Myers J G, Moore J A, Ojha M, Johnston K W, Ethier C R
Department of Mechanical and Industrial Engineering, University of Toronto, Ontario, Canada.
Ann Biomed Eng. 2001 Feb;29(2):109-20. doi: 10.1114/1.1349703.
Evidence suggests that atherogenesis is linked to local hemodynamic factors such as wall shear stress. We investigated the velocity and wall shear stress patterns within a human right coronary artery (RCA), an important site of atherosclerotic lesion development. Emphasis was placed on evaluating the effect of flow waveform and inlet flow velocity profile on the hemodynamics in the proximal, medial, and distal arterial regions. Using the finite-element method, velocity and wall shear stress patterns in a rigid, anatomically realistic model of a human RCA were computed. Steady flow simulations (ReD=500) were performed with three different inlet velocity profiles; pulsatile flow simulations utilized two different flow waveforms (both with Womersley parameter=1.82, mean ReD=233), as well as two of the three inlet profiles. Velocity profiles showed Dean-like secondary flow features that were remarkably sensitive to the local curvature of the RCA model. Particularly noteworthy was the "rotation" of these Dean-like profiles, which produced large local variations in wall shear stress along the sidewalls of the RCA model. Changes in the inlet velocity profiles did not produce significant changes in the arterial velocity and wall shear stress patterns. Pulsatile flow simulations exhibited remarkably similar cycle-average wall shear stress distributions regardless of waveform and inlet velocity profile. The oscillatory shear index was very small and was attributed to flow reversal in the waveform, rather than separation. Cumulatively, these results illustrate that geometric effects (particularly local three-dimensional curvature) dominate RCA hemodynamics, implying that studies attempting to link hemodynamics with atherogenesis should replicate the patient-specific RCA geometry.
有证据表明，动脉粥样硬化的形成与局部血流动力学因素有关，如壁面剪应力。我们研究了人类右冠状动脉（RCA）内的速度和壁面剪应力模式，RCA是动脉粥样硬化病变发展的一个重要部位。重点在于评估血流波形和入口流速剖面（速度分布图）对动脉近端、中段和远端区域血流动力学的影响。使用有限元方法，计算了一个刚性的、符合人体解剖学实际的RCA模型中的速度和壁面剪应力模式。采用三种不同的入口流速剖面进行了稳态流动模拟（雷诺数ReD = 500）；脉动流模拟使用了两种不同的血流波形（两者的沃默斯利参数均为1.82，平均雷诺数ReD = 233），以及三种入口剖面中的两种。速度剖面显示出类似迪恩流的二次流特征，这些特征对RCA模型的局部曲率非常敏感。特别值得注意的是这些类似迪恩流剖面的“旋转”，这在RCA模型侧壁上产生了壁面剪应力的大幅局部变化。入口流速剖面的变化并未在动脉速度和壁面剪应力模式中产生显著变化。无论波形和入口流速剖面如何，脉动流模拟都呈现出非常相似的周期平均壁面剪应力分布。振荡剪切指数非常小，这归因于波形中的血流逆转，而非分离。总的来说，这些结果表明几何效应（特别是局部三维曲率）主导了RCA的血流动力学，这意味着试图将血流动力学与动脉粥样硬化形成联系起来的研究应复制患者特异性的RCA几何形状。
