Congenital Pulmonary Atresia (PA)

Pulmonary atresia (PA) is a complicated congenital (present at birth) defect that occurs due to abnormal development of the fetal heart during the first eight weeks of pregnancy.

The pulmonary valve is found between the right ventricle (RV) and the pulmonary artery. It has three leaflets that function like a one-way door, allowing oxygen depleted blood to flow from the right pumping chamber (RV) out to the lungs to pick up oxygen. This valve closes as the RV relaxes so that blood does not go backwards into the right ventricle.

With pulmonary atresia, problems with valve development prevent the leaflets from opening, therefore, blood cannot flow forward from the right ventricle to the lungs. Before birth, while the fetus is developing, this is not a threat to life because the placenta provides oxygen for the baby and the lungs are not being used to oxygenate the blood. Blood entering the right side of the fetal heart passes through an opening called the foramen ovale that allows oxygen-rich (red) blood from the placenta to pass through to the left side of the heart and proceed to the body.

In some cases, there may be a second opening, this time in the ventricular wall, that allows blood in the right ventricle a way out. This opening is called a ventricular septal defect (VSD). If there is no VSD, the right ventricle receives little blood flow before birth and does not develop fully.

At birth, when the baby is separated from the placenta, the lungs open on the first breath and now must do the work of oxygenating the baby’s blood. However, with no pulmonary valve opening present, blood must find another route to reach the lungs and receive oxygen.

The foramen ovale normally shuts at birth, but may stay open in this situation, allowing oxygen-poor (blue) blood to pass from the right atrium to the left atrium. From there, it goes to the left ventricle, out the aorta, to the body. This situation cannot support life, since oxygen-poor (blue) blood cannot meet the body's demands. Newborns also have a connection between the aorta and the pulmonary artery, called the ductus arteriosus, that allows some of the oxygen-poor (blue) blood to pass into the lungs. Unfortunately, this ductus arteriosus normally closes within a few hours or days after birth.

Because of the low amount of oxygen provided to the body, pulmonary atresia is one of the heart problems that is labeled "blue-baby syndrome." Pulmonary atresia occurs in about one out of every 10,000 live births.

Causes of Pulmonary Atresia

The problem occurs as the heart is forming during the first eight weeks of fetal development.

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 of the time, this heart defect occurs sporadically (by chance), with no clear reason for its development.

Signs and Symptoms of Pulmonary Atresia

Cyanosis (blue color) is often present to some degree immediately after birth. Depending on other structural differences in the heart, it could range from mild to profound. The degree of cyanosis is related to the presence of other defects that allow blood to mix, including a patent (open) ductus arteriosus that is used to bypass the lungs during fetal life. This ductus arteriosus begins closing shortly after birth. Closure is prompted by the introduction of oxygen into the blood once the baby starts breathing on it’s own. Closure of this ductus starts within hours of being born and can take a few days to weeks. As the ductus closes the cyanosis will increase.

Some babies will have developed extra blood vessels, called collateral vessels, that take blood from an artery to the lungs. Depending on the size of these vessels, the baby may not be blue as early and may not need a surgical intervention for a longer period. Eventually, however, the baby will outgrow the capacity of these vessels to get enough blood to the lungs for oxygenation.

The following are the most common symptoms of pulmonary atresia. However, each child may experience symptoms differently. Symptoms may include:

  • Rapid breathing
  • Difficulty breathing
  • Irritability
  • Lethargy
  • Pale, cool, or clammy skin
  • Cyanosis

The symptoms of pulmonary atresia may resemble other medical conditions or heart problems. Always consult your child's physician for a diagnosis.

Diagnosis of Pulmonary Atresia

A pediatric cardiologist and/or a neonatologist may be involved in your child's care. A pediatric cardiologist specializes in the diagnosis and medical management of congenital heart defects, as well as heart problems that may develop later in childhood. A neonatologist specializes in illnesses affecting newborns, both premature and full-term.

Cyanosis is a major indication that there is a problem with your newborn. Your child's physician may have also heard a heart murmur during a physical examination. A heart murmur is simply a noise caused by the turbulence of blood flowing through the openings that allow the blood to mix.

Diagnostic Tests

Other diagnostic tests are needed to help with the diagnosis, and may include:

  • Chest X-ray, a diagnostic test which uses invisible electromagnetic energy beams to produce images of internal tissues, bones and organs onto film
  • 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
  • Echocardiogram (echo), a procedure that evaluates the structure and function of the heart by using sound waves recorded and displayed on a screen that produce a moving picture of the heart and heart valves
  • Cardiac catheterization, an invasive procedure that gives very detailed information about the structures inside the heart. Under sedation, a small, thin, flexible tube (catheter) is inserted into a blood vessel in the groin, and guided to the inside of the heart. Blood pressure and oxygen measurements are taken in the four chambers of the heart, as well as the pulmonary artery and aorta. Contrast dye is also injected to more clearly visualize the structures inside the heart.

This heart defect is often picked up before birth, during an ultrasound. Your obstetrician will refer you to a specialist who will perform a fetal echocardiogram. This can give you a chance to learn about this defect, and also helps your doctors prepare for the birth of your baby. When this diagnosis is known before birth, the baby can be stabilized with a medicine that can keep the fetal connections open until the baby is thoroughly examined and has an echocardiogram to confirm whether the baby will need surgery in the newborn period.

Treatment for Pulmonary Atresia

Specific treatment for pulmonary atresia will be determined by your child's physician based on:

  • Your child's age, overall health and medical history
  • Extent of the disease
  • Your child's tolerance for specific medications, procedures, or therapies
  • Expectations for the course of the disease
  • Your opinion or preference 

Adult and Adolescent Management

Adults with pulmonary atresia present in one of two ways. If they have not had surgical correction of their congenital heart disease, they are blue or cyanotic. All cyanotic patients require careful surveillance and management by congenital heart experts. Some patients who had pulmonary atresia will have had surgical correction of various types. All of these require lifelong surveillance by congenital heart experts.

Learn more about the Adolescent and Adult Congenital Heart Disease Program.

Last Updated 04/2019

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