Department of Mechanical Engineering, Isfahan University of Technology, Isfahan 8415683111, Iran.
J Biomech. 2011 Oct 13;44(15):2614-26. doi: 10.1016/j.jbiomech.2011.08.017. Epub 2011 Sep 8.
To study the effects of increase in the degree of stenosis severity and subsequent complexity of hemodynamic patterns on hemodynamic parameters, experimental investigations and numerical simulations were performed. The correlations between the large negative Stress Phase Angle (SPA), the low mean Wall Shear Stress (WSS) and high Oscillatory Shear Index (OSI) were investigated at the distal shoulder and post-stenotic regions as the outcomes of elevated stenosis severity. Models included non-Newtonian fluid flow in stenotic arteries with 30-80% symmetrical stenoses. To study the interactions between pulsatile WSS and pulsatile wall circumferential stress (WCS) acting on endothelial cells, SPA as the phase difference between WSS and WCS waves was used. Moreover, the distribution of SPA on the lumen axis was compared to the distributions of the mean WSS and OSI that have been regarded until now as the determinants of atherosclerosis-prone regions. Results indicate that an increase in stenosis severity, not only affects the mean WSS, mean WCS and pulse amplitudes, but also influences the phase difference between them. The SPA is large negative on the distal shoulder and post-stenotic areas where atherosclerotic plaque develops. The increasing stenosis severity and the subsequent increasing complexity of hemodynamic patterns affect the correlation between any of the low mean WSS and high OSI with large negative SPA, such that it not only leads to create and develop some regions where the correlation between any of the low mean WSS and high OSI with large negative SPA is well but also leads to create and develop other regions where such correlations fail.
为了研究狭窄严重程度增加以及随后血流动力学模式复杂性对血流动力学参数的影响，进行了实验研究和数值模拟。在远侧肩部和狭窄后区域，研究了大的负应力相位角（SPA）、低平均壁面切应力（WSS）和高脉动剪切指数（OSI）之间的相关性，作为狭窄严重程度升高的结果。模型包括狭窄动脉中的非牛顿流体流动，狭窄程度为 30-80%对称狭窄。为了研究作用于内皮细胞的脉动 WSS 和脉动壁周向应力（WCS）之间的相互作用，使用 SPA 作为 WSS 和 WCS 波之间的相位差。此外，还比较了 SPA 在管腔轴上的分布与平均 WSS 和 OSI 的分布，迄今为止，平均 WSS 和 OSI 被认为是动脉粥样硬化易患区域的决定因素。结果表明，狭窄严重程度的增加不仅会影响平均 WSS、平均 WCS 和脉冲幅度，还会影响它们之间的相位差。SPA 在远侧肩部和狭窄后区域为大负值，这些区域是动脉粥样硬化斑块发展的部位。狭窄严重程度的增加和随后血流动力学模式的复杂性增加会影响任何低平均 WSS 和高 OSI 与大负 SPA 之间的相关性，不仅会导致创建和发展一些区域，在这些区域中，任何低平均 WSS 和高 OSI 与大负 SPA 之间的相关性都很好，还会导致创建和发展其他区域，在这些区域中，这种相关性会失败。
