Duplicated superior vena cava in a patient with tetralogy of Fallot: A rare vascular anomaly.

Duplicated superior vena cava (SVC) is a congenital vascular anomaly that is typically asymptomatic and is diagnosed incidentally upon imaging. We describe the case of a 28-year-old man with a background of achondroplasia, treated pulmonary tuberculosis, and chronic smoking and cannabis use, presenting with acute exacerbation of exertional dyspnea. Cyanosis and hypoxemia were evident on clinical examination (SpO₂ 65% on 15 L/min oxygen), and imaging revealed apical sequelae, ventricular septal defect (VSD), and pulmonary hypertension. A computed tomography pulmonary angiogram (CTPA) excluded embolism but detected duplicated SVC with independent drainage, hemiazygos vein drainage to the left SVC, overriding aorta, hypoplastic pulmonary arteries, and right ventricular outflow tract stenosis-a diagnosis of Tetralogy of Fallot (TOF) was thus confirmed. This case highlights the need to remember duplicated SVC vascular malformation in critical patients as these might prove to be critical in diagnosis as well as therapeutic strategy, especially in the setting of complex congenital cardiac disease.