Coronary Anatomy and Anomalies

AND ANOMALIES The right coronary artery (RCA) arises from the right coronary sinus and runs in the right AV groove (Fig. 5-1). Generally, the conus artery and the sinoatrial artery arise from the RCA. In approximately 85% of individuals, the posterior descending coronary artery arises from the RCA (defined as a right dominant coronary circulation). The left main coronary artery arises from the left coronary sinus. Within a few centimeters of its origin, it divides into the left anterior descending (LAD) coronary artery (in the anterior interventricular groove), the left circumflex coronary artery (in the atrioventricular groove) and, in a minority of cases, a ramus intermedius artery. Coronary artery anomalies are found in 1 to 1.5% of individuals (Fig. 5-2); most anomalies are benign. The most common anomaly is separate origins from the aorta of the LAD and left circumflex (i.e., absence of a left main coronary artery), which occurs in 0.4 to 1% of individuals and is occasionally associated with a bicuspid aortic valve. Clinically significant anomalies include origin of a coronary artery from the opposite coronary sinus (e.g., left main artery originating from the right coronary sinus), the presence of a single coronary ostium (and hence a single coronary artery), and origin of a coronary artery from the pulmonary artery.