ABSTRACT. We determined whether closing the ductus arteriosus of the fetal lamb several d before birth would cause persistent pulmonary hypertension after birth. Six experimental fetuses who had their ductus arteriosus ligated 3-17 d before delivery, three control fetuses who had sham ligation of the ductus arteriosus 14 d before delivery, and six control fetuses who had no prenatal surgery were delivered by cesarean section between 138 and 144 d of gestation. Each was instrumented to measure pulmonary and systemic arterial pressures and pulmonary blood flow. Each newborn lamb was ventilated with room air during the first 45 min after birth and then with decreasing amounts of inspired oxygen from 108 to 9%. Pulmonary arterial pressure decreased significantly when ventilation was begun in the control lambs but not in the lambs who had their ductus arteriosus ligated before deliverv.Throughout the experiment, pulmonary arterial pressure and total pulmonary resistance were significantly higher, and pulmonary blood flow was significantly lower in the lambs who had their ductus arteriosus ligated before delivery. In two of them, pulmonary arterial pressure was greater than or equal to systemic arterial pressure, even during ventilation with 100% oxygen. This animal preparation provides a method of investigating persistent pulmonary hypertension in the newborn lamb and may provide insight into an etiology of the syndrome of persistent pulmonary hypertension of the newborn. (Pediatr Res 25:245-250,1989) sion? There are at least two major differences between the pulmonary circulation of the fetus and that of the adult during chronic hypoxia. In the fetus, right ventricular output is shunted away from the lungs across the ductus arteriosus (7, 8) and the peripheral, intraacinar arteries of the pulmonary ciruclation are not remodeled (9). Perhaps the diversion of right ventricluar output somehow protects the intraacinar arteries and prevents the development of persistent pulmonary hypertension (10, 1 1). There are reports of long-term survival of the fetus after closure of the ductus arteriosus (12, 13). We performed this study to determine whether closing the ductus arteriosus of the fetal lamb several d before birth would cause persistent pulmonary hypertension after birth. MATERIALS AND METHODSA total of 21 fetal lambs were used for this study. Term gestation in sheep is 146 d. Twelve experimental fetuses had their ductus arteriosus ligated when they were between 123 and 135 d of gestation, 3-17 d before delivery. Three control fetuses had sham ligation of the ductus arteriosus when they were 127 d of gestation, 14 d before delivery. Six control lambs had no surgery before delivery. Each surviving fetus was delivered between 138 and 144 d of gestation.Ligation and sham ligation of ductus arteriosus before delivery. Each of 15 pregnant ewes was induced into anesthesia with an intravenous injection of sodium thiamylal. Surgery was then performed under halothane anesthesia. The uterus was exvosed through a midline abdomin...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.