TEMPLATE-BASED CAPTURE VERIFICATION FOR MULTI-SITE PACING

• US 20070219593A1
• Filed: 05/29/2007
• Published: 09/20/2007
• Est. Priority Date: 10/26/2001
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Ternes, David, Yonce, David
• Granted Patent: US 8,406,880 B2
• Time in Patent Office: Days
• US Class Current: 607/28
• CPC Class Codes: A61B 5/35 by template matching
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61B 5/7264 Classification of physiological signals or data, e.g. using neural networks, statistical classifiers, expert systems or fuzzy systems neural networks per se G06N3/00; expert systems per se G06N5/00
• 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 1/3682 with a variable atrioventricular delay
• CPC Class Codes: A61N 1/3684 for stimulating the heart at multiple sites of the ventricle or the atrium
• CPC Class Codes: A61N 1/36842 Multi-site stimulation in the same chamber
• CPC Class Codes: A61N 1/36843 Bi-ventricular stimulation
• CPC Class Codes: A61N 1/3712 Auto-capture, i.e. automatic adjustment of the stimulation threshold
• CPC Class Codes: G16H 50/20 for computer-aided diagnosis, e.g. based on medical expert systems

Abstract

An apparatus and method for verifying capture by first and second pacing pulses in which an evoked response waveform recorded during a pacing event is compared with template waveforms representing capture by the first, second, and both pacing pulses. The evoked response is then classified as representing a type of capture represented by a template waveform if the evoked response waveform highly correlates with one template waveform and has correlation values with the other template waveforms within specified bounds.

Claims

1. A cardiac pacemaker, comprising:

first and second pacing channels for delivering pacing pulses to electrodes disposed for pacing each of the paired atria or each of the paired ventricles;

a controller for controlling the delivery of pacing pulses in accordance with a programmed pacing mode;

an evoked response sensing channel for sensing an evoked response generated after a pacing pulse; and

,

wherein the controller is programmed to;

deliver first and second pacing pulses from the first and second pacing channels, respectively, during a cardiac cycle;

record a test electrogram from the evoked response sensing channel during delivery of the first and second pacing pulses;

measure a parameter related to the signal energy of the test electrogram;

compare the test electrogram with template electrograms representing capture of the heart by both of the first and second pacing pulses, representing capture by a pacing pulse delivered only from the first pacing channel, and representing capture by a pacing pulse delivered only from the second pacing channel; and

,

determine which of the delivered first and second pacing pulses have achieved capture based upon the template comparisons and the value of the parameter related to the signal energy of the test electrogram.

2. The pacemaker of claim 1 wherein the controller is programmed to compare the test and template electrograms by performing a time-domain cross-correlation.

3. The pacemaker of claim 1 wherein the first and second pacing channels are configurable as right and left ventricular pacing channels, the evoked response sensing channel is configurable with an electrode disposed near the right ventricle, and wherein the controller is programmed to classify the test electrogram as representing right ventricular (RV) capture, left ventricular (LV) capture, or biventricular (BiV) capture based upon a comparison of the test electrogram with RV, LV, and BiV templates representing RV, LV, and BiV capture, respectively, and to further distinguish between RV capture and BiV capture based upon the value of the parameter related to the signal energy of the test electrogram and the value of similar parameters for the BiV and RV templates.

4. The pacemaker of claim 1 wherein the first and second pacing channels are configurable as right and left ventricular pacing channels, the evoked response sensing channel is configurable with an electrode disposed near the left ventricle, and wherein the controller is programmed to classify the test electrogram as representing right ventricular (RV) capture, left ventricular (LV) capture, or biventricular (BiV) capture based upon a comparison of the test electrogram with RV, LV, and BiV templates representing RV, LV, and BiV capture, respectively, and to further distinguish between LV capture and BiV capture based upon the value of the parameter related to the signal energy of the test electrogram and the value of similar parameters for the BiV and LV templates.

5. The pacemaker of claim 1 wherein the parameter related to the signal energy of a test electrogram is the signal energy during a sub-window interval of 200-300 ms following the pace.

6. The pacemaker of claim 1 wherein the controller is further programmed to vary the pulse energy of the pacing pulses in order to determine a capture threshold for a pacing channel.

7. The pacemaker of claim 6 wherein the controller is further programmed to lower the pacing pulse energy of a pacing channel until capture is no longer achieved by that channel in order to determine the capture threshold.

8. The pacemaker of claim 7 wherein the controller is programmed to determine a capture threshold for each of the first and second pacing channels by lowering the pacing energy of each pacing channel separately until the test electrogram no longer matches the template electrogram representing capture by both of the first and second pacing pulses.

9. The pacemaker of claim 7 wherein the controller is programmed to determine a capture threshold of the first and second pacing channels by:

lowering the pacing energy of the first pacing channel until the test electrogram matches the template electrogram representing capture by the second pacing pulse but does not match the template electrogram representing capture by the first pacing pulse; and

,

lowering the pacing energy of the second pacing channel until the test electrogram matches a template electrogram representing capture by the first pacing pulse but does not match the template electrogram representing capture by the second pacing pulse.

10. The pacemaker of claim 6 wherein the controller is further programmed to adjust the pacing pulse energy of a pacing channel in accordance with the results of the capture threshold determination.

11. A method for operating a cardiac pacemaker, comprising:

delivering first and second pacing pulses during a cardiac cycle to electrodes disposed for pacing each of the paired atria or each of the paired ventricles in accordance with a programmed pacing mode;

sensing an evoked response generated after a pacing pulse;

recording a test electrogram from the evoked response sensing channel during delivery of the first and second pacing pulses;

measuring a parameter related to the signal energy of the test electrogram;

comparing the test electrogram with template electrograms representing capture of the heart by both of the first and second pacing pulses, representing capture by a pacing pulse delivered only from the first pacing channel, and representing capture by a pacing pulse delivered only from the second pacing channel; and

,

determining which of the delivered first and second pacing pulses have achieved capture based upon the template comparisons and the value of the parameter related to the signal energy of the test electrogram.

12. The method of claim 11 wherein the comparison of the test and template electrograms implemented by performing a time-domain cross-correlation.

13. The method of claim 11 wherein the first and second pacing channels are configured as right and left ventricular pacing channels, the evoked response sensing channel is configured with an electrode disposed near the right ventricle, and further comprising classifying the test electrogram as representing right ventricular (RV) capture, left ventricular (LV) capture, or biventricular (BiV) capture based upon a comparison of the test electrogram with RV, LV, and BiV templates representing RV, LV, and BiV capture, respectively, and farther distinguishing between RV capture and BiV capture based upon the value of the parameter related to the signal energy of the test electrogram and the value of similar parameters for the BiV and RV templates.

14. The method of claim 11 wherein the first and second pacing channels are configured as right and left ventricular pacing channels, the evoked response sensing channel is configured with an electrode disposed near the left ventricle, and further comprising classifying the test electrogram as representing right ventricular (RV) capture, left ventricular (LV) capture, or biventricular (BiV) capture based upon a comparison of the test electrogram with RV, LV, and BiV templates representing RV, LV, and BiV capture, respectively, and further distinguishing between LV capture and BiV capture based upon the value of the parameter related to the signal energy of the test electrogram and the value of similar parameters for the BiV and LV templates.

15. The method of claim 11 wherein the parameter related to the signal energy of a test electrogram is the signal energy during a sub-window interval of 200-300 ms following the pace.

16. The method of claim 11 further comprising varying the pulse energy of the pacing pulses in order to determine a capture threshold for a pacing channel.

17. The method of claim 16 wherein the controller is further programmed to lower the pacing pulse energy of a pacing channel until capture is no longer achieved by that channel in order to determine the capture threshold.

18. The method of claim 17 further comprising determining a capture threshold for each of the first and second pacing channels by lowering the pacing energy of each pacing channel separately until the test electrogram no longer matches the template electrogram representing capture by both of the first and second pacing pulses.

19. The method of claim 17 further comprising determining a capture threshold of the first and second pacing channels by:

lowering the pacing energy of the first pacing channel until the test electrogram matches the template electrogram representing capture by the second pacing pulse but does not match the template electrogram representing capture by the first pacing pulse; and

,

lowering the pacing energy of the second pacing channel until the test electrogram matches a template electrogram representing capture by the first pacing pulse but does not match the template electrogram representing capture by the second pacing pulse.

20. The method of claim 16 further comprising adjusting the pacing pulse energy of a pacing channel in accordance with the results of the capture threshold determination.