Fluid Mechanics Division, Faculty of Engineering, Demokrition University of Thrace, Vas. Sofias 12, 67100 Xanthi, Greece.
Med Eng Phys. 2010 Oct;32(8):867-77. doi: 10.1016/j.medengphy.2010.05.011. Epub 2010 Jul 2.
The blood flow and transportation of molecules in the cardiovascular system plays crucial role in the genesis and progression of atherosclerosis. Atherosclerosis shows predilection in regions of the arterial tree with hemodynamic particularities, as local disturbances of wall shear stress in space, and locally high concentrations of lipoprotein. A semi-permeable nature of the arterial wall computational model is incorporated with hydraulic conductivity and permeability treated as wall shear stress dependent. Six image-based human diseased right coronary arteries (RCA) are used to elucidate the low-density lipoprotein (LDL) transport. The 3D reconstruction technique is a combination of angiography and IVUS. The numerical simulation couples the flow equations with the transport equation applying realistic boundary conditions at the wall. The coupling of fluid dynamics and solute dynamics at the endothelium is achieved by the Kedem-Katchalsky equation (water infiltration). The luminal surface LDL concentration at the arterial wall is flow-dependent with local variations due to geometric features. The relationship between WSS and luminal surface concentration of LDL indicates that LDL is elevated at locations where WSS is low. There is medium correlation (Pearson) between low WSS and high LDL. The degree of elevation in luminal surface LDL concentration is mostly affected by the water infiltration velocity at the vessel wall. Under constant water infiltration the shear dependent endothelial permeability effects, in comparison to those using constant value, are marginal. Area-averaged normalized LDL concentration over the RCAs, using constant water infiltration and endothelial permeability is 3.6% higher than that at the entrance. Area-averaged normalized LDL concentration over the RCAs, using shear dependent water infiltration and endothelial permeability is 9.6%. Perspective computational fluid dynamics users, incorporating mass transfer (LDL) within the blood flow, are forced to treat the problem using shear dependent endothelial values.
心血管系统中的血液流动和分子运输在动脉粥样硬化的发生和发展中起着至关重要的作用。动脉粥样硬化在动脉树中具有血液动力学特性的区域表现出偏好，因为局部壁面切应力的空间干扰以及脂蛋白的局部高浓度。动脉壁的半渗透性质的计算模型与水力传导率和渗透率相结合，将其视为壁面切应力相关。使用六个基于图像的人类病变右冠状动脉（RCA）来阐明低密度脂蛋白（LDL）的运输。3D 重建技术是血管造影和 IVUS 的结合。数值模拟将流动方程与运输方程相结合，在壁面应用实际边界条件。通过 Kedem-Katchalsky 方程（水渗透）在流体内动力学和溶质动力学之间实现耦合。由于几何特征，在动脉壁处，腔内表面 LDL 浓度与流动相关，并且存在局部变化。WSS 与腔内表面 LDL 浓度之间的关系表明，LDL 在 WSS 低的位置升高。低 WSS 与高 LDL 之间存在中度相关性（Pearson）。腔内表面 LDL 浓度的升高程度主要受血管壁上水渗透速度的影响。在恒定水渗透下，与使用恒定值相比，剪切依赖性内皮通透性的影响微不足道。使用恒定水渗透和内皮通透性，RCA 上的平均归一化 LDL 浓度比入口处高 3.6%。使用剪切依赖性水渗透和内皮通透性，RCA 上的平均归一化 LDL 浓度为 9.6%。将质量传递（LDL）纳入血流中的计算流体动力学的用户，被迫使用剪切依赖性内皮值来处理该问题。
