Three-dimensional active bidomain model for bipolar stimulation

A 3D bidomain model with cardiac membrane dynamics was built to analyze excitation and propagation of electrical activity caused by a pacing stimulus. The objective of this study is to investigate the effect of orientation of a bipolar electrode and tissue fibers on pacing thresholds (PT) and propagation patterns, as well as the differences in results obtained by using two membrane models: Fitzhugh-Nagumo (FHN) and Luo-Rudy phase I (LRI). The results show that a 3D bidomain model with LRI kinetics allows simulation of realistic pacing stimuli and the simulations produce reasonable estimates of pacing threshold and conduction velocity. The pacing threshold with a vertical bipolar electrode is higher than with a horizontal bipole with either LRI of FHN.