Claims
- 1. A system for delivering an atrial defibrillation shock pulse, the system comprising:
an atrial sensing channel to detect atrial fibrillation; a ventricular sensing channel to sense ventricular depolarizations (R waves); a shock pulse generator to generate the atrial defibrillation shock pulse; and a controller coupled to the atrial channel, the ventricular channel, and the shock pulse generator, the controller being programmed to:
measure a first R-R interval associated with a first R-wave; estimate a first QT interval based on the first R-R interval; measure a second R-R interval associated with a second R-wave subsequent to the first R-wave; and deliver the atrial defibrillation shock pulse synchronously with the second R-wave if the second R-R interval is longer than the first QT interval.
- 2. The system of claim 1, comprising an implantable cardioverter/defibrillator.
- 3. The system of claim 2, further comprising a pacemaker.
- 4. The system of claim 1, wherein the controller is programmed to deliver the atrial defibrillation shock pulse synchronously with the second R-wave if the second R-R interval is longer than the first QT interval by a specified therapy margin.
- 5. The system of claim 4, wherein the controller is programmed to deliver the atrial defibrillation shock pulse synchronously with the second R-wave if:
the second R-R interval is longer than the first QT interval by the specified therapy margin; and the second R-R interval is longer than a specified minimum value.
- 6. The system of claim 4, wherein the specified therapy margin is approximately 60 milliseconds.
- 7. The system of claim 4, wherein the controller is programmed to deliver the atrial defibrillation shock pulse synchronously with the second R-wave if the second R-R interval exceeds a specified sufficiently-long interval irrespective of the length of the first QT interval and the therapy margin.
- 8. The system of claim 4, further comprising an impedance measurement circuit adapted to detect an impedance signal indicative of ventricular systole for validating the R-wave sensing.
- 9. A method for delivering an atrial defibrillation shock pulse, the method comprising:
detecting an episode of atrial fibrillation; sensing ventricular depolarizations (R waves); measuring a first R-R interval associated with a first R-wave; estimating a first QT interval based on the first R-R interval; measuring a second R-R interval associated with a second R-wave subsequent to the first R-wave; and delivering the atrial defibrillation shock pulse synchronously with the second R-wave if the second R-R interval is longer than the first QT interval.
- 10. The method of claim 9, wherein delivering the atrial defibrillation shock pulse comprises delivering the atrial defibrillation shock pulse synchronously with the second R-wave if the second R-R interval is longer than the first QT interval by a specified therapy margin.
- 11. The method of claim 10, wherein delivering the atrial defibrillation shock pulse comprises delivering the atrial defibrillation shock pulse synchronously with the second R-wave if:
the second R-R interval is longer than the first QT interval by the specified therapy margin; and the second R-R interval is longer than a specified minimum value.
- 12. The method of claim 11, wherein the specified therapy margin is approximately 60 milliseconds.
- 13. The method of claim 11, wherein delivering the atrial defibrillation shock pulse comprises delivering the atrial defibrillation shock pulse synchronously with the second R-wave if the second R-R interval exceeds a specified sufficiently-long interval irrespective of the length of the first QT interval and the therapy margin.
- 14. The method of claim 11, further comprising detecting an impedance signal indicative of ventricular systole to improve a reliability of the R-wave sensing.
- 15. A method for delivering cardiac defibrillation therapy, the method comprising:
detecting fibrillation; sensing ventricular depolarizations (R waves); measuring R-R intervals each associated with one of the R waves; determining whether a current R-R interval exceeds a specified sufficiently-long interval (SL), the current R-R interval associated with a current R wave; delivering a defibrillation shock pulse synchronously with the current R wave if the current R-R interval exceeds the SL; and delivering the defibrillation shock pulse synchronously with a current R wave if:
the current R-R interval exceeds a specified minimum interval (MI); and the current R-R interval exceeds a value given as K ln (R-Rprev)−C+TM, wherein K and C are each a specified constant and TM is a specified therapy margin, and R-Rprev is a previous R-R interval associated with an R wave immediately preceding the current R-wave.
- 16. The method of claim 15, further comprising detecting an impedance signal indicative of ventricular systole, and wherein measuring R-R intervals each associated with one of the R-waves comprises measuring the R-R intervals each associated with the one of the R-waves and an impedance signal detected synchronously with the one of the R-waves.
- 17. The method of claim 15, further comprising determining values of MI, SL, K, C, and TM based upon population data.
- 18. The method of claim 15, further comprising tailoring values of MI, SL, K, C, and TM to an individual patient.
- 19. The method of claim 15, further comprising determining values of MI, SL, K, C, and TM based upon at least one of population data and individual patient data.
- 20. The method of claim 19, wherein K and C are approximately 166.2 and 715.5, respectively, and wherein the R-R intervals are measured in milliseconds.
- 21. The method of claim 19, wherein K and C are approximately 185.5 and 812.3, respectively, and wherein the R-R intervals are measured in milliseconds.
- 22. The method of claim 19, wherein TM is approximately 60 milliseconds.
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] This patent application is a continuation of U.S. patent application Ser. No. 09/661,875, filed on Sep. 14, 2000, the specification of which is incorporated herein by reference.
Continuations (1)
|
Number |
Date |
Country |
Parent |
09661875 |
Sep 2000 |
US |
Child |
10334397 |
Dec 2002 |
US |