A 2-month-old infant has mild cyanosis and a soft systolic murmur at the left upper sternal border. Chest X-ray shows cardiomegaly with a widened superior mediastinum giving a 'snowman' appearance, along with plethora. Which is the MOST likely diagnosis?

• A Supracardiac total anomalous pulmonary venous connection ✓
• B Truncus arteriosus
• C Hypoplastic left heart syndrome
• D Pulmonary atresia with intact ventricular septum

Explanation

The snowman or 'figure of 8' cardiac silhouette results from dilated vertical veins, innominate vein and SVC in supracardiac TAPVC, which is also the commonest type (about 50% of cases). It appears after infancy as these channels enlarge. Obstructed infracardiac TAPVC presents neonatally with severe cyanosis and a normal-sized heart with venous congestion, so the plethoric enlarged heart here rules that distractor out.

Reference: Nelson Textbook of Pediatrics, 21st ed.

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Written and medically reviewed by the StethoPrep medical team.