[New aspects on the pathogenesis of patent ductus arteriosus in premature infants].

It is generally accepted that vasodilator prostaglandins are involved in the pathogenesis of persistent ductus arteriosus (PDA) in preterm infants suffering from respiratory distress syndrome (RDS). When studying the prostaglandin metabolism it became apparent that in about 80% of these infants the activity of PGI2 and/or PGE2 was increased. In parallel to weaning infants from the respirator a decrease in prostaglandin activity was observed which was associated with ductal closure. The inhibition of prostaglandin synthesis with indomethacin had the same effect. Considering the various lines of evidence that an artificially ventilated lung is releasing vasodilatory prostaglandins into the circulation we postulated the following sequence of events in the pathogenesis of PDA in preterm infants: development of RDS or other pulmonary lesions which require artificial ventilation; this mechanical intervention causes permanent shear stress and barotrauma on the pulmonary tissue; this stress causes release of arachidonic acid from phospholipids; subsequently vasodilatory prostanoids, such as PGI2 and PGE2 are released and reach the pulmonary circulation and the ductus arteriosus. As a consequence the left-to-right shunt causes pulmonary hypercirculation with further need to continue artificial ventilation. A vicious circle is established. This circle can be broken by ductus ligation, by indomethacin treatment, by less traumatic artificial ventilation or by early weaning from the respirator with theophylline.