Patent ductus arteriosus anatomy
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor-In-Chief: Priyamvada Singh, M.B.B.S. [2], Cafer Zorkun, M.D., Ph.D. [3], Assistant Editor-In-Chief: Kristin Feeney, B.S. [4]
Overview
Patent ductus arteriosus is a heart condition that is normal but reverses soon after birth. In a persistent PDA, there is an irregular transmission of blood between two of the most important arteries (aorta and pulmonary artery) in close proximity to the heart. Although the ductus arteriosus normally seals off within a few days, in PDA, the newborn's ductus arteriosus does not close, but remains patent.
Anatomy
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 blood flow. 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.
Abormal Closure of Ductus Arteriosus
The abnormal closure of the ductus arteriosus results in patent ductus arteriosus. Patent ductus arteriosus is a heart condition that is normal but reverses soon after birth. In a persistent PDA, there is an irregular transmission of blood between two of the most important arteries in close proximity to the heart. Although the ductus arteriosus normally seals off within a few days, in PDA, the newborn's ductus arteriosus does not close, but remains patent. PDA is common in infants with persistent respiratory problems such as hypoxia, and has a high occurrence in premature children. In hypoxic newborns, too little oxygen reaches the lungs to produce sufficient levels of bradykinin and subsequent closing of the DA. Premature children are more likely to be hypoxic and thus have PDA because of their underdeveloped heart and lungs.In some babies, on the other hand, the ductus arteriosus remains open. This opening permits blood to surge unswerving starting from the aorta into the pulmonary artery.
A patent ductus arteriosus allows oxygenated blood to flow down its pressure gradient from the aorta to the pulmonary arteries. Thus, some of the infant's oxygenated blood does not reach the body, and the infant becomes short of breath. The heart rate hastens, thereby increasing the speed with which blood is oxygenated and delivered to the body. Left untreated, the infant will likely suffer from congestive heart failure, as his heart is unable to meet the metabolic demands of his body.
In some cases, such as in transposition of the great vessels (the pulmonary artery and the aorta), a PDA may need to remain open. In this cardiovascular condition, the PDA is the only way that oxygenated blood can mix with deoxygenated blood. In these cases, prostaglandins are used to keep the patent ductus arteriosus open.
Shown below is the image below shows the gross anatomy of heart with patent ductus arteriosus.
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