The influence of blood velocity and vessel geometric parameters on wall shear stress

•The degree of influence of blood flow velocity and basilar artery geometry parameters on wall shear stress is quantified.•Among all geometrical parameters and velocity assessed in this study, the proximal velocity at the vertebral-basilar bifurcation plane has the highest influence in the wall shear stress percentile profile.•Proximal velocity has a high influence on high wall shear stress percentiles, and average diameter has a high influence on low wall shear stress percentiles. The degree of influence is interchangeable.•Tortuosity of basilar artery only correlates with high wall shear stress percentile (the 97.5th percentile). Vascular geometry was proposed to be one risk factor of atherosclerosis (AS). When developing this hypothesis, the discussion of geometry-wall shear stress (WSS) has often been included. However, further exploration on how various geometric parameters were affecting WSS was needed. The purpose of this study was to investigate the influence degree of vessel geometric parameters and blood velocity on WSS. A computational fluid dynamics (CFD) analyses of the vertebral and basilar arteries (VA and BA, respectively) was used. Twenty patients with no plaques or vessel wall thickening at the VA and BA were included. CFD analyses using both specific vessel models and flow conditions measured by ultrasound Doppler were performed. Subsequently, CFD results were post-processed with multiple linear regression to investigate numerical correlations between geometrical and flow parameters and WSS. The results of the multiple linear regression analysis further demonstrated that the BA proximal velocity was the most influential factor positively influencing BA WSS. The lower the WSS was, the stronger the influence brought by BA average diameter would be. The regression demonstrated that the contributions brought by average diameter and proximal velocity in lower WSS regions were lower than that in higher WSS regions. Tortuosity was only positively correlated with 97.5th WSS percentile, and vessel length and curvature showed no correlation with WSS. This study quantified the influence degree of BA morphology and flow velocity on WSS, which may have practical implications for predicting hemodynamic risks.