US Patent 7418293 Multiple pulse defibrillation for subcutaneous implantable cardiac devices

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.