Patent ductus arteriosus is a congenital heart defect (present at birth).

Patent ductus arteriosus is a persistent opening between the two major blood vessels (the aorta and the pulmonary artery) leading from the heart. The pulmonary artery carries blood from the heart to the lungs, where the blood gets oxygenated. From the lungs, this oxygenated blood again returns to the heart. From the heart, this oxygen-rich blood is supplied to the body through the aorta.

In the womb, a temporary blood vessel (the ductus arteriosus) forms a normal part of a baby’s circulatory system. The fetus or the baby in the womb receives oxygen from the mother’s circulation. Therefore, the fetal heart is not dependent on the fetal lungs for oxygenating the blood. The ductus arteriosus directly connects the aorta and the pulmonary artery bypassing the lungs, thus streamlining the fetal circulation. After birth, the baby’s lungs take over the job of oxygenation of the blood. The body stops producing the chemicals required for keeping ductus arteriosus open. After birth, the ductus arteriosus usually closes within the first few hours or days.

When the ductus arteriosus remains open (patent), it is called patent ductus arteriosus or PDA.

How common is patent ductus arteriosus in India?

Patent ductus arteriosus is the second most common congenital heart defect after ventricular septal defect. According to studies, more than 80% of PDAs close themselves within eight weeks of birth. Persistent PDAs occur in about 1 in 2500 babies. The incidence of PDAs is more common in girls than boys (2:1).

How do patent ductus arteriosus can affect my child’s health?

The PDA allows the mixing of oxygen-rich blood (blood high in oxygen) in the aorta with the oxygen-poor blood (blood low in oxygen) in the pulmonary artery. Due to it, the pulmonary artery carries a higher amount of oxygen-poor blood into the lungs, thus putting a strain on the heart and increased blood pressure in the pulmonary arteries.

A small patent ductus arteriosus often remains asymptomatic, therefore not requiring any treatment. However, a large patent ductus arteriosus may cause weakening of the heart muscle leading to heart failure and other complications.

Larger, untreated defects could cause the following complications:

1. High blood pressure in the lungs- Since PDA causes too much blood circulating through the heart’s main arteries, it may lead to pulmonary hypertension. Pulmonary hypertension can cause permanent lung damage.
2. Heart failure – A PDA can cause weakening of heart muscles, eventually leading to heart failure.
3. Heart infection (endocarditis)- People with patent ductus arteriosus are at a higher risk of an infection or inflammation of the inner lining of the heart.

What are the common signs and symptoms of PDA?

The symptoms of patent ductus arteriosus may vary with the size of the defect and whether the baby is premature or has completed a full term. A small size defect might cause no symptoms and may go undetected until adulthood. A large size defect can cause signs and symptoms similar to heart failure soon after birth.

The first sign of PDA can be a distinct murmur (heart sound) which your doctor may detect during a regular examination of the baby’s heart with a stethoscope.

A baby with a large size PDA may have the following signs and symptoms:

• Lack of appetite or poor eating
• Sweating while eating or crying
• Persistent breathlessness
• Fatigue and malaise
• Rapid heart rate

What are the risk factors that may cause PDA?

Some factors that may increase the risk of PDA are:

1. Premature birth- A patent ductus arteriosus is more common in babies born before completing 37 weeks of pregnancy than the babies born after a full term.
2. Family history – A family history of heart defects increases the risk of PDA.
3. Presence of genetic conditions – Genetic conditions such as Down syndrome increase the chances of the baby having a PDA.
4. Infection- Rubella infection during pregnancy increases your baby’s risk of heart defects. The rubella virus can cross the placenta thus, damaging the baby’s blood vessels and major organs.

5. Female predilection- The incidence of patent ductus arteriosus is twice as common in females compared to males.

How is Patent Ductus Arteriosus (PDA) Diagnosed?

After detecting a distinct heart murmur using a stethoscope, a doctor may recommend the following tests to confirm PDA:

• Chest Xray
• ECG to measure the heart’s electrical activity
• Echocardiogram – An echo shows how big the opening is
• Blood Tests

What are the different ways of treating a PDA?

The treatment of PDA depends on the extent and severity of the defect.

Small size defects do not increase any pressure on the heart and lungs, therefore, warranting no medical or surgical interventions. They usually close on their own within few weeks of birth.

A PDA can be treated in 3 ways:

1. Medicine- For preterm babies, the cardiologists may prescribe some medicines to close the defect. But after few weeks, the medicines are not effective in closing the defect.
2. Catheter-based procedures- A cardiac surgeon inserts a catheter (long thin tube) through the blood vessels in the legs, reaches the heart and defect, and inserts a coil through this catheter to close the defect.
3. Surgery – Surgery is done when catheter-based procedures cannot close the defect.

Dr. Arun Bableshwar | Consultant – Cardiology – Paediatric | SDM Narayana Heart Centre, Dharwad