Dual chamber pacemaker which detects, confirms and terminates pacemaker mediated tachycardia

• US 5,423,868 A
• Filed: 04/12/1994
• Issued: 06/13/1995
• Est. Priority Date: 04/12/1994
• Status: Expired due to Term

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories)
• Original Assignee: Telectronics Pacing Systems, Inc (Abbott Laboratories)
• Inventors: Chinn, Stephen R., Gani, Matthew J., Nappholz, Tibor
• Primary Examiner(s): Kamm, William E.
• Assistant Examiner(s): Getzow, Scott M.
• Application Number:
  US08/226,462
• Time in Patent Office: 427 Days
• Field of Search: 607/14, 607/9
• US Class Current: 607/14
• CPC Class Codes: A61N 1/3622 comprising two or more electrodes co-operating with different heart regions
• CPC Class Codes: A61N 1/368 comprising more than one electrode co-operating with different heart regions A61N1/3622, A61N1/3627 take precedence

Abstract

A dual-chamber pacemaker for confirming pacemaker mediated tachycardia (PMT) after initial detection. The minimum V-V pacing interval is extended to be slightly longer than the interval of the sensed atrial rate. If the A-V Delay intervals in successive cycles remain constant, as opposed to progressively increasing in Wenckebach fashion, then PMT is confirmed.

Claims

1. A method of confirming the presence of pacemaker mediated tachycardia (PMT) following the initial detection thereof comprising the steps of:

(a) measuring the intrinsic rate of the patient'"'"'s heart,

(b) adjusting the minimum V-V interval, corresponding to the maximum pacing rate of the pacemaker, to be slightly longer than the intrinsic interval corresponding to said measured rate,

(c) determining whether the A-V Delay intervals in successive cycles progressively increase in Wenckebach fashion or remain constant, and

(d) confirming the presence of PMT if the A-V Delay intervals in successive cycles remain constant.

2. A method in accordance with claim 1 wherein each pacemaker cycle includes sequential A-V Delay, PVARP, API and Alert intervals, and the steps for confirming the presence of PMT are performed only if a predetermined number of successive P-P intervals are stable.

3. A method in accordance with claim 2 wherein the steps for confirming the presence of PMT are performed only if a predetermined number of successive P-waves occur at a rate above a threshold value.

4. A method in accordance with claim 3 wherein, following the confirmation of PMT, the PMT is terminated by extending the V-V interval of the pacemaker and forcing an A-pace followed by a V-pace.

5. A method in accordance with claim 4 wherein said A-pace is generated following a P-wave but delayed sufficiently to avoid atrial competition.

6. A method in accordance with claim 5 wherein atrial competition is avoided by interposing an API interval between said P-wave and said A-pace.

7. A method in accordance with claim 1 wherein the steps for confirming the presence of PMT are performed only if a predetermined number of successive P-P intervals are stable.

8. A method in accordance with claim 7 wherein, following the confirmation of PMT, the PMT is terminated by extending the V-V interval of the pacemaker and forcing an A-pace followed by a V-pace.

9. A method in accordance with claim 8 wherein said A-pace is generated following a P-wave but delayed sufficiently to avoid atrial competition.

10. A method in accordance with claim 1 wherein, following the confirmation of PMT, the PMT is terminated by extending the V-V interval of the pacemaker and forcing an A-pace followed by a V-pace.

11. A method in accordance with claim 10 wherein said A-pace is generated following a P-wave but delayed sufficiently to avoid atrial competition.

12. A method in accordance with claim 11 wherein each pacemaker cycle includes sequential A-V Delay, PVARP, API and alert intervals, and atrial competition is avoided by interposing an API interval between said P-wave and said A-pace.

13. A dual-chamber pacemaker comprising means for generating atrial pacing pulses, means for generating ventricular pacing pulses, means for sensing atrial P-waves, means for sensing ventricular R-waves, and means for confirming the presence of pacemaker mediated tachycardia (PMT) following the initial detection thereof;

said confirming means including means for measuring the intrinsic rate of the patient'"'"'s heart, means for adjusting the minimum V-V interval, corresponding to the maximum pacing rate of the pacemaker, to be slightly longer than the intrinsic interval corresponding to said measured rate, means for determining whether the A-V Delay intervals in successive cycles progressively increase in Wenckebach fashion or remain constant, and means for confirming the presence of PMT if the A-V Delay intervals in successive cycles remain constant.

14. A pacemaker in accordance with claim 13 wherein each pacemaker cycle includes sequential A-V Delay, PVARP, API and Alert intervals, and said means for confirming the presence of PMT operates only if a predetermined number of successive P-P intervals are stable.

15. A pacemaker in accordance with claim 14 wherein said means for confirming the presence of PMT operates only if a predetermined number of successive P-waves occur at a rate above a threshold value.

16. A pacemaker in accordance with claim 15 further including means, operative following the confirmation of PMT, for terminating the PMT by extending the V-V interval of the pacemaker and forcing an atrial pacing pulse followed by a ventricular pacing pulse.

17. A pacemaker in accordance with claim 16 further including means for controlling said atrial pacing pulse to be generated following sensing of a P-wave but delayed sufficiently to avoid atrial competition.

18. A pacemaker in accordance with claim 17 wherein said controlling means operates to interpose an API interval between said P-wave and said atrial pacing pulse.

19. A pacemaker in accordance with claim 13 further including means, operative following the confirmation of PMT, for terminating the PMT by extending the V-V interval of the pacemaker and forcing an atrial pacing pulse followed by a ventricular pacing pulse.

20. A pacemaker in accordance with claim 19 further including means for controlling said atrial pacing pulse to be generated following sensing of a P-wave but delayed sufficiently to avoid atrial competition.

21. A pacemaker in accordance with claim 20 wherein each pacemaker cycle includes sequential A-V Delay, PVARP, API and Alert intervals, and said controlling means operates to interpose an API interval between said P-wave and said atrial pacing pulse.