Simulation of anisotropic propagation in the myocardium with a hybrid bidomain model

We describe simulations of propagated electrical excitation in threedimensional anisotropic myocardial muscle. According to the bidomain theory, anisotropic electrical conductivities are presented as tensors in the intracellular and interstitial domains (D_i and D_e, respectively). Under the assumption of equal anisotropy ratio (D_i = kD_e), subthreshold behaviour of the excitable elements is governed by a parabolic reaction-diffusion equation for the membrane potential, solvable even on a desktop computer. In the case of more general anisotropies (D_i ≠ kD_e), also the interstitial potential needs to be solved simultaneously from an elliptic partial differential equation, requiring a supercomputer for large arrays of excitable elements. In both cases, the elements obey cellular automata rules in the suprathreshold state.We present preliminary results of the propagated excitation for different anisotropy ratios in a three-dimensional slab geometry.