Modified ionic models of cardiac tissue for efficient large scale computations.

Recirculation of excitation, or re-entry, is one of the most important mechanisms of life-threatening cardiac arrhythmias and fibrillation. Modelling these phenomena requires large scale computations in two and three-dimensional slabs of cardiac tissue. Because of computational constraints, most of the studies use simplified (non-ionic) models of cardiac tissue, which are electrophysiologically less accurate than the detailed ionic models. In this paper, we propose a method to modify ionic models of cardiac tissue into an intermediate class of models, which are almost as efficient for computations as simplified models, and retain most of the properties of the original ionic models, such as the shape of the action potential, the restitution of action potential duration and of the conduction velocity, as well as unchanged description of most of the ionic currents.