A 3 year old girl with cyanotic congenital heart disease had ventricular septal defect and pulmonary atresia. The arterial saturation was 76%. Confluent central pulmonary arteries were seen from suprasternal view on echocardiography, but the origin was not clear. A cardiac catheterisation to delineate the details of pulmonary artery anatomy showed two small major aortopulmonary collaterals supplying the left upper and right upper part of the lungs, but the central pulmonary arteries were not seen on descending thoracic aortogram. An ascending aortogram subsequently showed the pulmonary artery arising from the coronary artery. Selective injection into the left coronary artery showed dilated proximal segment of the left coronary artery and main pulmonary artery was arising from it as a first branch (right).

The pulmonary blood supply in patients with ventricular septal defect and pulmonary atresia is highly variable. Some form of coronary artery to pulmonary artery collaterals may be present in up to 10% of these patients, but the origin of pulmonary arteries from coronary arteries (through a fistulous communication, or directly) is rare. In 70% of cases, the left coronary artery is a source of pulmonary blood flow. Severe cyanosis, or increased pulmonary blood flow with congestive heart failure, pulmonary hypertension and pulmonary artery aneurysm, have been described in such patients. Coronary artery steal may be expected, but usually does not occur. Surgical correction using autologous material, or a homograft to connect the pulmonary artery to the right ventricle, and ligation or unifocalisation of collateral supply are reported.

Selective injection into the left coronary artery (right anterior oblique view) showing the pulmonary artery arising from the left coronary artery. MPA, main pulmonary artery; LAD, left anterior descending coronary artery; LCX, left circumflex artery.