Circumferential switching between multiple electrode pairs within a biphasic shock lowers implantable defibrillator thresholds

In order to maximize the efficiency of implantable cardioverter-defibrillators (ICDs) it is important to optimize the waveform and electrode placement so as to minimize the energy necessary for successful defibrillation. We placed six electrodes in, near, and on pig hearts in order to explore the efficacy of dividing a biphasic waveform into a series of pulses delivered to four quadrants of the heart so as to more evenly distribute current. Each phase of the waveform was split into four or eight pulses. It was found that dividing the shock into pulses and distributing current around the heart reduced the average voltage and energy required for defibrillation