Patent Ductus Arteriosus (PDA) – Causes, Treatment and Prevention

Definition

Patent Ductus Arteriosus is a heart problem that is frequently noted in the first few weeks or months after birth. It is characterized by the persistence of a normal prenatal connection between the aorta and the pulmonary artery which allows oxygen-rich (red) blood that should go to the body to recirculate through the lungs.

All babies are born with this connection between the aorta and the pulmonary artery. While your baby was developing in the uterus, it was not necessary for blood to circulate through the lungs because oxygen was provided through the placenta. During pregnancy, a connection was necessary to allow oxygen-rich (red) blood to bypass your baby’s lungs and proceed into the body. This normal connection that all babies have is called a ductus arteriosus.

At birth, the placenta is removed when the umbilical cord is cut. Your baby’s lungs must now provide oxygen to his or her body. As your baby takes the first breath, the blood vessels in the lungs open up, and blood begins to flow through them to pick up oxygen. At this point, the ductus arteriosus is not needed to bypass the lungs. Under normal circumstances, within the first few days after birth, the ductus arteriosus closes and blood no longer passes through it.

In some babies, however, the ductus arteriosus remains open (patent) and the condition now becomes known as patent ductus arteriosus (PDA). The opening between the aorta and the pulmonary artery allows oxygen-rich (red) blood to recirculate into the lungs. Patent ductus arteriosus occurs twice as often in girls as in boys.

Epidemiology

The ductus arteriosus will close in virtually all healthy term newborns by 72 hours of age. The incidence of PDA in premature infants is inversely proportional to gestational age. In infants who are > 30 weeks gestation at birth, 90% will have a closed ductus at day 4, and 98% will be closed by the time of discharge. Infants born weighing less than 1000 grams are at the highest risk for PDA. In this population, 70% will have a PDA on day 7. In at least 10% of other congenital heart disorders, a patent ductus may be present.

Pathophysiology of PDA

The ductus arteriosus is a normal connection between the pulmonary artery and aorta; it is necessary for proper fetal circulation. At birth, the rise in PaO2 and decline in prostaglandin concentration cause closure of the ductus arteriosus, typically beginning within the first 10 to 15 hours of life. If this normal process does not occur, the ductus arteriosus will remain patent.

Physiologic consequences depend on ductal size. A small ductus rarely causes symptoms. A large ductus causes a large left-to-right shunt. Over time, a large shunt results in left heart enlargement, pulmonary artery hypertension, and elevated pulmonary vascular resistance, ultimately leading to Eisenmenger syndrome.

Patent Ductus Arteriosus Risk Factors

Some factors that may increase the risk of PDA are:

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.

Family history- A family history of heart defects increases the risk of PDA.

Presence of genetic conditions- Genetic conditions such as Down syndrome increase the chances of the baby having a PDA.

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.

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

Causes of Patent Ductus Arteriosus

In many children, there is no known reason for the ductus arteriosus remaining open. However, PDA is seen more often in the following:

• Premature infants
• Infants born to a mother who had rubella during the first trimester of pregnancy

Some congenital heart defects may have a genetic link, either occurring due to a defect in a gene, a chromosome abnormality, or environmental exposure, causing heart problems to occur more often in certain families. Most often, a PDA heart defect occurs sporadically (by chance), with no clear reason for its development.

Patent ductus arteriosus can also occur in combination with other heart defects.

Symptoms of Patent Ductus Arteriosus

A heart murmur may be the only sign that a baby has patent ductus arteriosus (PDA). A heart murmur is an extra or unusual sound heard during the heartbeat. Heart murmurs also have other causes besides PDA, and most murmurs are harmless.

Some infants may develop signs or symptoms of volume overload on the heart and excess blood flow in the lungs. Signs and symptoms may include:

• Fast breathing, working hard to breathe, or shortness of breath. Premature infants may need increased oxygen or help breathing from a ventilator.
• Poor feeding and poor weight gain.
• Tiring easily.
• Sweating with exertion, such as while feeding.

Patent Ductus Arteriosus Complications

A small patent ductus arteriosus might not cause complications. Larger, untreated defects could cause:

High blood pressure in the lungs: Too much blood circulating through the heart’s main arteries through a patent ductus arteriosus can lead to pulmonary hypertension, which can cause permanent lung damage. A large patent ductus arteriosus can lead to Eisenmenger syndrome, an irreversible type of pulmonary hypertension.

Heart failure: A patent ductus arteriosus can eventually cause the heart to enlarge and weaken, leading to heart failure, a chronic condition in which the heart can’t pump effectively.

Heart infection (endocarditis): People who have structural heart problems, such as a patent ductus arteriosus, are at a higher risk of an inflammation of the heart’s inner lining than are people who have healthy hearts.

Diagnosis and test

The child’s doctor may hear a heart murmur during a physical examination, and refer the child to a pediatric cardiologist for a diagnosis. A heart murmur is a noise caused by the turbulence of blood flowing through the PDA.

The pediatric cardiologists who specializes in the diagnosis and medical management of congenital heart defects will perform a physical examination, listen to the heart and lungs, and make other observations that help in the diagnosis. The loudness and quality of the murmur (such as, harsh or blowing) as well as location within the chest where the murmur is heard best will give the cardiologist an initial idea of which heart problem the child may have. The cardiologist may recommend the following tests:

Chest X-ray: A diagnostic test that uses invisible X-ray beams to produce images of internal tissues, bones and organs onto film. With a PDA, the heart may be enlarged due to larger amounts of blood flow recirculating through the lungs back to the heart. Also, there may be changes that take place in the lungs due to extra blood flow that can be seen on an X-ray. Learn more about X-ray.

Electrocardiogram (ECG or EKG): A test that records the electrical activity of the heart, shows abnormal rhythms (arrhythmias or dysrhythmias), and detects heart muscle stress. Learn more about electrocardiogram.

Echocardiogram (echo): A non-invasive procedure that evaluates the structure and function of the heart by using sound waves recorded on an electronic sensor that produce a moving picture of the heart and heart valves. An echo can show the pattern of blood flow through the PDA, and determine how large the opening is, as well as how much blood is passing through it. An echo is the most common way that a PDA is diagnosed. Learn more about echocardiogram.

Treatment and medications

Treatment will depend on how severe the patent ductus arteriosus condition is and on your child’s symptoms, age and general health. If left untreated, patent ductus arteriosus may lead to long-term lung damage as well as damage to the blood vessels in the lungs

A small patent ductus arteriosus with no symptoms may close on its own as your child grows. A patent ductus arteriosus that causes symptoms will need to be treated with medicine or heart surgery. The cardiologist will check periodically to see whether the patent ductus arteriosus is closing on its own, and, if the PDA does not close, it will be fixed to prevent lung problems.

Treatment of patent ductus arteriosus may include the following:

Medications

Your baby may need medicines help the heart work better.

• In premature infants, the medicine indomethacin may help close the patent ductus arteriosus. Indomethacin is given intravenously and it helps stimulate the muscles inside the patent ductus arteriosus to tighten and close the connection.
• Some babies may need diuretic medicines to help the heart and lungs work better. Diuretics help the kidneys remove extra fluid from the body, which may be needed when the heart is not working well

Nutrition

Most infants with patent ductus arteriosus eat and grow normally; however, some premature infants or infants with large PDAs may become tired when feeding. They may not be able to eat enough to gain weight. Nutrition choices include:

• High-calorie supplements: Special nutritional supplements may be added to formula or pumped breastmilk to increase the number of calories. Your baby can drink less and still have enough calories to grow properly.
• Supplemental tube feedings: Supplemental feedings are given through a small, flexible tube. The tube passes through the nose, down the esophagus, and into the stomach. The feedings can either be added to or take the place of bottle-feedings. Infants who can drink part of their bottles, but not all, may be fed the rest through the feeding tube. Infants who are too tired to bottle-feed may get all of their formula or breastmilk through the feeding tube.

Cardiac catheterization

Closure of the patent ductus arteriosus can be done using cardiac catheterization. Metal mesh coils or blocking devices can be put in the PDA using a catheter. This patent ductus arteriosus treatment is usually reserved for beyond infancy and for those whose PDA is not very large.

Heart surgery

Surgical closure of a patent ductus arteriosus involves closing the PDA with stitches or clips. This prevents the extra blood from entering the lungs. Premature babies require this surgery and it is usually advised for babies younger than six months of age who have large defects and who have symptoms such as poor weight gain and fast breathing. For babies who do not have symptoms, surgery may be delayed until after 6 to 12 months of age. Your child’s cardiologist will recommend if and when the surgery should be done.

There are two types of surgery that are used to close a PDA:

Keyhole surgery

Most PDAs are small, so can be successfully closed using keyhole surgery. This surgery involves passing a long thin tube (catheter) through a vein or artery in the heart. The ductus arteriosus is then sealed using a small stainless-steel coil or plug.

Surgical ligation

This may be needed if your baby has a large PDA. During this surgery, a surgeon will make a small cut on the left side of your baby’s chest. They will then put a metal clip around the ductus arteriosus to close it.

For both types of surgery, your baby will be put under a general anesthetic (put to sleep).

The idea of your baby having surgery may seem like a scary thought. But surgery to treat a PDA is usually successful and many babies recover quickly. The surgeons will explain what they plan to do before surgery and talk about what will happen and any risks with you.

Prevention of Patent Ductus Arteriosus

There’s no sure way to prevent having a baby with a patent ductus arteriosus. However, it’s important to do everything possible to have a healthy pregnancy. Here are some of the basics:

Seek early prenatal care, even before you’re pregnant: Quitting smoking, reducing stress, and stopping birth control are all things to talk to your doctor about before you get pregnant. Also, discuss the medications you’re taking.

• Eat a healthy diet: Include a vitamin supplement that contains folic acid.
• Exercise regularly: Work with your doctor to develop an exercise plan that’s right for you.
• Avoid risks. These include harmful substances such as alcohol, cigarettes, and illegal drugs. Also, avoid hot tubs and saunas.
• Avoid infections: Update your vaccinations before becoming pregnant. Certain types of infections can be harmful to a developing baby.
• Keep diabetes under control: If you have diabetes, work with your doctor to manage the condition before and during pregnancy.

If you have a family history of heart defects or other genetic disorders, consider talking with a genetic counselor before becoming pregnant.