Optimal Transvenous Coil Position on Active-can Single-coil ICD Defibrillation Efficacy: A Simulation Study

The implantable cardioverter defibrillator with an active can and a single coil lead is effective in treating ventricular fibrillation, but the lead placement associated with the high defibrillation efficacy is still controversial and remains largely empirical. In this study, an anatomically realistic finite difference model of the thorax was developed based on MRI cross-sectional images of a human thorax to examine the effect of transvenous coil placement on defibrillation efficacy. Four electrode configurations with the coil was placed, respectively, in the right ventricular (RV) apex, in the middle of RV cavity, along the free wall in RV, or along the septal wall in RV, were simulated and their defibrillation efficacies were evaluated based on a set of metrics including voltage defibrillation threshold, current defibrillation threshold, interelectrode impedance, potential gradient distribution uniformity, current density distribution, and myocardium damage. It was found that the optimal electrode configuration is to position the coil in the middle of the RV cavity. The results were compared with the results from a simplified thoracic model. The comparison indicates that for a given electrode configuration a simplified representation of the thorax may overestimate defibrillation efficacy.