Blood flow and vessel mechanics in a physiologically realistic model of a human carotid arterial bifurcation

The pulsatile flow in an anatomically realistic compliant human carotid bif urcation was simulated numerically. Pressure and mass flow waveforms in the carotid arteries were obtained from an individual subject using non-invasi ve techniques. The geometry of the computational model was reconstructed fr om magnetic resonance angiograms. Maps of time-average wall shear stress, c ontours of velocity in the flow field as well as wall movement and tensile stress on the arterial wall are all presented. Inconsistent with previous f indings from idealised geometry models, flow in the carotid sinus is domina ted by a strong helical flow accompanied by a single secondary vortex motio n. This type of flow is induced primarily by the asymmetry and curvature of the in vivo geometry. Flow simulations have been carried out under the rig id wall assumption and for the compliant wall, respectively. Comparison of the results demonstrates the quantitative influence of the vessel wall moti on. Generally there is a reduction in the magnitude of wall shear stress, w ith its degree depending on location and phase of the cardiac cycle. The re gion of slow or reversed flow was greater, in both spatial and temporal ter ms in the compliant model, but the global. characteristics of the flow and stress patterns remain unchanged. The analysis of mechanical stresses on th e vessel surface shows a complicated stress field. Stress concentration occ urs at both the anterior and posterior aspects of the proximal internal bul b. These are also regions of low wall shear stress. The comparison of compu ted and measured wall movement generally shows good agreement. (C) 2000 Els evier Science Ltd. All rights reserved.