A rare case of 'superdominant' single coronary artery.

A 45 year male patient with no risk factors and no associated cardiac anomaly presented to us with exertional chest pain since 10 years. During coronary angiography, we were unable to intubate the left main coronary artery. Cannulation of the right coronary ostium showed a 'superdominant' Right coronary artery, which initially followed the course of the normal right coronary artery, then proceeded via a posterolateral segment into the course of the normal left circumflex artery, and finally followed the course of the normal left anterior descending artery (Images 1-3).CT coronary angiogram confirmed the findings (Images4-5). Intramyocardial bridging was also seen which explained the angina. This subtype is named type R-IA according to Lipton's classification and is by far the most rare type of single coronary artery with an incidence of 0.0008%. Some patients may present with myocardial ischemia or stable angina. The exact mechanism is unknown but may be related to intramyocardial bridging or coursing of epicardial arteries between great arteries.