Some babies develop a condition called persistent patent ductus arteriosus (PDA) soon after birth. It occurs when a vessel – critical to blood circulation before birth but not necessary after birth – does not close as it should. Before birth, the vessel, called the ductus arteriosus, connects the two major arteries from the heart: the pulmonary artery, which carries blood from the heart to the lungs, and the aorta, which carries blood from the heart to the body. Before birth, the PDA diverts oxygen-containing blood from the placenta away from the lungs, which are collapsed, and carries it to the aorta to be distributed to the body.
When the baby is born and begins to breathe, the lungs provide oxygen to the blood instead of the placenta. The ductus arteriosus is supposed to close by itself within a few days. But in some babies it stays open (patent). When the PDA remains open, blood is able to flow directly from the aorta into the pulmonary artery, which delivers blood to the lungs. This flow is in the opposite direction from when the baby was in the womb. This causes extra blood flow to go to the lungs, can place strain on the heart, and increase the blood pressure in the lung arteries.
PDA affects about 3,000 infants each year in the United States, according to the National Heart, Lung and Blood Institute. The sixth most common heart defect, PDA is more common in premature (born too early) babies, but it also occurs in full-term infants. PDA is twice as common in girls as boys. The risk of PDA is increased at higher altitudes due to oxygen concentrations that are lower than at sea level.
PDA may be mild with no symptoms or ill effects. Or it may be serious, with symptoms that include difficulty breathing, shortness of breath, poor weight gain, and other symptoms of congestive heart failure (CHF).
Progression and Possible Complications
If a moderate or large PDA is not treated, extra strain is placed on the heart and lung vessels – irreversible damage to the blood vessels of the lungs can occur. If untreated, this damage can lead to death, typically in the fourth or fifth decade of life. Infection of the blood vessels may also occur. This condition, called bacterial endocarditis, may be life threatening.
In some babies born with PDA and with an otherwise normal heart, the vessel shrinks and closes on its own. In others, the PDA may need to be closed. Three options are available for closing the PDA: medications, a catheterization procedure and surgery.
When PDA causes congestive heart failure in the neonatal period (this is more likely in premature infants), medications such as indomethacin or ibuprofen given by IV may be prescribed. These medications work best in premature babies and typically do not work outside the neonatal period.
In infants born with certain other heart defects, doctors may actually want to keep the ductus arteriosus open to maintain blood flow to the body or lungs until surgery can be performed to repair the defective heart structures. Medication (prostaglandin E1) may be given to keep the vessel open.
Catheterization to Close the PDA
Doctors may choose to close a PDA using a procedure performed in the hospital’s catheterization lab, or “cath lab.” In this procedure, a small thin tube, or catheter, is inserted into a blood vessel at the top of the leg and threaded through the arteries to the ductus arteriosus. The doctor then delivers a small “occluding,” or closure, device through the catheter to the point at which the PDA that is connected to the pulmonary artery. There, the doctor implants the device to close the ductus arteriosus.
When neither medications nor catheterization closure are helpful in treating PDA, surgical closure may be chosen. The procedure is performed through a thoracotomy (surgical incision) in the side of the chest while the heart continues to beat.