A computer simulation study of the effects on the body surface potentials with an anisotropic myocardia heart model

A computeried visual heart model is developed based on anisotropic myocardia and inhomogenous torso. Using this model, we can observe how the distributions of body surface potential are influenced by three primary facts: anisotropic myocardia, inhomogenous torso, and different individual figures. This paper focuses on the first fact. The anistropic myocardia heart model with 53 dipoles includes atria, ventricles, and a special conduction system. The ventricles consist of myocardia which form fiber-like structures. The orientations of myocardia fiber rotate counterclockwise from the epicardial layer to the endocardial layer for a total rotation of 90 degrees. Since the rotation angle is different at each point, the fiber directions of model cells also vary spatially. The propagation of excitation is an ellipsoidal wavelet centered at the exciting model cell. The long semiaxis of the wavelet is along the fiber direction with higher conductive velocity, and the other two short semiaxes are along the transversal directions with lower conductive velocities. Thus, an algorithm is developed to calculate the excitation sequence of the heart Based on the excitation sequence of the heart, the body surface potential can be calculated. The results of comparative simulation of excitation, BSPM, VCG, and ECG with isotropic and anisotropic heart model show that the anisotropic myocardia influence the distributions of body surface potential in some degree. The influences can be observed by BSPM and VCG, respectively, but no significant differences can be seen by EGG.