Qiu Y, Tarbell J M
Department of Chemical Engineering, Pennsylvania State University, University Park 16802, USA.
J Biomech Eng. 2000 Feb;122(1):77-85. doi: 10.1115/1.429629.
The endothelial cells (ECs) lining a blood vessel wall are exposed to both the wall shear stress (WSS) of blood flow and the circumferential strain (CS) of pulsing artery wall motion. These two forces and their interaction are believed to play a role in determining remodeling of the vessel wall and development of arterial disease (atherosclerosis). This study focused on the WSS and CS dynamic behavior in a compliant model of a coronary artery taking into account the curvature of the bending artery and physiological radial wall motion. A three-dimensional finite element model with transient flow and moving boundaries was set up to simulate pulsatile flow with physiological pressure and flow wave forms characteristic of the coronary arteries. The characteristic coronary artery curvature and flow conditions applied to the simulation were: aspect ratio (lambda) = 10, diameter variation (DV) = 6 percent, mean Reynolds number (Re) = 150, and unsteadiness parameter (alpha) = 3. The results show that mean WSS is about 50 percent lower on the inside wall than the outside wall while WSS oscillation is stronger on the inside wall. The stress phase angle (SPA) between CS and WSS, which characterizes the dynamics of the mechanical force pattern applied to the endothelial cell layer, shows that CS and WSS are more out of phase in the coronaries than in any other region of the circulation (-220 deg on the outside wall, -250 deg on the inside wall). This suggests that in addition to WSS, SPA may play a role in localization of coronary atherosclerosis.
血管壁内衬的内皮细胞（ECs）既受到血流的壁面剪切应力（WSS），也受到脉动动脉壁运动的周向应变（CS）。这两种力及其相互作用被认为在决定血管壁重塑和动脉疾病（动脉粥样硬化）的发展中起作用。本研究聚焦于考虑弯曲动脉曲率和生理径向壁运动的冠状动脉顺应性模型中的WSS和CS动态行为。建立了一个具有瞬态流动和移动边界的三维有限元模型，以模拟具有冠状动脉特征性生理压力和血流波形的脉动血流。应用于模拟的特征性冠状动脉曲率和血流条件为：纵横比（λ）=10，直径变化（DV）=6%，平均雷诺数（Re）=150，非定常参数（α）=3。结果表明，内壁的平均WSS比外壁低约50%，而内壁的WSS振荡更强。CS和WSS之间的应力相角（SPA）表征了施加在内皮细胞层上的机械力模式的动态特性，表明冠状动脉中CS和WSS的相位差比循环中任何其他区域都更大（外壁为-220°，内壁为-250°）。这表明除了WSS之外，SPA可能在冠状动脉粥样硬化的定位中起作用。
