Patent ID: 7203547

Claim:
A method for providing pacing and defibrillation therapy using an implantable medical device having pulse generation circuitry selectively coupled to ventricular tip and ring electrodes and right atrial tip and ring electrodes for delivering pacing pulses to the heart of a patient and defibrillation shock generation circuitry selectively coupled to a right ventricular coil electrode and a device housing electrode for delivering a defibrillation shock to the heart of a patient, said method comprising: upon detecting a need for pacing therapy, selectively delivering power from a first power source employing polycarbon monofluoride (CFx) to pacing pulse generation circuitry for generating pacing pulses; and upon detecting a need for ventricular defibrillation therapy, holding the ventricular and atrial ring electrodes at a voltage equal to that of the right ventricular coil and selectively delivering power from a second power source employing lithium manganese dioxide (LiMn02) to the defibrillation shock generation circuitry for generating shocks for ventricular defibrillation.