The influence of cardiac trabeculae on ventricular mechanics

Cardiac trabeculae are cylindrical structures arranged in a complex shape which cover the endocardial surfaces of ventricles. The trabeculae consist of axially arranged cardiac fibers and represent a significant percentage of the ventricular mass (from 12% to 17%). The aim of the project is to study the influence of the trabecular mass on heart performances. A finite-element model of the left ventricle was developed. To compare different models (with or without trabecular structures) the ventricle was simplified as a truncated ellipsoid and the trabeculae, if present, as cylindrical strands oriented along the ventricular axis direction laying onto the endocardium. The total muscular mass and the intraventricular volume were kept constant in all the models. To model the mechanical behavior of the cardiac tissue, the Holzapfel constitutive relation was chosen. Cardiac fibers were oriented helically in the compact ventricular wall and axially in the trabeculae. Physiologic atrial pressure was set during the ventricular filling phase, while an adequate RCR model was connected downstream the ventricle to simulate the systemic circulation. The results show a significant role of trabeculae on ventricular behavior: the presence of trabecular mass contributes to the ventricular filling, allowing a higher ventricular stroke volume at the same atrial pressure.