Single Persistent Left Superior Vena Cava Draining Into the Left Atrium Causing Neonatal Cyanosis: A Case Report

The persistence of the left superior vena cava (PLSVC) is the most common variant of systemic venous drainage. It is usually diagnosed through echocardiography, with the PLSVC typically draining into the right atrium via the coronary sinus without hemodynamic consequences. In cases of a single PLSVC (without right superior vena cava), it generally drains into the right atrium. However, when it drains directly into the left atrium, systemic venous return bypasses the right atrium, causing cyanosis and hypoxemia.

Term newborn was admitted to the neonatal intensive care unit due to hypoxemia. Respiratory support and other therapies to improve oxygenation were used, without success.

In the echocardiography to rule out congenital heart disease, a single PLSVC drains directly into the left atrium, without any associated congenital heart disease as a cause of cyanosis.

The patient was gradually weaned off invasive ventilation and nitric oxygen therapy. An atrial septostomy was performed at 4 months to improve right ventricular filling. At 5 months of age, corrective surgery was performed to redirect the PLSVC flow to the right atrium.

At 11 months of age, she remains asymptomatic and with normal oxygen saturation. Her echocardiography shows normal right ventricular dimensions and function, with normal flow of the pulmonary veins and across the baffle.

In conclusion, although rare, a single PLSVC should be considered in the differential diagnosis of neonates with persisting hypoxemia and cyanosis that do not respond to standard treatments.