Anomalous origin of right coronary artery from pulmonary artery.

Anomalous origin of coronary artery from the pulmonary artery is a rare anomaly that most frequently involves the left coronary artery and very rarely the right coronary artery. These lesions can be missed on echocardiography unless carefully looked for. We describe a case of isolated anomalous origin of right coronary artery from pulmonary artery diagnosed on echocardiography and confirmed by computed tomography (CT) angiography.

A 3½ month old male child presented with history of fast breathing and excessive crying for past one month. He had been treated for respiratory tract infection with congestive failure.

His physical examination revealed heart rate of 122/ min, respiratory rate 36/ min. Normal first and second heart sounds. There was a grade II/VI early systolic murmur at left upper sternal border. Chest X-ray was unremarkable and ECG was normal with no evidence of ischemia. An echocardiogram revealed normal segmental analysis, with normal biventricular contractility. The left coronary artery was dilated [Figure 1]. Color Doppler examination suggested presence of multiple collaterals across the interventricular septum between right and left coronary arteries. There was a diastolic flow into the main pulmonary artery, close to the pulmonary valve. Upon further evaluation the Right Coronary artery was seen to be arising from the Pulmonary artery [Figures 2–4].

Figure 1

Transthoracic echo imaging showing dilated left coronary artery originating normally

Figure 2

Transthoracic echo imaging showing anomalous origin of right coronary artery from pulmonary artery

Figure 4

3D reconstruction of CT images showing anomalous origin of right coronary artery from pulmonary artery and its further course in right atrioventricular groove (RCA: Right coronary artery, LCA: Left coronary artery, AO: Aorta, PA: Pulmonary artery)

Axial section of CT angiogram showing anomalous origin of right coronary artery from pulmonary artery (RCA: Right coronary artery, AO: Aorta, PA: Pulmonary artery)

Anomalous origin of right coronary artery from pulmonary artery is a rare yet serious congenital coronary disorder. In 1945, Soloff described four possible types of anomalies of the coronary artery originating from the pulmonary artery. These can be an anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA), right coronary artery from the pulmonary artery (ARCAPA), both coronary arteries from the pulmonary artery and an accessory coronary artery from the pulmonary artery. Among these, ALCAPA is the most common anomaly, with an incidence of 0.008% in the general population compared to a rate of 0.002% for ARCAPA. Only 25-30% cases of ARCAPA are associated with structural heart defects.[1] Many patients with isolated ARCAPA remain asymptomatic and it is diagnosed incidentally with other types of cardiac anomalies. Twelve cases were diagnosed in infants ≤1 year of age, 44 were diagnosed in children ≤18 years of age, 17 were adults >60 years of age, and eight subjects were of unknown age.[2] Massive collateralization between the normal and anomalous vessel is needed to maintain adequate myocardial perfusion in the presence of coronary steal. Coronary steal occurs when the anomalous vessel acts as a vein, which collects blood from the normal coronary artery through collaterals and delivers it to the pulmonary artery. Patients with associated cardiac anomalies are diagnosed early in life compared to patients with isolated ARCAPA. Those without associated cardiac defects may present with heart murmur, congestive symptoms, sudden cardiac death or may remain asymptomatic and detected incidentally during evaluation of other problem (e.g. coronary angiography in the older age group).[3] Associated cardiac defects were reported in 22% of the patients reported with ARCAPA. The cardiac defects found in these patients were aortopulmonary window, tetralogy of Fallot, VSD, PDAAQ3, and aortic stenosis.[4] ECG in ARCAPA may be normal or it may show left ventricular hypertrophy or deep Q waves in inferior leads.[5]