Fast post-antitachycardia pacing redetection algorithm

• US 20050261744A1
• Filed: 05/24/2004
• Published: 11/24/2005
• Est. Priority Date: 05/24/2004
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Li, Dan
• Granted Patent: US 7,616,994 B2
• Time in Patent Office: Days
• US Class Current: 607/14
• CPC Class Codes: A61N 1/3622 comprising two or more electrodes co-operating with different heart regions

Abstract

A method comprising detecting a ventricular tachycardia heart rhythm in a patient, providing anti-tachycardia pacing (ATP) therapy to the patient in response to the ventricular tachycardia heart rhythm, waiting a first time duration after the ATP therapy ends, and monitoring ventricular depolarizations after the first time duration has elapsed. The monitoring includes measuring time intervals between the ventricular depolarizations, and if a consecutive number of the intervals between the ventricular depolarizations are shorter than a first threshold interval value, then the method includes deeming that the ventricular tachycardia rhythm persists. Otherwise, if a fraction of the intervals between the ventricular depolarizations are shorter than a second threshold interval value, then the method includes deeming that the ventricular tachycardia heart rhythm persists, and otherwise deeming that the ventricular tachycardia rhythm is converted.

Claims

1. A method comprising:

detecting a ventricular tachycardia heart rhythm in a patient;

providing anti-tachycardia pacing (ATP) therapy to the patient in response to the ventricular tachycardia heart rhythm;

waiting a first time duration after the ATP therapy ends;

monitoring ventricular depolarizations after the first time duration has elapsed, wherein the monitoring includes measuring time intervals between the ventricular depolarizations; and

if a consecutive number of the intervals between the ventricular depolarizations are shorter than a first threshold interval value, then deeming that the ventricular tachycardia rhythm persists, otherwise,

if a fraction of the intervals between the ventricular depolarizations are shorter than a second threshold interval value, then deeming that the ventricular tachycardia heart rhythm persists, otherwise, deeming that the ventricular tachycardia rhythm is converted.

2. The method of claim 1, wherein the first and second threshold interval values are the same value.

3. The method if claim 1, wherein the monitoring the ventricular depolarizations includes measuring a ventricular depolarization rate, wherein the method further includes measuring an atrial depolarization rate for the patient, and wherein the deeming that the ventricular tachycardia rhythm is converted, includes first performing an additional test, wherein the additional test includes:

if the ventricular rate exceeds the atrial rate by a threshold rate difference value then deeming that the ventricular tachycardia heart rhythm persists, otherwise,

deeming that the ventricular tachycardia rhythm is converted.

4. The method of claim 1, wherein the monitoring the ventricular depolarizations after the first time duration includes monitoring the ventricular depolarizations during a second time duration, and wherein the deeming that the ventricular tachycardia rhythm is converted includes deeming the ventricular tachycardia rhythm is converted if the second time duration elapses without deeming that the ventricular tachycardia rhythm persists.

5. The method of claim 1, wherein the monitoring the ventricular depolarizations includes monitoring the ventricular depolarizations using an implantable medical device.

6. The method of claim 1, wherein the method further includes providing anti-tachycardia therapy if deeming that the ventricular tachycardia heart rhythm persists.

7. The method of claim 6, wherein the providing the anti-tachycardia therapy includes providing defibrillation therapy.

8. The method of claim 6, wherein the providing the anti-tachycardia therapy includes providing ATP therapy.

9. The method of claim 6, wherein the providing the anti-tachycardia therapy includes providing drug therapy.

10. A system, comprising:

an implantable medical device comprising;

a signal sensing circuit coupled to at least one electrode, the electrode located to sense a cardiac signal of a ventricle of a heart of a patient;

a therapy circuit;

a timer circuit; and

a controller coupled to the signal sensing circuit, the timer circuit, and the therapy circuit, wherein the controller is operable in;

detecting a ventricular tachycardia heart rhythm from the cardiac signal;

initiating anti-tachycardia pacing (ATP) therapy to the patient in response to the ventricular tachycardia heart rhythm;

measuring time intervals between ventricular depolarizations after providing ATP therapy;

comparing the intervals to a threshold interval value; and

if a consecutive number of the intervals are shorter than the threshold interval value, then deeming that the ventricular tachycardia rhythm persists, otherwise,

if a fraction of the intervals are shorter than the threshold interval value, then deem that the ventricular tachycardia heart rhythm persists, otherwise

deem that the ventricular tachycardia heart rhythm is converted.

11. The system of claim 10, wherein the implantable medical device further includes:

an atrial signal sensing circuit coupled to at least one second electrode and the controller, the at least one second electrode located to sense a cardiac signal of an atrium of the heart; and

wherein the controller is further operable in measuring both a ventricular depolarization rate and an atrial depolarization rate for the patient, and if the ventricular depolarization rate exceeds the atrial depolarization rate by a threshold rate difference value then deem that the ventricular tachycardia heart rhythm persists, otherwise deem that the ventricular tachycardia rhythm is converted.

12. The system of claim 10, wherein the controller is operable to time a programmable wait duration after providing ATP therapy and before measuring time intervals.

13. The system of claim 10, wherein the controller is operable to time a programmable redetection duration during which the controller measures the time intervals between the ventricular depolarizations, and wherein the controller deems the ventricular tachycardia heart rhythm is converted if the redetection duration elapses without deeming that the ventricular tachycardia heart rhythm persisted.

14. The system of claim 10, wherein the therapy circuit includes a defibrillation therapy circuit and the implantable medical device provides defibrillation therapy if the ventricular tachycardia heart rhythm is deemed to persist.

15. The system of claim 14, wherein the implantable medical device provides ATP therapy while the defibrillation therapy circuit is charging, and wherein the controller is operable to determine if the ventricular tachycardia rhythm is converted while the defibrillation therapy circuit is charging.

16. The system of claim 15, wherein the controller is operable to abort the charging of the defibrillation therapy circuit if the ventricular tachycardia rhythm is deemed converted.

17. The system of claim 10, wherein the implantable medical device provides ATP therapy if the ventricular tachycardia heart rhythm is deemed to persist.

18. The system of claim 10, wherein the therapy circuit includes a drug therapy circuit and the implantable medical device provides drug therapy if the ventricular tachycardia heart rhythm is deemed to persist.

19. The system of claim 10, wherein the implantable medical device further includes a memory coupled to the controller, wherein the controller is operable to store patient information about whether a ventricular tachycardia heart rhythm was converted.

20. The system of claim 10, wherein the system further includes an external device operable to communicate with the implantable device, wherein the external device includes a display to display patient information about at least one of a redetection duration and whether a ventricular tachycardia heart rhythm was converted.

21. The system of claim 20, wherein the patient information includes a histogram of patient information about at least one of a redetection duration and whether a ventricular tachycardia heart rhythm was converted.

22. The system of claim 20, wherein the external device is operable to communicate with a computer network.

23. A method comprising:

measuring first time intervals between ventricular depolarizations of a heart, the measuring including using an implantable medical device;

measuring both a ventricular depolarization rate and an atrial depolarization rate of the heart; and

if a consecutive number of intervals between the ventricular depolarizations are shorter than a threshold interval value, then deeming that a ventricular tachycardia rhythm exists, otherwise,

if a fraction of the intervals between the ventricular depolarizations are shorter than the threshold interval value, then deeming that the ventricular tachycardia heart rhythm exists, otherwise,

if the ventricular rate exceeds the atrial rate by a threshold rate difference value then deeming that the ventricular tachycardia heart rhythm exists, otherwise

deeming that the ventricular tachycardia heart rhythm does not exist.

24. The method of claim 23, wherein the method further includes providing therapy to the heart if the ventricular tachycardia heart rhythm is deemed to exist.

25. The method of claim 24, wherein providing therapy to the heart includes providing anti-tachycardia pacing (ATP) therapy.

26. The method of claim 25, wherein the method further includes waiting a time duration after the ATP therapy ends;

measuring second time intervals between ventricular depolarizations, and both a second ventricular depolarization rate and a second atrial depolarization rate after the time duration elapses; and

if a consecutive number of second intervals between ventricular depolarizations are shorter than the threshold interval value, then deeming that the ventricular tachycardia rhythm persists, otherwise,

if a fraction of the second intervals between ventricular depolarizations are shorter than the threshold interval value, then deeming that the ventricular tachycardia heart rhythm persists, otherwise

if the second ventricular rate exceeds the second atrial rate by a threshold rate difference value then deeming that the ventricular tachycardia heart rhythm persists, otherwise

deeming that the ventricular tachycardia heart rhythm is converted.