Ductus arteriosus closure

Associate Editor-In-Chief:; Keri Shafer, M.D. [mailto:kshafer@bidmc.harvard.edu] Priyamvada Singh, MBBS mailto:psingh@perfuse.org

Assistant Editor-In-Chief: Kristin Feeney, B.S. mailto:kfeeney@perfuse.org

Normal ductus arteriosus closure
In the developing fetus, the ductus arteriosus (DA) is a shunt connecting the pulmonary artery to the aortic arch that allows much of the blood from the right ventricle to bypass the fetus' fluid-filled lungs. During fetal development, this shunt protects the right ventricle from pumping against the high resistance in the lungs, which can lead to right ventricular failure if the DA closes in-utero.

When the newborn takes its first breath, the lungs open and pulmonary pressure decreases below that of the left heart. At the same time, the lungs release bradykinin to constrict the smooth muscle wall of the DA and reduce bloodflow. Additionally, because of reduced pulmonary resistance, more blood flows from the pulmonary arteries to the lungs and thus the lungs deliver more oxygenated blood to the left heart. This further increases aortic pressure so that blood no longer flows from the pulmonary artery to the aorta via the DA.

In normal newborns, the DA is closed within 15 hours after birth, and is completely sealed after three weeks. The fall in circulating maternal prostaglandins contributes to this. A nonfunctional vestige of the DA, called the ligamentum arteriosum, remains in the normal adult heart.