A cyanotic newborn is noted to have differential cyanosis — upper limbs are pink and lower limbs are cyanosed. Echocardiography confirms the diagnosis. Which congenital cardiac lesion best explains this finding?

• A Transposition of the great arteries (TGA)
• B Total anomalous pulmonary venous connection (TAPVC)
• C Pulmonary atresia with intact ventricular septum
• D Coarctation of aorta with patent ductus arteriosus (PDA) carrying desaturated blood to the descending aorta ✓

Explanation

Differential cyanosis (pink upper limbs, cyanosed lower limbs) occurs when desaturated blood enters the descending aorta via a right-to-left shunting PDA, while the upper body receives oxygenated blood from the left ventricle via the aorta before the ductal entry point. This pattern occurs with preductal coarctation of the aorta (or interrupted aortic arch) combined with a PDA, where right ventricular blood (deoxygenated) bypasses the lungs and enters the descending aorta through the duct. Reversed differential cyanosis (cyanotic upper limbs, pink lower limbs) occurs in TGA with PDA.

Reference: Ghai Essential Pediatrics, 10th ed.

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Written and medically reviewed by the StethoPrep medical team.