Cor Triatriatum Dexter

This video depicts the repair of an extremely rare congenital heart defect known as cor triatriatum dexter. In this condition, the right valve of the sinus venosus fails to involute and effectively separates the smooth and trabeculated portions of the right atrium. The degree of separation (ie, right atrial septation) will determine if the patient is asymptomatic or has signs of right heart failure due to inflow obstruction to the right ventricle. Patients with an atrial septal defect can be cyanotic.

The patient was a full-term infant who presented with profound cyanosis after failing a newborn pulse oximetry screening at 24 hours of life. The preoperative echocardiogram showed four well-formed chambers, but the cause of cyanosis was difficult to ascertain. A large thin membrane consistent with cor triatriatum dexter was identified, creating intermittent obstruction to flow into the right ventricle. In this case, the membrane almost appeared to be excessive tricuspid valve tissue in some views. Cor triatriatum dexter, while extremely uncommon, should remain on the differential for cyanosis in a newborn.

Suggested Reading

1. Mackman CA, Liedel JL, Woods RK, Samyn MM. A case series of patients with cor triatriatum dexter: unique cause of neonatal cyanosis. Pediatr Cardiol. 2015;36(1):240-243.
2. Galli MA, Galletti L, Schena F, Salvini L, Mosca F, Danzi GB. A rare case of neonatal cyanosis due ‘cor triatriatum dexter’ and a review of the literature. J Cardiovasc Med (Hagerstown). 2009;10(7):535-538.