Refractory period variations and reentries: comparison between computer simulation and effects of antiarrhythmic drugs

Simulations of the propagation of a depolarizing wave through the ventricular wall, based on the Huygens construction method, are presented. The aim of this work is to study the influence of changes in the refractory period on the reentry process. Computer simulations of a decrease in the refractory period are made. Two effects occur, involving the spatial size and time periodicity of the cyclic reentry. It is shown that the spatial size of the reentrant area decreases with the refractory period. It is also shown that the time frequency of the reentry increases when the refractory period decreases. An increase in the refractory period which immediately stops the reentry was also simulated. It is shown that the wavefront of the periodic wave, always traveling at the same constant conduction velocity, encounters cells with longer refractory periods and thus can no longer propagate. It is concluded that critical size or wavelength is an important parameter. Any process which increases critical size has an antiarrhythmic effect. Contrariwise, any process which decreases critical size favors reentries and arrhythmias