METHOD AND APPARATUS FOR DETECTING AND DISCRIMINATING TACHYCARDIA

• US 20110270102A1
• Filed: 04/28/2010
• Published: 11/03/2011
• Est. Priority Date: 04/28/2010
• Status: Abandoned Application

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Gillberg, Jeffrey M., Stadler, Robert W., Zhang, Xusheng
• Application Number:
  US12/768,773
• Publication Number:
  US 20110270102A1
• Time in Patent Office: Days
• US Class Current: 600/512
• CPC Class Codes: A61B 5/02405 Determining heart rate variability
• CPC Class Codes: A61B 5/35 by template matching
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61N 1/3621 for treating or preventing abnormally high heart rate
• CPC Class Codes: A61N 1/36514 controlled by a physiological quantity other than heart potential, e.g. blood pressure controlled by two or more physical parameters A61N1/36585
• CPC Class Codes: A61N 1/39622 Pacing therapy

Abstract

A medical device and associated method for discriminating cardiac events includes sensing a cardiac signal spatially located across approximately a full duration of a predetermined sensing window. A match score is determined corresponding to the sensed cardiac signal. A beat feature of multiple beat features across less than the full duration of the sensing window is determined, the beat feature being selected from the multiple beat features in response to the match score. Cardiac event evidence is accumulated in response to the match score and the determined beat feature, and cardiac events are discriminated in response to the accumulated cardiac evidence.

Claims

1. A method of discriminating cardiac events, comprising:

sensing a cardiac signal spatially located across approximately a full duration of a predetermined sensing window;

determining a match score corresponding to the sensed cardiac signal;

determining a beat feature of a plurality of beat features across less than the full duration of the sensing window, the beat feature being selected from the plurality of beat features in response to the match score;

accumulating cardiac event evidence in response to the match score and the determined beat feature; and

discriminating cardiac events in response to the accumulated cardiac evidence.

2. The method of claim 1, wherein determining a match score comprises sensing a cardiac signal along one or both of a first sensing vector and a second sensing vector different from the first sensing vector, and wherein the first sensing vector corresponds to a far field sensing vector and the second sensing vector corresponds to a near field sensing vector.

3. The method of claim 2, wherein the match score is determined in response to the far field sensing vector and the beat feature is determined in response to the near field sensing vector.

4. The method of claim 1, wherein accumulating cardiac event evidence comprises performing one of increasing and decreasing an event counter in response to the determined match score and the determined beat feature.

5. The method of claim 2, further comprising:

determining whether the match score is within one of a first match zone corresponding to a first cardiac event, and a second match zone corresponding to a second cardiac event;

determining whether the determined beat feature is within one of the first match zone and the second match zone;

decreasing an event counter by a first value in response to the match score being within the first match zone and the determined beat feature being within the first match zone; and

decreasing the event counter by a second value less than the first value in response to the match score being within the first match zone and the determined beat feature being within the second match zone.

6. The method of claim 2, further comprising:

determining whether the match score is within one of a first match zone corresponding to a first cardiac event, a second match zone corresponding to the first cardiac event, and a third match zone corresponding to a second cardiac event different from the first cardiac event; and

determining whether the determined beat feature is within one of the first match zone, the second match zone, and the third match zone, wherein the first match zone has a first correlation with a non-treatable cardiac event, the second match zone has a second correlation with the non-treatable cardiac event less than the first correlation with the non-treatable event, and the third match zone is correlated with a treatable cardiac event.

7. The method of claim 6, further comprising:

increasing an event counter in response to the first match score being in the second match zone and the beat feature being within the third match zone; and

decreasing the event counter in response to the first match score being in the second match zone and the beat feature being within one of the first match zone and the second match zone.

8. The method of claim 7, wherein the non-treatable cardiac event corresponds to a supraventricular tachycardia event and the treatable cardiac event corresponds to ventricular tachycardia.

9. The method of claim 2, further comprising:

determining whether the match score is within one of a first match zone corresponding to a first cardiac event, a second match zone corresponding to the first cardiac event, a third match zone corresponding to a second cardiac event different from the first cardiac event, and a fourth match zone corresponding to the second cardiac event; and

determining whether the determined beat feature is within one of the first match zone, the second match zone, the third match zone, and the fourth match zone, wherein the first match zone has a first correlation with a treatable cardiac event, the second match zone has a second correlation with the treatable cardiac event less than the first correlation with the treatable event, the third match zone has a first correlation with a non-treatable cardiac event, and the fourth match zone has a second correlation with the non-treatable cardiac event greater than the first correlation with the non-treatable event.

10. The method of claim 9, further comprising:

decreasing an event counter in response to the first match score being in the second match zone and the beat feature being in the fourth match zone; and

increasing the event counter in response to the first match score being in the second match zone and the beat feature not being in the fourth match zone.

11. The method of claim 9, further comprising:

increasing an event counter by a first value in response to the first match score being in the first match zone and the second match score being in the first match zone; and

increasing the event counter by a second value less than the first value in response to the first match score being in the first match zone and the second match score being in one of the second match zone, the third match zone and the fourth match zone.

12. The method of claim 2, wherein determining a match score comprises:

determining a first match score corresponding to the cardiac signals sensed along the first sensing vector;

determining whether the first match score is within one of a first match zone corresponding to a first cardiac event, a second match zone corresponding to the first cardiac event, a third match zone corresponding to a second cardiac event different from the first cardiac event, and a fourth match zone corresponding to the second cardiac event;

determining a second match score corresponding to the cardiac signals sensed along the second sensing vector;

determining whether the second match score is within one of the first match zone, the second match zone, the third match zone and the fourth match zone;

determining whether the determined beat feature is within one of the first match zone, the second match zone, the third match zone, and the fourth match zone, wherein the first match zone has a first correlation with a treatable cardiac event, the second match zone has a second correlation with the treatable cardiac event less than the first correlation with the treatable event, the third match zone is correlated with a non-treatable cardiac event, and the fourth match zone has a second correlation with the non-treatable cardiac event greater than the first correlation with the non-treatable event;

decreasing an event counter by a first value in response to the first match score being in the second match zone and the beat feature corresponding to the first sensing vector being in the fourth match zone;

decreasing the event counter by a second value greater than the first value in response to the first match score being in the second match zone and the beat feature corresponding to the second sensing vector being in the fourth match zone; and

increasing the event counter in response to the first match score being in the second match zone and the beat feature not being in the fourth match zone.

13. A medical device for discriminating cardiac events, comprising:

a plurality of electrodes sensing a cardiac signal spatially located across approximately a full duration of a predetermined sensing window; and

a processor configured to determine a match score corresponding to the sensed cardiac signal, determining a beat feature of a plurality of beat features across less than the full duration of the sensing window, the beat feature being selected from the plurality of beat features in response to the match score, accumulate cardiac event evidence in response to the match score and the determined beat feature, and discriminate cardiac events in response to the accumulated cardiac evidence.

14. The device of claim 13, wherein the plurality of electrodes comprises:

a first electrode pair sensing cardiac signals along a first sensing vector; and

a second electrode pair sensing cardiac signals along a second sensing vector different from the first sensing vector, wherein determining a match score comprises sensing a cardiac signal along one or both of the first sensing vector and the second sensing vector, and wherein the first sensing vector corresponds to a far field sensing vector and the second sensing vector corresponds to a near field sensing vector.

15. The device of claim 14, wherein the match score is determined in response to the far field sensing vector and the beat feature is determined in response to the near field sensing vector.

16. The device of claim 13, wherein the processor is configured to perform one of increasing and decreasing an event counter in response to the determined match score and the determined beat feature.

17. The device of claim 14, wherein the processor is further configured to:

determine whether the match score is within one of a first match zone corresponding to a first cardiac event, and a second match zone corresponding to a second cardiac event;

determine whether the determined beat feature is within one of the first match zone and the second match zone;

decrease an event counter by a first value in response to the match score being within the first match zone and the determined beat feature being within the first match zone; and

decrease the event counter by a second value less than the first value in response to the match score being within the first match zone and the determined beat feature being within the second match zone.

18. The device of claim 14, wherein the processor is further configured to:

determine whether the match score is within one of a first match zone corresponding to a first cardiac event, a second match zone corresponding to the first cardiac event, and a third match zone corresponding to a second cardiac event different from the first cardiac event; and

determine whether the determined beat feature is within one of the first match zone, the second match zone, and the third match zone, wherein the first match zone has a first correlation with a non-treatable cardiac event, the second match zone has a second correlation with the non-treatable cardiac event less than the first correlation with the non-treatable event, and the third match zone is correlated with a treatable cardiac event.

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

increase an event counter in response to the first match score being in the second match zone and the beat feature being within the third match zone; and

decrease the event counter in response to the first match score being in the second match zone and the beat feature being within one of the first match zone and the second match zone.

20. The device of claim 19, wherein the non-treatable cardiac event corresponds to a supraventricular tachycardia event and the treatable cardiac event corresponds to ventricular tachycardia.

21. The device of claim 14, wherein the processor is further configured to:

determine whether the match score is within one of a first match zone corresponding to a first cardiac event, a second match zone corresponding to the first cardiac event, a third match zone corresponding to a second cardiac event different from the first cardiac event, and a fourth match zone corresponding to the second cardiac event; and

determine whether the determined beat feature is within one of the first match zone, the second match zone, the third match zone, and the fourth match zone, wherein the first match zone has a first correlation with a treatable cardiac event, the second match zone has a second correlation with the treatable cardiac event less than the first correlation with the treatable event, the third match zone has a first correlation with a non-treatable cardiac event, and the fourth match zone has a second correlation with the non-treatable cardiac event greater than the first correlation with the non-treatable event.

22. The device of claim 21, wherein the processor is further configured to:

decrease an event counter in response to the first match score being in the second match zone and the beat feature being in the fourth match zone; and

increase the event counter in response to the first match score being in the second match zone and the beat feature not being in the fourth match zone.

23. The device of claim 21, wherein the processor is further configured to:

increase an event counter by a first value in response to the first match score being in the first match zone and the second match score being in the first match zone; and

increase the event counter by a second value less than the first value in response to the first match score being in the first match zone and the second match score being in one of the second match zone, the third match zone and the fourth match zone.

24. The device of claim 14, wherein the processor is further configured to:

determine a first match score corresponding to the cardiac signals sensed along the first sensing vector;

determine whether the first match score is within one of a first match zone corresponding to a first cardiac event, a second match zone corresponding to the first cardiac event, a third match zone corresponding to a second cardiac event different from the first cardiac event, and a fourth match zone corresponding to the second cardiac event;

determine a second match score corresponding to the cardiac signals sensed along the second sensing vector;

determine whether the second match score is within one of the first match zone, the second match zone, the third match zone and the fourth match zone;

determine whether the determined beat feature is within one of the first match zone, the second match zone, the third match zone, and the fourth match zone, wherein the first match zone has a first correlation with a treatable cardiac event, the second match zone has a second correlation with the treatable cardiac event less than the first correlation with the treatable event, the third match zone is correlated with a non-treatable cardiac event, and the fourth match zone has a second correlation with the non-treatable cardiac event greater than the first correlation with the non-treatable event;

decrease an event counter by a first value in response to the first match score being in the second match zone and the beat feature corresponding to the first sensing vector being in the fourth match zone;

decrease the event counter by a second value greater than the first value in response to the first match score being in the second match zone and the beat feature corresponding to the second sensing vector being in the fourth match zone; and

increase the event counter in response to the first match score being in the second match zone and the beat feature not being in the fourth match zone.

25. A computer readable medium having computer executable instructions for performing a method, the method comprising:

sensing a cardiac signal spatially located across approximately a full duration of a predetermined sensing window;

determining a match score corresponding to the sensed cardiac signal;

determining a beat feature of a plurality of beat features across less than the full duration of the sensing window, the beat feature being selected from the plurality of beat features in response to the match score;

accumulating cardiac event evidence in response to the match score and the determined beat feature; and

discriminating cardiac events in response to the accumulated cardiac evidence.