Apparatus and method for treating a tachyarrhythmia

• US 5,188,105 A
• Filed: 11/14/1990
• Issued: 02/23/1993
• Est. Priority Date: 11/14/1990
• Status: Expired due to Term

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Keimel, John G.
• Primary Examiner(s): Kamm, William E.
• Assistant Examiner(s): Getzow, Scott M.
• Application Number:
  US07/612,761
• Time in Patent Office: 832 Days
• Field of Search: 128/419 D
• US Class Current: 607/5
• CPC Class Codes: A61N 1/3621 for treating or preventing abnormally high heart rate
• CPC Class Codes: A61N 1/39622 Pacing therapy
• CPC Class Codes: A61N 1/3987 characterised by the timing or triggering of the shock

Abstract

An implantable cardioverter/defibrillator capable of detecting fibrillation and other tachyarrhythmias and of generating high energy cardioversion and defibrillation pulses. The device delivers cardioversion pulses and defibrillation pulses synchronized to heart rhythm, wherever possible. Delivery of cardioversion pulses requires verification of the continuing presence of a tachyarrhythmia, following charge up of the output capacitor in the pulse generator. In the event that cardioversion therapy is aborted, the charge on the capacitor is retained until subsequent detection of termination of the tachyarrthythmia. Defibrillation pulses are delivered synchronized to heart rhythm, wherever possible, but are delivered asynchronously if synchronization is not possible. Following delivery of a cardioversion or defibrillation pulse, the charge remaining on the capacitor is retained until detection of tachyarrhythmia or fibrillation termination, respectively.

Claims

1. In a cardiovertor/defibrillator comprising means for detecting fibrillation, means for detecting tachyarrhythmia and means for generating high energy cardioversion and defibrillation pulses, including capacitor means and means for charging said capacitor means upon detection of a tachyarrhythmia by said tachyarrhythmia detecting means, for delivery to the heart, the improvement comprising:

defibrillation pulse synchronization means for triggering said pulse generating means to deliver a defibrillation pulse in response to detection of fibrillation by said fibrillation detecting means, said defibrillation pulse synchronization means comprising means for sensing heart rhythm, means for defining a first set of requirements for said heart rhythm and means for triggering delivery of said defibrillation pulse when said first set of requirements are met; and

cardioversion pulse synchronization means for triggering said pulse generating means to deliver a cardioversion pulse in response to detection of tachyarrhythmia by said tachyarrhythmia detecting means, said cardioversion pulse synchronization means comprising means for sensing heart rhythm, means for defining a second set of requirements differing from said first set of requirements, and means for triggering delivery of said cardioversion pulse when said second set of requirements are met, wherein said cardioversion pulse synchronization means comprises;

means for defining at least two synchronization intervals following charging of said capacitor means;

means for detecting of R-waves during said synchronization intervals; and

triggering means responsive to the detection of R-waves during two successive ones of said synchronization intervals for triggering delivery of said cardioversion pulse synchronized to the detection of said R-wave during the second of said two successive synchronization intervals.

2. In a cardiovertor/defibrillator comprising means for detecting fibrillation, means for detecting tachyarrhythmia and means for generating high energy cardioversion and defibrillation pulses, including capacitor means and means for charging said capacitor means upon detection of a tachyarrhythmia by said tachyarrhythmia detecting means, for delivery to the heart the improvement comprising:

defibrillation pulse synchronization means for triggering said pulse generating means to delivery a defibrillation pulse in response to detection of fibrillation by said fibrillation detecting means, said defibrillation pulse synchronization means comprising means for sensing heart rhythm, means for defining a first set of requirements for said heart rhythm and means for triggering delivery of said defibrillation pulse when said first set of requirements are met; and

cardioversion pulse synchronization means for triggering said pulse generating means to deliver a cardioversion pulse in response to detection of tachyarrhythmia by said tachyarrhythmia detecting means, said cardioversion pulse synchronization means comprising means for sensing heart rhythm, means for defining a second set of requirements for said heart rhythm differing from said first set of requirements, and means for triggering delivery of said cardioversion pulse when said second set of requirements are met; and

wherein said defibrillation pulse synchronization means comprises;

means for defining at least one synchronization interval following charging of said capacitor means;

means for detecting the occurrence of an R-wave during said at least one synchronization interval;

means responsive to the detection of an R-wave during said synchronization interval for triggering the synchronized delivery of said defibrillation pulse; and

means for triggering the delivery of said defibrillation pulse at the expiration of said synchronization interval in the absence of the detection of an R-wave during said synchronization interval.

3. In a cardioverter comprising means for detection of heart rhythm, means for defining detection requirements for said heart rhythm, means for detection of an arrhythmia when said heart rhythm meets said detection requirements, output capacitor means for generating high energy pulses for delivery to the heart to terminate said arrhythmia, and means for charging said output capacitor means in response to detection of said arrhythmia;

the improvement comprising;

pulse synchronization means for triggering said pulse generating means to deliver a cardioversion pulse in response to detection of said arrhythmia by said detection means, said synchronization means comprising;

means for verifying the continued presence of said detected arrhythmia after charging of said capacitor means and for aborting the delivery of said high energy pulse unless the continuing presence of said arrhythmia is verified;

means for detecting the termination of said detected arrhythmia after charging of said capacitor means; and

means for retaining the charge on said capacitor means until the detection of the termination of said arrhythmia and for discharging the charge on said capacitor means in response to the detection of the termination of said detected tachyarrhythmia.

4. A cardioverter according to claim 3 wherein said verifying means comprises:

means for defining at least two synchronization intervals following charging of said capacitor means;

means for detection of R-waves during said synchronization intervals; and

means responsive to the detection of R-waves during two successive ones of said synchronization intervals for triggering delivery of said high energy pulse synchronized to the detection of said R-wave during the second of said two successive synchronization intervals.

5. A cardioverter according to claim 4 wherein said verifying means comprises means responsive to the failure to detect an R-wave during any one of said synchronization intervals for aborting the delivery of said high energy pulse.

6. In a defibrillator comprising means for detection of heart rhythm, means for defining detection requirements for said heart rhythm, means for detection of fibrillation when said heart rhythm meets said detection requirements, output capacitor means for generating high energy defibrillation pulses for delivery to the heart, and means for charging said output capacitor means in response to detection of fibrillation;

the improvement comprising;

defibrillation pulse synchronization means for triggering said pulse generating means to deliver a defibrillation pulse in response to detection of fibrillation by said fibrillation detection means, said fibrillation synchronization means comprising;

means for defining at least one synchronization interval following charging of said capacitor means;

means for detecting the occurrence of an R-wave during said at least one synchronization interval;

triggering means responsive to the detection ofan R-wave during a predetermined portion of said synchronization interval for triggering the synchronized delivery of said defibrillation pulse; and

means for triggering the delivery of said defibrillation pulse at the expiration of said synchronization interval in the absence of the occurrence of an R-wave during said synchronization interval.

7. A defibrillator according to claim 6 wherein said defining means comprises means for defining two synchronization intervals and wherein the first of said synchronization intervals further comprises a refractory interval, wherein said defining means is responsive to the detection of an R-wave during said refractory interval for initiating the second of said synchronization intervals and wherein said triggering means is responsive to the detection of an R-wave during either of said synchronization intervals.

8. In a cardioverter comprising means for detection of heart rhythm, means for defining detection requirements for said heart rhythm, means for detection of an arrhythmia when said heart rhythm meets said detection requirements, output capacitor means for generating high energy pulses for delivery to the heart to terminate said arrhythmia, and means for charging said output capacitor means in response to detection of said arrhythmia;

the improvement comprising;

pulse synchronization means for triggering said pulse generating means to deliver a high energy pulse in response to detection of said arrhythmia by said detection means, said pulse symchronization means comprising;

means for defining at least two synchronization intervals following charging of said capacitor means;

means for detection of R-waves during said synchronization intervals; and

triggering means responsive to the detection of R-waves during predetermined portions of two successive ones of said synchronization intervals for triggering delivery of said high energy pulse synchronized to the detection of said R-wave during the second of said second of said successive synchronization intervals.

9. A cardioverter according to claim 8 wherein said defining means comprises means for defining a refractory interval during the first of said synchronization intervals and wherein said defining means is responsive to the detection of an R-wave during said refractory interval and for initiating the second of said synchronization intervals.

10. A cardioverter according to claim 9 wherein said defining means comprises means for defining at least three synchronization intervals, wherein said defining means comprises means for defining refractory intervals during at least the first two of said synchronization intervals, and wherein said triggering means comprises means responsive to the detection of R-waves in the non-refractory portions of two successive ones of said synchronization intervals for triggering delivery of said high energy pulse.

11. In a cardioverter comprising means for detection of heart rhythm, means for defining detection requirements for said heart rhythm, means for detection of an arrhythmia when said heart rhythm meets said detection requirements, output capacitor means for generating high energy pulses for delivery to the heart to terminate said arrhythmia, and means for charging said output capacitor means in response to detection of said arrhythmia, the improvement comprising:

pulse synchronization means for triggering said pulse generating means to deliver a cardioversion pulse in response to detection of said arrhythmia by said detection means, said synchronization means comprising means for verifying the continued presence of said detected arrhythmia after charging of said capacitor means and for aborting the delivery of said high energy pulse unless the continuing presence of said arrhythmia is verified, said verifying means comprising means for determining whether the rhythm of said heart meets a first set of criteria;

means for detecting the termination of said detected arrhythmia after charging of said capacitor means, said means for detecting the termination of said detected arrhythmia comprising means for determining whether the rhythm of said heart meets second criteria, differing from said first criteria; and

means for retaining the charge on said capacitor means, after aborting the delivery of said high energy pulse by said verifying means, until detection of the termination of said arrhythmia and for discharging the charge on said capacitor in response to the detection of the termination of said detected arrhythmia.

12. In a cardioverter/defibrillator comprising means for detecting fibrillation, means for detecting tachyarrhythmia and means for generating high energy cardioversion and defibrillation pulses for delivery to the heart, the improvement comprising:

defibrillation pulse synchronization means for triggering said pulse generating means to delivery a defibrillation pulse in response to detection of fibrillation by said fibrillation detecting means, said defibrillation pulse synchronization means comprising means for defining a synchronization interval following detection of fibrillation by said fibrillation detecting means, means for triggering delivery of said defibrillation pulse synchronized to a depolarization of said heart occurring within said synchronization interval and means for triggering delivery of said defibrillation pulse at the expiration of said synchronization interval, in the absence of an occurrence of a depolarization of said heart during said synchronization interval; and

cardioversion pulse synchronization means for triggering said pulse generating means to deliver a cardioversion pulse in response to detection of tachyarrhythmia by said tachyarrhythmia detecting means, said cardioversion pulse synchronization means comprising means for defining a synchronization interval following detection of tachyarrhythmia by said detecting means, means for triggering delivery of a cardioversion pulse synchronized to a depolarization of said heart occurring within said synchronization interval and means for aborting delivery of a cardioversion pulse in response to the absence of a cardiac depolarization during said synchronization interval.