Patent Ductus Arteriosus

Patent ductus arteriosus is a heart condition where a blood vessel that should close shortly after birth remains open, allowing extra blood to flow to the lungs and putting strain on the heart.

Table of contents

• What is Patent Ductus Arteriosus?
• Who is Affected by PDA?
• What Causes PDA?
• Signs and Symptoms
• How is PDA Diagnosed?
• Treatment Options
• Outlook and Prognosis

What is Patent Ductus Arteriosus?

Patent ductus arteriosus, or PDA, is a heart condition that affects babies, particularly those born prematurely. It happens when a special blood vessel called the ductus arteriosus does not close as it should after birth.^[1]

Before a baby is born, the ductus arteriosus is a normal and necessary blood vessel. It connects two major arteries: the aorta (which carries blood from the heart to the body) and the pulmonary artery (which carries blood from the heart to the lungs). While in the womb, the baby gets oxygen directly from the mother’s placenta, so the lungs are not used. The ductus arteriosus carries blood away from the lungs and sends it directly to the body.^[3]

When a newborn breathes and begins to use the lungs, the ductus arteriosus is no longer needed. In most babies, it closes by itself during the first two days after birth.^[3] If the ductus does not close, the result is a patent (meaning “open”) ductus arteriosus.

When a baby has PDA, the ductus arteriosus does not close properly, leaving a small opening. This opening allows extra blood from the aorta to enter the baby’s lung arteries. The PDA lets oxygen-rich blood from the aorta mix with oxygen-poor blood in the pulmonary artery. As a result, too much blood flows into the lungs, which puts strain on the heart and increases blood pressure in the pulmonary arteries.^[3]

A small PDA may not cause any problems and might close on its own by the time the child is one year old. However, if the PDA is large, it can cause too much blood to flow to the lungs. The blood vessels and lungs have to work much harder to handle the extra blood, which can lead to fluid buildup in the lungs and make breathing and feeding difficult for the baby.^[3]

Who is Affected by PDA?

Patent ductus arteriosus is the most common heart condition in newborns. In term infants (babies born at full term), PDA accounts for 5 to 10% of all congenital heart disease, with a reported incidence of only 1 in 2,000 births.^[6] However, the condition is much more common in premature babies.

The risk of PDA increases dramatically the earlier a baby is born. About 10% of babies born between 30 and 37 weeks of pregnancy have PDA. This number rises to 80% for babies born between 25 and 28 weeks, and reaches 90% for babies born earlier than 24 weeks of pregnancy.^[4] The occurrence of PDA is inversely related to gestational age and weight, meaning the more premature and smaller the baby, the higher the risk.^[6]

PDA affects twice as many girls as boys.^[3] The condition is also more likely to stay open in premature infants, particularly those with lung disease.^[3]

What Causes PDA?

The exact cause of PDA is not fully known, but researchers believe that genetics might play a role.^[3] Several factors can increase the risk of a baby developing PDA.

PDA is more common in babies born prematurely. In premature infants, the condition is associated with immaturity, as normal physiologic mechanisms that contribute to closure—such as oxygen tension and decreased prostaglandins—are altered in prematurity.^[6]

Other risk factors include:

• Neonatal respiratory distress syndrome: Babies whose lungs did not get enough lubricating substance (surfactant) before birth may develop this breathing problem and also have a higher risk of PDA.^[4]
• German measles during pregnancy: Babies born to mothers who had rubella (German measles) during pregnancy may have a higher risk of PDA.^[4]
• Genetic disorders: PDA is more common among babies with genetic disorders such as Down syndrome.^[3]
• High volume of intravenous fluids: Receiving more than 170 mL/kg per day in the first week of life can increase the risk.^[10]
• Sepsis: Infection can increase the likelihood of PDA.^[10]

Signs and Symptoms

PDA symptoms vary depending on the size of the opening and the person’s age. A small PDA might not cause any symptoms. Some people do not notice symptoms until adulthood.^[1] Small PDAs may only cause a heart sound called a murmur that can be heard through a stethoscope.^[4]

A large PDA found during infancy or childhood can cause symptoms of heart failure soon after birth. Babies with a large PDA might experience:^[1][3]

• Poor eating, which leads to poor growth
• Sweating with crying or eating
• Constant fast breathing or being out of breath
• Easy tiring
• Rapid heart rate
• A bounding (strong and forceful) pulse
• Not feeding well
• Shortness of breath

A moderate or large PDA can cause babies to breathe faster and harder than normal, as their bodies try to keep up with the extra blood in their lung arteries.^[4] Larger PDAs may also cause rapid breathing, sweating during feedings, fatigue or tiredness, feeding and eating problems, poor weight gain or growth, and a fast pulse or heart rate.^[4]

How is PDA Diagnosed?

If a PDA is suspected, the doctor will perform a physical exam and ask questions about the medical history. The healthcare professional may hear a heart murmur while listening to the heart with a stethoscope.^[8] A murmur is often heard in babies with PDAs.^[3]

Several tests can help diagnose patent ductus arteriosus:

Echocardiogram (echo): This test uses sound waves to make pictures of the beating heart. It shows how blood flows through the heart and heart valves. An echocardiogram can tell if there is a persistent opening in the heart and can also show if there are higher pressures in the lung arteries. It shows the blood flow pattern through the PDA, how large the opening is, and how much blood is passing through it. An echocardiogram is the most common way that a PDA is diagnosed.^[8]

Chest X-ray: This test shows the condition of the heart and lungs. A chest X-ray may show an enlarged heart and lung changes in a baby with PDA.^[8]

Electrocardiogram (ECG or EKG): This quick and simple test records the electrical signals that make up the heartbeat. It shows how fast or how slow the heart is beating.^[8]

Cardiac catheterization: This test is not usually needed to diagnose patent ductus arteriosus, but it might be done if there are other heart conditions. A doctor places a thin, flexible tube called a catheter into a blood vessel, usually in the groin or wrist, and guides it to the heart. During this test, treatments may be done to close the patent ductus arteriosus.^[8]

Treatment Options

Treatments for patent ductus arteriosus depend on the age of the person being treated and the size of the PDA. Some people with small PDAs may only need regular health checkups to watch for changes.^[8] In most babies who have an otherwise normal heart, the PDA will shrink and close on its own in the first few days of life. Some smaller PDAs that do not close early will seal on their own by the time the child is one year old.^[3]

When treatment is needed, three management strategies are currently available:

Medical Management

This approach includes fluid restriction and diuretics as clinically appropriate. Medical management also consists of amelioration of congestive heart failure (CHF) symptoms, which is when the heart cannot pump blood effectively.^[12] Adequate nutrition, such as high-calorie formula or breast milk, may also be provided.^[19]

Pharmacologic closure can be achieved through administration of intravenous indomethacin or ibuprofen lysine. These are medications known as cyclooxygenase inhibitors that work by blocking the production of substances called prostaglandins that keep the ductus arteriosus open.^[6] Intravenous indomethacin or ibuprofen is frequently effective in closing a PDA if it is administered in the first 10 to 14 days of life.^[12] While both agents have shown similar efficacy, ibuprofen lysine has demonstrated an improved safety profile, particularly in terms of renal (kidney) effects, compared to indomethacin.^[6]

Catheter-Based Closure

Transcatheter closure has been established as the method of choice for treating a PDA in adults.^[18] This is a minimally invasive treatment option available to some people. The procedure involves making a small incision, typically in the groin, and inserting a small tube called a catheter to navigate through the blood vessels to the procedure site within the heart.^[13]

The doctor guides a device through the catheter to seal the PDA. Devices used include coils for small PDAs or larger devices like the Amplatzer Duct Occluder for larger openings.^[13] Once the device is placed in the PDA, the doctor carefully studies its position using cardiac imaging systems. Once satisfied with the position, the device is released to remain permanently in the channel. The catheter is removed and the procedure is completed.^[13] The procedure itself should last about one to two hours.^[13]

Surgical Ligation

When surgical ligation is indicated, it involves a thoracotomy, which is an operation where the surgeon makes an incision in the chest to access the heart.^[12] The surgeon then closes the ductus arteriosus. Surgical closure may be recommended when medication is not effective or when catheter-based procedures are not suitable.^[8]

All PDAs should be closed because of the risk of bacterial endocarditis (infection of the heart lining) associated with the open structure. Over time, the increased pulmonary blood flow can lead to pulmonary vascular obstructive disease, which is ultimately fatal.^[12]

Outlook and Prognosis

If left untreated for a prolonged period, a PDA can lead to the development of pulmonary hypertension (high blood pressure in the lungs) and blood vessel damage.^[4] Potential complications of a persistently patent ductus arteriosus after birth include heart failure, kidney dysfunction, necrotizing enterocolitis (a serious intestinal condition), intraventricular hemorrhage (bleeding in the brain), and altered postnatal nutrition and growth. In addition, PDA is a risk factor for the development of chronic lung disease.^[6]

The mortality of untreated PDA in adults (without correction for the size of the PDA) is estimated to be 1.8% per year.^[18] However, potential complications and infant mortality rates associated with PDA can approach 30%.^[6]

With proper treatment—whether through medication, catheter-based closure, or surgery—most people with PDA can have normal, healthy lives. Early detection and appropriate management are key to preventing complications and ensuring the best possible outcome.