Fluid mechanics and mass transport analysis in stenosed carotid arteries

The fluid dynamics distal to a stenosis in vivo, and its effect on mass transport of LDL and oxygen were analyzed through a computational simulation. The in vivo carotid artery stenosis was created by denuding the arterial intimal surface in a Yucatan miniswine atheroma model. The animals were then fed high cholesterol diet. After 8 weeks, images of the atheroma forming arterial segments were obtained using intravascular ultrasound (IVUS) and reconstructed into a three-dimensional mesh. The computational model included unsteady flow analysis with time varying inflow velocity and with the measured distensibility specified as boundary conditions, as well as LDL and oxygen transport analysis. The results indicated flow separation and reattachment distal to the stenosis. Mean wall shear stress was the highest at the stenosis throat and became negative at the flow re-circulation zone. In the high wall shear stress regions LDL accumulation was reduced while oxygen transport was increased. In the low wall shear regions, the reduced arterial flows enhanced LDL accumulation but at the same time decreased the oxygen concentration. The analysis indicated that regions distal to the stenosis with oxygen deprivation and enhanced LDL accumulation in low wall shear regions may result in further growth of atheroma.