A 1-month-old boy was referred to our unit for discrete cyanosis during breastfeeding. There was no familial history of congenital heart disease. He was born at 34 weeks of gestation after a normal pregnancy. On examination, cardiac auscultation was normal and oxygen saturation was 97%. There were no signs of cardiac insufficiency. Two-dimensional transthoracic echocardiography revealed a left superior vena cava (LSVC) draining into the roof of the left atrium ( Fig. 1 A and Supplementary data, Video 1 ). There was a persistent foramen ovale with a discrete left-to-right shunt. The coronary sinus was not dilated. A computed tomography (CT) scan confirmed the abnormal systemic venal return ( Fig. 1 B and C). The coronary sinus did not communicate with the LSVC and its drainage ostium measured 2.3 mm in diameter. The LSVC and right superior vena cava were not connected by any left innominate vein. No additional cardiac anomaly was seen. At 13 months of age, the patient was dyspnoeic and sweated at effort. The saturation rate was 91% at rest. Using a 2/10 mm plug, the percutaneous closure of the LSVC was successful ( Fig. 2 A). The device was introduced via the left jugular vein. Both echocardiography and CT scan did not reveal any persistent shunt after the procedure ( Fig. 2 B and C). The patient recovered a normal peripheral saturation without any dyspnoea.
