In patent ductus arteriosus (PDA), the blood vessel connecting the pulmonary artery and the aorta (ductus arteriosus) fails to close as it usually does shortly after birth.
Patent ductus arteriosus is a heart defect that occurs when the normal channel between the pulmonary artery and the aorta in the fetus does not close at birth.
Often there are no symptoms, and the diagnosis is suspected based on a heart murmur the doctor hears with a stethoscope.
Premature newborns are especially susceptible to patent ductus arteriosus and are more likely to have symptoms, including trouble breathing (especially when feeding).
In full-term newborns, treatment with medications is less likely to be successful, especially since these infants are usually a bit older when the diagnosis of PDA is made. Unless they have symptoms, surgical treatment is often delayed beyond one or two years of age because the ductus arteriosus may close on its own.
(See also Overview of Heart Defects.)
The ductus arteriosus is a blood vessel that connects the two great arteries leaving the heart, the pulmonary artery and the aorta (see Normal Fetal Circulation). The ductus allows blood to bypass the fetus's not-yet-functioning lungs by traveling from the pulmonary artery to the aorta and out to the fetus's body. In the fetus, blood arriving at the heart has received oxygen from the placenta. This oxygenated blood can be delivered to the body through two connections, the foramen ovale and ductus arteriosus. Immediately after birth, these connections close. Also, when the umbilical cord is cut, the newborn no longer receives blood from the placenta, and all oxygen must come through the infant's lungs. Thus, the ductus arteriosus is no longer needed and usually closes within the first days of life.
While the fetus is in the womb and during the newborn's first few days of life, the ductus is open. In patent ductus arteriosus (patent is a medical term that means open), the ductus stays open. When the ductus stays open after birth, the direction of flow through the ductus reverses and a left-to-right shunt develops. This means that some blood in the aorta that has already picked up oxygen from the lungs goes back through the ductus and into the pulmonary artery, which causes extra blood flow into the lungs.
A patent ductus arteriosus that is moderate or large also causes high blood pressure in the lungs, which may eventually damage the blood vessels of the lungs. A patent ductus increases the risk of developing endocarditis, a serious heart infection.
Patent Ductus Arteriosus: Failure to Close
The ductus arteriosus is a blood vessel that connects the pulmonary artery and the aorta. In the fetus, it enables blood to bypass the lungs. The fetus does not breathe air, and thus blood does not need to pass through the lungs to be oxygenated. After birth, blood does need to be oxygenated in the lungs, and normally the ductus arteriosus closes quickly, usually within days up to 2 weeks. In patent ductus arteriosus, this connection does not close, allowing some oxygenated blood, intended for the body, to return to the lungs. As a result, the blood vessels in the lungs may be overloaded and the body may not receive enough oxygenated blood. |
Symptoms of Patent Ductus Arteriosus
A small patent ductus arteriosus often causes no symptoms. When a PDA is larger, it may cause rapid or labored breathing, especially in premature infants with immature lungs. Blood pressure may be low. Some infants have difficulty feeding and poor growth.
Diagnosis of Patent Ductus Arteriosus
Echocardiography
Doctors often suspect a patent ductus if they hear a certain kind of heart murmur while listening with a stethoscope. A heart murmur is a sound created by turbulent blood flow through narrowed or leaking heart valves or through abnormal heart structures. In older children, the murmur has been described as sounding like a washing machine. In premature infants, the heart murmur may be less distinct. The pulses are often increased in the presence of a patent ductus arteriosus, and the pulse is sometimes described as bounding.
Echocardiography (ultrasonography of the heart) confirms the diagnosis.
Electrocardiography (ECG) and chest x-rays are typically done. Results may be normal, or they may show an enlarged heart.
Treatment of Patent Ductus Arteriosus
Medication to help close the ductus
Sometimes a plug or other specialized device inserted through a catheter, or surgery
In full-term newborns and infants who do not have symptoms, doctors may allow time for the PDA to close on its own before they suggest treatment.
If the ductus arteriosus is still open by the time infants are 1 or 2 years of age, it is extremely unlikely to close on its own. At that time, doctors usually recommend a procedure to close the PDA to eliminate the risk of endocarditis.
In most cases, doctors close the patent ductus arteriosus by inserting a small device or coil during cardiac catheterization. During this procedure, the closure device is attached to the end of a long, thin tube (catheter). The catheter is inserted into the large vein in the groin. The catheter is carefully pushed up through the blood vessel until it reaches the heart and then advanced a little further until the tip with the device is in the ductus. Once the device is in the proper location, it is expanded to close the ductus.
Occasionally, particularly when the ductus is unusually large, doctors do surgery to close the ductus.
Children need to take antibiotics before visits to the dentist and before certain surgeries (such as on the respiratory tract), during the first 6 months after closure of the ductus. Sometimes antibiotics are needed for a longer time if surgery is unable to completely close the ductus. These antibiotics are used to prevent a serious heart infection called endocarditis.
More Information
The following English-language resources may be useful. Please note that THE MANUAL is not responsible for the content of these resources.
American Heart Association: Common Heart Defects: Provides an overview of common birth defects of the heart for parents and caregivers
American Heart Association: Infective Endocarditis: Provides an overview of infective endocarditis, including summarizing antibiotic use, for parents and caregivers
