IDENTIFICATION AND REMEDIATION OF OVERSENSED CARDIAC EVENTS USING FAR-FIELD ELECTROGRAMS

• US 20100106209A1
• Filed: 10/29/2008
• Published: 04/29/2010
• Est. Priority Date: 10/29/2008
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Ruzin, Donald James, Gunderson, Bruce D.
• Granted Patent: US 8,078,277 B2
• Time in Patent Office: Days
• US Class Current: 607/17
• CPC Class Codes: A61N 1/3622 comprising two or more electrodes co-operating with different heart regions
• CPC Class Codes: A61N 1/3704 Circuits specially adapted therefor, e.g. for sensitivity control

Abstract

In general, the disclosure is directed to techniques for identification and remediation of oversensed cardiac events using far-field electrograms (FFEGMs). Identification of oversensed cardiac events can be used in an ICD to prevent ventricular fibrillation (VF) detection, and thereby avoid delivery of an unnecessary defibrillation shock. Alternatively, or additionally, identification of oversensed cardiac events can be used in an ICD to support delivery of bradycardia pacing during an oversensing condition. In some cases, bradycardia pacing delivered in response to detection of oversensed cardiac events may include pacing pulses from multiple vectors to provide redundancy in the event the oversensing may be due to a lead-related condition.

Claims

1. A method comprising:

acquiring a first cardiac signal via a first sense electrode configuration;

acquiring a second cardiac signal via a second sense electrode configuration;

detecting cardiac events in the first cardiac signal;

identifying at least some of the cardiac events detected in the first cardiac signal as oversensed events based on whether one or more characteristics of the second cardiac signal confirm the cardiac events; and

controlling delivery of cardiac electrical stimulation therapy to a patient based on the identification of the oversensed events.

2. The method of claim 1, wherein controlling delivery of cardiac electrical stimulation therapy comprises:

determining time intervals between the detected events that are not identified as oversensed events; and

controlling delivery of cardiac electrical stimulation therapy to the patient based on the time intervals.

3. The method of claim 2, wherein controlling delivery comprises:

detecting that one of the time intervals is greater than a threshold time interval; and

delivering pacing therapy to the patient in response to the detection that one of the time intervals is greater than the threshold time interval.

4. The method of claim 3, wherein delivering pacing therapy comprises:

delivering first pacing therapy via a first stimulation electrode configuration in response to the detection that one of the time intervals is greater than the threshold time interval; and

delivering second pacing therapy via a second stimulation electrode configuration in response to the detection that one of the time intervals is greater than the threshold time interval.

5. The method of claim 4, wherein the first stimulation electrode configuration comprises electrodes carried by a first lead implanted to deliver the first pacing therapy to a first chamber of the heart, and the second stimulation electrode configuration comprises electrodes carried by a second lead implanted to deliver the second pacing therapy to a second chamber of the heart.

6. The method of claim 4, further comprising measuring impedance values of at least one of the first and second stimulation electrode configurations.

7. The method of claim 2, wherein controlling delivery comprises:

determining a count of a number of the time intervals that are shorter than a threshold time interval;

detecting that the count is greater than a threshold count; and

delivering at least one of cardioversion or defibrillation therapy to the patient in response to the detection that the count is greater than the threshold count.

8. The method of claim 2, wherein controlling delivery comprises:

detecting that one of the time intervals is greater than a threshold time interval;

delivering pacing therapy to the patient in response to the detection that one of the time intervals is greater than the threshold time interval;

determining a count of a number of the time intervals that are shorter than a threshold time interval;

detecting that the count is greater than a threshold count; and

delivering at least one of cardioversion or defibrillation therapy to the patient in response to the detection that the count is greater than the threshold count.

9. The method of claim 1, wherein the first cardiac signal is a near-field electrogram signal, the second cardiac signal is a far-field electrogram signal, the first sense electrode configuration comprises a tip electrode and a ring electrode carried by a ventricular lead, and the second sense electrode configuration comprises a coil electrode carried by the ventricular lead and a can electrode carried by a housing of the implantable medical device.

10. The method of claim 1, wherein identifying at least some cardiac events detected in the first cardiac signal as oversensed events comprises identifying each of the detected cardiac events as an oversensed event if an amplitude of the second cardiac signal at a time substantially coincident with the respective detected cardiac event is below a threshold amplitude.

11. An implantable medical device comprising:

an electrical sensing module configured to acquire first cardiac signal via a first sense electrode configuration, and acquire a second cardiac signal via a second sense electrode configuration;

a stimulation module configured to deliver cardiac electrical stimulation therapy to a patient via stimulation electrodes; and

a processor configured to detect cardiac events in the first cardiac signal, identify at least some of the cardiac events detected in the first cardiac signal as oversensed events based on whether one or more characteristics of the second cardiac signal confirm the cardiac events, and control the stimulation module to deliver the cardiac electrical stimulation therapy to the patient based on the identification of the oversensed events.

12. The device of claim 11, wherein the processor is configured to determine time intervals between the detected events that are not identified as oversensed events, and control the stimulation module to deliver cardiac electrical stimulation therapy to the patient based on the time intervals.

13. The device of claim 12, wherein the processor is configured to detect that one of the time intervals is greater than a threshold time interval, and control the stimulation module to deliver pacing therapy to the patient in response to the detection that one of the time intervals is greater than the threshold time interval.

14. The device of claim 13, wherein the processor is configured to control the stimulation module to deliver first pacing therapy via a first stimulation electrode configuration in response to the detection that one of the time intervals is greater than the threshold time interval, and deliver second pacing therapy via a second stimulation electrode configuration in response to the detection that one of the time intervals is greater than the threshold time interval.

15. The device of claim 14, further comprising the first stimulation electrode configuration and the second stimulation electrode configuration, wherein the first stimulation electrode configuration comprises electrodes carried by a first implantable lead to deliver the first pacing therapy to a first chamber of the heart, and the second stimulation electrode configuration comprises electrodes carried by a second lead implantable to deliver the first pacing therapy to a second chamber of the heart.

16. The method of claim 14, further comprising an impedance measurement module configured to measure impedance values of at least one of the first and second stimulation electrode configurations.

17. The device of claim 12, wherein the processor is configured to:

determine a count of a number of the time intervals that are shorter than a threshold time interval;

detecting that the count is greater than a threshold count; and

control the stimulation module to deliver at least one of cardioversion or defibrillation therapy to the patient in response to the detection that the count is greater than the threshold count.

18. The device of claim 12, wherein the processor is configured to:

detect that one of the time intervals is greater than a threshold time interval;

deliver pacing therapy to the patient in response to the detection that one of the time intervals is greater than the threshold time interval;

determine a count of a number of the time intervals that are shorter than a threshold time interval;

detect that the count is greater than a threshold count; and

deliver at least one of cardioversion or defibrillation therapy to the patient in response to the detection that the count is greater than the threshold count.

19. The device of claim 11, wherein the first cardiac signal is a near-field electrogram signal, the second cardiac signal is a far-field electrogram signal, the device further comprising a ventricular lead, the first sense electrode configuration, and the second sense electrode configuration, wherein the first sense electrode configuration comprises a tip electrode and a ring electrode carried by the ventricular lead, and the second sense electrode configuration comprises a coil electrode carried by the ventricular lead and a can electrode carried by a housing of the implantable medical device.

20. The device of claim 11, wherein the processor is configured to identify each of the detected cardiac events as an oversensed event if an amplitude of the second cardiac signal at a time substantially coincident with the respective detected cardiac event is below a threshold amplitude.

21. An implantable medical device comprising:

means for acquiring a first cardiac signal via a first sense electrode configuration;

means for acquiring a second cardiac signal via a second sense electrode configuration;

means for detecting cardiac events in the first cardiac signal;

means for identifying at least some of the cardiac events detected in the first cardiac signal as oversensed events based on whether one or more characteristics of the second cardiac signal confirm the cardiac events; and

means for controlling delivery of cardiac electrical stimulation therapy to a patient based on the identification of the oversensed events.

22. The device of claim 21, wherein the means for controlling delivery of cardiac electrical stimulation therapy comprises:

means for determining time intervals between the detected events that are not identified as oversensed events; and

means for controlling delivery of cardiac electrical stimulation therapy to the patient based on the time intervals.

23. The device of claim 22, wherein the means for controlling delivery comprises:

means for detecting that one of the time intervals is greater than a threshold time interval; and

means for delivering pacing therapy to the patient in response to the detection that one of the time intervals is greater than the threshold time interval.

24. The device of claim 23, wherein the means for delivering pacing therapy comprises:

means for delivering first pacing therapy via a first stimulation electrode configuration in response to the detection that one of the time intervals is greater than the threshold time interval; and

means for delivering second pacing therapy via a second stimulation electrode configuration in response to the detection that one of the time intervals is greater than the threshold time interval.

25. The method of claim 24, wherein the first stimulation electrode configuration comprises electrodes carried by a first lead implantable to deliver the first pacing therapy to a first chamber of the heart, and the second stimulation electrode configuration comprises electrodes carried by a second lead implantable to deliver the second pacing therapy to a second chamber of the heart.

26. The method of claim 24, further comprising means for measuring impedance values of at least one of the first and second stimulation electrode configurations.

27. The device of claim 22, wherein the means for controlling delivery comprises:

means for determining a count of a number of the time intervals that are shorter than a threshold time interval;

means for detecting that the count is greater than a threshold count; and

means for delivering at least one of cardioversion or defibrillation therapy to the patient in response to the detection that the count is greater than the threshold count.

28. The device of claim 22, wherein the means for controlling delivery comprises:

means for detecting that one of the time intervals is greater than a threshold time interval;

means for delivering pacing therapy to the patient in response to the detection that one of the time intervals is greater than the threshold time interval;

means for determining a count of a number of the time intervals that are shorter than a threshold time interval;

means for detecting that the count is greater than a threshold count; and

means for delivering at least one of cardioversion or defibrillation therapy to the patient in response to the detection that the count is greater than the threshold count.

29. The device of claim 21, wherein the first cardiac signal is a near-field electrogram signal, the second cardiac signal is a far-field electrogram signal, the first sense electrode configuration comprises a tip electrode and a ring electrode carried by a ventricular lead, and the second sense electrode configuration comprises a coil electrode carried by the ventricular lead and a can electrode carried by a housing of the implantable medical device.

30. The device of claim 21, wherein the means for identifying at least some cardiac events detected in the first cardiac signal as oversensed events comprises means for identifying each of the detected cardiac events as an oversensed event if an amplitude of the second cardiac signal at a time substantially coincident with the respective detected cardiac event is below a threshold amplitude.

31. A computer-readable storage medium comprising instructions that, when executed by a processor in an implantable medical device, cause the processor to:

detect cardiac events in a first cardiac signal acquired via a first sense electrode configuration;

identify at least some of the cardiac events detected in the first cardiac signal as oversensed events based on whether one or more characteristics of a second cardiac signal acquired via a second sense electrode configuration confirm the cardiac events; and

control a stimulation module to deliver of cardiac electrical stimulation therapy to a patient based on the identification of the oversensed events.

32. The computer-readable storage medium of claim 31, wherein the instructions cause the processor to:

determine time intervals between the detected events that are not identified as oversensed events; and

control the stimulation module to deliver cardiac electrical stimulation therapy to the patient based on the time intervals.

33. The computer-readable storage medium of claim 32, wherein the instructions cause the processor to:

detect that one of the time intervals is greater than a threshold time interval; and

control the stimulation module to deliver pacing therapy to the patient in response to the detection that one of the time intervals is greater than the threshold time interval.

34. The computer-readable storage medium of claim 33, wherein the instructions cause the processor to:

control the stimulation module to deliver first pacing therapy via a first stimulation electrode configuration in response to the detection that one of the time intervals is greater than the threshold time interval; and

control the stimulation module to deliver second pacing therapy via a second stimulation electrode configuration in response to the detection that one of the time intervals is greater than the threshold time interval.

35. The computer-readable storage medium of claim 33, wherein the instructions cause the processor to obtain measured impedance values of at least one of the first and second stimulation electrode configurations.

36. The computer-readable storage medium of claim 32, wherein the instructions cause the processor to:

determine a count of a number of the time intervals that are shorter than a threshold time interval;

detect that the count is greater than a threshold count; and

control the stimulation module to deliver at least one of cardioversion or defibrillation therapy to the patient in response to the detection that the count is greater than the threshold count.

37. The computer-readable storage medium of claim 32, wherein the instructions cause the processor to:

detect that one of the time intervals is greater than a threshold time interval;

control the stimulation module to deliver pacing therapy to the patient in response to the detection that one of the time intervals is greater than the threshold time interval;

determine a count of a number of the time intervals that are shorter than a threshold time interval;

detect that the count is greater than a threshold count; and

control the stimulation module to deliver at least one of cardioversion or defibrillation therapy to the patient in response to the detection that the count is greater than the threshold count.

38. The computer-readable storage medium of claim 31, wherein the first cardiac signal is a near-field electrogram signal, the second cardiac signal is a far-field electrogram signal, the first sense electrode configuration comprises a tip electrode and a ring electrode carried by a ventricular lead, and the second sense electrode configuration comprises a coil electrode carried by the ventricular lead and a can electrode carried by a housing of the implantable medical device.

39. The computer-readable storage medium of claim 31, wherein the instructions cause the processor to identify each of the detected cardiac events as an oversensed event if an amplitude of the second cardiac signal at a time substantially coincident with the respective detected cardiac event is below a threshold amplitude.