Persistent fetal circulation
The circulation of blood in the fetus is somewhat different from that of the baby after birth. This transition from fetal to neonatal circulation is one of the major physiologic changes after delivery. Before birth, the lungs are collapsed and the blood pressure in the lungs is quite high. This results in a very low blood flow through the lungs. After delivery, the lungs expand and the blood pressure in the lungs decreases.
In some babies, although the lungs expand the blood vessels in the lungs remain constricted resulting in persistently high blood pressure in the lungs. This reduces the amount of blood that the infant can pump through the lungs. This decreased blood flow through the lungs after birth is called persistent fetal circulation because it is a persistence of the pattern of blood flow normally seen prior to birth during the fetal period.
Infections, malformations of the lung or diaphragm, and lung immaturity can all cause persistent fetal circulation. This is a very serious, although infrequent, newborn problem. Several new treatments for persistent fetal circulation have been developed in the past few years and have increased survival of infants with this problem. The more medically correct name for persistent fetal circulation is persistent pulmonary hypertension.
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