초록 ▼

Cardiac stimulation methods and systems provide for multiple pulse defibrillation, and involve sensing a fibrillation event, determining a fibrillation cycle length associated with the fibrillation event, and delivering a plurality of defibrillation pulses to treat the fibrillation event. Defibrilla

Cardiac stimulation methods and systems provide for multiple pulse defibrillation, and involve sensing a fibrillation event, determining a fibrillation cycle length associated with the fibrillation event, and delivering a plurality of defibrillation pulses to treat the fibrillation event. Defibrillation pulses are delivered using a combination of subcutaneous non-intrathoracic electrodes. Delivery of each defibrillation waveform subsequent to a first defibrillation waveform is separated in time by a delay associated with the fibrillation cycle length. Delays between defibrillation waveform delivery may be associated with a percentage of the fibrillation cycle length.

대표청구항 ▼

What is claimed is: 1. A method of delivering a subcutaneous defibrillation therapy, comprising: selecting at least a pair of subcutaneous non-intrathoracic electrodes from a plurality of subcutaneous non-intrathoracic electrodes, the pair selected to provide an increased cardiac signal-to-noise ra

What is claimed is: 1. A method of delivering a subcutaneous defibrillation therapy, comprising: selecting at least a pair of subcutaneous non-intrathoracic electrodes from a plurality of subcutaneous non-intrathoracic electrodes, the pair selected to provide an increased cardiac signal-to-noise ratio relative to other pairs of the plurality of subcutaneous non-intrathoracic electrodes; sensing a fibrillation event using the selected pair of subcutaneous non-intrathoracic electrodes of the plurality of subcutaneous non-intrathoracic electrodes; determining a fibrillation cycle length associated with the fibrillation event; and delivering, using one or more combinations of electrodes of the plurality of subcutaneous non-intrathoracic electrodes, a plurality of defibrillation pulses to treat the fibrillation event, wherein the electrodes of each electrode combination are structurally supported in a fixed relationship such that the electrodes of each respective electrode combination are located extra-thoracically at opposing sides of the heart, and delivery of a latter pulse of the defibrillation pulses subsequent to a former pulse of the defibrillation pulses is separated in time by a first delay associated with the fibrillation cycle length. 2. The method of claim 1, further comprising delivering, using at least one of the combinations of electrodes, an additional defibrillation pulse following a second delay relative to delivery of the latter defibrillation pulse, the second delay associated with a percentage of the fibrillation cycle length. 3. The method of claim 2, wherein the first and second delays are associated with different percentages of the fibrillation cycle length. 4. The method of claim 1, wherein the former pulse is delivered from an electrode combination of the one or more electrode combinations different from that of the latter pulse. 5. The method of claim 1, wherein the fibrillation event is sensed by the selected subcutaneous non-intrathoracic electrode pair corresponding to a first electrode combination of the one or more electrode combinations and one or both of the former and latter pulses are delivered from a second electrode combination of the one or more electrode combinations. 6. The method of claim 1, wherein the fibrillation event comprises a ventricular fibrillation event. 7. The method of claim 1, wherein the first delay is greater than about 50 percent of the fibrillation cycle length. 8. The method of claim 1, wherein the first delay is greater than about 75 percent of the fibrillation cycle length. 9. The method of claim 1, wherein the first delay is about 75 to 100 percent of the fibrillation cycle length. 10. The method of claim 1, wherein the fibrillation cycle length is determined using a Fourier analysis of the fibrillation event. 11. The method of claim 1, wherein the fibrillation cycle length is determined using an auto-correlation analysis of the fibrillation event. 12. The method of claim 1, wherein the fibrillation cycle length is determined by counting signal features of the fibrillation event over a duration of time. 13. The method of claim 1, wherein the former and latter pulses are substantially similar in terms of one or more of amplitude, duration, and phase. 14. The method of claim 1, wherein the former and latter pulses are substantially different in terms of one or more of amplitude, duration, and phase. 15. The method of claim 1, wherein the former and latter pulses comprise monophasic waveforms. 16. The method of claim 1, wherein the former and latter pulses comprise biphasic waveforms. 17. The method of claim 1, wherein one of the former and latter pulses comprises a monophasic waveform and the other of the former and latter pulses comprises a biphasic waveform. 18. The method of claim 1, wherein the fibrillation event comprises a ventricular tachycardia event. 19. The method of claim 1, wherein delivering the plurality of defibrillation pulses comprises delivering at least one pulse of the plurality of defibrillation pulses using a first electrode combination of the one or more combinations of electrodes, the first electrode combination comprising a superior electrode located superior relative to the heart and an inferior electrode located inferior relative to the heart. 20. The method of claim 1, wherein delivering the plurality of defibrillation pulses comprises delivering at least one pulse of the plurality of defibrillation pulses using a first electrode combination of the one or more combinations of electrodes, the first electrode combination comprising an anterior electrode located anterior relative to the heart and a posterior electrode located posterior relative to the heart. 21. A system for delivering a subcutaneous defibrillation therapy, comprising: a housing configured for subcutaneous non-intrathoracic placement relative to a patient's heart; detection circuitry provided in the housing, the detection circuitry configured to detect a fibrillation event; energy delivery circuitry provided in the housing; a plurality of combinations of electrodes configured for subcutaneous non-intrathoracic placement relative to the patient's heart, the electrodes of each electrode combination coupled to the detection and energy delivery circuitry and structurally supported in a fixed relationship such that the electrodes of each electrode combination are located extra-thoracically at opposing sides of the heart; and a controller provided in the housing and coupled to the detection and energy delivery circuitry, the controller configured to select a pair of subcutaneous non-intrathoracic electrodes from the plurality of electrode combinations based on an increased cardiac signal-to-noise ratio associated with the selected pair of subcutaneous non-intrathoracic electrodes relative to other pairs of the plurality of electrode combinations and to determine a fibrillation cycle length associated with the fibrillation event using the selected pair of subcutaneous non-intrathoracic electrodes, the controller coordinating delivery of a latter defibrillation pulse following a delay relative to delivery of a former defibrillation pulse, the delay defining a percentage of the fibrillation cycle length. 22. The system of claim 21, wherein the controller is configured to deliver an additional defibrillation pulse following a second delay relative to delivery of the latter defibrillation pulse, the second delay defining a percentage of the fibrillation cycle length. 23. The system of claim 21, wherein the selected electrode combination is used for detection of the fibrillation event and delivery of the former and latter defibrillation pulses. 24. The system of claim 21, wherein a first electrode combination of the plurality of electrode combinations is used for detection of the fibrillation event and a second electrode combination of the plurality of electrode combinations is used for delivery of the former and latter defibrillation pulses. 25. The system of claim 21, wherein a first electrode combination of the plurality of electrode combinations is used for delivery of the former defibrillation pulse and a second electrode combination of the plurality of electrode combinations is used for delivery of the latter defibrillation pulse. 26. The system of claim 21, wherein the delay is greater than about 50 percent of the fibrillation cycle length. 27. The system of claim 21, wherein the delay is greater than about 75 percent of the fibrillation cycle length. 28. The system of claim 19, wherein the delay is about 75 to 100 percent of the fibrillation cycle length. 29. The system of claim 21, wherein the controller is configured to determine the fibrillation cycle length using a Fourier analysis of the fibrillation event. 30. The system of claim 21, wherein the controller is configured to determine the fibrillation cycle length using an auto-correlation analysis of the fibrillation event. 31. The system of claim 21, wherein the controller is configured to determine the fibrillation cycle length by counting signal features of the fibrillation event over a duration of time. 32. The system of claim 21, wherein the former and latter defibrillation pulses are substantially similar in terms of one or more of amplitude, duration, and phase. 33. The system of claim 21, wherein the former and latter defibrillation pulses are substantially different in terms of one or more of amplitude, duration, and phase. 34. The system of claim 21, wherein the former and latter defibrillation pulses comprise monophasic waveforms. 35. The system of claim 21, wherein the former and latter defibrillation pulses comprise biphasic waveforms. 36. The system of claim 21, wherein one of the former and latter defibrillation pulses comprises a monophasic waveform and the other of the former and latter defibrillation pulses comprises a biphasic waveform. 37. The system of claim 21, wherein the fibrillation event comprises a ventricular tachycardia event or a ventricular fibrillation event. 38. The system of claim 21, further comprising a first electrode combination of the plurality of combinations of electrodes, the first electrode combination comprising a superior electrode located superior relative to the heart and an inferior electrode located inferior relative to the heart. 39. The system of claim 21, further comprising a first electrode combination of the plurality of combinations of electrodes, the first electrode combination comprising an anterior electrode located anterior relative to the heart and a posterior electrode located posterior relative to the heart. 40. A system for delivering a subcutaneous defibrillation therapy, comprising: means for selecting a pair of subcutaneous non-intrathoracic electrodes from a plurality of subcutaneous non-intrathoracic electrodes, the pair selected to provide an increased cardiac signal-to-noise ratio relative to other pairs of the plurality of subcutaneous non-intrathoracic electrodes; means for sensing a fibrillation event using the selected pair of subcutaneous non-intrathoracic electrodes of the plurality of subcutaneous non-intrathoracic electrodes; means for determining a fibrillation cycle length associated with the fibrillation event; means for delivering, using a first combination of electrodes of the plurality of subcutaneous non-intrathoracic electrodes, a former defibrillation pulse to treat the fibrillation event; means for delivering, using the first combination or a second combination of electrodes of the plurality of subcutaneous non-intrathoracic electrodes, a latter defibrillation pulse following a delay relative to delivery of the former defibrillation pulse to treat the fibrillation event, the delay associated with a percentage of the fibrillation cycle length; and means for structurally supporting the electrodes of each of the first and the second electrode combinations in a fixed relationship such that the electrodes of each respective electrode combination are located extra-thoracically at opposing sides of the heart.