.

6. The device of claim 1, wherein the sensor processing circuit is configured to produce the activity level signal and the heart sound signal concurrently.

7. The device of claim 6, wherein the sensor processing circuit comprises:

a first band-pass filter having the first set of cutoff frequencies;

a first amplifier having the first gain;

a second band-pass filter having the second set of cutoff frequencies; and

a second amplifier having the second gain.

8. The device of claim 7, wherein the first band-pass filter has a first set of programmable cutoff frequencies, and the second band-pass filter has a second set of programmable cutoff frequencies.

9. The device of claim 7, wherein the first amplifier having a first programmable gain, and the second amplifier has a second programmable gain.

10. The method for operating an implantable medical device, the method comprising:

sensing a signal indicative of physical activities and heart sounds using a single implantable sensor;

producing an activity level signal by filtering the sensed signal using first cutoff frequencies and amplifying the sensed signal using a first gain;

producing a heart sound signal by filtering the sensed signal using second cutoff frequencies and amplifying the sensed signal using a second gain; and

controlling delivery of cardiac pacing pulses from the implantable medical device using the activity level signal and the heart sound signal.

11. The method of claim 10, wherein sensing the signal comprises sensing an acceleration signal using an implantable accelerometer.

12. The method of claim 10, comprising:

producing the activity level signal during a first time period; and

producing the heart sound signal during a second time period,

wherein the first time period and the second time period do not overlap.

13. The method of claim 12, comprising producing the activity level signal and the heart sound signal using a band-pass filter having programmable cutoff frequencies and an amplifier having a programmable gain, wherein producing the activity level signal comprises:

programming the programmable cutoff frequencies to the first cutoff frequencies for the first time period; and

programming the programmable gain to the first gain for the first time period,

and producing the heart sound signal comprises;

programming the programmable cutoff frequencies to the second cutoff frequencies for the second time period; and

programming the programmable gain to the second gain for the second time period.

14. The method of claim 10, comprising producing the activity level signal and the heart sound signal concurrently.

15. The method of claim 14, comprising:

producing the activity level signal using a first band-pass filter having the first cutoff frequencies and a first amplifier having the first gain; and

producing the activity level signal using a second band-pass filter having the second cutoff frequencies and a second amplifier having the second gain.

16. An implantable medical device, comprising:

means for sensing a signal indicative of physical activities and heart sounds using a single implantable sensor; and

means for controlling gains and cutoff frequencies for producing an activity level signal and a heart sound signal using the sensed signal.

17. The device of claim 16, comprising means for controlling cardiac pacing using one or more of the activity level signal and the heart sound signal.

18. The device of claim 17, wherein the means for controlling cardiac pacing comprise means for determining one or more pacing parameters using the one or more of the activity level signal and the heart sound signal.

19. The device of claim 18, wherein the means for controlling gains and cutoff frequencies comprises means for controlling gains and cutoff frequencies for producing the activity level signal and the heart sound signal concurrently.

20. The device of claim 18, wherein the means for controlling gains and cutoff frequencies comprises means for controlling gains and cutoff frequencies for producing the activity level signal during a first time period and producing the heart sound signal during a second time period, wherein the first time period and the second time period do not overlap.