Multidirectional ECG coherent optimal timing of defibrillation shocks

• US 5,741,304 A
• Filed: 10/17/1995
• Issued: 04/21/1998
• Est. Priority Date: 10/17/1995
• Status: Expired due to Fees

• Current Assignee: University Of Kentucky Research Foundation (University of Kentucky)
• Original Assignee: University Of Kentucky Research Foundation (University of Kentucky)
• Inventors: Patwardhan, Abhijit R., Leonelli, Fabio M.
• Primary Examiner(s): Kamm, William E.
• Assistant Examiner(s): EVANISKO, GEORGE ROBERT
• Application Number:
  US08/544,301
• Time in Patent Office: 917 Days
• Field of Search: 128/705, 128/699, 607/5
• US Class Current: 607/5
• CPC Class Codes: A61N 1/3925 Monitoring; Protecting

Abstract

A method for of delivering a defibrillation shock to a heart at an optimal time to stop ventricular fibrillation which involves obtaining an electrocardiogram of a heart in at least two directions, determining a time-coherency of the electrocardiogram based upon each of the at least two directions, and computing a tracking function from the time-coherency. An optimal time to apply a defibrillation shock to the heart is determined by locating a local maximum on the tracking function. The method utilizes spacia characteristics of the ventricular fibrillation. The method can be incorporated into implantable cardioverter defibrillators utilizing existing hardware technology.

Claims

1. A method of determining an optimal time to apply a defibrillation shock to a heart which comprises the steps of:

obtaining an electrocardiogram of a heart in at least two directions;

determining a time-coherency of said electrocardiogram based upon each of said at least two directions;

computing a tracking function from said time-coherency; and

locating a local maximum of said tracking function which exceeds a preset defibrillation threshold, which local maximum represents an optimal time to apply a defibrillation shock to said heart; and

delivering a defibrillation shock to the heart at said optimal time.

2. A method of determining an optimal time to apply a defibrillation shock to a heart according to claim 1, wherein said at least two directions comprise orthogonal directions.

3. A method of determining an optimal time to apply a defibrillation shock to a heart according to claim 1, wherein said at least two directions comprise three directions.

4. A method of determining an optimal time to apply a defibrillation shock to a heart according to claim 3, wherein said three directions are orthogonal.

5. A method of determining an optimal time to apply a defibrillation shock to a heart according to claim 1, comprising performing said steps with an implantable cardioverter defibrillator.

6. A method of delivering a defibrillation shock to a heart at an optimal time to stop ventricular fibrillation which comprises the steps of:

obtaining an electrocardiogram of a heart in at least two directions;

determining a time-coherency of said electrocardiogram based upon each of said at least two directions;

computing a tracking function from said time-coherency;

locating a local maximum of said tracking function which exceeds a preset defibrillation threshold, which local maximum represents an optimal time to apply a defibrillation shock to said heart; and

applying a defibrillation shock to said heart at said optimal time represented by said local maximum of said tracking function.

7. A method of determining an optimal time to apply a defibrillation shock to a heart according to claim 6, wherein said at least two directions comprise orthogonal directions.

8. A method of determining an optimal time to apply a defibrillation shock to a heart according to claim 6, wherein said at least two directions comprise three directions.

9. A method of determining an optimal time to apply a defibrillation shock to a heart according to claim 8, wherein said three directions are orthogonal.

10. A method of determining an optimal time to apply a defibrillation shock to a heart according to claim 6, comprising performing said steps with an implantable cardioverter defibrillator.

11. In an implantable cardioverter defibrillator having means to detect ventricular fibrillation and to apply a defibrillation shock to a heart, the improvement comprising means to:

obtain an electrocardiogram of a heart in at least two directions;

determine a time-coherency of said electrocardiogram based upon each of said at least two directions;

compute a tracking function from said time-coherency;

locate a local maximum of said tracking function which exceeds a preset defibrillation threshold, which local maximum represents an optimal time to apply a defibrillation shock to said heart; and

apply a defibrillation shock to said heart at said optimal time represented by said local maximum of said tracking function.