Atrial capture detection via atrial-ventricular conduction

• US 20040088019A1
• Filed: 10/31/2002
• Published: 05/06/2004
• Est. Priority Date: 10/31/2002
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Rueter, John C., Mongeon, Luc R.
• Granted Patent: US 7,433,736 B2
• Time in Patent Office: Days
• US Class Current: 607/27
• CPC Class Codes: A61N 1/3712 Auto-capture, i.e. automatic adjustment of the stimulation threshold
• CPC Class Codes: A61N 1/3714 Atrial capture

Abstract

Techniques for increase the accuracy of detection of atrial capture may involve determining a ventricular sensing window for ventricular senses associated with atrial test pulses based on observed ventricular senses. For example, an implanted medical device may deliver atrial test pulses to a patient at a time prior to respective atrial pacing pulses to evaluate atrial capture. The implanted medical device observes ventricular senses in response to the atrial test pulses. The implanted medical device may determine a point such as, for example, a midpoint of the ventricular sensing window for the ventricular senses and shift a midpoint of the default ventricular window to the determined midpoint. Further, the implanted medical device may measure patient parameters, such as heart rate and activity level, and determine a ventricular sensing window for ventricular senses associated with atrial test pulses based on the observed ventricular senses and measured patient parameters.

Claims

1. A method comprising:

delivering atrial test pulses to a patient at a time prior to respective atrial pacing pulses to evaluate atrial capture;

observing ventricular senses in response to the atrial test pulses; and

determining a ventricular sensing window for the ventricular senses associated with the atrial test pulses based on the observed ventricular senses.

2. The method of claim 1, wherein determining a ventricular sensing window for the ventricular senses includes determining a midpoint of the ventricular sensing window for the ventricular senses.

3. The method of claim 2, further comprising shifting a midpoint of a default ventricular sensing window to the determined midpoint.

4. The method of claim 2, further comprising increasing the length of the ventricular sensing window to include the determined midpoint.

5. The method of claim 2, wherein determining a midpoint of the ventricular sensing window includes:

calculating an atrial test pulse-ventricular sense (APt-VS) interval associated with each of the atrial test pulses; and

calculating an average of the APt-VS intervals to determine the midpoint of the ventricular sensing window.

6. The method of claim 1, wherein the atrial test pulses are of an energy magnitude known to capture the atrium.

7. The method of claim 1, wherein the atrial test pulses are of a similar energy magnitude.

8. The method of claim 1, further comprising performing an atrial stimulation threshold test using the determined ventricular sensing window.

9. The method of claim 8, wherein performing an atrial stimulation threshold test includes:

applying an atrial stimulation test pulse; and

increasing an energy magnitude of the atrial stimulation test pulse when a ventricular sense does not occur within the determined ventricular sensing window.

10. The method of claim 9, wherein increasing the energy magnitude of the atrial test pulse includes increasing an amplitude of the atrial test pulse.

11. The method of claim 9, wherein increasing the energy magnitude of the atrial test pulse includes increasing a pulse width of the atrial test pulse.

12. The method of claim 1, further comprising storing the determined ventricular sensing window in memory.

13. The method of claim 1, further comprising updating the determined ventricular sensing window.

14. The method of claim 13, wherein updating the determined ventricular sensing window includes updating the determined ventricular sensing window at a regular interval.

15. The method of claim 14, wherein the regular interval includes one of daily, weekly, and monthly.

16. The method of claim 1, further comprising:

sensing a patient parameter;

determining the ventricular sensing window for the ventricular senses associated with the atrial test pulses based on the observed ventricular senses and the sensed patient parameter.

17. The method of claim 16, wherein the patient parameter includes at least one of an activity level of the patient and a heart rate.

18. An implantable medical device comprising:

a pacing circuit to generate atrial test pulses;

an electrode to deliver the atrial test pulses to a patient prior to respective atrial pacing pulses to evaluate atrial capture;

a sensor to detect ventricular senses in response to the atrial test pulses; and

a processor to determine a ventricular sensing window for the ventricular senses associated with the atrial test pulses based on the observed ventricular senses.

19. The device of claim 18, wherein the processor determines a ventricular sensing window for the ventricular senses by determining a midpoint of the ventricular sensing window for the ventricular senses.

20. The device of claim 19, wherein the processor shifts a midpoint of a default ventricular sensing window to the determined midpoint.

21. The device of claim 19, wherein the processor increases the length of the ventricular sensing window to include the determined midpoint.

22. The device of claim 19, wherein the processor determines the midpoint of the ventricular sensing window by calculating an atrial test pulse-ventricular sense (APt-VS) interval associated with each of the atrial test pulses and calculating an average of the APt-VS intervals to determine the midpoint of the ventricular sensing window.

23. The device of claim 18, wherein the device performs an atrial stimulation threshold test using the determined ventricular sensing window.

24. The device of claim 18, wherein the processor stores the determined ventricular sensing window in memory.

25. The device of claim 24, wherein the memory in random access memory.

26. The device of claim 18, wherein the processor updates the determined ventricular sensing window.

27. The device of claim 18, further comprising a sensor to sense a patient parameter, and wherein the processor determines the ventricular sensing window for the ventricular senses associated with the atrial test pulses based on the observed ventricular senses and the sensed patient parameter.

28. The device of claim 27, wherein the patient parameter includes at least one of an activity level of the patient and a heart rate.

29. The device of claim 27, wherein the sensor includes at least one of an oxygenation sensor, a pressure sensor, a pH sensor, a respiration sensor, and a piezoelectric sensor.

30. A method comprising:

delivering cardiac test pulses to a patient at a time prior to respective cardiac pacing pulses to evaluate capture;

observing depolarizations in response to the cardiac test pulses; and

determining a sensing window for the depolarizations associated with the cardiac test pulses based on the observed depolarizations.

31. The method of claim 30, wherein the cardiac test pulses includes atrial test pulses.

32. The method of claim 30, wherein the cardiac test pulses include ventricular test pulses.

33. An implantable medical device comprising:

a pacing circuit to generate atrial test pulses;

an electrode to deliver the cardiac test pulses to a patient prior to respective cardiac pacing pulses to evaluate capture;

a sensor to detect depolarizations in response to the cardiac test pulses; and

a processor to determine a sensing window for the depolarizations associated with the cardiac test pulses based on the observed depolarizations.

34. The device of claim 33, wherein the cardiac test pulses includes atrial test pulses.

35. The device of claim 33, wherein the cardiac test pulses include ventricular test pulses.

36. An implantable medical device comprising:

means for delivering atrial test pulses to a patient at a time prior to respective atrial pacing pulses to evaluate atrial capture;

means for observing ventricular senses in response to the atrial test pulses; and

means for determining a ventricular sensing window for the ventricular senses associated with the atrial test pulses based on the observed ventricular senses.

37. The device of claim 36, wherein the determining means determines a midpoint of the ventricular sensing window for the ventricular senses.

38. The device of claim 37, further comprising means for shifting a midpoint of a default ventricular sensing window to the determined midpoint.

39. The device of claim 37, further comprising means for increasing the length of the ventricular sensing window to include the determined midpoint.

40. The device of claim 37, wherein the determining means includes:

means for calculating an atrial test pulse-ventricular sense (APt-VS) interval associated with each of the atrial test pulses; and

means for calculating an average of the APt-VS intervals to determine the midpoint of the ventricular sensing window.