心肌桥壁冠状动脉血液动力学数值模拟

Numerical simulation for hemodynamics of the myocardial bridging parietal coronary artery

目的数值模拟心肌桥壁冠状动脉血液动力学,探索心肌桥壁冠状动脉近心端易发生动脉粥样硬化的血液动力学机理。方法建立随心搏运动的局部狭窄直圆管模型模拟心肌桥壁冠状动脉形态学,管壁为薄壁线弹性体,血流遵循不可压缩牛顿流体的一维管流方程组,用Lax-Wendroff方法数值求解。结果心肌桥壁冠状动脉血液动力学与正常冠状动脉血液动力学相比有很大差异,血流量#壁切应力和壁切应力梯度均不同。在心肌桥壁冠状动脉中,近心端壁切应力及壁切应力梯度的变化要远大于远心端。对于有两段心肌桥的情况,它们的壁切应力和壁切应力梯度变化趋势基本一致,但距心室较远的心肌桥,其壁切应力和壁切应力梯度要大于靠近心室的那段心肌桥,且随时间的变化程度也更剧烈。结论数值模拟结果表明,心肌桥壁冠状动脉血液动力学不同于正常冠状动脉血液动力学,近心端壁切应力及壁切应力梯度的变化要远大于远心端,从而对动脉管内皮细胞产生重要影响,这可能是心肌桥壁冠状动脉近心端易发生动脉粥样硬化的血液动力学机理。

Objective To numerically simulate the blood flow in myocardial bridging parietal coronary artery and investigate the hemodynamics mechanism of the fact that atherosclerosis is more likely to occur in proximal seg- ment of the parietal coronary artery. Methods The model, a straight tube with local stenosis which moved along with heart beating being used in order to simulate the morphology of myocardial bridging parietal coronary artery, was established. The wall of the tube was assumed as a thin wall linear elastomer, and the blood flow was as- sumed as a series of one-dimensional flow equations following incompressible Newtonian fluid. The Lax-Wendroff method was also adopted to solve the governing equations numerically. Results There were significant differ- ences in blood flow, wall shear stress and wall shear stress gradient between parietal coronary artery and normal coronary artery. For parietal coronary artery, the changes of wall shear stress and wall shear stress gradient were more dramatic in proximal segment than those in distal segment. As for two myocardial bridgings in one cor- onary artery, the trend of the wall shear stress and wall shear stress gradient was essentially the same, but the wall shear stress and wall shear stress gradient in myocardial bridging far from the ventricle were larger than those in myocardial bridging near the ventricle, with a more dramatic change along the time during one cardiac cycle. Conclusions Simulation results indicate that hemodynamics of parietal coronary artery is different from that of normal coronary artery. Changes of wall shear stress and wall shear stress gradient are more dramatic in proxi- mal segment than those in distal segment, thus having an important impact on the local endothelial cells. It miqhtbe the hemodynamic mechanism of the fact that atherosclerosis is more likely to be developed in proximal seg- ment of parietal coronary artery.