Normally the epicardial coronary arteries are located outside the myocardium. Occasionally a segment of the epicardial coronary artery passes through the myocardium. This causes a narrowing of that region when the heart contracts in systole, known as myocardial bridging. Myocardial bridging can be recognized as narrowing of a region of the coronary artery in systole which normalizes in diastole. Usually myocardial bridges do not cause ischemia, though rarely it can do so. Generally myocardial bridges are left alone, though some operators would prefer stenting of bridging areas presumably causing ischemia.