Question

A neonate has cyanosis, pulmonary oligemia, and a normal cardiac shadow. What could be the diagnosis?

• A. Tetralogy of Fallot
• B. Pulmonary atresia
• C. Transposition of great vessels
• D. Ebstein's anomaly

Hint:

Cyanosis appearing right at birth is most often transposition of the great vessels, the top cause of day-one cyanotic heart disease.

Answer 1

The Correct Option is C

This question asks which cyanotic heart lesion best fits cyanosis appearing right at birth, along with pulmonary oligemia and a normal-sized heart on x-ray.

1. Tetralogy of Fallot: gives the textbook normal-sized, boot-shaped heart with oligemia, but its cyanosis more often builds up gradually over the first weeks to months as infundibular narrowing worsens, rather than being obvious in the newborn period.
2. Pulmonary atresia: usually shows an enlarged right atrium on x-ray because blood backs up through the tricuspid valve, so the heart tends to look bigger than normal, not normal sized.
3. Transposition of great vessels: is the single most common cause of cyanosis appearing within the first day or two of life, since the two circulations run in parallel and only mix through a shunt. Before cardiomegaly develops over the following days, the heart can still look normal, and if there is any associated narrowing of the pulmonary outflow, the lungs show oligemia instead of the usual plethora.
4. Ebstein's anomaly: is known for a massively enlarged, wall to wall heart shadow on x-ray, which rules it out here since the heart is described as normal sized.

Putting the timing, the oligemia, and the still-normal heart size together, transposition of the great vessels fits best among these four choices.

Let's summarize:

• Transposition of the great vessels is the top cause of cyanosis presenting right in the neonatal period.
• Ebstein's anomaly and pulmonary atresia usually show an enlarged heart, not a normal one, which rules them out here.

So the likely diagnosis is transposition of the great vessels.