A cyanotic newborn has an ECG showing left superior axis deviation, right atrial enlargement, and dominant left ventricular forces with no right ventricular depolarisation forces. Which diagnosis does this combination STRONGLY suggest?

• A Ebstein anomaly of the tricuspid valve
• B Pulmonary atresia with intact ventricular septum
• C Transposition of the great arteries
• D Tricuspid atresia ✓

Explanation

Tricuspid atresia classically shows left axis deviation (left superior QRS axis), right atrial enlargement, and left ventricular dominance because there is no functioning right ventricle to generate rightward forces. In any cyanotic infant, left axis deviation is highly suggestive of tricuspid atresia since most other cyanotic lesions show right axis deviation. Ebstein anomaly and pulmonary atresia with intact septum show right-sided dominance, and d-TGA usually has right axis deviation with RVH.

Reference: Park's Pediatric Cardiology for Practitioners, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.