Anomalous right coronary artery from the pulmonary artery

Last revised by Craig Hacking on 22 Feb 2024

Anomalous right coronary artery from the pulmonary artery (ARCAPA), is a rare congenital coronary artery anomaly and is considered one of the most severe of such anomalies.

This abnormality only accounts for less than 0.1% of all congenital cardiac anomalies 1 and is up to four times less prevalent than anomalous left coronary artery from the pulmonary artery (ALCAPA). There is a slight male predominance.

ARCAPA may be associated with a range of other cardiac abnormalities 1, most commonly an aortopulmonary septal defect (also known surgically as aortopulmonary window) which is seen in 10 % of cases.

Other associations include (in decreasing order of frequency) 1:

Patients may range from being completely asymptomatic with or without a murmur to presenting with sudden cardiac death. Patients are more likely to present later in life compared with those with ALCAPA. In a review of 223 patients in 193 papers 1, 38% were asymptomatic at the time of diagnosis and the median age at diagnosis was 14 years with a bimodal age distribution at <1 year and 40 to 60 years. Almost 50% of patients had a murmur at the time of diagnosis.

ALCAPA refers to a cardiovascular anomaly where the right main coronary artery arises from the pulmonary trunk instead of the left coronary sinus of the ascending aorta. The etiology is not well understood. The pathophysiology is similar to that seen in ALCAPA.

ECG-gated cardiac CT allows direct visualization of anomalous right main coronary arterial origin from the posterior aspect of the pulmonary artery. The left coronary artery may be unusually dilated and tortuous with evidence of collateral formation. Intercoronary collateral arteries along the external surface of the heart or within the interventricular septum may also be seen.

Surgical treatment aims to prevent coronary steal and restore the normal anatomic origin of the RCA 1. The RCA origin can either be re-implanted onto the aorta or ligated then bypassed with an arterial or venous graft. The surgery is often performed with cardiopulmonary bypass.

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