Bovine myocardial bridge morphology and association with coronary atherosclerosis

RESUMO

Coronary arteries and their branches run through the subepicardial layer and penetrate the myocardium. In some cases, these vessels run intramyocardially for variable lenghts and then return to the subepicardial surface. The cardiac musculature that covers these vessels is known as a myocardial bridge. The presence of a myocardial bridge may protected the covered arterial segment against the development of atherosclerosis. In this report, we examined the pre-, post- and myocardial bridge segments of branches of bovine coronary arteries and compared them to corresponding sections of coronary arteries not covered by a myocardial bridge, in order to establish a possible morphofunctional association. Twelve interventricular paraconal branches from coronary arteries with or without a myocardial bridge (pre-, post- and myocardial bridge segments) were obtained from adult bulls of mixed breed. The samples were processed and stained to detect elastic, collagen and muscle fibers and were analyzed by light microscopy. The histological appearance of the pre-myocardial bridge segments differed from that of the other segments with or without a myocardial bridge in that the intimal layer was well-developed. By analogy, the morphology of the pre-myocardial bridge in bovine vessles suggests that there may be a high incidence of atherosclerosis in the pre-myocardial bridge tissue of human vessels.