Apparatus and method for treating ventricular tachyarrhythmias

• US 20090234400A1
• Filed: 04/20/2009
• Published: 09/17/2009
• Est. Priority Date: 04/30/1997
• Status: Active Grant

• Current Assignee: David B. Krig, James O. Gilkerson, Jan D. Wald, Robert D. Dreher, William J. Linder, William L. Zimmer
• Original Assignee: David B. Krig, James O. Gilkerson, Jan D. Wald, Robert D. Dreher, William J. Linder, William L. Zimmer
• Inventors: Gilkerson, James O., Linder, William J., Krig, David B., Zimmer, William L., Dreher, Robert D., Wald, Jan D.
• Granted Patent: US 8,046,068 B2
• Time in Patent Office: Days
• US Class Current: 607/4
• CPC Class Codes: A61N 1/3622 comprising two or more electrodes co-operating with different heart regions
• CPC Class Codes: A61N 1/395 for treating atrial fibrillation
• CPC Class Codes: A61N 1/39622 Pacing therapy

Abstract

A system and method for selectively treating a ventricular tachycardia based on sensed atrial and ventricular intervals from the patient'"'"'s heart. A detection window of the ten most recent atrial and ventricular intervals are analyzed for the occurrence of either tachycardia or fibrillation. When a majority of the sensed intervals are satisfied, the apparatus starts a duration time interval. Ventricular intervals and atrial intervals are compare, ventricular interval greater than the atrial interval by a bias factor the system delivers tachycardia therapy to the heart. Alternatively, the method withholds tachycardia therapy to the heart when the atrial rate is classified as atrial fibrillation and the ventricular response is unstable.

Claims

1. A method, comprising:

sensing atrial and ventricular events representative of cardiac rhythms;

detecting at least one of a ventricular tachycardia and a ventricular fibrillation;

analyzing the cardiac rhythms during a first time interval for assessing an origin of the at least one of a ventricular tachycardia and a ventricular fibrillation, the first time interval started when the at least one of a ventricular tachycardia and a ventricular fibrillation is detected; and

delaying or inhibiting a ventricular tachycardia therapy if the origin of the at least one of a ventricular tachycardia and a ventricular fibrillation is in an atrium.

2. The method of claim 1, wherein analyzing the cardiac rhythms includes:

determining an average atrial rate from the sensed atrial events and determining an average ventricular rate from sensed ventricular events; and

determining whether the average ventricular rate is not greater than the average atrial rate by at least a bias factor during the first time interval.

3. The method of claim 1, wherein analyzing the cardiac rhythms includes:

determining a ventricular rate from sensed ventricular events;

determining an onset rate, the onset rate being the rate of transition of a ventricular rate from a slower sinus rate to a tachycardia rate; and

determining whether the onset rate is equal to or greater than an onset threshold value.

4. The method of claim 1, wherein analyzing the cardiac rhythms includes:

determining a ventricular rate from sensed ventricular events; and

determining whether the ventricular rate is unstable, wherein the ventricular rate is unstable when an average variance of ventricular intervals exceeds a stability interval threshold value.

5. The method of claim 4, wherein analyzing the cardiac rhythms further includes determining an occurrence of atrial fibrillation from the sensed atrial events.

6. The method of claim 1, wherein detecting the at least one of a ventricular tachycardia and a ventricular fibrillation comprises:

determining ventricular interval rates from pairs of consecutively sensed ventricular events in a detection window; and

declaring that the at least one of a ventricular tachycardia and a ventricular fibrillation is detected when a first predetermined percentage of the ventricular interval rates in the detection window are classified as fast ventricular intervals.

7. The method of claim 6, further comprising starting the first time interval programmed for a duration associated with the ventricular interval rates once the at least one of a ventricular tachycardia and a ventricular fibrillation is detected.

8. The method of claim 6, further comprising:

determining whether the fast ventricular intervals sustain during the first time interval; and

delivering ventricular tachycardia therapy at the end of the first time interval if the origin of the at least one of a ventricular tachycardia and a ventricular fibrillation is in a ventricle and if the fast ventricular intervals sustain during the first time interval.

9. The method of claim 8, further comprising resetting the first time interval to zero when the fast ventricular intervals fail to sustain during the first time interval.

10. A system, comprising:

means for sensing atrial events and ventricular events;

means for determining ventricular interval rates from pairs of consecutively sensed ventricular events in a detection window;

means for declaring the detection window satisfied when a first predetermined percentage of the ventricular interval rates in the detection window are classified as fast ventricular intervals;

means for starting a first time interval programmed for a duration associated with the ventricular interval rates once the detection window is declared satisfied; and

means for determining whether to inhibit a ventricular tachycardia therapy at the end of the first time interval.

11. The system of claim 10, wherein the means for determining whether to inhibit the ventricular tachycardia therapy comprises means for determining whether the fast ventricular intervals sustain during the first time interval.

12. The system of claim 11, wherein the means for determining whether the fast ventricular intervals sustain comprises:

means for declaring that the detection window remains satisfied when a second predetermined percentage of the ventricular interval rates in the detection window are classified as fast ventricular intervals; and

means for resetting the first time interval to zero when the detection window fails to remain satisfied during the first time interval.

13. The system of claim 11, wherein the means for determining whether to inhibit the ventricular tachycardia therapy comprises means for determining the origin of the fast ventricular intervals during the first time interval.

14. An implantable cardioverter-defibrillator, comprising:

sensing circuitry adapted to sense atrial and ventricular events representative of cardiac rhythms;

therapy delivery circuitry adapted to apply or inhibit a ventricular tachycardia therapy; and

control circuitry coupled to the sensing circuitry and therapy circuitry, the control circuitry adapted to;

detect at least one of a ventricular tachycardia and a ventricular fibrillation;

analyze the cardiac rhythms during a first time interval for assessing an origin of the at least one of a ventricular tachycardia and a ventricular fibrillation, the first time interval started when the at least one of a ventricular tachycardia and a ventricular fibrillation is detected; and

delay or inhibit the ventricular tachycardia therapy if the origin of the at least one of a ventricular tachycardia and a ventricular fibrillation is in an atrium.

15. The implantable cardioverter-defibrillator of claim 14, wherein the control circuitry is adapted to:

determine an average atrial rate from the sensed atrial events;

determine an average ventricular rate from the sensed ventricular events; and

determine whether the average ventricular rate is not greater than the average atrial rate by at least a bias factor.

16. The implantable cardioverter-defibrillator of claim 15, wherein the therapy delivery circuitry is adapted to inhibit the ventricular tachycardia therapy if the average ventricular rate is not greater than the average atrial rate by at least the bias factor.

17. The implantable cardioverter-defibrillator of claim 14, wherein the control circuitry is adapted to determine whether an onset rate is gradual during the first time interval, wherein the onset rate is the rate of transition of a ventricular rate from a slower sinus rate to a tachycardia rate and the onset rate is gradual when the onset rate is equal to or greater than an onset threshold value, and wherein the therapy delivery circuitry is adapted to inhibit the ventricular tachycardia therapy when the onset rate is gradual.

18. The implantable cardioverter-defibrillator of claim 14, wherein the control circuitry is adapted to determine whether the ventricular rate is unstable, wherein the ventricular rate is unstable when an average variance of ventricular intervals exceeds a stability interval threshold value, and wherein the therapy delivery circuitry is adapted to inhibit the ventricular tachycardia therapy when the ventricular rate is unstable.

19. The implantable cardioverter-defibrillator of claim 18, wherein the control circuitry is adapted to determine an occurrence of atrial fibrillation from the sensed atrial events, and wherein the therapy delivery circuitry is adapted to inhibit the ventricular tachycardia therapy if the ventricular rate is unstable and atrial fibrillation is occurring.

20. The implantable cardioverter-defibrillator of claim 14, wherein the control circuitry is adapted to:

determine ventricular interval rates from pairs of consecutively sensed ventricular events in a detection window;

declare that the at least one of a ventricular tachycardia and a ventricular fibrillation is detected when a first predetermined percentage of the ventricular interval rates in the detection window are classified as fast ventricular intervals; and

determine whether the fast ventricular intervals sustain during the first time interval, and wherein the therapy delivery circuitry is adapted to deliver the ventricular tachycardia therapy at the end of the first time interval if the origin of the at least one of a ventricular tachycardia and a ventricular fibrillation is in a ventricle and if the fast ventricular intervals sustain during the first time interval.