Cardiac rhythm management system with cross-chamber soft blanking

• US 6,169,918 B1
• Filed: 10/28/1998
• Issued: 01/02/2001
• Est. Priority Date: 10/28/1998
• Status: Expired due to Term

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Haefner, Paul A., Seim, Gary Thomas
• Primary Examiner(s): EVANISKO, GEORGE ROBERT
• Application Number:
  US09/181,482
• Time in Patent Office: 797 Days
• Field of Search: 607/4, 607/5, 607/9, 600/509, 600/510, 600/521, 128/901, 128/902
• US Class Current: 600/509
• CPC Class Codes: A61N 1/3704 Circuits specially adapted therefor, e.g. for sensitivity control
• CPC Class Codes: Y10S 128/901 Suppression of noise in electric signal

Abstract

A cardiac rhythm management system provides cross-chamber “soft blanking.” It senses desired electrical heart activity signals associated with a first chamber electrode while reducing unwanted signals (paces and depolarizations) associated with a second chamber of the heart. Detection of a cross-chamber event associated with the second chamber increase a time-varying first chamber sensing threshold, but does not result in completely ignoring signals associated with the first chamber for an appreciable amount of time. As a result, actual first chamber events are less likely to escape detection, such that critically important therapy is properly delivered to the patient.

Claims

1. A method of detecting electrical first and second chamber heart activity signals associated with first and second chambers of a heart, respectively, the method comprising:

detecting a first chamber event indicated by the first chamber heart activity signal;

increasing, in response to the first chamber event, a time-varying first chamber sensing threshold to a first peak value, and then decreasing the first chamber sensing threshold with time from the first peak value toward a first steady-state value;

detecting a second chamber event indicated by the second chamber heart activity signal; and

increasing, in response to the second chamber event, the first chamber sensing threshold to a second peak value, which is between the first peak and first steady-state values, and then decreasing the first chamber sensing threshold with time from the second peak value toward a second steady-state value.

2. The method of claim 1, in which detecting the first chamber event includes an action selected from the group consisting of:

detecting a first chamber depolarization that exceeds the first chamber sensing threshold; and

detecting a first chamber pace pulse.

3. The method of claim 1, in which detecting the second chamber event includes detecting a second chamber depolarization that exceeds a second chamber sensing threshold.

4. The method of claim 3, in which the second chamber sensing threshold is time-varying.

5. The method of claim 1, in which detecting the second chamber event includes detecting a second chamber pace pulse.

6. The method of claim 1, in which detecting the first and second chamber events is selected from the group consisting of:

detecting the first chamber event associated with a right atrium and detecting the second chamber event associated with a right ventricle;

detecting the first chamber event associated with a right atrium and detecting the second chamber event associated with a left ventricle;

detecting the first chamber event associated with a right atrium and detecting the second chamber event associated with a left atrium;

detecting the first chamber event associated with a right ventricle and detecting the second chamber event associated with a right atrium;

detecting the first chamber event associated with a right ventricle and detecting the second chamber event associated with a left atrium;

detecting the first chamber event associated with a right ventricle and detecting the second chamber event associated with a left ventricle;

detecting the first chamber event associated with a left atrium and detecting the second chamber event associated with a left ventricle;

detecting the first chamber event associated with a left atrium and detecting the second chamber event associated with a right ventricle;

detecting the first chamber event associated with a left atrium and detecting the second chamber event associated with a right atrium;

detecting the first chamber event associated with a left ventricle and detecting the second chamber event associated with a left atrium;

detecting the first chamber event associated with a left ventricle and detecting the second chamber event associated with a right ventricle; and

detecting the first chamber event associated with a left ventricle and detecting the second chamber event associated with a right atrium.

7. The method of claim 1, further comprising, in response to detecting the second chamber event, ignoring the first chamber heart activity signal for a time period of less than approximately 15 milliseconds before increasing the first chamber sensing threshold to the second peak value.

8. The method of claim 1, in which the first steady-state value of the first chamber sensing threshold is approximately equal to the second steady-state value of the first chamber sensing threshold.

9. The method of claim 1, in which the second peak value of the first chamber sensing threshold is approximately ⅜

of the first peak value of the first chamber sensing threshold.

10. The method of claim 1, in which the second peak value of the first chamber sensing threshold is approximately ⅜

of an AGC lower limit when the first peak value of the first chamber sensing threshold is less than or equal to the AGC lower limit.

11. A method of detecting electrical first chamber and second chamber heart activity signals associated with first and second chambers of a heart, respectively, the method comprising:

detecting a first chamber event indicated by the first chamber heart activity signal, wherein the first chamber event consists of one of a first chamber pace pulse or a first chamber depolarization that exceeds a time-varying first chamber sensing threshold;

increasing, in response to the first chamber event, the first chamber sensing threshold to a first peak value, and then decreasing the first chamber sensing threshold with time from the first peak value toward a first steady-state value;

detecting a second chamber event indicated by the second chamber heart activity signal, wherein the second chamber event consists of one of a second chamber pace pulse or a second chamber depolarization that exceeds a time-varying second chamber sensing threshold;

increasing, in response to the second chamber event, the first chamber sensing threshold to a second peak value, which is between the first peak and first steady-state values, and then decreasing the first chamber sensing threshold with time from the second peak value toward a second steady-state value; and

increasing, in response to the second chamber event, the second chamber sensing threshold to a third peak value, and then decreasing the second chamber sensing threshold from the third peak value toward a third steady-state value.

12. The method of claim 11, in which decreasing the first chamber sensing threshold includes decreasing the first chamber sensing threshold in discrete steps from the first peak value toward the first steady-state value.

13. The method of claim 11, in which decreasing the second chamber sensing threshold includes decreasing the second chamber sensing threshold in discrete steps from the third peak value toward the third steady-state value.

14. The method of claim 11, in which the first steady-state value of the first chamber sensing threshold is approximately equal to the second steady-state value of the first chamber sensing threshold.

15. The method of claim 11, in which the first steady-state value of the first chamber sensing threshold is different from the third steady-state value of the second chamber sensing threshold.

16. The method of claim 11, in which the second peak value of the first chamber sensing threshold is approximately ⅜

of the first peak value of the first chamber sensing threshold.

17. The method of claim 11, in which the second peak value of the first chamber sensing threshold is approximately ⅜

of an AGC lower limit when the first peak value of the first chamber sensing threshold is less than or equal to the AGC lower limit.

18. The method of claim 11, in which detecting the first and second chamber events is selected from the group consisting of:

detecting the first chamber event associated with a right atrium and detecting the second chamber event associated with a right ventricle;

detecting the first chamber event associated with a right atrium and detecting the second chamber event associated with a left ventricle;

detecting the first chamber event associated with a right atrium and detecting the second chamber event associated with a left atrium;

detecting the first chamber event associated with a right ventricle and detecting the second chamber event associated with a right atrium;

detecting the first chamber event associated with a right ventricle and detecting the second chamber event associated with a left atrium;

detecting the first chamber event associated with a right ventricle and detecting the second chamber event associated with a left ventricle;

detecting the first chamber event associated with a left atrium and detecting the second chamber event associated with a left ventricle;

detecting the first chamber event associated with a left atrium and detecting the second chamber event associated with a right ventricle;

detecting the first chamber event associated with a left atrium and detecting the second chamber event associated with a right atrium;

detecting the first chamber event associated with a left ventricle and detecting the second chamber event associated with a left atrium;

detecting the first chamber event associated with a left ventricle and detecting the second chamber event associated with a right ventricle; and

detecting the first chamber event associated with a left ventricle and detecting the second chamber event associated with a night atrium.

19. A method of detecting electrical first chamber and second chamber heart activity signals associated with a first and second chambers of a heart, respectively, the method comprising:

detecting a first chamber event indicated by the first chamber heart activity signal, wherein the first chamber event consists of one of a first chamber pace pulse or a first chamber depolarization that exceeds a time-varying first chamber sensing threshold;

increasing, in response to the first chamber event, the first chamber sensing threshold to a first peak value, and then decreasing the first chamber sensing threshold with time from the first peak value toward a first steady-state value;

detecting a second chamber event indicated by the second chamber heart activity signal, wherein the second chamber event consists of one of a second chamber pace pulse or a second chamber depolarization that exceeds a time-varying second chamber sensing threshold; and

if the first chamber sensing threshold has decreased approximately below a predetermined comparison value, which is between the first peak and first steady-state values, then increasing, in response to the second chamber event, the first chamber sensing threshold to a second peak value, which is between the first peak and first steady-state values, and then decreasing the first chamber sensing threshold with time from the second peak value toward a second steady-state value.

20. The method of claim 19, in which the predetermined comparison value is approximately equivalent to the second peak value of the first chamber sensing threshold.

21. The method of claim 19, in which the first and second steady-state values of the first chamber sensing threshold are approximately equivalent.

22. Thc method of claim 19, in which decreasing the first chamber sensing threshold with time from the first peak value toward the first steady-state value includes decreasing the first chamber sensing threshold in discrete steps from the first peak value toward the first steady-state value.

23. The method of claim 19, further comprising increasing, in response to detecting the second chamber event, the second chamber sensing threshold to a third peak value, and then decreasing the second chamber sensing threshold with time from the third peak value toward a third steady-state value.

24. The method of claim 23, in which decreasing the second chamber sensing threshold includes decreasing the second chamber sensing threshold in discrete steps from the third peak value toward the third steady-state value.

25. The method of claim 19, in which the second peak value of the first chamber sensing threshold is approximately ⅜

of the first peak value of the first chamber sensing threshold.

26. A method of detecting electrical first chamber and second chamber heart activity signals associated with first and second chambers of a heart, respectively, the method comprising:

(A) detecting a first chamber depolarization indicated by the first chamber heart activity signal, wherein the first chamber depolarization exceeds a time-varying first chamber sensing threshold;

(B) increasing, in response to the first chamber depolarization, a time-varying first chamber sensing threshold to a first peak value, and then decreasing the first chamber sensing threshold with time from the first peak value toward a first steady-state value;

(C) detecting a second chamber event indicated by the second chamber heart activity signal;

(D) increasing, in response to the second chamber event, the first chamber sensing threshold to a second peak value, which is between the first peak and first steady-state values, and then decreasing the first chamber sensing threshold with time from the second peak value toward a second steady-state value; and

(E) adjusting the first peak value of the first chamber sensing threshold based at least in part on an amplitude of the first chamber depolarization detected in (A).

27. The method of claim 26, in which (A)-(E) are repeated, and (E) includes adjusting the first peak value of the first chamber sensing threshold based on a plurality of first chamber depolarizations resulting from the repeating of (A).

28. The method of claim 26, in which the second chamber event of (C) is a second chamber depolarization that exceeds a time-varying second chamber sensing threshold, and further comprising:

(F) increasing, in response to the second chamber depolarization, the second chamber sensing threshold to a third peak value, and then decreasing the second chamber sensing threshold with time from the third peak value toward a third steady-state value; and

(G) adjusting the third peak value of the second chamber sensing threshold based at least in part on an amplitude of the second chamber depolarization detected in (C).

29. The method of claim 28, in which (A)-(G) are repeated, and (E) includes adjusting the first peak value of the first chamber sensing threshold based on a plurality of first chamber depolarizations resulting from the repeating of (A), and (G) includes adjusting the third peak value of the second chamber sensing threshold based on a plurality of second chamber depolarizations resulting from the repeating of (G).

30. The method of claim 26, in which the second peak value of the first chamber sensing threshold is approximately ⅜

of the first peak value of the first chamber sensing threshold.

31. A system for automatically adjusting a sensing threshold in a cardiac rhythm management device, the system comprising:

a first chamber detector, electrically coupled to detect a first chamber event associated with a first chamber of a heart;

a second chamber detector, electrically coupled to detect a second chamber event associated with a second chamber of the heart; and

a threshold controller, including a time-varying first chamber sensing threshold, the threshold controller being coupled to the first chamber detector, the first chamber sensing threshold increasing, in response to the first chamber event, to a first peak value, the first chamber sensing threshold then decreasing with time from the first peak value toward a first steady-state value, the threshold detector also being coupled to the second chamber detector, the first chamber sensing threshold increasing, in response to the second chamber event, to a second peak value, which is between the first peak and first steady-state values, the first chamber sensing threshold then decreasing with time from the second peak value toward a second steady-state value.

32. The system of claim 31, in which the first chamber event is a first chamber depolarization, and the threshold controller includes a peak adjustment circuit that adjusts the first peak value of the first chamber sensing threshold based on a detected amplitude of the first chamber depolarization received from the first chamber detector.

33. The system of claim 31, further comprising an automatic gain control (AGC) circuit, coupled to the first chamber detector, the AGC circuit adjusting a detected amplitude of the first chamber depolarization received from the first chamber detector.

34. The system of claim 31, further comprising:

a first leadwire, adapted for coupling the first chamber detector to the first chamber of the heart; and

a second leadwire, adapted for coupling the second chamber detector to the second chamber of the heart.

35. The system of claim 31, in which the first and second chambers are selected from the group consisting of:

the first chamber including a right atrium and the second chamber including a right ventricle;

the first chamber including a right atrium the second chamber including a left ventricle;

the first chamber including a right atrium and the second chamber including a left atrium;

the first chamber including a right ventricle the second chamber including a right atrium;

the first chamber including a right ventricle and the second chamber including a left atrium;

the first chamber including a right ventricle and the second chamber including a left ventricle;

the first chamber including a left atrium and the second chamber including a left ventricle;

the first chamber including a left atrium and the second chamber including a right ventricle;

the first chamber including a left atrium and the second chamber including a right atrium;

the first chamber including a left ventricle and the second chamber including a left atrium;

the first chamber including a left ventricle and the second chamber including a right ventricle; and

the first chamber including a left ventricle and the second chamber including a right atrium.

36. A system for automatically adjusting a sensing threshold in a cardiac rhythm management device, the system comprising:

a first chamber detector, electrically coupled to detect a first chamber event associated with a first chamber of a heart;

a second chamber detector, electrically coupled to detect a second chamber event associated with a second chamber of the heart; and

a threshold controller, including a time-varying first chamber sensing threshold, the threshold controller being coupled to the first chamber detector, the first chamber sensing threshold increasing, in response to the first chamber event, to a first peak value, the first chamber sensing threshold then decreasing with time from the first peak value toward a first steady-state value, the threshold detector also being coupled to the second chamber detector, wherein if thc first chamber sensing threshold has decreased at the time of the second chamber event to approximately below a predetermined comparison value that is between the first peak and first steady-state values, then;

(a) the first chamber sensing threshold increases in response to the second chamber event to a second peak value, which is between the first peak and first steady-state values, and (b) the first chamber sensing threshold then decreases with time from the second peak value toward a second steady-state value.

37. The system of claim 36, in which the first chamber event is a first chamber depolarization, and the threshold controller includes a peak adjustment circuit that adjusts the first peak value of the first chamber sensing threshold based on a detected amplitude of the first chamber depolarization received from the first chamber detector.

38. The system of claim 36, further comprising an automatic gain control (AGC) circuit, coupled to the first chamber detector, the AGC circuit adjusting a detected amplitude of the first chamber depolarization received from the first chamber detector.

39. The system of claim 36, further comprising:

a first leadwire, adapted for coupling the first chamber detector to a portion of the heart that is associated with the first chamber of the heart; and

a second leadwire, adapted for coupling the second chamber detector to a portion of the heart that is associated with the second chamber of the heart.

40. The system of claim 36, in which the first and second chambers are selected from the group consisting of:

the first chamber including a right atrium and the second chamber including a right ventricle;

the first chamber including a right atrium the second chamber including a left ventricle;

the first chamber including a right atrium and the second chamber including a left atrium;

the first chamber including a right ventricle the second chamber including a right atrium;

the first chamber including a right ventricle and the second chamber including a left atrium;

the first chamber including a right ventricle and the second chamber including a left ventricle;

the first chamber including a left atrium and the second chamber including a left ventricle;

the first chamber including a left atrium and the second chamber including a right ventricle;

the first chamber including a left atrium and the second chamber including a right atrium;

the first chamber including a left ventricle and the second chamber including a left atrium;

the first chamber including a left ventricle and the second chamber including a right ventricle; and

the first chamber including a left ventricle and the second chamber including a right atrium.