Soulis Johannes V, Giannoglou George D, Chatzizisis Yiannis S, Farmakis Thomas M, Giannakoulas George A, Parcharidis George E, Louridas George E
Fluid Mechanics Division, School of Engineering, Democrition University of Thrace, Xanthi, Greece.
Coron Artery Dis. 2006 May;17(4):351-8. doi: 10.1097/00019501-200606000-00005.
To investigate the wall shear stress oscillation in a normal human left coronary artery bifurcation computational model by applying non-Newtonian blood properties and phasic flow.
The three-dimensional geometry of the investigated model included the left main coronary artery along with its two main branches, namely the left anterior descending and the left circumflex artery. For the computational analyses a pulsatile non-Newtonian flow was applied. To evaluate the cyclic variations in wall shear stress, six characteristic time-points of the cardiac cycle were selected. The non-Newtonian wall shear stress variation was compared with the Newtonian one.
The wall shear stress varied remarkably in time and space. The flow divider region encountered higher wall shear stress values than the lateral walls throughout the entire cardiac cycle. The wall shear stress exhibited remarkably lower and oscillatory values in systole as compared with that in diastole in the entire bifurcation region, especially in the lateral walls. Although the Newtonian wall shear stress experienced consistently lower values throughout the entire cardiac cycle than the non-Newtonian wall shear stress, the general pattern of lower wall shear stress values at the lateral walls, particularly during systole, was evident regardless of the blood properties.
The lateral walls of the bifurcation, where low and oscillating wall shear stress is observed, are more susceptible to atherosclerosis. The systolic period, rather than the diastolic one, favors the development and progression of atherosclerosis. The blood viscosity properties do not seem to qualitatively affect the spatial and temporal distribution of the wall shear stress.
通过应用非牛顿血液特性和搏动血流，研究正常人体左冠状动脉分叉处计算模型中的壁面剪应力振荡。
所研究模型的三维几何结构包括左冠状动脉主干及其两个主要分支，即左前降支和左旋支动脉。计算分析采用搏动性非牛顿血流。为评估壁面剪应力的周期性变化，选取了心动周期的六个特征时间点。将非牛顿壁面剪应力变化与牛顿壁面剪应力变化进行比较。
壁面剪应力在时间和空间上有显著变化。在整个心动周期中，分流区域的壁面剪应力值高于侧壁。与整个分叉区域舒张期相比，收缩期壁面剪应力值明显更低且呈振荡性，尤其是在侧壁。尽管在整个心动周期中牛顿壁面剪应力值始终低于非牛顿壁面剪应力值，但无论血液特性如何，侧壁壁面剪应力值较低的总体模式都很明显，尤其是在收缩期。
观察到壁面剪应力较低且呈振荡性的分叉侧壁更容易发生动脉粥样硬化。动脉粥样硬化的发生和发展更倾向于收缩期而非舒张期。血液黏度特性似乎并未定性地影响壁面剪应力的时空分布。
