Myocardial bars and bridges and sudden death.

A congenital variant of the anatomical arrangement of the coronary arteries, that can be observed both angiographically and at autopsy, is the embedding of these vessels within a tunnel of the subepicardial myocardium. Both clinical and pathological claims and counterclaims have been made as to the functional consequences of this variation, the implication being that the contraction of the peri-vascular myocardium particularly at accentuated heart rates would cause occlusion of the blood flow within these arteries. The consensus is that this variant is only of significance when it occurs around a significant portion of a dominant left main coronary artery in which instances it may be the cause of sudden death during the course of strenuous exercise.