Since the first human implant of a completely implantable cardiac defibrillator in 1980, research has focused on making the smallest, most efficient device. Currently the main size constraints of these devices are the battery and capacitor sizes [1]. If energy requirements for defibrillation could be reduced without affecting the efficacy of the device, then battery size could be decreased and/or battery life increased. Also, the capacitors used could be reduced in size. Furthermore, the reduced shock strength might lead to fewer side affects including conduction disturbances and ventricular dysfunction as well as myocardial necrosis when exposing the myocardium to high energy defibrillation shocks. Besides developing more efficient battery and capacitor systems, efforts are focusing on more efficient lead systems and defibrillation waveforms that require less energy for defibrillation [1].