A computer modeling study of the relationship between intramural fiber rotation and the spatial distribution of repolarization properties in ventricular myocardium

Using a two dimensional computer model, we examined the effect of an abrupt, 90° intramural fiber rotation on the spatial distribution of repolarization properties. The model depicted a 7.2 mm×3.5 mm transmural slice of ventricular myocardium, with an isotropic region representing fiber orientation perpendicular to the plane of the slice and an uniformly anisotropic region representing fiber orientation parallel with the plane of the slice. Simulations used the Luo-Rudy membrane model equations to calculate transmembrane potentials. We found that stimulating a corner of the anisotropic region produces a uniform distribution of action potential duration (APD) over the entire sheet of myocardium, whereas stimulating a corner of the isotropic region produces a nonuniform distribution of APD. We conclude that, with certain stimuli, fiber rotation can create nonuniform spatial distributions of APD