Implantable cardiac stimulating device and method for administering synchronized cardioversion shock therapy to provide preemptive depolarization

• US 5,601,609 A
• Filed: 03/14/1995
• Issued: 02/11/1997
• Est. Priority Date: 09/15/1993
• Status: Expired due to Term

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories)
• Inventors: Duncan, James L.
• Primary Examiner(s): Jastrzab, Jeffrey R.
• Application Number:
  US08/403,593
• Time in Patent Office: 700 Days
• Field of Search: 607/4, 607/5, 607/14
• US Class Current: 607/5
• CPC Class Codes: A61N 1/3987 characterised by the timing or triggering of the shock

Abstract

An implantable cardioversion shock therapy system is provided which delays delivery of a cardioversion shock until late in the cardiac cycle to optimize the chance for the vast majority of ventricular myocardial tissue to be non-refractory. The system in intended to increase efficacy and safety by properly synchronizing the cardioversion shock to the appropriate portion of the cardiac cycle to successfully terminate a tachycardia episode. The timing of the cardioversion shock is programmable as either a percentage of measured tachycardia cycle length or fixed delay in milliseconds.

Claims

1. An implantable cardioversion shock therapy system, comprising:

sensing means for sensing intrinsic R-waves;

pulse generating means for generating a cardioversion shock and for delivering the cardioversion shock to cardiac tissue; and

control means, responsive to the sensing means, for analyzing the R-waves to confirm a tachycardia episode, and for controlling the pulse generating means to trigger the cardioversion shock after a predetermined delay corresponding to a period when the cardiac tissue is repolarized, the predetermined delay being synchronized from a last R-wave following the confirmation of the tachycardia episode so that the cardioversion shock preempts a successive R-wave.

2. The system of claim 1, further comprising:

an external programming means for sending system operating parameters to and receiving data from the control means;

telemetry means, coupled to the control means, for receiving the system operating parameters, including the predetermined delay, from the external programming means.

3. The system of claim 1, wherein the control means further comprises:

means for defining the predetermined delay as a predetermined fixed time interval which is expected to occur when the cardiac tissue is repolarized.

4. The system of claim 3, wherein the predetermined fixed time interval is at least greater than 300 msec.

5. The system of claim 3, wherein:

the control means further includes means for determining a tachycardia cycle length; and

the predetermined fixed time interval is a programmable value between 150 ms and the tachycardia cycle length.

6. The system of claim 1, wherein the control means further comprises:

means for determining a tachycardia cycle length; and

means for defining the predetermined delay as a predetermined percentage of the tachycardia cycle length which is expected to occur when the cardiac tissue is repolarized.

7. The system of claim 6, wherein the predetermined percentage of the tachycardia cycle length is in the range of 30-99% of the tachycardia cycle length.

8. An implantable system for administering cardioversion shock therapy to cardiac tissue in accordance with a tachycardia rate of a patient to preempt an expected tachycardia beat, the system comprising:

sensing means for sensing intrinsic R-waves;

pulse generating means for generating a cardioversion shock and delivering the cardioversion shock to the cardiac tissue; and

control means, responsive to the sensing means, for analyzing the intrinsic R-waves to determine a tachycardia cycle length, and for triggering the pulse generating means to deliver the cardioversion shock after a predetermined time, determined as a function of the tachycardia cycle length, has elapsed following a preceding tachycardia beat to elicit a heartbeat that preempts the expected tachycardia beat.

9. The system of claim 8, wherein the function of the tachycardia cycle length is a predetermined percentage of the tachycardia cycle length.

10. The system of claim 9, further comprising:

an external programming means for sending system operating parameters to and receiving data from the control means;

telemetry means, coupled to the control means, for receiving the system operating parameters, including the predetermined percentage, from the external programming.

11. An implantable cardioversion shock therapy system, comprising:

cardiac sensing means for sensing naturally occurring cardiac depolarizations in a selected chamber of a patient'"'"'s heart;

pulse generator means for providing a cardioversion shock of sufficient energy to terminate a tachycardia episode in the selected chamber of the heart;

a shocking lead, coupled to the pulse generator means, for delivering the cardioversion shock to the selected chamber of the heart; and

processing means, coupled to the cardiac sensing means and the pulse generator means, for confirming a tachycardia episode based on the sensed cardiac depolarizations and for controlling the pulse generator means to provide the cardioversion shock after a predetermined time interval following confirmation of the tachycardia episode to preempt an expected tachycardia beat.

12. The system of claim 11, wherein the processing means further comprises:

control means for defining the predetermined time interval as an alert interval corresponding to an expected alert period of the heart following the refractory period and prior to the next expected tachycardia beat.

13. The system of claim 12, wherein:

the processing means includes means for determining a tachycardia cycle length; and

the control means includes means for defining the predetermined time interval as a predetermined percentage of the tachycardia cycle length following a preceding tachycardia beat.

14. The system of claim 13, wherein the predetermined percentage of the tachycardia cycle length is in the range of 30-99% of the tachycardia cycle length.

15. The system of claim 11, wherein the control means further comprises:

means for defining the predetermined time interval as a predetermined fixed time interval, triggered from a preceding tachycardia beat, which is expected to occur when the cardiac tissue is repolarized.

16. The system of claim 15, wherein:

the control means further includes means for determining a tachycardia cycle length; and

the predetermined fixed time interval is a programmable value between 150 ms and the tachycardia cycle length.

17. An implantable cardioversion shock therapy system, comprising:

means for detecting a tachycardia episode;

means for delivering a cardioversion shock to cardiac tissue in response to the tachycardia episode; and

means for delaying delivery of the cardioversion shock by a predetermined time interval measured from a preceding tachycardia beat and preemptively before an expected tachycardia beat.

18. A method of providing cardioversion shock therapy to cardiac tissue, comprising the steps of:

detecting a tachycardia episode; and

delivering a cardioversion shock after a predetermined delay period corresponding to a period between a preceding tachycardia beat and an expected tachycardia beat when the cardiac tissue is non-refractory following detection of the tachycardia episode.

19. The method of claim 18, wherein the delaying step comprises the step of:

delivering the cardioversion shock after a predetermined fixed time interval following the preceding tachycardia beat has elapsed.

20. The method of claim 18, wherein the delaying step comprises the steps of:

determining a tachycardia cycle length; and

delivering the cardioversion shock after a length of time corresponding to a predetermined percentage of the tachycardia cycle length has elapsed following the preceding tachycardia beat.

21. The method of claim 18, wherein the detecting step comprises the step of:

detecting a ventricular tachycardia episode.

22. The method of claim 18, wherein the detecting step comprises the step of:

detecting an atrial tachycardia episode.

23. A method of administering cardioversion shock therapy to cardiac tissue to preempt an expected tachycardia beat, comprising the steps of:

detecting an occurrence of a tachycardia episode;

determining a tachycardia cycle length of the tachycardia episode; and

delivering a cardioversion shock to the cardiac tissue after a length of time, determined as a function of preceding tachycardia beat so that the cardioversion shock is delivered when the cardiac tissue is repolarized.

24. The method of claim 23, wherein the function of the tachycardia cycle length is a predetermined percentage of the tachycardia cycle length.

25. An implantable cardioversion shock therapy system, comprising:

sensing means for sensing intrinsic P-waves;

pulse generating means for generating a cardioversion shock and for delivering the cardioversion shock to cardiac tissue; and

control means, responsive to the sensing means, for analyzing the P-waves to confirm an atrial tachycardia episode, and for controlling the pulse generating means to trigger the cardioversion shock after a predetermined delay, corresponding to a period when the cardiac tissue is repolarized, the predetermined delay being synchronized from a last P-wave following the confirmation of the atrial tachycardia episode so that the cardioversion shock preempts a successive P-wave.

26. The system of claim 25, further comprising:

an external programming means for sending system operating parameters to and receiving data from the control means;

telemetry means, coupled to the control means, for receiving the system operating parameters, including the predetermined delay, from the external programming means.

27. The system of claim 25, wherein the control means further comprises:

means for defining the predetermined delay as a predetermined fixed time interval which is expected to occur when the cardiac tissue is repolarized.

28. The system of claim 27, wherein the predetermined fixed time interval is at least greater than 300 msec.

29. The system of claim 27, wherein:

the control means further includes means for determining a tachycardia cycle length; and

the predetermined fixed time interval is a programmable value between 150 ms and the tachycardia cycle length.

30. The system of claim 25, wherein the control means further comprises:

means for determining a tachycardia cycle length; and

means for defining the predetermined delay as a predetermined percentage of the tachycardia cycle length which is expected to occur when the cardiac tissue is repolarized.

31. The system of claim 30, wherein the predetermined percentage of the tachycardia cycle length is in the range of 30-99% of the tachycardia cycle length.