Patent Ductus Arteriosus (PDA)

What is patent ductus arteriosus (PDA)?
Patent ductus arteriosus (PDA) is a condition in which the connecting blood vessel between the pulmonary artery and the aorta in fetal circulation, called the ductus arteriosus, stays open in a newborn baby.

Because the placenta does the work of exchanging oxygen (O2) and carbon dioxide (CO2) through the mother's circulation, the fetal lungs are not used for breathing. Instead of blood flowing to the lungs to pick up oxygen and then flowing to the rest of the body, the fetal circulation shunts (bypasses) most of the blood away from the lungs. In the fetus, blood is shunted from the pulmonary artery to the aorta through the ductus arteriosus. However, with the first breaths of air the baby takes at birth, the fetal circulation changes. A larger amount of blood is sent to the lungs to pick up oxygen. Because the ductus arteriosus is no longer needed, it normally begins to wither and close off.

What causes patent ductus arteriosus?

Some babies are more likely to have PDA, especially premature babies. Babies with respiratory problems at birth may have a difficult time increasing the pressure inside the lungs and changing the blood flow. PDA is also a common congenital (present at birth) heart defect and may occur along with other heart defects. It is twice as common in females as in males.

Why is patent ductus arteriosus a concern?

Problems are more likely to occur if the opening of the PDA is large. The shunting causes too much blood to flow to the lungs and not enough to the other parts of the body. There may be changes in the blood pressure, and the heart may enlarge as it tries to make up for the abnormal blood flow. Babies with PDA may be at risk for infection or inflammation of the arteries. Severe PDA can cause slow growth, and may result in heart failure. In premature babies, PDA can complicate respiratory problems, making the distributing of oxygen more difficult.

What are the symptoms of patent ductus arteriosus?

Babies with small PDAs may not have any observable symptoms, but those with a larger opening often do. The following are the most common symptoms of PDA. However, each baby may experience symptoms differently. Symptoms may include:

Strong pulses.
Heart murmur.
Enlarged heart size.
Respiratory difficulty.
Cyanosis (blue coloring).

The symptoms of PDA may resemble other conditions or medical problems. Always consult your baby's physician for a diagnosis.

How is patent ductus arteriosus diagnosed?

In addition to a complete medical history and physical examination (especially listening to the heart for sounds of the murmur that are common with PDA), diagnostic procedures may include:

Electrocardiogram - a test that records the electrical activity of the heart, shows abnormal rhythms and, detects heart muscle damage.
X-ray - a diagnostic test which uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs onto film.
Echocardiogram - a noninvasive test that uses sound waves to produce a study of the motion of the heart's chambers and valves.
Cardiac catheterization (when other heart defects are suspected) - a test in which a small catheter (hollow tube) is guided through a vein or artery into the heart to help see any defects on x-ray.

Treatment of patent ductus arteriosus:

Specific treatment for patent ductus arteriosus will be determined by your baby's physician based on:

Your baby's gestational age, overall health and medical history.
Extent of the disease.
Your baby's tolerance for specific medications, procedures or therapies.
Expectations for the course of the disease.
Your opinion or preference.

Small PDAs may not require treatment or may close without treatment.

In premature babies, an aspirin-type drug called indomethacin is often given. Indomethacin has been shown to be very effective in causing the PDA to close. Further studies are being done to find out if it will also help prevent PDA in babies at risk for the condition.

If a PDA does not respond to medication, or is due to causes other than prematurity, surgery may be needed. This surgery is called ligation and involves placing a suture around the ductus to close it.

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