Definition

Patent ductus arteriosus (PDA) is an abnormal opening between the aorta (the largest artery in the body) and the pulmonary artery. This opening is called the ductus arteriosus, which is part of the fetal circulatory system and should close shortly after birth. If the ductus arteriosus remains open, the condition is referred to as patent ductus arteriosus. This condition is commonly seen in about 5-10% of all congenital heart disease patients in infants.

Causes

The ductus arteriosus is an opening that connects the aorta and the pulmonary artery in the fetal circulatory system. It functions to divert blood away from the lungs, as the fetal lungs are still developing and not yet involved in gas exchange. Instead, the fetus receives oxygen from the mother's blood.

Every baby is born with a ductus arteriosus. After birth, this opening is no longer needed, so it typically narrows and closes within a few days. In premature infants, the closure may take longer than in full-term babies. Furthermore, the failure of the ductus arteriosus to close is more common in premature infants. In most cases of PDA, the exact cause is unknown.

This condition causes too much blood to flow to the lungs and heart. If untreated, the increased pressure in the lungs can lead to heart enlargement. This enlargement can weaken the heart muscles and worsen the condition.

Risk Factor

Risk factors for PDA include:

• Premature birth. Failure of the ductus arteriosus to close is more common in premature babies.
• Family history and other genetic conditions. A family history of congenital heart disease and genetic conditions like Down syndrome increases the risk of PDA.
• Rubella infection during pregnancy. If a mother is infected with German measles (rubella) during pregnancy, the fetus has a higher risk of developing PDA. The rubella virus can cross the placenta and enter the baby’s bloodstream, damaging the baby’s circulatory system, including the heart.
• High-altitude birth. Babies born at altitudes above 2,500 meters have a higher risk of PDA than those born at lower altitudes.
• Female gender. PDA is twice as common in female infants as in male infants.

Symptoms

A small patent ductus arteriosus may not cause symptoms because the heart and lungs do not need to work harder. However, if the opening is large, the baby may breathe faster and with more difficulty than a healthy baby. The baby may also have difficulty feeding and tire easily, which can lead to delayed growth. These symptoms may not appear until several weeks after birth.

Other symptoms may include high blood pressure in the lungs due to the excessive blood flow. If untreated, damage to the pulmonary arteries can occur.

Diagnosis

PDA can be identified by a number of tests and symptoms. A doctor may initially notice the condition by listening to the baby's heart sounds if the PDA is small enough. PDA is an opening that shouldn't exist, which results in extra heart sounds, such as heart murmurs. Both soft and loud heart murmurs are possible.

Radiological and laboratory tests are additional available tests. It is possible to conduct laboratory tests such as electrocardiography, blood gas analysis, and complete blood count. It is possible to perform a complete blood count to determine the baby's blood cell levels, which may reveal the presence of congenital heart disease, PDA, or other conditions. In the meantime, babies without heart damage may have normal blood gas analysis results. Blood gas analysis results may indicate elevated blood acidity and low oxygen levels in infants or children who have suffered heart damage. Heart recording, or electrocardiography (ECG) examination, is highly dependent on the size of the PDA. If the PDA is small, the examination results may be normal. However, in large PDAs, the ECG may reveal an enlarged heart.

Chest X-rays, Doppler echocardiography, catheterization, and angiography are all possible imaging tests. Chest X-rays use X-rays emitted into the patient's chest to reveal the contents of the chest cavity. If the PDA has been present for a long time and is large, the results of this examination may be consistent with the presence of an enlarged heart. Unfortunately, this examination cannot display the PDA directly. Meanwhile, Doppler echocardiography uses sound waves and color to determine the origin of blood flow. Echocardiography can detect PDA.

Catheterization and angiography are not required unless complications are present, as these procedures are typically used in conjunction with treatment. Catheterization involves inserting a tube into a blood vessel, and angiography visualizes blood flow through the vessel. These procedures allow doctors to measure the size of the ductus arteriosus and oxygen levels and detect other heart and blood vessel abnormalities.

Management

Treatment for PDA depends on its size and severity. Small PDAs usually don’t require intervention since they cause no symptoms and may close on their own in the first few months of life. In premature infants, medications may be used to close the PDA. These medications are safe for infants but must be prescribed by a doctor.

If the PDA needs to be closed, doctors typically perform catheterization and angiography to plan the closure. A small device, such as a plug, is inserted through a tube into the ductus arteriosus to block the blood flow.

Another option is surgery. Surgeons will make a small incision on the left side of the chest, between the ribs, and tie off or clip the ductus arteriosus to close it. If no other heart defects are present, this restores normal blood flow.

After catheterization or surgery, your child may need regular checkups to monitor their growth. Children treated for PDA generally grow normally and do not require further medication or intervention.

Complications

Complications of untreated large PDA include:

• Pulmonary hypertension (high blood pressure in the lungs). Excessive blood flow through the pulmonary arteries can lead to long-term damage, and in severe cases, Eisenmenger syndrome may develop. This irreversible condition causes high lung pressure and cyanosis (bluish skin due to low oxygen levels).
• Heart failure. PDA can cause heart enlargement and muscle weakening, leading to heart failure, a condition where the heart cannot pump blood effectively.
• Heart infection (endocarditis). People with structural heart defects, such as PDA, are at higher risk for heart inflammation caused by infection.

Prevention

Preventing PDA involves maintaining a healthy pregnancy, which includes:

• Attending antenatal care, even before pregnancy. Before pregnancy, consult a doctor to stop smoking, reduce stress, and stop contraceptive use. Discuss any medications you can take during pregnancy.
• Good nutrition. Eating a nutritious diet and taking folic acid supplements ensure healthy fetal development.
• Regular exercise. Consult your doctor for a suitable exercise plan.
• Avoid risks. Avoid alcohol, smoking, illegal drugs, and high-temperature environments like hot tubs and saunas.
• Prevent infections. Ensure your immunizations are up to date before pregnancy. Some infections, preventable by vaccines, can harm fetal development.
• Manage blood sugar levels. If you have type II diabetes, consult your doctor about controlling your blood sugar before pregnancy.

When to See a Doctor?

Seek medical attention if your baby or child shows the following symptoms:

• Fatigue during feeding, eating, or playing
• Inadequate weight gain or weight loss
• Shortness of breath during feeding or crying
• Rapid or labored breathing

These symptoms may indicate congenital heart disease, including PDA or other conditions. Prompt medical evaluation can lead to timely treatment, improving your child’s future growth and development.

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