Coronary Artery Fistula: Pre-conal and Retro-conal Artery Ring

Background: Coronary artery fistulae are rare, usually congenital, abnormal connections between one of the coronary arteries and either a chamber or blood vessel. We present a case with previously unreported concomitant multiple left to right coronary large caliber connections. The prevalence of open-ended circulation with bi-directional flow between two coronaries is unknown and should be differentiated from coronary collaterals which have distinct pathophysiology.

Methods: 45-year old man presented with episodic severe chest pain and underwent coronary angiography and, given angiographic findings, right heart catheterization. Left main angiography demonstrated a network of severely tortuous anomalous vessels arising from proximal Left Anterior Descending (LAD) artery directed toward Right Ventricular Outflow Tract (RVOT) and right coronary cusp. The LAD and left circumflex (LCX) proper had mild luminal irregularities only with distal TIMI III flow present. Right coronary angiography demonstrated severely tortuous anomalous vessel arising from the right coronary cusp (possibly distinct ostia from the RCA proper) with multiple collaterals directed and surrounding the RVOT. The LAD filled with RCA injection. Additionally, a 50% mid RCA stenosis was identified. Right heart catheterization was normal with including a normal Qp/Qp of 1.

An ECG-gated computed tomography (CT) scan was performed to help further delineate the coronary anatomy. We were able to identify concomitant pre-conal and retro-conal right to left coronary fistulae. A branch arising from the proximal LAD also demonstrated connection to the descending aorta and a separate small branch demonstrated connection with the main pulmonary artery.

Conclusion: We hypothesize that the moderate stenotic lesions in RCA and LAD had lower threshold to cause ischemia given the pre-obstruction fistulae. All treatment options were discussed with the patient and he opted for surgical management. To our knowledge, this is the first reported cased of concomitant pre and retro-conal coronary ring communicating right and left coronary circulations.