Method and apparatus for adaptive tachycardia and fibrillation discrimination

• US 6,230,055 B1
• Filed: 08/20/1999
• Issued: 05/08/2001
• Est. Priority Date: 08/20/1999
• Status: Expired due to Term

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: KenKnight, Bruce H., Manicka, Yatheendhar, Sun, Weimin, Tze, Martin
• Primary Examiner(s): Getzow, Scott M.
• Application Number:
  US09/378,591
• Time in Patent Office: 627 Days
• Field of Search: 607/4, 607/5, 607/6, 607/7, 607/8, 607/14
• US Class Current: 607/5
• CPC Class Codes: A61N 1/3622 comprising two or more electrodes co-operating with different heart regions
• CPC Class Codes: A61N 1/39622 Pacing therapy

Abstract

An implantable cardioverter/defibrillator with antitachycardia pacing capability and method for operating same in which the detection zone boundary used to discriminate between tachycardia and fibrillation is adaptively adjusted based upon operating experience. Rate zones are provided for further classifying detected episodes of tachycardia and fibrillation according to the certainty of their being correctly identified based upon past operating experience. Adjustments of the rate zones and the fibrillation detection zone boundary are made based upon the results of antitachycardia pacing in attempting to terminate arrhythmic episodes.

Claims

1. A method for operating an implantable cardioverter/defibrillator with antitachycardia pacing capability, comprising:

detecting a cardiac arrhythmia by measuring a heart rate and determining the rate to be above a selected arrhythmia threshold value;

classifying the arrhythmia as a tachycardia or a fibrillation according to whether the heart rate is below or above, respectively, a selected fibrillation detection zone boundary,

delivering antitachycardia pacing therapy if the arrhythmia is classified as a tachycardia; and

,

decreasing the fibrillation detection zone boundary if the antitachycardia pacing fails to terminate an arrhythmia classified as a tachycardia.

2. The method of claim 1 further comprising:

further classifying the arrhythmia according to whether the arrhythmia is within a boundary zone defined as a selected range of heart rates with upper and lower limits above and below, respectively, the fibrillation rate boundary, wherein the arrhythmia is designated a boundary zone arrhythmia if the arrhythmia falls within the boundary zone; and

,

increasing the fibrillation detection zone boundary by an amount such that the lower limit of the boundary zone equals the measured heart rate if the antitachycardia pacing therapy is successful in terminating a boundary zone tachycardia.

3. The method of claim 2 further comprising:

decreasing the fibrillation detection zone boundary by a selected amount if the antitachycardia pacing fails to terminate a tachycardia not within the boundary zone; and

,

decreasing the fibrillation detection zone boundary by an amount such that the detection zone boundary equals the measured heart rate if the antitachycardia pacing therapy fails to terminate a boundary zone tachycardia.

4. The method of claim 3 further comprising:

delivering antitachycardia pacing therapy if the arrhythmia is classified as a boundary zone fibrillation;

increasing the fibrillation detection zone boundary by a selected amount if the antitachycardia pacing therapy is successful in terminating a boundary zone fibrillation; and

,

decreasing the fibrillation detection zone boundary by a selected amount if the antitachycardia pacing therapy fails to terminate a boundary zone fibrillation.

5. The method of claim 3 further comprising:

delivering antitachycardia pacing therapy if the arrhythmia is classified as a boundary zone fibrillation;

increasing the fibrillation detection zone boundary by an amount such that the detection zone boundary equals the measured heart rate if the antitachycardia pacing therapy is successful in terminating a boundary zone fibrillation.

6. The method of claim 5 further comprising decreasing the fibrillation detection zone boundary by an amount such that the upper limit of the boundary zone equals the measured heart rate if the antitachycardia pacing therapy fails to terminate a boundary zone tachycardia.

7. The method of claim 6 further comprising:

further classifying a fibrillation according to whether the fibrillation is within a soft zone defined as a selected range of heart rates with a selected upper limit and a lower limit equal to the upper limit of the boundary zone, wherein the fibrillation is designated a boundary zone fibrillation if the fibrillation falls within the soft zone;

delivering antitachycardia pacing therapy if the fibrillation is classified as a boundary zone fibrillation; and

,

increasing the fibrillation detection zone boundary by a selected amount if the antitachycardia pacing therapy is successful in terminating a soft zone fibrillation.

8. The method of claim 7 further comprising decreasing the upper limit of the soft zone by a selected amount if the antitachycardia pacing therapy fails to terminate a soft zone fibrillation.

9. The method of claim 8 wherein the values of the fibrillation rate boundary, the boundary zone upper and lower limits, and the soft zone upper limit are defined so as to be positively correlated with a measured heart rate stability value over a selected range of stability values.

10. The method of claim 8 wherein the values of the fibrillation rate boundary, the boundary zone upper and lower limits, and the soft zone upper limit are defined so as to vary in proportion to a measured heart rate stability value up to a selected upper limit.

11. The method of claim 8 further comprising delivering a shock pulse if the fibrillation has a measured heart rate above the soft zone upper limit.

12. An implantable cardioverter/defibrillator with antitachycardia pacing capability, comprising:

a sensing channel for measuring heart rate;

an antitachycardia pace generator;

a shock pulse generator, and,

logic circuitry for implementing the method recited in claim 1.

13. The implantable cardioverter/defibrillator of claim 12 further comprising logic circuitry for implementing the method recited in claim 8.

14. The implantable cardioverter/defibrillator of claim 12 further comprising logic circuitry for implementing the method recited in claim 10.

15. A processor-readable storage medium having processor-executable instructions for performing the method recited in claim 1.

16. The processor-readable storage medium of claim 15 further having processor-executable instructions for performing the method recited in claim 2.

17. The processor-readable storage medium of claim 15 further having processor-executable instructions for performing the method recited in claim 5.

18. The processor-readable storage medium of claim 15 further having processor-executable instructions for performing the method recited in claim 6.

19. The processor-readable storage medium of claim 15 further having processor-executable instructions for performing the method recited in claim 8.

20. The processor-readable storage medium of claim 15 further having processor-executable instructions for performing the method recited in claim 10.