Hitesh Aggarwal, MD
Overview and Natural History
Anomalous aortic origin of a coronary artery (AAOCA) is a congenital abnormality of the origin or course of a coronary artery that arises from the aorta.1 Normal coronary artery anatomy is characterized by two ostia centrally placed in the right and left sinus of Valsalva. The main left coronary artery (LCA) originates from the left ostium, branching into the left anterior descending artery and circumflex artery, which courses around the left atrioventricular groove; the right coronary artery (RCA) arises from the right ostium, providing an infundibular branch to the anterior side of the heart, and then courses backward in the atrioventricular groove.7 In AAOCA, the origin of one of the coronary arteries is from the wrong sinus of Valsalva.
Epidemiology
AAOCA is the second leading cause accounting for 17% of sudden cardiac death in young athletes in the United States.2 The reported prevalence of AAOCA varies depending on diagnostic method applied: 0.06-0.9% for anomalous right coronary artery (ARCA), 0.025-0.15% for anomalous left coronary artery (ALCA), and 0.02-0.67% for anomalous circumflex coronary artery. 1,3,4
Types
It can be classified based on the origin from the aorta as follows:
They are further subdivided based on an anomalous course:
It is also important to characterize ostial morphology of the anomalous coronary artery which is classified as:1
While echo can diagnose anomalous origin of the coronary artery, technical challenges limit its ability to accurately predict anomalous course and ostial morphology. CT and MRI are useful additional imaging modalities use to define these features if a diagnosis of anomalous coronary artery is suspected.
Hemodynamics
A vast majority of patients with AAOCA are asymptomatic and sudden death can be the first manifestation in some patients. There is no clear consensus on the mechanisms of ischemia in AAOCA. Presumably, compression of anomalous coronary artery occurs during exercise, leading to myocardial ischemia and ventricular fibrillation/tachycardia. Proposed mechanisms for coronary compressions include: 1,5
Goals of echocardiography
Echocardiogram is an excellent tool to screen for coronary anomalies in children. Important views in transthoracic echocardiogram include: 6
It is recommended to use high-frequency probes and small sector width to optimize high spatial and temporal resolution. Generally, 3-5 beats clip is preferred and still frames should be avoided.