A dynamic model for cardiac defibrillation

A detailed two-dimensional (2-D) finite element model (FEM) for the electroconductive anatomy of a human thorax was formulated to investigate the unsteady diffusion of the electromagnetic field that occurs during defibrillation. An equivalent electric circuit simulating a defibrillator is solved to generate the analytic form of the defibrillation current, that is further used as input (boundary condition) to the field problem. Specific insights in the defibrillation process, not apparent through an electrokinetic analysis, such as dynamic patterns of current density that irrigates the heart and the important role played in the diffusion process by chest wall, intercostal muscles and interstitial fluid, were evidenced. Our results lead to a deeper understanding of the anatomic structure response to defibrillation and suggest that a different approach to its optimization may be needed