Pulmonary atresia (uh-TREE-zhuh) is a heart defect present at birth (congenital) that's usually diagnosed soon after birth. In pulmonary atresia, the valve that lets blood out of the heart to go to the lungs (pulmonary valve) doesn't form correctly.

Instead of opening and closing to allow blood to travel from the heart to the lungs, a solid sheet of tissue forms. So, blood can't travel its usual route to pick up oxygen from the lungs. Instead, some blood travels to the lungs through other natural passages within the heart and its arteries.

These passages are necessary when a baby is developing in the womb, and they typically close soon after birth. Babies with pulmonary atresia typically have a bluish cast to their skin because they aren't getting enough oxygen.

Pulmonary atresia is a life-threatening situation. Procedures to correct a baby's heart condition and medications to help a baby's heart work more effectively are the first steps to treat pulmonary atresia.



If a baby is born with pulmonary atresia, symptoms will be noticeable soon after birth. Signs and symptoms might include:

  • Blue- or gray-toned skin (cyanosis)
  • Fast breathing or shortness of breath
  • Easily tiring or being fatigued
  • Feeding problems

When to see a doctor

A baby with pulmonary atresia will most likely be diagnosed soon after birth. However, if your baby has symptoms of pulmonary atresia after you've returned home, seek emergency medical attention.


There's no known cause of pulmonary atresia. To understand how pulmonary atresia occurs, it may be helpful to know how the heart works.

How the heart works

The heart is divided into four hollow chambers, two on the right and two on the left. In performing its basic job — pumping blood throughout the body — the heart uses its left and right sides for different tasks.

The right side of the heart moves blood to the lungs through vessels called pulmonary arteries. In the lungs, blood picks up oxygen then returns to the heart's left side through the pulmonary veins. The left side of the heart then pumps the blood through the aorta and out to the rest of the body to supply the body with oxygen.

Blood moves through the heart in one direction through valves that open and close as the heart beats. The valve that allows blood out of the heart and into the lungs to pick up oxygen is called the pulmonary valve.

In pulmonary atresia, the pulmonary valve doesn't develop properly, preventing it from opening. Blood can't flow from the right ventricle to the lungs.

Before birth, the irregular valve isn't life-threatening, because the placenta provides oxygen for the baby instead of the lungs. Blood entering the right side of the baby's heart passes through a hole (foramen ovale) between the top chambers of the baby's heart, so the oxygen-rich blood can be pumped out to the rest of the baby's body through the aorta.

After birth, the lungs are supposed to provide oxygen to the body. In pulmonary atresia, without a working pulmonary valve, blood must find another route to reach the baby's lungs. The foramen ovale usually shuts soon after birth, but it may stay open in pulmonary atresia.

Newborn babies also have a temporary connection (ductus arteriosus) between the aorta and the pulmonary artery. This passage allows some of the oxygen-poor blood to travel to the lungs, where it can pick up oxygen to supply the baby's body. The ductus arteriosus typically closes soon after birth, but it can be kept open with medications.

Sometimes, there may be a second hole in the tissue that separates the main pumping chambers of the baby's heart. This hole is a ventricular septal defect (VSD).

The VSD allows a pathway for blood to pass through the right ventricle into the left ventricle. Children with pulmonary atresia and a VSD often have additional problems with the lungs and the arteries that bring blood to the lungs.

If there's no VSD, the right ventricle receives little blood flow before birth and often doesn't develop fully. This is a condition called pulmonary atresia with intact ventricular septum (PA/IVS).

Risk factors

The exact cause of a congenital heart defect, such as pulmonary atresia, is usually unknown. However, several things may increase a baby's risk of a congenital heart defect, including:

  • A parent who has a congenital heart defect
  • Obesity in the mother before pregnancy
  • Smoking before or during pregnancy
  • A mother who has poorly controlled diabetes
  • Use of some types of medications during pregnancy, such as certain acne drugs and blood pressure medications


Without treatment, pulmonary atresia usually leads to death. Regular health checkups are needed after pulmonary atresia surgery to carefully monitor for complications.

Potential complications of pulmonary atresia and other structural heart problems include:

  • Bacterial infection of the inner lining of the heart and valves (infectious endocarditis)
  • Irregular heart rhythms (arrhythmias)
  • Heart failure


Because the exact cause of pulmonary atresia is unknown, it may not be possible to prevent it. However, some things can be done before or during pregnancy to help reduce a baby's overall risk of congenital heart defects, such as:

  • Control chronic medical conditions. If you have diabetes, keeping your blood sugar in check can reduce the risk of heart defects. If you have other chronic conditions, such as high blood pressure or epilepsy, that require the use of medications, discuss the risks and benefits of these drugs with your health care provider.
  • Don't smoke. Smoking cigarettes during pregnancy may increase the risk of heart defects in a baby.
  • Maintain a healthy weight. Obesity increases the risk of having a baby with a congenital heart defect.
  • Get a German measles (rubella) vaccine. German measles during pregnancy may affect a baby's heart development. Being vaccinated before becoming pregnant likely eliminates this risk. However, no link has been shown between rubella and the development of pulmonary atresia.

Pulmonary atresia care at Mayo Clinic

March 12, 2022
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