Patent Ductus Arteriosus (PDA)

How the ductus arteriosus works

Before birth, a baby does not breathe air, so most blood bypasses the lungs. The ductus arteriosus carries blood from the pulmonary artery directly into the aorta. After birth, when the baby starts breathing and oxygen levels rise, the ductus normally closes within the first few days of life.

If it stays open, blood flows the other way, from the high-pressure aorta into the pulmonary artery. The lungs receive extra blood, and the left side of the heart has to pump more. A large PDA can cause heart failure, and over years, lung blood vessel damage (pulmonary hypertension).

Causes and risk factors

• Prematurity: the most important factor. The ductus is less responsive to the signals that close it, and many very premature babies have a PDA.
• Breathing problems in newborns
• Genetic conditions such as Down syndrome
• Maternal rubella infection during pregnancy
• Birth at high altitude
• Other heart defects: PDA can occur with atrial septal defect, ventricular septal defect and others. In some complex heart defects, the PDA must be kept open with medicine until surgery because it is supplying vital blood flow

Symptoms

Small PDA

Often no symptoms. It may only be found as a murmur during a checkup.

Large PDA

• Fast or labored breathing
• Poor feeding, tiring or sweating during feeds
• Slow weight gain (poor weight gain)
• Fast heart rate
• Frequent respiratory infections
• In premature babies: difficulty coming off breathing support, and low blood pressure

Older children and adults

A moderate PDA may cause breathlessness or tiredness with exercise and palpitations. Untreated large PDAs can lead to heart failure and pulmonary hypertension.

Diagnosis

• Heart murmur: a continuous "machinery-like" murmur under the left collarbone is typical, though premature babies may have a different sound.
• Bounding pulses and a wide pulse pressure.
• Echocardiogram: ultrasound of the heart is the main test. It shows the PDA, its size and direction of blood flow, and its effect on the heart.
• Chest X-ray and ECG may show heart enlargement or strain.
• Cardiac catheterization is sometimes used, often at the same time as closure.

Treatment

Watchful waiting

Many PDAs in premature babies close on their own within weeks. Small PDAs in full-term babies may close within the first year. Babies are monitored with repeated echocardiograms.

Medicines (premature babies)

Ibuprofen, indomethacin or acetaminophen given by a neonatal team can help close the ductus in some premature babies. These are used under hospital supervision and are not effective in full-term babies.

Catheter device closure

A thin tube is passed through a blood vessel in the leg to the heart, and a small plug or coil is placed to close the PDA. This is the usual treatment for older infants, children and adults, and is now also used in some premature babies. Recovery is quick.

Surgical closure

The PDA is tied off or clipped through a small incision in the side of the chest. It is used for small premature babies when other treatments are not suitable or have failed.

Supportive care

Fluid management, diuretics, extra calories for growth, and breathing support as needed.

Complications

• Heart failure
• Pulmonary hypertension and, rarely if untreated for many years, Eisenmenger syndrome, where blood flow reverses and causes blue skin
• Endocarditis, an infection of the heart lining (see endocarditis)
• In premature babies, a large PDA is linked to chronic lung disease and bowel problems

Outlook

The outlook is excellent for most children. A PDA that closes on its own, or is closed by medicine, catheter or surgery, usually allows a normal, active life with no restrictions. Long-term follow-up depends on the size of the PDA and any other heart conditions.

Frequently asked questions

What is patent ductus arteriosus?

Patent ductus arteriosus is a condition in which a blood vessel that connects the aorta and pulmonary artery before birth stays open after birth. Extra blood flows to the lungs, which can make the heart and lungs work harder. It is especially common in premature babies.

Does PDA close on its own?

Often, yes. Many PDAs in premature babies close within days to weeks, and small PDAs in full-term babies can close during the first year. Larger PDAs that persist or cause symptoms usually need closure with medicine, a catheter device or surgery.

What are the symptoms of PDA in babies?

A small PDA may cause no symptoms. A large PDA can cause fast or labored breathing, poor feeding, sweating during feeds, slow weight gain, a fast heart rate and frequent chest infections. A doctor may hear a heart murmur.

Is PDA closure surgery safe?

Yes. Catheter device closure and surgical closure are well-established, safe procedures with high success rates. Catheter closure avoids open surgery and usually allows a quick recovery. The approach depends on the child's size, age and the PDA's shape.