Computational fluid dynamic (CFD) methods can offer an additional important layer of functional information to enrich and complement the anatomical information. A link between atherogenesis and wall shear stress (WSS) forces, defined as the internal friction forces between the flowing blood and the vessel wall, has been proposed, suggesting that Inhibitors,research,lifescience,medical high shear stress could lead to both mechanical damage to the endothelial cells (ECs) and potential denudation (Fry 1968, 1969). Low and oscillatory shear stress promote monocyte
adhesion to the EC through the increased expression of vascular adhesion molecule-1 (VCAM-1), which bind integrins expressed on leukocytes and direct their Inhibitors,research,lifescience,medical firm adhesion to and entry into EC (Caro et al. 1971; Berger and Jou 2000). In contrast, atheroprotective flow activated Nrf2 and protected EC against oxidative stress injury (Dai et al. 2007). Vessel geometry and hemodynamic forces are major regulatory factors of normal and pathologic vessel wall Inhibitors,research,lifescience,medical function in arteries (Berger and Jou 2000). Most studies in this field have been carried out in carefully controlled in vitro experimental setups,
which do not reproduce the in vivo characteristics of blood flow through stenosed vessels. Although CFD analysis has been applied to theoretical stenoses, detailed simulations that predict the spatial and temporal pattern of WSS within actual patient-based stenotic lesions are scarce because of computational complexity (Thomas et al. 2003) and a lack of high-resolution spatial data describing the three-dimensional (3D) geometry of atherosclerotic vessels. Patients and Methods Eight patients Inhibitors,research,lifescience,medical (two female, median age 76 years) with symptomatic CS of the cervical carotid bifurcation recalcitrant to medical therapy were evaluated. Five lesions were located on the left side (63%). Three patients had ischemic Inhibitors,research,lifescience,medical symptoms at
the time of evaluation. The patients underwent catheter-based Resminostat digital-subtraction cerebral angiography in biplane and 3D rotational modes. Median degree of stenosis by ultrasonographic Doppler examinations performed in seven of eight patients was 95% and median angiographic stenosis was 88% by NASCET criteria (Nagel et al. 1991). A detailed description of the CFD methods has been previously described (Schirmer and Malek 2007a, b). Briefly the 3D volumetric datasets, reconstructed from rotational angiograms, were segmented and used to generate hybrid, predominantly hexahedral, meshes with refinement zones over the area of the carotid bifurcation and the internal carotid (ICA). Computations were carried out using RAD001 Fluent (Ver. 6.2.16, Fluent Inc, Lebanon, NH) on a cluster of parallel computers.