FINITE-ELEMENT MODELS OF THORACIC CONDUCTIVE ANATOMY - SENSITIVITY TOCHANGES IN INHOMOGENEITY AND ANISOTROPY

A moderately detailed 3-D finite element model of the conductive anato my of a canine thorax was used to examine the sensitivity of the resul ts obtained during simulated transthoracic defibrillation to variation s in skeletal muscle anisotropy and differing degrees of model inhomog eneity. Our results suggest that the myocardial current density distri bution is not particularly sensitive to the method used to model skele tal muscle anisotropy. However, anisotropy variations caused defibrill ation parameters such as paddle to paddle impedance and threshold curr ent to change by as much as 50%. We found a greater sensitivity in the myocardial current density and the defibrillation parameters to varia tions in model inhomogeneity. The changes observed in both depended su bstantially on paddle placement. This sensitivity to paddle placement highlights the difficulty in predicting how a reduction in anatomical detail will affect the myocardial current density distribution. In gen eral, we found the defibrillation parameters to be more sensitive than the myocardial current density distribution to the variations in anat omical detail we examined.