US Patent 6987999 Implantable defibrillator with alternating counter electrode

An implantable cardiac stimulation device delivers successive defibrillation waveforms using alternating counter electrodes selected from a case electrode and an electrode located on a coronary sinus lead. The case electrode and coronary sinus electrode may be selected individually in an alternating fashion such that the defibrillation pathway alternates between two single pathways during a defibrillation regimen. The case electrode and the coronary sinus electrode may also be used simultaneously in parallel to create a dual pathway. Defibrillation waveforms may then be delivered in a cyclical fashion between the individual counter electrodes and the combined counter electrodes such that alternation between single pathways and a dual pathway is achieved.