Neonatal Case of Fetal Pleural Effusion Caused by Cor Triatriatum Dexter with Postnatal Worsening of Superior Vena Cava Syndrome.

Fetal pleural effusion is most commonly associated with lymphatic abnormalities such as congenital chylothorax or fetal heart failure, with obstruction of the systemic venous return representing a particularly rare and underrecognized cause. Herein, we report the case of a neonate with fetal pleural effusion caused by cor triatriatum dexter, in whom superior vena cava syndrome developed and progressed after birth. The infant was delivered at 33 weeks of gestation because of premature rupture of membranes, with a birth weight of 1.9 kg. The patient’s pleural effusion and upper-body edema worsened shortly after birth as a result of fixed intracardiac venous obstruction. We propose that obstruction of the SVC by a persistent right atrial membrane elevated central venous and thoracic duct pressures, ultimately leading to refractory chylothorax. At 61 days of life, when body weight reached 3.1 kg, surgical resection of the right atrial membrane with enlargement of the superior and inferior vena cava vessels was performed. Because of mild right ventricular hypoplasia, the atrial septal defect was initially partially closed during surgery; however, persistent systemic venous congestion after the operation necessitated balloon atrial septostomy to enlarge the interatrial communication. Pleural effusion and edema resolved completely. This case highlights the fact that systemic venous obstruction caused by cor triatriatum dexter represents a rare but important cause of refractory fetal pleural effusion of which clinicians should remain aware.