Apparatus and method for ventricular rate regularization

• US 20040010295A1
• Filed: 06/13/2003
• Published: 01/15/2004
• Est. Priority Date: 12/29/2000
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Stahmann, Jeffrey E., Kramer, Andrew P.
• Granted Patent: US 7,142,915 B2
• Time in Patent Office: Days
• US Class Current: 607/25
• CPC Class Codes: A61N 1/3622 comprising two or more electrodes co-operating with different heart regions

Abstract

A method and system for operating a cardiac rhythm management device which employs pacing therapy to regularize the ventricular rhythm. Such ventricular rate regularization may be employed with conventional bradycardia pacing, ventricular resynchronization therapy, or anti-tachyarrhythmia therapy.

Claims

1. A method for operating a cardiac pacemaker, comprising:

sensing ventricular depolarizations through a ventricular sensing channel and generating ventricular sense signals in accordance therewith;

pacing a ventricle upon expiration of a ventricular escape interval without receiving a ventricular sense from the ventricular sensing channel, wherein the ventricular escape interval starts with either a ventricular pace or a ventricular sense, the reciprocal of the ventricular escape interval being the lower rate limit of the pacemaker;

measuring an R-R interval associated with each ventricular sense, wherein an R-R interval is the time between a ventricular sense and the preceding ventricular sense or ventricular pace, the reciprocal of the R-R interval thus being the measured intrinsic ventricular rate; and

,

adjusting the ventricular escape interval in accordance with a measured R-R interval so that the lower rate limit adjusts in accordance with changes in the measured intrinsic ventricular rate.

2. The method of claim 1 wherein the ventricular escape interval is adjusted to move toward the measured R-R interval multiplied by a scaling factor.

3. The method of claim 2 wherein the ventricular escape interval is adjusted by computing a weighted average of the measured R-R interval multiplied by a scaling factor and the value of the ventricular escape interval.

4. The method of claim 1 wherein the ventricular escape interval is adjusted in accordance with a measured R-R interval after each ventricular sense.

5. The method of claim 1 further comprising adjusting the ventricular escape interval toward a value corresponding to a base lower rate limit after a ventricular pace.

6. The method of claim 5 wherein the ventricular escape interval is adjusted after a ventricular pace by multiplying the escape interval by a decay coefficient.

7. The method of claim 1 wherein the ventricular escape interval is adjusted by computing a weighted average of the measured R-R interval multiplied by a scaling factor and the previous value of the ventricular escape interval after each ventricular sense, and wherein the ventricular escape interval is adjusted by multiplying the escape interval by a decay coefficient after a ventricular pace.

8. The method of claim 7 wherein the scaling factor is selected to be greater than one such that the lower rate limit of the pacemaker is moved toward a fraction of the intrinsic ventricular rate after each ventricular sense.

9. The method of claim 7 wherein the scaling factor is selected to be less than one such that the lower rate limit of the pacemaker is moved toward a value that is above the intrinsic ventricular rate after each ventricular sense.

10. The method of claim 1 further comprising:

sensing ventricular rate and synchronized heart chambers through separate channels and generating sense signals upon detection of depolarization occurring in a chamber;

pacing the rate ventricle upon expiration of a ventricular escape interval without receiving a ventricular sense from the rate ventricular sensing channel, wherein the ventricular escape interval starts with either a ventricular pace or a ventricular sense, the reciprocal of the ventricular escape interval being the lower rate limit of the pacemaker;

measuring an R-R interval associated with each ventricular rate chamber sense, wherein an R-R interval is the time between a ventricular sense and the preceding ventricular sense or ventricular pace, the reciprocal of the R-R interval thus being the measured intrinsic ventricular rate;

adjusting the ventricular escape interval in accordance with the measured R-R interval so that the lower rate limit adjusts in accordance with changes in the measured intrinsic ventricular rate; and

,

pacing the synchronized ventricle in accordance with a synchronized pacing mode wherein a synchronized ventricle pace is delivered at a specified pacing instant defined with respect to expiration of a rate ventricle escape interval.

11. A cardiac rhythm management device, comprising:

a ventricular sensing channel for sensing ventricular depolarizations and generating ventricular sense signals in accordance therewith;

a ventricular pacing channel for pacing a ventricle;

a controller for controlling operation of the device such that a ventricular pace is delivered upon expiration of a ventricular escape interval without receiving a ventricular sense from either ventricular sensing channel, wherein the ventricular escape interval starts with either a ventricular pace or a ventricular sense, the reciprocal of the ventricular escape interval being the lower rate limit of the pacemaker;

wherein the controller is configured to measure an R-R interval associated with each ventricular sense, wherein an R-R interval is the time between a ventricular sense and the preceding ventricular sense or ventricular pace, the reciprocal of the R-R interval thus being the measured intrinsic ventricular rate; and

,

wherein the controller is configured to be capable of adjusting the ventricular escape interval in accordance with a measured R-R interval so that the lower rate limit adjusts in accordance with changes in the measured intrinsic ventricular rate.

12. The device of claim 11 wherein the ventricular escape interval is adjusted to move toward the measured R-R interval multiplied by a scaling factor.

13. The device of claim 12 wherein the ventricular escape interval is adjusted by computing a weighted average of the measured R-R interval multiplied by a scaling factor and the previous value of the ventricular escape interval.

14. The device of claim 11 wherein the ventricular escape interval is adjusted in accordance with a measured R-R interval after each ventricular sense.

15. The device of claim 11 wherein the controller is configured to adjust the ventricular escape interval toward a value corresponding to a base lower rate limit after a ventricular pace.

16. The device of claim 11 wherein the controller is configured to adjust the ventricular escape interval after a ventricular pace by multiplying the escape interval by a decay coefficient.

17. The device of claim 11 wherein the controller is configured to adjust the ventricular escape interval by computing a weighted average of the measured R-R interval multiplied by a scaling factor and the previous value of the ventricular escape interval after each ventricular sense, and wherein the ventricular escape interval is adjusted by multiplying the escape interval by a decay coefficient after a ventricular pace.

18. The device of claim 12 wherein the scaling factor is selected to be greater than one such that the lower rate limit of the device is moved toward a fraction of the intrinsic ventricular rate after each ventricular sense.

19. The device of claim 12 wherein the scaling factor is selected to be less than one such that the lower rate limit of the device is moved toward a value that is above the intrinsic ventricular rate after each ventricular sense.

20. The device of claim 11 further comprising:

sensing channels for sensing depolarizations from ventricles designated as a rate ventricle and a synchronized ventricle;

wherein the ventricular escape interval and R-R intervals are defined with respect to rate ventricle events; and

,

wherein the controller is programmed to pace the synchronized chamber in accordance with a synchronized pacing mode such that a synchronized ventricle pace is delivered at a specified pacing instant defined with respect to expiration of the rate ventricle escape interval.

21. The device of claim 11 further comprising a shock pulse generator and shock electrodes for delivering a defibrillation shock to a heart chamber upon detection of a tachyarrhythmia.

22. The device of claim 21 wherein the device is configured to deliver defibrillation shocks to the atria.

23. The device of claim 21 wherein the controller is programmed such that the ventricular escape interval is adjusted in accordance with a measured R-R interval upon detection of a tachyarrhythmia.