Method and Apparatus for Identifying Oversensing Using Far-Field Intracardiac Electrograms and Marker Channels

• US 20130060117A1
• Filed: 11/05/2012
• Published: 03/07/2013
• Est. Priority Date: 04/18/2005
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Gunderson, Bruce D., Bounds, Chad A., Brown, Mark L., Patel, Amisha S.
• Granted Patent: US 8,792,971 B2
• Time in Patent Office: Days
• US Class Current: 600/374
• CPC Class Codes: A61B 5/352 Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval
• CPC Class Codes: A61B 5/363 Detecting tachycardia or bradycardia
• CPC Class Codes: A61B 5/7217 of noise originating from a therapeutic or surgical apparatus, e.g. from a pacemaker
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• 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 1/3622 comprising two or more electrodes co-operating with different heart regions
• CPC Class Codes: A61N 1/3702 Physiological parameters A61N1/365 takes precedence; evoked response A61N1/371
• CPC Class Codes: A61N 1/3704 Circuits specially adapted therefor, e.g. for sensitivity control

Abstract

A method for identifying oversensing in implantable medical devices (IMDs), such as implantable cardioverter defibrillators (ICDs), is described. A near-field electrogram signal and a far-field electrogram signal are obtained via a near-field electrode pair and a far-field electrode pair. The near-field electrogram signal is compared to the far-field electrogram signal and a determination of whether oversensing exists is made based on the comparison. In some instances, a scheduled therapy is withheld in response to determining that oversensing exists.

Claims

1. An implantable medical system comprising:

at least one implantable lead that includes a plurality of electrodes;

an implantable medical device coupled to the at least one implantable lead, the implantable medical device including;

a memory configured to store a near-field electrogram signal and a far-field electrogram signal; and

a microprocessor configured to obtain the near-field electrogram signal, obtain the far-field electrogram signal, compare the near-field electrogram signal to the far-field electrogram signal, and determine whether oversensing exists based on the comparison.

2. The implantable medical system of claim 1, wherein the microprocessor compares the near-field electrogram signal to the far-field electrogram signal by comparing a number of cardiac events detected in the near-field electrogram signal to a number of cardiac events detected in the far-field electrogram signal.

3. The implantable medical system of claim 1, wherein the microprocessor withholds a therapy in response to determining that oversensing exists.

4. The implantable medical system of claim 1, wherein the microprocessor determines whether correlation exists between sensed events in the near-field electrogram signal and sensed events in the far-field electrogram signal and determines that oversensing exists when there is insufficient correlation between sensed events in the near-field electrogram signal and sensed events in the far-field electrogram signal.

5. The implantable medical system of claim 4, wherein the microprocessor determines that there is insufficient correlation between sensed events in the near-field electrogram signal and sensed events in the far-field electrogram signal when the near-field electrogram signal exhibits an erratic signal while the far-field electrical signal does not exhibit an erratic signal during the same timeframe.

6. The implantable medical system of claim 1, wherein the microprocessor compares the near-field electrogram signal to the far-field electrogram by mapping each cardiac event in the far-field electrogram signal to a corresponding cardiac event in the near-field electrogram signal.

7. The implantable medical system of claim 6, wherein the microprocessor maps each cardiac event in the far-field electrogram signal to a corresponding cardiac event in the near-field electrogram signal that occurs most closely in time.

8. The implantable medical system of claim 6, wherein the microprocessor maps each cardiac event in the far-field electrogram signal to a corresponding cardiac event in the near-field electrogram signal that occurs within plus or minus a predetermined number milliseconds from the cardiac event in the far-field electrogram signal.

9. The implantable medical system of claim 6, wherein the microprocessor determines that oversensing exists when a first predetermined number of cardiac events in the near-field electrogram signal that are not mapped to corresponding cardiac events in the far-field electrogram signal occur within a second predetermined number of cardiac events in the near-field electrogram signal that are mapped to corresponding cardiac events in the far-field electrogram signal.

10. The implantable medical system of claim 6, wherein the microprocessor determines a number of cardiac events in the near-field electrogram signal, determines a number of mapped cardiac events in the near-field electrogram signal, compares the total number of cardiac events in the near-field electrogram signal to a threshold value, the threshold value being determined a function of the number of mapped cardiac events in the near-field electrogram signal, and determines that oversensing exists when the total number of cardiac events in the near-field electrogram signal is greater than the threshold value and a first predetermined number of cardiac events in the near-field electrogram signal that are not mapped to corresponding cardiac events in the far-field electrogram signal occur within a second predetermined number of cardiac events in the near-field electrogram signal that are mapped to corresponding cardiac events in the far-field electrogram signal.

11. A method comprising:

obtaining a near-field electrogram signal;

obtaining a far-field electrogram signal;

comparing the near-field electrogram signal to the far-field electrogram signal; and

determining whether oversensing exists based on the comparison.

12. The method of claim 11, wherein comparing the near-field electrogram signal to the far-field electrogram signal comprises comparing a number of cardiac events detected in the near-field electrogram signal to a number of cardiac events detected in the far-field electrogram signal.

13. The method of claim 11, further comprising withholding a therapy in response to determining that oversensing exists.

14. The method of claim 11, wherein

comparing the near-field electrogram signal to the far-field electrogram signal comprises determining whether correlation exists between sensed events in the near-field electrogram signal and sensed events in the far-field electrogram signal, and

determining whether oversensing exists based on the comparison comprises determining that oversensing exists when there is insufficient correlation between sensed events in the near-field electrogram signal and sensed events in the far-field electrogram signal.

15. The method of claim 14, wherein determining that oversensing exists when no correlation exists between sensed events in the near-field electrogram signal and sensed events in the far-field electrogram signal comprises determining that oversensing exists when the near-field electrogram signal exhibits an erratic signal while the far-field electrical signal does not exhibit an erratic signal during the same timeframe.

16. The method of claim 11, wherein comparing the near-field electrogram signal to the far-field electrogram comprises mapping each cardiac event in the far-field electrogram signal to a corresponding cardiac event in the near-field electrogram signal.

17. The method of claim 16, wherein mapping each cardiac event in the far-field electrogram signal to a corresponding cardiac event in the near-field electrogram signal comprises mapping each cardiac event in the far-field electrogram signal to a corresponding cardiac event in the near-field electrogram signal that occurs most closely in time.

18. The method of claim 16, wherein mapping each cardiac event in the far-field electrogram signal to a corresponding cardiac event in the near-field electrogram signal comprises mapping each cardiac event in the far-field electrogram signal to a corresponding cardiac event in the near-field electrogram signal that occurs within plus or minus a predetermined number milliseconds from the cardiac event in the far-field electrogram signal.

19. The method of claim 16, wherein determining whether oversensing exists based on the comparison comprises determining that oversensing exists when a first predetermined number of cardiac events in the near-field electrogram signal that are not mapped to corresponding cardiac events in the far-field electrogram signal occur within a second predetermined number of cardiac events in the near-field electrogram signal that are mapped to corresponding cardiac events in the far-field electrogram signal.

20. The method of claim 16, wherein determining whether oversensing exists based on the comparison comprises:

determining a number of cardiac events in the near-field electrogram signal;

determining a number of mapped cardiac events in the near-field electrogram signal;

comparing the total number of cardiac events in the near-field electrogram signal to a threshold value, the threshold value being determined a function of the number of mapped cardiac events in the near-field electrogram signal; and

determining that oversensing exists when the total number of cardiac events in the near-field electrogram signal is greater than the threshold value and a first predetermined number of cardiac events in the near-field electrogram signal that are not mapped to corresponding cardiac events in the far-field electrogram signal occur within a second predetermined number of cardiac events in the near-field electrogram signal that are mapped to corresponding cardiac events in the far-field electrogram signal.

21-28. -28. (canceled)