Effects of Fibre Orientation on Electrocardiographic and Mechanical Functions in a Computational Human Biventricular Model

The helix orientated fibres in the ventricular wall modulate the cardiac electromechanical functions. Experimental data of the helix angle through the ventricular wall have been reported from histological and image-based methods, exhibiting large variability. It is, however, still unclear how this variability influences electrocardiographic characteristics and mechanical functions of human hearts, as characterized through computer simulations. This paper investigates the effects of the range and transmural gradient of the helix angle on electrocardiogram, pressure-volume loops, circumferential contraction, wall thickening, longitudinal shortening and twist, by using state-of-the-art computational human biventricular modelling and simulation. Five models of the helix angle are considered based on in vivo diffusion tensor magnetic resonance imaging data. We found that both electrocardiographic and mechanical biomarkers are influenced by these two factors, through the mechanism of regulating the proportion of circumferentially-orientated fibres. With the increase in this proportion, the T-wave amplitude decreases, circumferential contraction and twist increase while longitudinal shortening decreases.