Influence of myocardial anisotropy on global excitation sequence of the heart and body surface electrocardiogram: a simulation study

Myocardial anisotropy was incorporated into a three-dimensional heart model, which contained approximately 50,000 discrete units and was assigned with electrophysiologic parameters including action potential, conduction velocity, electric conductivity and others. The fiber orientation of the heart model was made to be different from layer to layer and to rotate 10 degrees per layer counterclockwise in increasing depth from epicardium to endocardium. The total rotation angle was 120 degrees. Anisotropic conduction velocity and electric conductivity were taken into account. The influence of myocardial anisotropy on the global excitation pattern of the heart and on the body surface potentials was investigated in a comparative study with isotropic and anisotropic models. The simulated results showed that incorporating myocardial anisotropy did not change the normality of an isotropic model for a normal heart. On the other hand, simulation of ventricular fibrillation with isotropic and anisotropic models showed that anisotropy may play an important role in forming reentry