Delayed Diagnosis of Cor Triatriatum Dexter: A Case Report and Comprehensive Review of Embryology, Imaging, and Management.

Cor triatriatum dexter (CTD) is a rare congenital cardiac anomaly resulting from the persistence of the right valve of the sinus venosus, leading to partial or complete partitioning of the right atrium. It accounts for a minority of congenital heart defects and may present with various clinical features ranging from asymptomatic incidental findings to severe right-sided heart failure. We report the case of a 45-year-old female with longstanding exertional dyspnea, peripheral edema, hepatomegaly, and severe bilateral varicose veins. Abdominal imaging revealed features of hepatic congestion, whereas echocardiography revealed a markedly dilated inferior vena cava (IVC) and a membrane at the junction of the IVC and right atrium. Transesophageal echocardiography confirmed a fibromuscular membrane consistent with CTD, partially obstructing systemic venous return. The patient also had a preserved left ventricular systolic function. CTD arises from incomplete regression of the embryonic right venous valve. The degree of membrane perforation influences the severity of obstruction and clinical symptoms. While an incomplete CTD can be clinically silent, significant septation may lead to elevated right atrial pressures and systemic venous congestion. This case emphasizes the diagnostic utility of multimodality imaging in adults with unexplained right-sided heart failure symptoms and highlights CTD's potential role in chronic venous disorders. This case adds to the limited literature on conservatively managed adult CTD, highlighting the impact of financial barriers on therapeutic decision-making. CTD, although rare, should be considered in the differential diagnosis of right-sided congestion in adults, particularly when it is accompanied by unexplained IVC dilation, hepatic congestion, and chronic venous insufficiency. Early recognition through echocardiography and other imaging modalities is essential for guiding appropriate management and avoiding misdiagnosis.