REENTRY 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 w ere 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 resultin g from different types of sources and geometrical obstructions, includ ing point stimuli at the apex and three-dimensional re-entrant behavio r resulting from single or multiple re-entrant sources. We found that: re-entrant pattern from scroll wave activity can generate collision a reas on the epicardium, and it can generate apparent point (focal) sou rces due to tissue anisotropy: the filaments (organizing centers) for re-entrant patterns can be maintained entirely within the myocardial w all, having a surface pattern similar to those from a point (focal) so urce and no surface expression of its re-entrant nature.