An assessment of variable thickness and fiber orientation of the skeletal muscle layer on electrocardiographic calculations

A realistic model of a canine torso which includes extensive detail about skeletal muscle layer thickness and fiber orientation is compared with two other uniformly anisotropic models. A transfer coefficient is developed which relates torso potentials to epicardial potentials for a given anisotropic skeletal muscle layer thickness and muscle fiber orientation. The transfer coefficient is valid for any set of measured epicardial potentials and is independent of the conductivity of the heart. Transfer coefficients calculated for different thicknesses and muscle fiber orientations of the skeletal muscle layer are used to compute torso potentials directly from measured epicardial potentials. A comparison of the measured torso potentials with the potentials calculated from the different transfer coefficients indicates the effectiveness of including variations in fiber orientation and in thickness of the skeletal muscle layer in the model.