Influence of Purkinje-muscle coupling on EAD development: a simulation study

Early after depolarizations (EADs) are irregularities that occur during the repolarization phase of the action potential (AP) interrupting or delaying normal repolarization. In this work, computer simulations have been used to study the influence of Purkinje-muscle coupling on EADs generated in Purkinje cells. The electrical behaviour of the ventricular (V) and Purkinje (P) cells have been simulated using the Luo-Rudy phase II model and the DiFrancesco-Noble equations, respectively. EADs were induced in the P cells by enhancing the Ca/sup 2+/ current through the L-type channels and partially blocking the delayed rectifying K/sup +/ current. The authors' results suggest that the P-V connection reduces the likelihood of appearance of EADs in Purkinje fibers (PFs). Moreover, when EADs occur in P cells, there is a range of coupling values that allows their propagation as APs to the V cells.