The critical radius of stimulation electrode related to heart activation

This article examines the dependence of stimulation current threshold on stimulation electrode radius and other cardiac tissue parameters. The dependence was evaluated on a homogeneous slab model of the heart wall, with local membrane properties determined by modified FitzHugh-Nagumo model. Simulation results reveal that stimulation current density threshold depends proportionally on diffusivity related to tissue conductivity and on membrane excitation threshold. It is also inversely proportional to stimulation electrode radius. The critical radius of the stimulation electrode for the given model parameters estimated to be 0.8 mm was compared with simulation results. Stimulation electrodes with smaller radius are ineffective in eliciting excitation in the cardiac tissue.