Dynamic morphology based atrial automatic threshold

• US 20080119905A1
• Filed: 11/17/2006
• Published: 05/22/2008
• Est. Priority Date: 11/17/2006
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Bohn, Derek D., Garg, Ankur, Enrooth, Eric K.
• Granted Patent: US 8,290,590 B2
• Time in Patent Office: Days
• US Class Current: 607/28
• CPC Class Codes: A61N 1/371 Capture, i.e. successful stimulation
• CPC Class Codes: A61N 1/3712 Auto-capture, i.e. automatic adjustment of the stimulation threshold

Abstract

Methods and systems for performing capture threshold tests are described. During an initialization procedure a capture detection interval and capture detection threshold are determined based on peak values of cardiac signals sensed following the supracapture threshold initialization pulses. Following initialization, a plurality of pacing pulses to the atrium are delivered and the peak values of the cardiac signals sensed following each of the plurality of pacing pulses are determined. The peak values are compared to the pacing artifact threshold and the capture detection threshold. A timing of each of the peak values is compared to the capture detection interval. For each pacing pulse, discrimination between a captured response, a noncaptured response, and a fusion response is based on the peak value and timing comparisons.

Claims

1. A method for determining a cardiac response to atrial pacing, comprising:

providing a pacing artifact threshold associated with peak values of one or more pacing artifact signals sensed in an atrium;

determining a capture detection threshold associated with peak values of one or more evoked response signal sensed in the atrium;

comparing a peak value of a cardiac signal sensed following an atrial pacing pulse to the pacing artifact threshold and the capture detection threshold; and

discriminating between capture, noncapture, and fusion of the atrium based on the comparison.

2. The method of claim 1, further comprising adjusting the capture detection threshold based on the peak value of the cardiac signal if the cardiac signal is classified as an evoked response signal.

3. The method of claim 1, further comprising:

determining a capture detection interval associated with peak times of the evoked response signals;

comparing the peak timing of the cardiac signal to the interval; and

discriminating between capture, noncapture, and fusion based on the comparison.

4. The method of claim 3, further comprising adjusting the capture detection interval based on the peak timing of the cardiac signal.

5. The method of claim 3, further comprising adjusting the pacing artifact threshold based on the peak value of the cardiac signal if the cardiac signal is classified as noncaptured response signal.

6. A capture threshold test method, comprising:

performing a capture threshold test initialization, comprising;

providing a pacing artifact threshold;

delivering a plurality of supracapture threshold initialization pulses to the atrium; and

determining a capture detection threshold based on peak values of cardiac signals sensed following the supracapture threshold initialization pulses;

determining a capture detection interval based on timing of the peak values of the cardiac signals sensed following the supracapture threshold initialization pulses; and

performing a capture threshold test, comprising;

delivering a plurality of pacing pulses to the atrium;

detecting peak values of cardiac signals sensed following the plurality of pacing pulses;

comparing each of the peak values to the pacing artifact threshold and the capture detection threshold;

comparing a timing of each of the peak values to the capture detection interval; and

for each pacing pulse, discriminating between a captured response, noncaptured response, and a fusion response based on the peak value and timing comparisons.

7. The method of claim 6, further comprising adjusting the capture detection threshold beat by beat based on the peak values of cardiac signals associated with the captured response during the capture threshold test.

8. The method of claim 6, further comprising adjusting the capture detection interval beat by beat based on peak value timing of cardiac signals associated with the captured response during the capture threshold test.

9. The method of claim 6, further comprising adjusting the pacing artifact threshold based on one or more noncaptured cardiac signals.

10. The method of claim 6, wherein performing the capture threshold test further comprises:

for each pacing pulse of the plurality of pacing pulses, determining, relative to the pacing artifact threshold, the capture detection threshold, and the capture detection interval, a location of a peak value of the cardiac signal sensed following the pacing pulse;

assigning one or more response values respectively associated with one or more likely cardiac responses to the pacing pulse based on the location of the peak value; and

performing at least one function of the capture threshold test based on the response values.

11. The method of claim 10, wherein at least one of the response values comprise fractional values.

12. The method of claim 10, wherein at least one of the response values comprise integer values.

13. The method of claim 10, wherein performing the at least one function comprises confirming loss of capture based on a sum of the response values associated with the noncaptured response.

14. The method of claim 10, wherein performing the at least one function comprises modifying a pacing energy of the threshold test based on a sum of the response values associated with the captured response.

15. The method of claim 10, wherein performing the at least one function comprises modifying a pacing rate of the threshold test based on a sum of the response values associated with the fusion response.

16. A cardiac rhythm management system, comprising:

a control processor configured to control delivery of atrial pacing pulses via a pulse generator;

a sensing circuit configured to sense a cardiac signal following an atrial pacing pulse;

a pacing response classification processor configured to compare a peak value of the cardiac signal to a capture detection interval, capture detection threshold and a pacing artifact threshold and to discriminate between capture, noncapture, and fusion in the atrium based on the comparison.

17. The system of claim 16, wherein the pacing response classification processor is configured to adjust the capture detection threshold using a cardiac signal classified as an evoked response.

18. The system of claim 16, wherein the pacing response classification processor is configured to adjust the pacing artifact threshold using a cardiac signal classified as a noncaptured response.

19. The system of claim 16, wherein:

the control processor is configured to control delivery of pacing pulses during a capture threshold test; and

the pacing response classification processor is configured to assign one or more pacing response values, the one or more response values respectively associated with one or more likely cardiac responses to the pacing pulse, based on the comparison of the peak value of the cardiac signal to the capture detection threshold and to the pacing artifact threshold, each of the response values associated with capture, noncapture or fusion.

20. The system of claim 19, wherein the one or more pacing response values comprises a fractional value.

21. The system of claim 19, wherein at least one function of the capture threshold test is performed based on the response values.

22. The system of claim 19, wherein the pacing response classification processor is configured to confirm loss of capture based on a sum of response values associated with noncapture.

23. The system of claim 19, wherein the controller is configured to modify a pacing energy or pacing rate of the capture threshold test based on a sum of response values associated with capture.

24. A system for determining a cardiac response to atrial pacing, comprising:

means for providing a pacing artifact threshold associated with peak values of one or more pacing artifact signals sensed in an atrium;

means for determining a capture detection threshold associated with peak values of one or more evoked response signal sensed in the atrium;

means for comparing a peak value of a cardiac signal sensed following an atrial pacing pulse to the pacing artifact threshold and the capture detection threshold; and

means for discriminating between capture, noncapture, and fusion of the atrium based on the comparison.