In-vitro investigation of very long defibrillation shocks: Design and testing of a capacitor-free defibrillator

The aim of this paper is to describe a defibrillator that allows the delivery of arbitrary waveform shocks, with energy up to 10J and duration up to 100 ms. In addition, data from shocks delivered to isolated rabbitpsilas hearts are presented. The solutions adopted in the design and realization of the defibrillator were: rechargeable battery power; linear AB class power amplifier output in bridge configuration; optical isolation of analog and digital lines to and from the PC and earth ground; measure of the actual voltage, current and energy delivered to the load. Laboratory testing showed that the defibrillator is capable to deliver shocks with a rising time less than 150 us, no tilting also for very long waveforms (100 ms), peak current up to 10 A. The system was then used on rabbit hearts to define a protocol to investigate the effect of waveform duration on defibrillation threshold. We demonstrate the feasibility of an experimental defibrillator for the generation and delivery of true arbitrary waveforms.