Re-entry in an anatomical model of the heart

We have developed an electrophysiological computer model of the intact right and left ventricles of a canine heart using anatomical data of geometry and fiber orientation. The dynamics of the excitable tissue were represented using a FitzHugh-Nagumo model, with a diffusion matrix chosen to account for tissue anisotropy and fiber orientation. In our numerical experiments we simulated wave propagation patterns resulting from different types of sources and geometrical obstructions, including point stimuli at the apex and three-dimensional re-entrant behavior resulting from single or multiple re-entrant sources. We found that: re-entrant pattern from scroll wave activity can generate collision areas on the epicardium, and it can generate apparent point (focal) sources due to tissue anisotropy: the filaments (organizing centers) for re-entrant patterns can be maintained entirely within the myocardial wall, having a surface pattern similar to those from a point (focal) source and no surface expression of its re-entrant nature.