Identify the condition shown in the X-ray?

Appeared in: NORCET-11 Prelims

Explanation

The 'snowman' or 'figure-of-eight' sign on chest X-ray is classic for supracardiac TAPVR.
This appearance is due to a large supracardiac shadow above the heart (vertical vein and innominate vein) and the normal cardiac shadow below.
In supracardiac TAPVR, pulmonary veins drain into a vertical vein, then into the innominate vein and SVC, bypassing the left atrium.
Other cyanotic heart diseases do not produce this radiological sign.
Diagnosis is confirmed by echocardiography, but the X-ray finding is highly suggestive.

Option A: Ebstein anomaly does not produce a snowman or figure-of-eight appearance on X-ray. It is characterized by an enlarged right atrium and a small right ventricle, sometimes described as a 'box-shaped' heart.
Option B: Tetralogy of Fallot typically shows a 'boot-shaped' heart (coeur en sabot) on X-ray due to right ventricular hypertrophy and upturned apex, not a snowman appearance.
Option D: Tricuspid atresia does not produce a snowman sign. X-ray may show decreased pulmonary vascularity and a small or normal-sized heart, depending on associated defects.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Radiological identification of congenital heart disease (TAPVR) using classic X-ray signs as background academic context rather than a clinical decision trigger.
Recognizing the snowman sign on X-ray allows early suspicion and diagnosis of supracardiac TAPVR, which is a surgical emergency if obstructed.
Nurses should monitor for signs of cyanosis and respiratory distress in infants with suspected congenital heart disease.
What if? If the X-ray showed a boot-shaped heart instead, Tetralogy of Fallot would be the likely diagnosis, changing the management approach.

How to Approach the Question

Carefully observe the X-ray for classic shapes or silhouettes (e.g., snowman, boot, box).
Recall which congenital heart diseases are associated with specific radiological signs.
Eliminate options that do not match the described or visible X-ray features.
Use knowledge of pathophysiology to connect abnormal drainage patterns to radiological findings.
Confirm the answer with supporting clinical features if provided.

Concept Tested & Keywords

Concept Tested: Radiological identification of congenital heart disease (TAPVR) using classic X-ray signs
Stem keywords: X-ray, condition identification, congenital heart disease
Lead-in keywords: Identify
Clinical cues: snowman or figure-of-eight appearance on X-ray

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E6 Nelson Textbook of Pediatrics(2024) — Volume 2 p. 606-608

Practise the full NORCET-11 Prelims

Attempt every question from this paper in a timed mock, then review the full solution for each one.