Differential cyanosis is seen in

Ref Harrison 19 th ed pg 1523 Severe pulmonary vascular disease results in reversal of flow through the ductus; unoxygenated blood is shunted to the descending aoa; and the toes--but not the fingers--become cyanotic and clubbed, a finding termed differential cyanosis ). The leading causes of death in adults with patent ductus aeriosus are cardiac failure and infective endocarditis; occasionally, severe pulmonary vascular obstruction may cause aneurysmal dilatation, calcification, and rupture of the ductus.