Significance of myocardial bridge upon atherosclerosis in The LAD coronary artery

点击翻译按钮获取中文摘要

A part of the left anterior descending coronary artery running in the epicardial adipose tissue is often covered by myocardial tissue. This condition is designated as myocardial bridge (MB). We have previously noticed that the intima of the LAD covered by MB is never affected by atherosclerotic process. We investigate such protective effect of MB against atherosclerosis by immunohistochemical and electron microscopy. The intimal thickness beneath MB is remarkably thin in comparison with that before the entrance of MB and after the exit of MB. It consists of only few layers of smooth muscle cell with few collagen fibers and little matrix. All of the smooth muscle cells there show contractile form. In addition, not only there is no lipid deposition, but both types of foam cells derived from either macrophage or smooth muscle cells are absent. By scanning electron microscopy, the spindle-shaped endothelial cells are axially and regularly arranged along the course of the coronary artery. This denotes that the blood flow alternates into the condition of high shear stress under the MB.