ORIGINAL ARTICLE J of Evidence Based Med & Hlthcare, pISSN- 2349-2562, eISSN- 2349-2570/ Vol. 2/Issue 7/Feb 16, 2015 Page 851 MORPHO-HISTOLOGICAL STUDY OF MYOCARDIAL BRIDGES OF CADAVERIC HEARTS S. D. Nalinakumari 1 , N. Vinay Kumar 2 , S. Sasi Kumar 3 , T. S. Gugapriya 4 HOW TO CITE THIS ARTICLE: S. D. Nalinakumari, N. Vinay Kumar, S. Sasi Kumar, T. S. Gugapriya. ”Morpho-Histological Study of Myocardial Bridges of Cadaveric Hearts”. Journal of Evidence based Medicine and Healthcare; Volume 2, Issue 7, February 16, 2015; Page: 851-858. ABSTRACT: INTRODUCTION: A band overlying the intramural segment of coronary artery-a place where the artery goes through myocardium instead of epicardium is called myocardial bridging (MB). A wide variation of 0.5%-90.4% occurs in the incidence of MB by the cadaveric and angiographic study. More over the occurrence of atherosclerosis in coronary artery segments under myocardial bridges still remains controversial. And so, the incidence of myocardial bridges and their association to atherosclerosis formation in cadaveric hearts was done morphologically and histological in this study. METHODS: 30 cadaveric hearts from department of Anatomy were examined. After cleaning the fat from epicardium, course of all three coronary arteries were delineated and observed for presence of MB. In the hearts that exhibited MB, the location, length of MB, its distance from the coronary ostium was measured. Sections were made proximal to MB, under MB and distal to MB in the vessels. The perimeter of the vessels were measured. The section was processed for histological study of intimal–media thickness ratio. RESULT: 24 hearts showed MB in the left anterior interventricular artery. One showed MB in right coronary artery. Multiple MB in single artery was seen rarely. The length of the MB segment was around 4 cm on an average. Mostly the MB is seen in the mid to distal part of the artery. The intima was found to be thinned out in the section of the vessel underneath the MB. CONCLUSION: This study concludes that Left coronary artery is the commonest to have myocardial bridges. But the occurrence of this MB in the distal part of the vessel in contrast to previous studies is an important finding to be noted. The presence of intimal thinning underlying the myocardial bridges questions the previous studies that claimed MB‟s protection of vessels from atherosclerosis. KEYWORDS: Myocardial bridges, atherosclerosis, intimal media thickness, left coronary artery, heart. INTRODUCTION: The coronary arteries often run through the epicardial adipose tissue in its course and presents with a band of myocardial tissue overlying that segment. This myocardial band is named as myocardial bridge(MB). 1,2 It is reported to exist exclusively in left anterior descending artery (LAD) in its mid portion by few studies. 3,4 MB was considered as a benign anatomical variant rather than a congenital anomaly. 4,5,6 This was challenged by many studies that found close association between the presence of MB and cardiovascular disease(CHD), arrthymias and sudden cardiac death. 2,3,4,7,8,9,10,11,12 The reported incidence of MB ranges from 0.5- 90. 4% that includes cadaveric, angiographic and multi-detector CT studies. 13 Morphologically MB can be categorized into four types by combining descriptions of various studies as follows: 14 to 22