Sensitivity study of fiber orientation on stroke volume in the human left ventricle

Orientations of myocytes impact electric excitation propagation and mechanical contraction in the human heart. Measured fiber angles in experiments are obtained from different species (e. g. rat, canine, dog, human heart) and vary by various reasons. It is unclear to what extent non-exact fiber angles impact the quality of computational simulations. In this paper, mechanical simulations with different ventricular angles were performed and compared. The simulations covered the complete heart with both ventricles, both atria and the pericardium and were performed using finite element method. Helix angles were varied between 20° and 70° on endocardium and -70° and -20° on epicardium. Results showed that fiber orientations had only a minor contribution to the difference between endsystolic and enddiastolic pressure of <; 8.3%. The influence on stroke volume as well as AVPD is significant (changes by 34% for SV and 241% for APVD), but it could not be observed that a higher AVPD yields a higher stroke volume. Concludingly, fiber orientations are important for reliable computational simulations of human hearts and should be incorporated with great care.