METHOD AND APPARATUS FOR CAPTURE VERIFICATION AND THRESHOLD DETERMINATION

• US 20070162082A1
• Filed: 01/08/2007
• Published: 07/12/2007
• 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 8,364,265 B2
• Time in Patent Office: Days
• US Class Current: 607/28
• 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 1/3684 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

Abstract

An apparatus and method for verifying capture by a pacing pulse in which a test depolarization waveform recorded during a pacing event is compared with a template waveform representing capture by the pacing pulse. Capture verification in this manner may be used in pacemakers having multiple pacing channels for the atrial and/or ventricles where the multiple paces can interfere with conventional sensing of evoked responses in order to verify capture.

Claims

1. A cardiac pacemaker, comprising:

first and second pacing channels, each such channel comprising an electrode for disposing near a chamber of the heart, a pulse generator for outputting pacing pulses, and a channel interface for adjusting the pacing pulse energy;

a controller for controlling the operation of the pulse generators in response to sensed events and lapsed time intervals and in accordance with a programmed pacing mode;

an evoked response sensing channel comprising an electrode and a sense amplifier 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; and

,

compare the test electrogram with a template electrogram representing capture of the heart by both of the first and second pacing pulses, compare the test electrogram with a template electrogram representing capture by a pacing pulse delivered only from the first pacing channel, and compare the test electrogram with a template electrogram representing capture by a pacing pulse delivered only from the second pacing channel in order to determine which of the delivered pacing pulses have achieved capture.

2. The pacemaker of claim 1 wherein the first and second pacing channels are right and left ventricular pacing channels or right and left atrial pacing channels.

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

4. 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.

5. The pacemaker of claim 4 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.

6. The pacemaker of claim 5 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.

7. The pacemaker of claim 5 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.

8. The pacemaker of claim 4 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.

9. The pacemaker of claim 1 wherein the controller is programmed to determine if capture has been achieved during each cardiac cycle on a beat-to-beat basis.

10. The pacemaker of claim 1 wherein the controller is further programmed to deliver a safety pace if capture has not been achieved during a cardiac cycle.

11. A method comprising:

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

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

,

comparing the test electrogram with a template electrogram representing capture of the heart by both of the first and second pacing pulses, comparing the test electrogram with a template electrogram representing capture by a pacing pulse delivered only from the first pacing channel, and comparing the test electrogram with a template electrogram representing capture by a pacing pulse delivered only from the second pacing channel in order to determine which of the delivered pacing pulses have achieved capture.

12. The method of claim 11 wherein the first and second pacing pulses are delivered to either the right and left ventricles or the right and left atria.

13. 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.

14. The method of claim 13 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.

15. The method of claim 13 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.

16. A system comprising:

means for delivering first and second pacing pulses from first and second pacing channels, respectively, during a cardiac cycle;

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

,

means for comparing the test electrogram with a template electrogram representing capture of the heart by both of the first and second pacing pulses, means for comparing the test electrogram with a template electrogram representing capture by a pacing pulse delivered only from the first pacing channel, and means for comparing the test electrogram with a template electrogram representing capture by a pacing pulse delivered only from the second pacing channel in order to determine which of the delivered pacing pulses have achieved capture.

17. The system of claim 16 wherein the means for delivering first and second pacing pulses deliver pacing pulses to either the right and left ventricles or the right and left atria.

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

19. The system of claim 18 further comprising means for 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.

20. The system of claim 18 further comprising means for 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.