A 25 year old woman was referred to the cardiac centre with a six month history of deteriorating cyanosis, dyspnoea, and exercise intolerance stable since early childhood. Physical examination revealed severe cyanosis, grade 3 clubbing, single S2, and grade 3/6 continuous murmur in the right infraclavicular region. A chest x ray revealed a normal sized heart with prominent pulmonary bay. An ECG showed right atrial enlargement with right ventricular hypertrophy. A transthoracic echocardiogram revealed a large subaortic ventricular septal defect with more than 60% aortic override, atretic pulmonary valve, a hypertrophied right ventricle, and continuous flow in the right sided ductus between the right brachiocephalic and right pulmonary artery. The patient was diagnosed as having pulmonary atresia with ventricular septal defect (PA-VSD) with right patent ductus arteriosus (PDA). Arch angiography in left anterior oblique (LAO) 20° view revealed right sided PDA with short segment stenosis at the distal anastomotic site with right pulmonary artery (below left). Catheter course and selective injection of dye in the PDA confirmed the findings (below right).

The ductus embryologically originates from the distal portion of one of the six aortic arches and its persistence, site, and course are closely associated with the development of the aortic arch. Commonly seen on the left side even in a patient with right sided arch, the ductus can connect either the proximal right or left pulmonary artery to virtually any location on the aortic arch or proximal portion of the brachiocephalic artery. This case highlights a rare association of unilateral right PDA with left aortic arch in pulmonary atresia.