The Role of Vortical Structures and Axial Pressure Gradients in Promoting Atheroprotective Wall-Shear-Stress Distributions in Carotid Artery Models

Pathological blood flow-induced shear stress is associated with atherosclerosis, a cardiovascular disease that is a leading cause of deaths in the US. Physiological inflow CFD simulations are used to investigate three-dimensional vortical structures and their influence on pro-atherogenic stress distributions in two carotid artery bifurcation models – one healthy and one representative of a pre-disposed anatomy prone to develop atherosclerosis. Primary vortical structures were found in the internal carotid artery (ICA) sinus for both models, which significantly impact the wall-shear-stress distributions. However, the vortical structures were different in the two geometries in terms of time of formation in the cardiac cycle, downstream evolution, and lifespan. Additionally, differences in mass flow rate and pressure gradient within the ICA sinus were found. We hypothesize that the axial static pressure gradients are responsible for the observed different behavior of the vortical structure in the two cases. Thus, a fundamental study on vortex ring formation and evolution in the presence of static pressure gradients in radially confined spaces was conducted to further investigate pressure gradient effects.