Method and apparatus for assessing and treating myocardial wall stress

• US 20040054381A1
• Filed: 09/13/2002
• Published: 03/18/2004
• Est. Priority Date: 09/13/2002
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Pastore, Joseph M., Girouard, Steven D.
• Granted Patent: US 6,965,797 B2
• Time in Patent Office: Days
• US Class Current: 607/17
• CPC Class Codes: A61N 1/3627 for treating a mechanical deficiency of the heart, e.g. congestive heart failure or cardiomyopathy
• CPC Class Codes: A61N 1/36585 controlled by two or more physical parameters

Abstract

An apparatus and method for assessing myocardial wall stress is disclosed. The method may be used in conjunction with electro-stimulatory therapy for preventing or reversing ventricular remodeling. In such therapy, one or more stimulatory pulses are delivered to the heart such that a stressed region of the myocardium is pre-excited relative to other regions, thereby subjecting the stressed region to a lessened preload and afterload during systole. The unloading of the stressed myocardium over time effects reversal of undesirable ventricular remodeling.

Claims

1. A cardiac rhythm management device, comprising:

sensing channels for sensing cardiac electrical activity at a plurality of myocardial sites;

pacing channels for delivering pacing pulses to one or more myocardial sites;

a controller for controlling the delivery of pacing pulses in accordance with a programmed pacing mode;

circuitry for measuring activation-recovery intervals at a plurality of myocardial sites indicative of myocardial wall stress; and

,

circuitry for identifying one or more stressed myocardial sites based upon the measured activation-recovery intervals.

2. The device of claim 1 further comprising circuitry for delivering pacing pulses in a selected pulse output sequence such that an identified stressed site is excited before other myocardial regions during systole.

3. The device of claim 1 further comprising circuitry for switching a pulse output configuration that defines which pacing channels are used during a cardiac cycle such that an identified stressed site is excited before other myocardial regions during systole.

4. The device of claim 1 further comprising circuitry for measuring an activation-recovery interval as the time between a detected depolarization and a detected repolarization in an electrogram generated by a sensing channel.

5. The device of claim 1 further comprising circuitry for measuring activation-recovery intervals in order to identify stressed sites during intrinsic beats when a measured heart rate is within a specified range.

6. The device of claim 1 further comprising circuitry for measuring activation-recovery intervals in order to identify stressed sites during paced beats while delivering pacing pulses at a specified rate.

7. The device of claim 1 further comprising circuitry for adjusting a criterion for identifying stressed sites based upon measured activation-recovery intervals in accordance with measured heart rate.

8. The device of claim 1 further comprising circuitry for computing an average myocardial wall stress parameter based upon activation-recovery intervals measured at a plurality of myocardial sites.

9. The device of claim 8 wherein further comprising circuitry for delivering pacing pulses with a pulse output configuration and in a pulse output sequence selected to pre-excite particular myocardial sites and reduce the average myocardial wall stress.

10. The device of claim 1 further comprising circuitry for measuring activation-recovery intervals and identify stressed myocardial sites at periodic time intervals.

11. The device of claim 1 wherein the sensing and pacing channels are configured to pace and sense ventricular sites further comprising:

circuitry for delivering pacing pulses to one or more ventricular sites in accordance with a programmed pacing mode; and

circuitry for switching a pulse output configuration and a pulse output sequence defining the pacing mode in order to pre-excite identified stressed ventricular sites.

12. A method for operating a cardiac rhythm management device, comprising:

sensing cardiac electrical activity at a plurality of myocardial sites;

delivering pacing pulses to one or more myocardial sites;

measuring activation-recovery intervals at a plurality of myocardial sites indicative of myocardial wall stress; and

,

identifying one or more stressed myocardial sites based upon the measured activation-recovery intervals.

13. The method of claim 12 further comprising delivering pacing pulses in a selected pulse output sequence such that an identified stressed site is excited before other myocardial regions during systole.

14. The method of claim 12 further comprising switching a pulse output configuration that defines which pacing channels are used during a cardiac cycle such that an identified stressed site is excited before other myocardial regions during systole.

15. The method of claim 12 further comprising measuring an activation-recovery interval as the time between a detected depolarization and a detected repolarization in an electrogram.

16. The method of claim 12 further comprising measuring activation-recovery intervals in order to identify stressed sites during intrinsic beats when a measured heart rate is within a specified range.

17. The method of claim 12 further comprising measuring activation-recovery intervals in order to identify stressed sites during paced beats while delivering pacing pulses at a specified rate.

18. The method of claim 12 further comprising adjusting a criterion for identifying stressed sites based upon measured activation-recovery intervals in accordance with measured heart rate.

19. The method of claim 12 further comprising computing an average myocardial wall stress parameter based upon activation-recovery intervals measured at a plurality of myocardial sites.

20. The method of claim 19 further comprising delivering pacing pulses with a pulse output configuration and in a pulse output sequence selected to pre-excite particular myocardial sites and reduce the average myocardial wall stress.

21. The method of claim 12 further comprising identifying stressed sites with a threshold criterion applied to the measured activation-recovery intervals.

22. The method of claim 12 further comprising identifying a stressed site when an oscillation is detected in the measured activation-recovery interval at that site.