Abnormal blood supply to a normal lung: left circumflex artery branch supplying the right lung.

A middle-aged woman with hypertension presented with atypical chest pain of 1 month duration and had a positive exercise stress test. She underwent diagnostic coronary angiography which demonstrated an anomalous branch arising from the proximal part of the left circumflex artery supplying the right lung. She had atherosclerotic plaques in the right coronary artery and left anterior descending artery. Stress myocardial perfusion imaging did not reveal any inducible ischaemia in the left circumflex artery territory. She was started on medical therapy for coronary artery disease and is doing well on follow-up.