心肌桥对冠状动脉内皮细胞形态和粥样硬化的作用

目的 观察壁冠状动脉及其近段内皮细胞形态和内皮下组织特征，探讨心肌桥导致的血流动力学变化对动脉粥样硬化形成的影响。方法 用肝素-生理盐水和4％戊二醛溶液冲洗4例有心肌桥的新鲜人尸左冠状动脉，取壁冠状动脉近段、壁冠状动脉段、壁冠状动脉远段，扫描电镜观察其血管内皮细胞和基膜特征。结果 冠状动脉近段内皮细胞多呈扁平状或卵圆形，表面粗糙，有“虫啄样”缺损，细胞容易脱落。壁冠状动脉内皮细胞呈细长梭形，表面可有微绒毛和桥样结构，壁冠状动脉内皮细胞的形态指数低于其近段和远段的形态指数。结论 壁冠状动脉内皮细胞受到心肌桥压迫导致血流切变力增高产生适应性反应，对内皮细胞有保护作用，而其近段内皮细胞由于切变力较低容易被损伤，成为动脉粥样硬化发生的基础。

The effect of myocardial bridge on endothelial cell shape and formation of atherosclerosis in the coronary artery

Objective To assess the effect of myocardial bridge on the endothelial cell and formation of atherosclerosis in the coronary artery. Methods The shape of endothelial cell and status of atherosclerosis in 4 segments of mural coronary artery and their proximal portion were observed with a scanning electron microscope. Result The shape of endothelial cells of the section proximal to mural coronary artery was flat or ellipse with rough and defected surface and likely to be exfoliated. The exposed surface of the base membrane was irregular and rough. The base membrane of the mural coronary artery was covered completely by the long and fusiform endothelial cells with microvilli. The endothelial cell shape index in the mural coronary artery was lower than that in proximal and distal segments (P<0.01). Conclusion The endothelial cell of the mural coronary artery is free from atherosclerosis due to higher shear stress caused by myocardial bridge. The intima of the section proximal to mural coronary artery was likely to be sclerosed due to the lower and oscillatory shear force.