A Three-dimensional Boundary ElementModel Of The Electric Field From ImplantableDefibrillators

The delivery of high energy shocks from implantable defibrillators is largely influenced by the design and configuration of the delivery electrodes. To optimise electrode design and placement, a 3-D boundary element model of the electric field from implantable defibrillators was developed. The model used approximately 3500 constant quadrilateral elements, constructed from MRI scans, and consisted of eight isotropic regions that represented the chest, heart, left and right blood chambers and vessels, lungs, spine and sternum. Additional regions represented epicardial, endocardial and subcutaneous electrodes. The governing Laplace equation was solved to find potentials and gradients throughout the thorax. This paper discusses the implementation of the model and presents results that show differences in the electric field between an endocardial and epicardial electrode configuration.