Single coronary artery anomaly: branching of left coronary artery from right coronary artery with 2 distinct patterns.

Normal coronary vasculature has a left coronary artery arising from the left coronary cusp and a right coronary artery arising from the right coronary cusp. In about 0.024% of cases in the general population, there is no left main coronary artery. In fact, there is a single coronary artery, which arises from the right coronary cusp. We encountered 2 such cases with distinct patterns. The first case was a patient with angina who had an abnormal stress test for which he underwent coronary angiography. This revealed a single coronary artery arising from the right coronary cusp. This vessel gave rise to the right coronary artery, which had a varicose anatomy, with a critical lesion in the posterior descending artery. The left coronary artery passed anteriorly to the pulmonary artery with a critical lesion in the circumflex artery. In the second case, the patient also had angina with a normal noninvasive work-up but due to his persistent symptoms, coronary angiography was performed. This revealed a single coronary artery arising from the right coronary cusp. Subsequent CT angiography revealed that the left coronary artery coursed in between the aorta and pulmonary artery without critical lesions. In both cases, the patients underwent coronary artery bypass grafting.