Patent ductus arteriosus (PDA) is a congenital heart defect wherein a child's ductus arteriosus fails to close after birth. Symptoms are uncommon but in the first year of life include increased work of breathing and poor weight gain. In older children or adults the PDA may lead to congestive heart failure if left uncorrected.
When the newborn takes its first breath, the lungs open and pulmonary vascular resistance decreases. After birth also the lungs release bradykinin to constrict the smooth muscle wall of the DA and reduce bloodflow through the DA as it narrows and completely closes, usually within the first few weeks of life. In most newborn infants with a patent ductus arteriosus the blood flow is reversed from that of in utero flow, ie. the blood flow is from the higher pressure aorta to the now lower pressure pulmonary arteries.
In normal newborns, the DA is substantially closed within 12-24 hours after birth, and is completely sealed after three weeks. The fall in circulating maternal prostaglandins contributes to this. The residual scar tissue from the fibrotic remnants of DA, called the ligamentum arteriosum, remains in the normal adult heart.
A patent ductus arteriosus allows that portion of the oxygenated blood from the left heart to flow back to the lungs (following the pressure gradient from the higher pressure aorta to the pulmonary arteries). If this shunt amount is substantial, the infant becomes short of breath because there is not only the normal amount of unoxygenated blood that has returned from the body to go to the lungs but in addition there is the amount shunted through the PDA. The infant's work of breathing is increased, using up more calories and often interfering with feeding in infancy. This condition as a constellation of findings is called congestive heart failure.
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.
A chest X-ray may be taken, which reveals the overall size of infant's heart (as a reflection of the combined mass of the cardiac chambers) and the appearance of the blood flow to the lungs. A small PDA most often shows a normal sized heart and normal blood flow to the lungs. A large PDA generally shows an enlarged cardiac silhouette and increased blood flow to the lungs.
In certain cases it may be beneficial to the newborn to prevent closure of the ductus arteriosus. For example, in transposition of the great vessels a PDA may prolong the child's life until surgical correction is possible. The ductus arteriosus can be induced to remain open by administering prostaglandin analogs such as alprostadil (a prostaglandin E1 analog).
Recent days PDA can be closed by percutaneous interventional method, through femoral vein or femoral artery, a coil can be placed with the help of myocardial forceps to make an embolus, which closes the PDA without any surgery.