In a cyanotic neonate undergoing pulse oximetry screening, the preductal saturation measured in the right arm is higher than the postductal saturation measured in either lower limb. Which cardiac lesion classically produces this pattern of REVERSE differential cyanosis, that is, upper limbs pinker than lower limbs?

• A Patent ductus arteriosus with severe pulmonary hypertension and right-to-left ductal shunt
• B d-Transposition of the great arteries with patent ductus arteriosus ✓
• C Interrupted aortic arch with ventricular septal defect
• D Coarctation of the aorta with patent ductus arteriosus

Explanation

In d-transposition, poorly oxygenated aortic blood shunts from the aorta into the pulmonary artery through the ductus. The head and upper limbs are supplied from the aorta proximal to the ductus, while the descending aorta has been depleted of its better-oxygenated blood, so lower limbs are more desaturated than the right arm. In the other three lesions, ductal flow supplies the descending aorta, producing ordinary differential cyanosis with pinker upper limbs.

Reference: Park's Pediatric Cardiology for Practitioners, 7th ed.

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Written and medically reviewed by the StethoPrep medical team.