Method and apparatus for using physiologic stress in assessing myocardial electrical stability

• US 5,921,940 A
• Filed: 11/04/1997
• Issued: 07/13/1999
• Est. Priority Date: 02/20/1991
• Status: Expired due to Term

• Current Assignee: Georgetown University
• Original Assignee: Georgetown University
• Inventors: Nearing, Bruce D., Verrier, Richard L.
• Primary Examiner(s): Kamm, William E.
• Application Number:
  US08/963,871
• Time in Patent Office: 616 Days
• Field of Search: 600/515, 600/516, 600/518, 600/520
• US Class Current: 600/518
• CPC Class Codes: A61B 5/02405 Determining heart rate variability
• CPC Class Codes: A61B 5/349 Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61B 5/352 Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval
• CPC Class Codes: A61B 5/355 Detecting T-waves
• CPC Class Codes: A61B 5/36 Detecting PQ interval, PR interval or QT interval
• CPC Class Codes: A61B 5/363 Detecting tachycardia or bradycardia
• CPC Class Codes: A61B 5/4035 Evaluating the autonomic nervous system
• CPC Class Codes: A61B 5/4884 inducing physiological or psychological stress, e.g. applications for stress testing
• CPC Class Codes: A61B 5/7275 Determining trends in physiological measurement data; Predicting development of a medical condition based on physiological measurements, e.g. determining a risk factor
• CPC Class Codes: G16H 50/30 for calculating health indices; for individual health risk assessment

Abstract

The non-invasive, dynamic tracking and diagnosing of cardiac vulnerability to ventricular fibrillation involves analysis of both cardiac electrical stability and the influence of autonomic activity. The magnitude of alternation in an electrocardiogram is indicative of cardiac electrical stability. Alternans are made manifest by applying a physiologic stress such as exercise or behavioral stress to a subject.

Claims

1. Method for assessing alternation in an electrocardiogram signal comprising:

physiologically stressing a subject other than by pacing the heart via electrodes applied directly to the surface of the heart;

detecting the electrocardiogram signal from the subject; and

analyzing alternation in the electrocardiogram signal.

2. The method of claim 1, wherein said stressing step comprises:

physiologically stressing a subject with exercise.

3. The method of claim 1, wherein said stressing step comprises:

physiologically stressing a subject with behavioral stress.

4. The method of claim 1, wherein said detecting step comprises:

applying body surface electrodes to the subject to detect the electrocardiogram signal.

5. The method of claim 1, wherein said analyzing step comprises:

analyzing alternation in the electrocardiogram signal as the electrocardiogram signal is detected.

6. The method of claim 1, further comprising the step after said detecting step and before said analyzing step of:

storing the electrocardiogram signal as the electrocardiogram signal is detected.

7. The method of claim 6, wherein said analyzing step comprises:

retrieving said stored electrocardiogram signal; and

analyzing alternation in said stored electrocardiogram signal.

8. Method for assessing a temporal pattern of cycle-to-cycle variability in a physiologic waveform comprising:

physiologically stressing a subject to achieve a heart rate within a desired range other than by pacing the heart via electrodes applied directly to the surface of the heart;

detecting physiologic waveform signals from the subject; and

analyzing the temporal pattern of cycle-to-cycle variability in the physiologic waveform signals.

9. A system for assessing a temporal pattern of cycle-to-cycle variability in an electrocardiogram signal comprising:

means for detecting the electrocardiogram signal from a subject;

means for applying a physiologic stress to the subject other than pacing the heart via electrodes applied directly to the surface of the heart; and

means for analyzing alternation in the electrocardiogram signal pattern of cycle-to-cycle variability in the physiologic waveform.