Anomalous origin of the circumflex artery from the right coronary sinus is a well recognised variant. The artery passes in a retro-aortic location, and this variant is not thought to be haemodynamically significant. This is a non-malignant course, as it does not pass between two arterial structures.
The significance of this anomaly is that it may cause difficulty in catheterisation and interpretation at catheter angiogram. In contrast, cardiac CT easily elucidates the course of anomalous coronary arteries. A further clinical significance is that the circumflex artery partially encircles the aortic valve in this course, and may be damaged at arteriotomy in valve surgery if this anomalous course has not been recognised. Also it may be compressed following implantation of a prosthetic aortic valve.