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Patent Ductus Arteriosus

By Jeanne Marie Baffa, MD, Associate Professor of Pediatrics;Program Director, Pediatric Cardiology Fellowship and Director of Echocardiography, Sidney Kimmel Medical College at Thomas Jefferson University;Nemours/Afred I. duPont Hospital for Children

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 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. They are more likely to have symptoms, including trouble breathing (especially when feeding)

  • Treatment with ibuprofen or indomethacin often helps to close the PDA, particularly in premature infants. If drugs are not successful, surgery may be done.

  • In full-term newborns, treatment with drugs 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 because in these infants the PDA often closes on its own.

The ductus arteriosus is a blood vessel in the fetus that connects the two great arteries leaving the heart, the pulmonary artery and the aorta (see Normal Fetal Circulation). The ductus is a short-cut that allow blood from the veins to mix with blood that has already traveled to the lungs. In the fetus, because blood arriving at the heart has already received oxygen from the placenta, both venous blood and arterial blood contain oxygen, so mixing arterial blood and venous blood does not affect how much oxygen gets pumped to the body. This changes immediately after birth. When the umbilical cord is cut, the placenta (and therefore the mother's circulation) is no longer connected to the newborn's circulation, and all the newborn's oxygen comes through the lungs. Thus, the ductus arteriosus is no longer needed and usually closes within the first days of life. In the womb and during the 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, a left-to-right shunt develops, which means 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 will also cause high blood pressure in the lungs, which may eventually damage the blood vessels of the lungs. A patent ductus increases the risk of developing a serious heart infection, endocarditis.

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

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

  • 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.

Echocardiography (ultrasonography of the heart) confirms the diagnosis.

Electrocardiography (ECG) and chest x-rays are typically done. They may be normal or show an enlarged heart.

Treatment

  • Drugs to help close the ductus

  • Sometimes a plug or other specialized device inserted through a catheter, or surgery

Indomethacin or ibuprofen can be given to close a PDA. These drugs are most effective if given within the first 10 days after birth and are more effective in premature newborns than in full-term ones. Several doses may be given. If the PDA does not close after several doses, surgery may be done if there are signs that the PDA is harming the lungs and heart.

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 a PDA is still open by the time infants are 1 year 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 at the top of the child's leg. 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.

Some children need to take antibiotics before visits to the dentist and before certain surgeries (such as on the bowel or bladder). These antibiotics are used to prevent serious heart infections called endocarditis.

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