macroscopical and microscopical study on frequency of myocardial bridge (a cause of sudden death) in coronary artery of sheep heart

background: myocardial bridge (mb) is generally defined as a superfacial muscular band that forms sporadic or multiple across the coronary artery in dog, cat, sheep, and human. objectives: from the view of embryology mb is a preformatted structure with coronary artery during  forming. the type of study in human is during sonography and angiography examination, but in veterinary science the study on mb is  done after death examination. methods: this study was performed on over 50 sheep hearts that were prepared from slaughterhouse of shahr e kord. first, pericardium was opened and the heart brought out of the pericardial cavity and then the hearts were studied with concentrated light and lens on both sides. after the m b recognition,  their length and width were measured by a ruler. in both sides of the heart,the mb was  divided into 1/3 proximal, 1/3 middle and 1/3 distal. in all of the studied hearts, only 10 samples (20%) had m b. results: the average length of recognised mbs was 1.55±1.17 (sd) cm and  with width of 1.09±.092 (sd) cm. the positive samples were transferred to histology laboratory for preparation of cross section of heart and were stained with  h&e; staining.conclusions: the longitudinal section showed the long fibers of myocardium with continual narrow fibers and intercalated discs were located between them.