Teaching Case

49-year-old male with diabetes mellitus and atipic chest pain.

49-year-old male with diabetes mellitus and atipic chest pain who underwent MDCT coronary angiography for evaluation of coronary artery atherosclerotic disease.

MDCT demostrated myocardial bridging (MB) on the middle segment of the LAD. Depth and length of the MB was 4.6 mm and 50.9 mm, respectively. A calcific atherosclerotic plaque was also seen just proximal to tunneled segment. MB is a common inborn coronary anomaly, characterized by muscle overlying a segment of a coronary artery, which should flow epicardially. The vascular segment located within the myocardium is called “tunneled artery”. The artery most commonly involved is the left anterior descending coronary artery, and most muscle bridges occur between the proximal third and middle third portions of the vessel. Despite the fact that it is a congenital anomaly, symptoms usually do not develop before the third decade. MB of the coronary arteries are detected in 15% to 85% of autopsy series and in 0.5% to 16% angiographic studies. Although, MB has been considered a benign condition, some complications such as myocardial ischemia, myocardial infarction, myocardial stunning, left ventricular dysfunction, ventricular septal rupture, acute allograft failure in heart transplant, paroxysmal AV blockage, ventricular tachycardia and sudden cardiac death have been reported. Atherosclerotic changes were seen just proximal to tunneled artery more than within or distal to it. The current gold standard for diagnosing myocardial bridges is conventional coronary angiography, which shows the typical "milking effect" and a "step down–step up" phenomenon induced by systolic compression of the tunneled segment. The diagnosis of MB can also be made using intravascular ultrasound (IVUS), and intracoronary Doppler, which can visualize and quantify morphological and functional features of MB. MDCT is a recently used modality in diagnosis of MB. The advantage of MDCT over coronary angiography and IVUS is non-invasive identification of vulnerable atherosclerotic lesions, coronary artery anomalies, pericardium and myocardium pathologies, coronary artery bypass and stent patency and direct demonstration of the course of the artery through the myocardium as well as MB.