PDA (Patent ductus arteriosus) and the premature baby

What is it?

When a baby is growing in the womb, it receives oxygen via the umbilical cord from the placenta. The ductus arteriosus (DA) is a naturally occurring “short cut” between two major blood vessels coming out of different sides of the baby’s heart. It allows blood in the pulmonary artery (which leads to the lungs) to bypass the baby’s lungs, which are not yet functioning, and flow directly into the aorta, which sends the blood to other parts of the body, and also back out to the placenta for re-oxygenation.

After a baby is born and starts breathing, its lungs expand and blood flows into them. The short cut is no longer required and the lungs give out a hormone which constricts the duct, and it usually closes completely within days or weeks of the birth.

PDA, patent (persistent) ductus arteriosus, occurs when the duct fails to close after the baby is born.

Why does it occur?

PDA is common in premature children because their heart and lungs are underdeveloped and they are not able to produce sufficient levels of the hormone to close the DA.

Why is it a problem?

If the ductus fails to close, blood flows from the high-pressure aorta into the lower-pressure pulmonary artery (the reverse of the flow in the womb) and increases the amount of blood flowing into the lungs. As a result of the increased workload on the heart and lungs, the baby may be breathless and tired and show poor weight gain. In premature babies, PDA can complicate respiratory problems.

How is it treated?

Small PDAs may not require treatment or may close without treatment. In premature babies, an aspirin-type drug called indomethacin is often given. If a PDA does not respond to medication, surgery may be needed.

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This is one of a series of articles I’ve written for the L’il Aussie Prems newsletter under the heading of Premmie Health. Read my disclaimer here.