Patent ductus arteriosus (PDA) is a condition in which a blood vessel called the ductus arteriosus fails to close normally in an infant soon after birth. (The word "patent" means open.)

The condition leads to abnormal blood flow between the aorta and pulmonary artery, two major blood vessels surrounding the heart.

Before birth, the ductus arteriosus allows blood to bypass the baby's lungs by connecting the pulmonary arteries (which supply blood to the lungs) with the aorta (which supplies blood to the body). Soon after the infant is born and the lungs fill with air, this blood vessel is no longer needed. It will usually close within a couple of days. If the ductus arteriosus does not close, there will be abnormal blood circulation between the heart and lungs.

PDA is rare. It affects girls more often than boys. The condition is more common in premature infants and those with neonatal respiratory distress syndrome. Infants with genetic disorders, such as Down syndrome, and whose mothers had German measles (rubella) during pregnancy are at higher risk for PDA.

PDA is common in babies with congenital heart problems, such as hypoplastic left heart syndrome, transposition of the great vessels, and pulmonary stenosis.

A small PDA may not cause any symptoms. However, most infants do not tolerate a PDA and may have symptoms such as:

• Bounding pulse
• Fast breathing
• Poor feeding habits
• Shortness of breath
• Sweating while feeding
• Tiring very easily
• Poor growth

Babies with PDA often have a characteristic heart murmur that can be heard with a stethoscope. However, in premature infants, a heart murmur may not be heard. Doctor's may suspect the condition if the infant has breathing or feeding problems soon after birth.

Changes may be seen on chest x-rays. The diagnosis is confirmed with an echocardiogram.

Sometimes, a small PDA may not be diagnosed until later in childhood.

The goal of treatment, if the rest of circulation is normal or close to normal, is to close the PDA. In the presence of certain other heart problems, such as hypoplastic left heart syndrome, the PDA may actually be lifesaving.

Sometimes, a PDA may close on its own. Premature babies have a high rate of closure within the first 2 years of life. In full-term infants, a PDA rarely closes on its own after the first few weeks.

When treatment is appropriate, medications such as indomethacin or a special form of ibuprofen are generally the first choice.

If these measures do not work or can't be used, a medical procedure may be needed.

A transcatheter device closure is a minimally invasive procedure that uses a thin, hollow tube. The doctor passes a small metal coil or other blocking device through the catheter to the site of the PDA. This blocks blood flow through the vessel. Such endovascular coils have been used successfully as an alternative to surgery.

There is no agreement about which young babies are most likely to benefit from surgery if medications are not going to help, and which babies would be better off untreated. Surgery may be needed if the catheter procedure does not work or cannot be used. Surgery involves making a small cut between the ribs to repair the PDA. Surgical treatment of PDAs may be performed on older children even if they have no symptoms because the PDA will not close by itself.

If a small PDA remains open, heart symptoms may or may not eventually develop. Persons with a moderate or large PDA will usually develop heart problems sooner or later unless the PDA is closed.

Closure with medications can work very well in some situations, with few side effects. Early treatment with medications is more likely to be successful.

Surgery carries its own significant risks. It may eliminate some of the problems of a PDA, but it can also introduce a new set of problems. The potential benefits and risks should be weighed carefully before choosing surgery.

If the patent ductus is not closed, the infant has a risk of developing heart failure, bleeding in the lungs, problems with lung development, or infective endocarditis -- an infection of the inner lining of the heart.

This condition is usually diagnosed by a doctor examining your infant. Breathing and feeding problems in an infant can occasionally be due to an undiagnosed PDA.

Preventing preterm deliveries, where possible, is the most effective way to prevent PDA.

Zipes DP, Libby P, Bonow RO, Braunwald E, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine, 8th ed. St. Louis, Mo; WB Saunders; 2007.