An 8-month-old infant has progressive cyanosis without respiratory distress. Chest X-ray shows a large cardiac silhouette with a convex right upper mediastinal shadow and normal pulmonary vascularity, described as a 'snowman' appearance. Echocardiography confirms total anomalous pulmonary venous connection with all four pulmonary veins forming a confluence behind the heart that drains via a vertical vein. Where does the vertical vein drain?

• A Left innominate vein ✓
• B Inferior vena cava below the diaphragm
• C Portal vein
• D Coronary sinus

Explanation

In supracardiac TAPVC, the most common type, the pulmonary venous confluence drains upward through a left vertical vein into the left innominate vein, producing the widened superior mediastinum and snowman sign, visible once the thymus involutes after infancy. Infracardiac drainage into the portal system or IVC below the diaphragm is the type most likely to be obstructed and presents in the neonatal period. Coronary sinus drainage defines the cardiac type.

Reference: Park's Pediatric Cardiology for Practitioners, 7th ed.

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Written and medically reviewed by the StethoPrep medical team.