Patent ductus arteriosus (PDA) is the failure of a duct, or passageway, between two specific blood vessels to close. The blood vessels involved are the pulmonary artery and the aorta, two of the largest arteries in the body. It is a congenital heart disease, that is, a heart defect present at birth.
The pulmonary artery carries blood to the lungs. The aorta receives all the blood from the left ventricle of the heart and sends it to the rest of the body. In the normal heart, the passageway that connects these two blood vessels, called the ductus arteriosus, closes soon after birth. The closing of the duct helps keep the blood flowing in the right direction.
If the duct does not close, patent ductus arteriosus results. In PDA, some of the blood flows out of the aorta through the duct into the pulmonary artery instead of going to the rest of the body. This forces the lungs and heart to work much harder.
Serious cases of patent ductus arteriosus are diagnosed at birth. The infant will have abnormal pulses and heart murmurs that can be found during a physical exam. Sometimes a person with patent ductus arteriosus has no symptoms until middle age. In severe cases, the strain on the heart and lungs can cause congestive heart failure, a condition in which the weakened heart cannot pump blood effectively.
The cause of patent ductus arteriosus is unknown. One theory about the cause of PDA has to do with the action of a chemical made by the body. In the normal heart, levels of this chemical drop, and the duct closes soon after birth. But in PDA, the chemical remains active, and the duct stays open. Infection with the rubella virus has also been associated with a higher risk of developing PDA.
Proper vaccination with the MMR vaccine may minimize the incidence of PDA that is rubella-related. In most cases, nothing can be done to prevent PDA.
Tests used to diagnose patent ductus arteriosus include: electrocardiogram (ECG) echocardiogram, an ultrasound of the heart and its major blood vesselschest X-rays cardiac catheterization, a special X-ray of the heart made using a contrast media
These tests show the size of the heart and the amount of blood flowing through the duct.
Long-term effects depend on the severity of the patent ductus arteriosus. Sometimes no effects are noticed until adulthood. In other cases, the duct closes by itself. But if the defect places too much strain on the heart, congestive heart failure and congestion in the lungs can result.
Patent ductus arteriosus is not contagious, and poses no risk to others.
Milder cases of PDA are treated with medications as needed. Over time, the duct will often close by itself.
If time and medications fail to close a PDA, open heart surgery may be needed. Newborns with severe PDA may need surgery in the first month of life. In those with less severe forms of PDA, surgery can be postponed for several months or even years.
The medications may cause allergic reactions, stomach upset, and other side effects. Surgery can be complicated by bleeding, infection, and reactions to anesthesia.
There are usually few problems after recovery from PDA closure.
The person needs to make routine visits to the healthcare professional, so that any ongoing, new, or worsening symptoms can be monitored.
Merck Manual, 1999, Beers et al.
Harrison's Principles of Internal Medicine, 1997, Fauci et al.
Current Medical Diagnosis and Treatment, 1996, Tierney et al.
