De brillation in models of cardiac muscle

The propagation of electrical activity in cardiac tissue can be modelled by reaction diiusion equations, where a tensor of diiusion coeecients represents anisotropy due to bre orientation, and excitation is represented by high order, stii diierential systems. The eeects of external electrical stimulation, as in artiical pacemakers, or in deebrillators, requires bidomain models, in which intra-and ex-tracellular currents are treated separately. Simpliied approaches are taken to this problem to illustrate two methods of deebrillation; by a single large pulse, that eliminates all propagating activity, and by a series of smaller amplitude perturbations, that drive out re-entrant sources of excitation. Figure 1.1: Frames from a movie illustrating the irregular pattern of propagation in the canine ventricles during brillation