Predictive modeling of defibrillation using hexahedral and tetrahedral finite element models: recent advances.

Implanted cardioverter/defribillator (ICD) implants may be complicated by body size and anatomy. One approach to this problem has been the adoption of creative, extracardiac implant strategies using standard ICD components. Because data on safety or efficacy of such ad hoc implant strategies are lacking, we have developed image-based finite element models to compare electric fields and expected defibrillation thresholds (DFTs) using standard and novel electrode locations. In this article, we review recently published studies by our group using such models and progress in meshing strategies to improve efficiency and visualization. Our preliminary observations predict that they may be large changes in defibrillation thresholds with clinically relevant variations of electrode placement. Extracardiac ICDs of various lead configurations are predicted to be effective in both children and adults. This approach may aid both ICD development and patient-specific optimization of electrode placement, but the simplified nature of current models dictates further development and validation before clinical or industrial use.