Distribution of muscular bridges in the adult human heart

Abstract

Muscle bridges (MBs) are structures consisting of heart muscle tissue which pass above the coronary arteries and their branches. Although there are a relatively large number of descriptions of these MBs, researchers do not share a common view of the frequency of their occurrence, their location and their morphology, which remain the most controversial questions. The present research was carried out on 300 human hearts, adults of both sexes (161 male and 139 female), of between 21 and 76 years of age (mean age 48 years), in which no macroscopic developmental failures had been found. The hearts were preserved in formalinethanol solution. Selected coronary arteries were analysed. Images were examined of the perpendicular dissection of the coronary arteries and their neighbouring structures. On the basis of the analysis, the frequency of occurrence of MBs was defined as 31.3%. Muscular bridges were observed most frequently over the anterior interventricular branch of the left coronary artery (RIA) and, more rarely, over the right marginal branch of the left coronary artery (Rmd) and the circumflex branch of the left coronary artery (RCX). Using as criteria the number of muscular bridges in the heart and their location over particular coronary arteries, 4 types of configuration were established. With reference to the RIA, most MBs were located in the central part. We did not notice the same regularity with reference to other coronary arteries, nor did we observe MBs over coronary veins. Conclusions: muscular bridges are frequently observed structures in human hearts, most often seen over the anterior interventricular branch of the left coronary artery (RIA), mainly over its central segments, and occasionally over other arteries. MBs may occur in the heart singly or in a greater number and are found over the same or different vessels.