RESUMO
The success rate of direct current cardioversion (DCC), the most common method to convert atrial fibrillation (AF) to sinus rhythm (SR), depends on various factors including AF duration, prior anti-arrhythmic therapy, electrode position and size, transthoracic impedance, and the use of biphasic versus monophasic shocks. Recent, small clinical studies have reported using quadruple electrodes to deliver higher energy, in order to increase DCC success rates in refractory patients. This study aims to computationally model and compare double shock defibrillation with conventional single shock DCC, based on the two parameters, defibrillation threshold (DFT) and heterogeneity index (HI). DFT is the energy required to achieve a voltage gradient of 5 V/cm over 95% of the atrial myocardium. HI, calculated as the (95(th)-5(th))/50(th) percentile of atrial electric field magnitudes, is a measure of non-uniformity. The electric field distributions in the myocardium were generated for over five thousand different conventional and quadruple electrode placements with electrodes of two different sizes. Results show that there is a significant decrease in DFT (p0.01) and HI (p0.01) with increase in electrode size and quantity.
