Cardiac or respiratory cause of hypoxia in a newborn

A term baby boy was delivered overnight by emergency caesarean section for pathological cardiotocography. An uncle died in childhood due to ‘a problem with the aorta’. After initial cry, he required resuscitation including chest compressions. He was stabilised on nasal continuous positive airway pressure therapy (nCPAP). Oxygen saturations remained labile with a notable preductal and postductal gradient of 10% with brief preductal saturations...