Abstract:

Background: Recent studies have demonstrated major variations in carotid bifurcation geometry, in favor of the concept that individual vascular anatomy may play a role in the development of atherosclerosis. To test these assumptions, the present study aimed to investigate the impact of wide variations on carotid artery hemodynamics by computational fluid dynamic (CFD) simulations.

Method: In the present work, six groups of three-dimensional synthetic models of carotid bifurcation with different morphological parameters were established by ANSYS. The geometric variations included internal carotid artery（ICA）/common carotid artery (CCA) diameter ratio, sinus/CCA diameter ratio, external carotid artery (ECA)/CCA diameter ratio, ICA angle, tortuosity and planarity. Pulsatile blood flow through a model of the carotid artery bifurcation was simulated using a finite volume numerical method. The changes of inlet velocity during the cardiac cycle were taken into consideration while outlet pressure was a constant value. The simulated results were visualized in TECPLOT for subsequent analysis.

Result: The temporal average value of wall shear stress (AWSS) on the sinus wall was obtained from the hemodynamic simulations. Multiple regression analysis revealed a significant (P<0.001) relationship between AWSS and both ICA angle (=0.48) and sinus/CCA diameter ratio (=0.48). Larger ICA angles generally increase the AWSS on the sinus wall, hence lowering the risk of plaque build-up. In contrast, high sinus/CCA diameter ratio was found to decrease AWSS on the sinus for geometries with the baseline ICA angle.

Conclusion: Compared to benchmark model, the changes of carotid bifurcation geometry can lead to apparent differences in hemodynamics. It may therefore be reasonable to consider certain geometric features to be surrogate markers of low AWSS, which is mainly related to atherosclerotic formation.

Keywords: Atherosclerosis, Hemodynamics, Carotid Bifurcation, Wall Shear Stress.