FINITE-ELEMENT ANALYSIS OF DEFIBRILLATION FIELDS IN A HUMAN TORSO MODEL FOR VENTRICULAR DEFIBRILLATION

In order to optimize defibrillation electrode systems for ventricular defibrillation thresholds (DFTs), a Finite Element Torso model was bui lt from fast CT scans of a patient who had large cardiac dimensions (u pper bound of normal) but no heart disease. Clinically used defibrilla tion 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. The DFTs were calculated based on 95% ventricular m ass having voltage gradient > 5 V/cm and these results were also compa red with clinical data. The low voltage gradient regions with voltage gradient <5 V/cm were identified and the effect of electrode dimension and location on DFTs were also investigated for each system. A good c orrelation between the model results and the clinical data supports th e use of Finite Element Analysis of a human torso model for optimizati on of defibrillation electrode systems, This correlation also indicate s that the critical mass hypothesis is the primary mechanism of defibr illation. Both the FEA results and the clinical data show that Can+SVC -RV system offers the lowest voltage DFTs when compared with SVC-RV an d Can-RV systems. Analysis of the effect of RV, SVC and Can electrode dimensions and locations can have an important impact on defibrillatio n lead designs. (C) 1998 Elsevier Science Ltd. Ail rights reserved.