Research Project: Efficacy of Long Duration Biphasic Waveform Defibrillation
Principle Investigator: Jayna Stohlman
Despite the documented efficacy of external defibrillation, the means by which automatic external defibrillator (AED) shocks terminate ventricular fibrillation (VF) remains unclear. It has been shown that biphasic waveforms are more efficient than monophasic waveforms, which is why biphasic waveforms are now most commonly used in AEDs. It has also been shown that very long duration and untruncated monophasic waveforms can be ineffective, inducing re-fibrillation in the patient. The effectiveness of long-duration biphasic waveforms remains unclear. The goal of this research is to determine the effectiveness of long-duration biphasic truncated exponential waveforms for defibrillation. In collaboration with the Italian Institute of Health, we have successfully used a custom-made arbitrary waveform amplifier to deliver both monophasic and biphasic waveforms, with a range of programmable durations and output energy, to defibrillate Langendorff-perfused rabbit hearts. We propose to 1) characterize the effectiveness of the long-duration biphasic shocks using an isolated rabbit heart model of fibrillation, 2) determine if there is a risk for re-fibrillating the heart when long-duration biphasic defibrillation shocks are used, and 3) determine the longest duration biphasic waveform for safe defibrillation.
(Top) Schematic of optical mapping setup comprised of a light source to excite fluorescence probes in heart tissue and a detector to collect emitted light.
(Bottom) Fluorescent signal (ΔF) of transmembrane potential at one site during ventricular fibrillation (V-fib) and successful defibrillation and return to normal sinus rhythm (NSR).