HEART SOUNDS TEMPLATE COMPARISON TO IDENTIFY TRUE PACING MODE

• US 20140277243A1
• Filed: 02/24/2014
• Published: 09/18/2014
• Est. Priority Date: 03/12/2013
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Maskara, Barun, An, Qi, Thakur, Pramodsingh Hirasingh, Thompson, Julie A.
• Granted Patent: US 9,320,906 B2
• Time in Patent Office: Days
• US Class Current: 607/28
• CPC Class Codes: A61B 7/04 Electric stethoscopes microphones, acoustic transducers therefor H04R
• CPC Class Codes: A61N 1/3627 for treating a mechanical deficiency of the heart, e.g. congestive heart failure or cardiomyopathy
• CPC Class Codes: A61N 1/36578 controlled by mechanical motion of the heart wall, e.g. measured by an accelerometer or microphone
• CPC Class Codes: A61N 1/3684 for stimulating the heart at multiple sites of the ventricle or the atrium
• CPC Class Codes: A61N 1/36843 Bi-ventricular stimulation
• CPC Class Codes: A61N 1/371 Capture, i.e. successful stimulation

Abstract

An apparatus may include an implantable therapy circuit that provides bi-ventricular pacing to a subject, a heart sound signal sensing circuit that produces a sensed heart sound signal that is representative of at least one heart sound associated with mechanical cardiac activity, a memory circuit to store one or more heart sound templates of cardiac capture, and a comparison circuit that compares a segment of the sensed heart sound signal to the one or more heart sound templates of cardiac capture to identify ventricles in which cardiac capture was induced by the bi-ventricular pacing. In some situations, an indication of the ventricles in which cardiac capture was induced may be generated according to the comparison.

Claims

1. An apparatus comprising:

an implantable therapy circuit configured to provide a bi-ventricular pacing pulse to a subject as part of cardiac pacing therapy, wherein the bi-ventricular pacing pulse includes providing an electrical stimulation pulse to a right ventricle and an electrical stimulation pulse to a left ventricle;

a heart sound signal sensing circuit configured to produce a sensed heart sound signal that is representative of at least one heart sound associated with mechanical cardiac activity of a subject;

a memory circuit configured to store one or more heart sound templates of cardiac capture; and

a comparison circuit configured to;

compare a segment of the sensed heart sound signal to the one or more heart sound templates of cardiac capture to identify ventricles in which cardiac capture was induced by the bi-ventricular pacing pulse; and

generate an indication of the ventricles in which capture was induced according to the comparison and providing the indication to at least one of a user or process.

2. The apparatus of claim 1, including:

a cardiac signal sensing circuit configured to provide a sensed cardiac signal representative of electrical cardiac activity of the subject;

a detection circuit configured to detect an episode of atrial fibrillation using the sensed cardiac signal; and

a control circuit configured to initiate delivery of one or more bi-ventricular pacing pulses during the detected episode of atrial fibrillation,

wherein the comparison circuit is configured to generate an indication of the ventricles in which capture was induced by one or more bi-ventricular pacing pulses provided during the detected episode of atrial fibrillation.

3. The apparatus of claim 1, wherein the comparison circuit is configured to compare the segment of the sensed heart sound signal to at least one of a template heart sound signal representative of a heart sound signal sensed during pacing of only a right ventricle (RV), a template heart sound signal representative of a heart sound signal sensed during pacing of only a left ventricle (LV), a template heart sound signal representative of a heart sound signal sensed during bi-ventricular pacing, and a template heart sound signal representative of ventricular contraction resulting from intrinsic depolarization;

and generate the indication of the ventricles in which capture was induced or an indication of no cardiac capture according to the comparison.

4. The apparatus of claim 1, wherein the heart sound signal sensing circuit is configured to sense a heart sound signal that includes at least a portion of a sensed S1 heart sound, and wherein the comparison circuit is configured to compare a segment of the sensed heart sound signal that includes the at least a portion of a sensed S1 heart sound to one or more templates representative of an S1 heart sound.

5. The apparatus of claim 1, wherein the comparison circuit is configured to generate an indication that updates, according to the comparison, a count of capture induced in the RV only, a count of capture induced in the LV only, a count of capture induced in both ventricles, and a count of lack of capture in the ventricles.

6. The apparatus of claim 1, including a template circuit configured to generate heart sound templates representative of cardiac capture in the RV, in the LV, and in both ventricles, and generating a heart sound template representative of ventricular contraction due to intrinsic depolarization.

7. The apparatus of claim 6, including a control circuit configured to initiate a template mode in which one or more electrical stimulation pulses are delivered to one or both ventricles, wherein the electrical stimulation pulses are provided using a stimulation interval that is less than a shortest detected intrinsic depolarization interval, and wherein the template circuit is configured to generate a heart sound template using one or more heart sound signals sensed when providing the one or more electrical stimulation pulses to the one or both ventricles in the template mode.

8. The apparatus of claim 1, including:

a template circuit configured to generate a candidate heart sound template representative of at least one of cardiac capture in the RV only, cardiac capture in the LV only, cardiac capture in both ventricles, or representative of ventricular contraction resulting from intrinsic depolarization; and

a control circuit configured to receive an indication of acceptance of the candidate template, and wherein the control circuit is configured to initiate a comparison of a segment of a sensed heart sound signal to the candidate template upon receiving the indication of acceptance of the candidate template.

9. The apparatus of claim 1, including:

a template circuit configured to;

generate a candidate heart sound template representative of cardiac capture resulting from an electrical stimulation pulse delivered to at least one of the RV only, the LV only, or to both ventricles; and

calculate a metric of separation of the candidate heart sound template from a heart sound template representative of ventricular contraction resulting from intrinsic depolarization; and

a control circuit configured to initiate a comparison of a segment of a sensed heart sound signal to the candidate heart sound template according to the calculated metric.

10. The apparatus of claim 1, including a heart rate detection circuit, wherein the comparison circuit is configured to scale the one or more heart sound templates of cardiac capture in one or both of time and amplitude as a function of detected heart rate, wherein compare the segment of the sensed heart sound signal to one or more scaled heart sound templates.

11. A method comprising

providing, to a subject by an implantable device, a bi-ventricular pacing pulse as part of cardiac pacing therapy, wherein the bi-ventricular pacing pulse includes providing an electrical stimulation pulse to a right ventricle and an electrical stimulation pulse to a left ventricle;

sensing a heart sound signal from the subject in association with the bi-ventricular pacing pulse, wherein a heart sound signal is associated with mechanical activity of the heart of the subject;

comparing, by the implantable device, a segment of the sensed heart sound signal to one or more heart sound templates of cardiac capture to identify ventricles in which cardiac capture was induced by the bi-ventricular pacing pulse; and

generating an indication of the ventricles in which capture was induced according to the comparison and providing the indication to at least one of a user or process.

12. The method of claim 11, including detecting, by the implantable device, an episode of atrial fibrillation, wherein providing a bi-ventricular pacing pulse includes providing one or more bi-ventricular pacing pulses during the episode of atrial fibrillation, and wherein the generating an indication includes generating an indication of the ventricles in which capture was induced by the one or more bi-ventricular pacing pulses provided during the episode of atrial fibrillation.

13. The method of claim 11, wherein comparing a segment of the sensed heart sound signal includes comparing the segment of the sensed heart sound signal to at least one of a template heart sound signal representative of a heart sound signal sensed during pacing of only a right ventricle (RV), a template heart sound signal representative of a heart sound signal sensed during pacing of only a left ventricle (LV), a template heart sound signal representative of a heart sound signal sensed during bi-ventricular pacing, and a template heart sound signal representative of ventricular contraction resulting from intrinsic depolarization.

14. The method of claim 11, wherein sensing a heart sound signal includes sensing a heart sound signal that includes at least a portion of a sensed S1 heart sound, and wherein comparing a segment of the sensed heart sound signal includes comparing a segment of the sensed heart sound signal that includes the at least a portion of a sensed S1 heart sound to one or more templates representative of an S1 heart sound.

15. The method of claim 11, wherein generating an indication includes updating, according to the comparison, a count of capture induced in the RV only, a count of capture induced in the LV only, a count of capture induced in both ventricles, and a count of lack of capture in the ventricles.

16. The method of claim 11, including generating, by the implantable device, heart sound templates representative of cardiac capture in the RV, in the LV, and in both ventricles, and generating a heart sound template representative of ventricular contraction due to intrinsic depolarization.

17. The method of claim 16, wherein generating heart sound templates representative of cardiac capture includes generating a heart sound template using one or more heart sound signals sensed when providing electrical stimulation pulses to one or both ventricles using a stimulation interval that is less than a shortest detected intrinsic depolarization interval.

18. The method of claim 11, including:

generating, by the implantable device, a candidate heart sound template representative of at least one of cardiac capture in the RV only, cardiac capture in the LV only, cardiac capture in both ventricles, or ventricular contraction resulting from intrinsic depolarization;

receiving, by the implantable device, an indication of acceptance of the candidate heart sound template; and

classifying the candidate heart sound template as usable in a comparison to a segment of a sensed heart sound signal upon receiving the indication of acceptance of the candidate template.

19. The method of claim 11, including:

generating, by the implantable device, a candidate heart sound template representative of cardiac capture resulting from at least one of a pacing stimulation pulse provided to the RV only, a pacing stimulation pulse provided to the LV only, or a pacing stimulation pulse provided to both ventricles;

calculating a metric of separation of the candidate heart sound template from a heart sound template representative of ventricular contraction resulting from intrinsic depolarization; and

classifying the candidate heart sound template as usable in a comparison to a segment of a sensed heart sound signal according to the calculated metric.

20. The method of claim 11, including:

determining a heart rate of the subject; and

scaling the one or more heart sound templates of cardiac capture in or both of time and amplitude as a function of the determined heart rate, wherein comparing a segment of the sensed heart sound signal includes comparing a segment of the sensed heart sound signal to one or more scaled heart sound templates.