Effect of fibre orientation on diastolic mechanics of human ventricle

Fibre orientation of myocardial wall plays a significant role in ventricular wall stress, which is assumed to be responsible for many cardiac mechanics, including ventricular remodelling, associated with heart failure. Previous studies, conducted to identify the effects of fibre orientation on left -ventricle (LV) diastolic mechanics, used only animal´s myocardium properties (no human data) and therefore, may not apply for predicting human cardiac mechanics. In the present study, computational modelling of LV diastole was carried out to investigate the effects of fibre orientation on LV end diastolic pressure volume relation (EDPVR) and wall stress distribution using subject-specific in vivo passive properties of human myocardium for two human hearts. Results indicated that LV inflation increased when fibres were aligned more towards LV longitudinal axis and the effect was more notable when the fibre angle was higher in endocardium than epicardium wall. Changes in fibre angle distribution considerably altered fibre stress distribution of LV wall and the changes were significant in anterior and lateral regions of equatorial and apical locations. Furthermore, the regions of high fibre stress from midwall to endocardium were gradually confined towards endocardium with the decrease in fibre angle. Such information will be useful for future studies/diagnoses of LV mechanics in normal and pathological conditions.