Simulation calculations of cardiac virtual cathode effects

The anisotropic bidomain model has been used to perform computer simulations of cardiac tissue stimulated externally. Virtual cathode distances, Rvc, are found to be affected by type of stimulation and the degree of conductance between the extracellular domain and the ground provided by, for example, a saline bath. For no such conductance, hyperpolarizing blocking regions develop in the longitudinal direction of propagation. These regions are much reduced by even a small conductance to ground. They do not occur for transmembrane stimulation. They result in much reduced Rvc sizes in the longitudinal direction even in the presence of some ground conductance, and negative Rvc values for no such conductance.