Question:
A 2-day-old neonate presents with pallor and cyanosis. Chest X-ray shows decreased pulmonary blood flow, and ECG reveals left axis deviation. Which is the most likely diagnosis?
A 2-day-old neonate presents with pallor and cyanosis. Chest X-ray shows decreased pulmonary blood flow, and ECG reveals left axis deviation. Which is the most likely diagnosis?
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ECG Pearl: Cyanotic infant + Left Axis Deviation + LVH = Tricuspid Atresia (or rarely AVSD single ventricle). Most other cyanotic CHD (TOF, TGA, TAPVC) have Right Axis Deviation with RVH!
Updated On: Sep 3, 2026
- Tetralogy of Fallot
- Tricuspid Atresia
- Transposition of Great Arteries (TGA)
- Truncus Arteriosus
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The Correct Option is B
Solution and Explanation
Concept:
Tricuspid atresia is a cyanotic congenital heart lesion characterized by complete agenesis of the tricuspid valve, leading to absent direct communication between the right atrium and right ventricle.
It produces a classic electrocardiographic signature that uniquely separates it from nearly all other cyanotic heart defects in neonates.
Explanation:
• In normal neonates, right ventricular dominance produces a physiological right axis deviation (RAD) and right ventricular hypertrophy (RVH) on ECG.
• In tricuspid atresia, systemic venous blood in the right atrium must shunt right-to-left through an obligatory ASD/PFO into the left atrium, where it mixes with pulmonary venous blood and enters the dominant left ventricle.
• Because the right ventricle is hypoplastic and the left ventricle handles total systemic and pulmonary cardiac output, the neonatal ECG characteristically demonstrates Left Axis Deviation (LAD, typically $-30^\circ\text{ to }-90^\circ$) and Left Ventricular Hypertrophy (LVH).
• Chest radiography shows decreased pulmonary vascular markings (oligemic lung fields) because of severe subpulmonary stenosis or pulmonary atresia.
• By comparison, Tetralogy of Fallot, TGA, and Truncus arteriosus exhibit right axis deviation and right ventricular dominance on neonatal ECG.
Final Answer:
A cyanotic neonate with decreased pulmonary blood flow and an ECG demonstrating left axis deviation with LVH has the hallmark findings of Tricuspid Atresia.
Tricuspid atresia is a cyanotic congenital heart lesion characterized by complete agenesis of the tricuspid valve, leading to absent direct communication between the right atrium and right ventricle.
It produces a classic electrocardiographic signature that uniquely separates it from nearly all other cyanotic heart defects in neonates.
Explanation:
• In normal neonates, right ventricular dominance produces a physiological right axis deviation (RAD) and right ventricular hypertrophy (RVH) on ECG.
• In tricuspid atresia, systemic venous blood in the right atrium must shunt right-to-left through an obligatory ASD/PFO into the left atrium, where it mixes with pulmonary venous blood and enters the dominant left ventricle.
• Because the right ventricle is hypoplastic and the left ventricle handles total systemic and pulmonary cardiac output, the neonatal ECG characteristically demonstrates Left Axis Deviation (LAD, typically $-30^\circ\text{ to }-90^\circ$) and Left Ventricular Hypertrophy (LVH).
• Chest radiography shows decreased pulmonary vascular markings (oligemic lung fields) because of severe subpulmonary stenosis or pulmonary atresia.
• By comparison, Tetralogy of Fallot, TGA, and Truncus arteriosus exhibit right axis deviation and right ventricular dominance on neonatal ECG.
Final Answer:
A cyanotic neonate with decreased pulmonary blood flow and an ECG demonstrating left axis deviation with LVH has the hallmark findings of Tricuspid Atresia.
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