Multiple pulse defibrillation for subcutaneous implantable cardiac devices

• US 8,000,786 B2
• Filed: 08/12/2008
• Issued: 08/16/2011
• Est. Priority Date: 11/09/2004
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Sweeney, Robert J.
• Primary Examiner(s): Manuel; George
• Application Number:
  US12/228,327
• Publication Number:
  US 20080306561A1
• Time in Patent Office: 1,099 Days
• Field of Search: 607/5, 607/116
• US Class Current: 607/5
• CPC Class Codes: A61N 1/3906 characterised by the form of the shockwave
• CPC Class Codes: A61N 1/3956 Implantable devices for applying electric shocks to the heart, e.g. for cardioversion

Abstract

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.

Claims

1. A method of delivering a subcutaneous defibrillation therapy from an extra-thoracic location, comprising:

selecting at least a pair of subcutaneous electrodes from a plurality of subcutaneous electrodes positioned extra-thoracically relative to a patient'"'"'s heart, the pair selected to provide an increased cardiac signal-to-noise ratio relative to other pairs of the plurality of subcutaneous electrodes;

sensing a fibrillation event using the selected pair of subcutaneous electrodes of the plurality of subcutaneous electrodes;

determining a fibrillation cycle length associated with the sensed fibrillation event; and

delivering, using one or more combinations of electrodes of the plurality of subcutaneous electrodes, a plurality of defibrillation pulses to treat the fibrillation event, wherein 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 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 first delay is greater than about 50 percent of the fibrillation cycle length.

7. The method of claim 1, wherein the first delay is greater than about 75 percent of the fibrillation cycle length.

8. The method of claim 1, wherein the first delay is about 75 to 100 percent of the fibrillation cycle length.

9. The method of claim 1, wherein the fibrillation cycle length is determined using a Fourier analysis of the fibrillation event or an auto-correlation analysis of the fibrillation event.

10. 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.

11. 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.

12. 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.

13. The method of claim 1, wherein the former and latter pulses comprise monophasic waveforms, polyphasic waveforms, or a combination of monophasic and polyphasic waveforms.

14. A system for delivering a subcutaneous defibrillation therapy from an extra-thoracic location, comprising:

a housing configured for subcutaneous 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 extra-thoracic placement relative to the patient'"'"'s heart, the electrodes of each electrode combination coupled to the detection and energy delivery circuitry; 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 electrodes from the plurality of electrode combinations based on an increased cardiac signal-to-noise ratio associated with the selected pair of subcutaneous 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 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.

15. The system of claim 14, 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.

16. The system of claim 14, wherein the selected electrode combination is used for detection of the fibrillation event and delivery of the former and latter defibrillation pulses.

17. The system of claim 14, 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 at least one of the former and latter defibrillation pulses.

18. The system of claim 14, 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.

19. The system of claim 14, wherein the delay is greater than about 50 percent of the fibrillation cycle length.

20. The system of claim 14, wherein the delay is greater than about 75 percent of the fibrillation cycle length.

21. The system of claim 14, wherein the delay is about 75 to 100 percent of the fibrillation cycle length.

22. The system of claim 14, wherein the controller is configured to determine the fibrillation cycle length using a Fourier analysis of the fibrillation event or an auto-correlation analysis of the fibrillation event.

23. The system of claim 14, wherein the controller is configured to determine the fibrillation cycle length by counting signal features of the fibrillation event over a duration of time.

24. The system of claim 14, wherein the former and latter defibrillation pulses are substantially similar in terms of one or more of amplitude, duration, and phase.

25. The system of claim 14, wherein the former and latter defibrillation pulses are substantially different in terms of one or more of amplitude, duration, and phase.

26. The system of claim 14, wherein the former and latter defibrillation pulses comprise monophasic waveforms, polyphasic waveforms, or a combination of monophasic and polyphasic waveforms.

27. A system for delivering a subcutaneous defibrillation therapy from an extra-thoracic location, comprising:

means for selecting a pair of subcutaneous electrodes from a plurality of subcutaneous extra-thoracic electrodes, the pair selected to provide an increased cardiac signal-to-noise ratio relative to other pairs of the plurality of subcutaneous extra-thoracic electrodes;

means for sensing a fibrillation event using the selected pair of subcutaneous extra-thoracic electrodes of the plurality of subcutaneous extra-thoracic 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 extra-thoracic electrodes, a former defibrillation pulse to treat the fibrillation event; and

means for delivering, using the first combination or a second combination of electrodes of the plurality of subcutaneous extra-thoracic 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.