Patient based computational fluid dynamic characterization of carotid bifurcation stenosis before and after endovascular revascularization.

INTRODUCTION: Hemodynamic forces play a critical role in determining the molecular phenotype of the endothelial cell and in influencing vascular remodeling. A lesion based computational fluid dynamic (CFD) modeling approach is presented to understand the complex spatial and temporal hemodynamic changes that prevail in carotid stenosis (CS) in patients with critical CS undergoing carotid artery stenting (CAS).
METHODS: High resolution three-dimensional rotational angiography volumetric datasets were acquired before and after treatment in eight patients, segmented and used to generate a high quality structured hexahedral computational mesh with boundary layer refinement. CFD analysis was carried out using a time dependent laminar flow model implementing non-Newtonian realistic blood viscosity for blood, and used to compute wall shear stress (WSS) and its gradient (WSSG).
RESULTS: CAS restored fully or near laminar flow in all cases in our series. In addition, WSS was found to decrease in the stented region in all cases, reduced to near normal levels of 34±14 dyn/cm(2) with significant blunting of the extreme pretreatment WSSG to levels lower than 1000 dyn/cm(3).
CONCLUSIONS: In this series of patients with symptomatic CS, CFD simulation enabled estimation of the hemodynamic effect of CAS, leading to reversal of abnormal flow patterns and wall shear forces around the arterial stenosis, with normalization of flow laminarity and wall shear spatiotempotal patterns known to be associated with adverse endothelial cell function.