Persistent transitional circulation.

Six infants presented within 24 hours of birth with cyanosis. The clinical findings, combined with catheter studies in 4 cases, led to the conclusion that there was a persistent fetal direction of ductus arteriosus flow with pulmonary hypertension, i.e. a `persistent transitional circulation'. The occurrence was 1/1454 live births, and it is thus an important condition to recognize and differentiate from cyanotic congenital heart disease. 4 of the children went through the transition to a normal infant circulation with medical treatment alone, one died before this occurred, and one recovered after an exchange transfusion. The cause of the persistent transitional circulation is not clear, but it is probably the end result of several different pathological processes.