Relationship between anatomy and ventricular defibrillation thresholds in two finite element human torso models

In order to investigate the anatomical variables that affect ventricular defibrillation thresholds (DFTs), Finite Element Thorax models were built from MRI and fast CT images of two patients. One patent had a dilated left ventricle (LV), LV hypertrophy, 30% ejection fraction, and a relatively small RV. The other patient had large cardiac dimensions (upper bound of normal) but no heart disease. The primary defibrillation electrode configurations, i.e. Superior Vena Cava (SVC) to Right Ventricle (RV) (SVC-RV), left pectoral Can to RV (Can-RV) and Can+SVC-RV, were analyzed and compared in the two models. The DFTs were calculated based on 95% ventricular mass with voltage gradient greater than 5 V/cm and these results were also compared with the clinical data. The FEA results show that anatomical variation can affect ventricular DFTs for certain lead configurations. The DFTs with Can+SVC-RV and Can-RV systems are robust and relatively insensitive to these anatomical differences