Retrocardiac Innominate Vein: A Rare Vascular Anomaly Associated With Congenital Heart Disease.

Atrial septal defects are common congenital heart anomalies and may coexist with rare systemic venous abnormalities. We describe a one-year-old female with a large secundum atrial septal defect and an unusual retrocardiac innominate vein. Transthoracic echocardiography suggested a persistent left superior vena cava, but the innominate vein was absent from its usual location and the coronary sinus was not dilated. Cardiac CT angiography demonstrated a retrocardiac innominate vein draining into the azygos system and subsequently to the right atrium. Surgical atrial septal defect closure was successful. Recognition of this anomaly is essential for accurate diagnosis and procedural planning.