Effects of severity and eccentricity of carotid stenosis on pulsatile blood flow

Pulsatile blood flow in a stenosed human carotid sinus was investigated numerically to study effects of stenotic severity and eccentricity. The inadequacy of "percent stenosis" alone in characterizing flow past a lesion has been pointed out, and this work shows that eccentricity is another important parameter to describe such flows more accurately. Increased importance of unsteady components in the velocity field was found with higher degrees of stenosis, along with strongly elevated wall shear stress at the stenosis and decreased mean flow through the bifurcation at very high stenotic constrictions. This work also indicates the importance of accurately accounting for distal vasodilation in predicting velocity through the stenosis. Stenosis eccentricity tends to amplify the effects of stenosis on the flow, in particular causing enlarged recirculation zones and elevated wall shear stresses on the outboard side of the internal carotid artery distal to the stenosis. Eccentricity is an important characteristic of a stenosis, and the evolution over time of axisymmetric and eccentric lesions of similar severity is likely to be significantly different.