Numerical simulation of intra and extracellular electric fields in a tridimensional anisotropic model of cardiac muscle

A study is made of how cardiac tissue responds to externally applied currents. The bidomain model is extended to a three dimensional block of myocardium which is represented by a set of plane layers of parallel fibers with direction rotating from endocardium to epicardium. The problem is mathematically expressed by a system of partial differential equations Lu = f, where L is the elliptic operator related to the tensor of anisotropic conductivity, u is the vector of intra and extracellular potentials, and f represents the vector of currents injected in the intra and extracellular domain, respectively. The finite element method is used to approximate the solution by piecewise trilinear polynomials on a uniform grid. Numerical results are obtained for different kinds of current injections.