Pulmonary Atresia

Pulmonary atresia is a congenital heart defect (the baby is born with it) in which the pulmonary valve does not develop normally or remains blocked after birth. ("Atresia" means absent and pulmonary refers to the lungs.)

The structure of the heart

The heart has four chambers—the right atrium and the left atrium (plural: atria) on top and the right and left ventricles (pumping chambers) on the bottom. The heart is divided by a solid wall called the septum into two sides: the right side sends blood to the lungs to get oxygen, while the left side of the heart moves oxygen-rich blood to the rest of the body through the aorta (the main artery in the heart).

Inside the Heart

There are also four valves in the heart, which open and close to allow blood to move through the chambers:

• The tricuspid valve, located on the right side of the heart between the right ventricle and the right atrium;
• The pulmonary valve, located on the right side of the heart between the right ventricle and the pulmonary artery (the blood vessel that carries blood to the lungs);
• The mitral valve, located between the left ventricle and the left atrium;
• The aortic valve, located on the left side of the heart, between the aorta and the left ventricle

The pulmonary valve has three flaps (also called leaflets or cusps) that normally open to let blood flow forward from the right ventricle into the pulmonary artery. The leaflets also close to prevent blood from flowing backward into the heart.

In some babies with pulmonary atresia, the right ventricle of the heart, the pulmonary artery, and the tricuspid valve may be underdeveloped. Some infants may also have a ventricular septal defect, or opening in the wall (septum) between the right and left ventricles. This opening allows oxygen-rich blood to mix with oxygen-poor blood.

If there is no pulmonary valve or if it is blocked, blood cannot flow through the pulmonary artery to reach the lungs, where it receives oxygen. Instead, oxygen-poor (blue) blood is pumped throughout the body. The lips, fingers, and toes of the infant may appear blue because of a lack of oxygen in the blood. This condition is known as cyanosis.

The fetal heart has an opening (the foramen ovale) between the pulmonary artery and the aorta. It usually closes after birth, but sometimes remains open in newborns who have pulmonary atresia. The foramen ovale allows oxygen-poor blood to pass from the right atrium to the left atrium of the heart, where it flows through the left ventricle to the aorta.

Newborns also have another passageway between the aorta and the pulmonary artery. This passageway, called the ductus arteriosus, begins to close within a few hours to days after birth. While the ductus arteriosus remains open, some oxygen-poor blood is still able to reach the lungs.

What causes pulmonary atresia?

Pulmonary atresia occurs in about 1 out of 10,000 live births. Pulmonary atresia occurs during the first eight weeks that the fetus is developing in the womb. The exact cause is unknown. Genetic factors, such as an abnormal gene or chromosomal defect, may increase the chances of heart defects in certain families. (Some children with genetic disorders may be at greater risk for developing pulmonary atresia.)

What are the symptoms of pulmonary atresia?

Symptoms of pulmonary atresia often appear within the first few hours or days of life and may include:

• Rapid breathing
• A bluish tinge to the skin, especially the lips, fingers, and toes
• Cool, pale, or clammy skin
• Breathing problems
• Fatigue or tiredness
• Irritability
• Poor feeding

How is pulmonary atresia diagnosed?

The health care provider will check the child’s heart and lungs to determine if there are any problems. If there is a heart murmur or another irregularity, additional tests may be ordered. These tests may include:

• Chest X-rays
• Electrocardiogram (EKG or ECG)—measures the electrical activity of the heart to determine if there is any stress on the heart muscle
• Echocardiogram—A procedure that uses sound waves to produce a moving picture of the heart and heart valves
• Cardiac catheterization—A procedure to view the heart in which a small, flexible tube is inserted into the body through the groin and passed through to the inside of the heart. Contrast dye may be used to provide a stronger image of the heart and heart valves.

How is pulmonary atresia treated?

The treatment of pulmonary atresia depend on the child’s general health, age, and medical history, and how the condition is affecting the child. Usually, surgery will be required to treat the heart defect and help improve blood flow to the lungs.

As a temporary measure, newborns with pulmonary atresia are usually given an intravenous drug (injected into a vein) called prostaglandin E1 (alprostadil) to prevent the ductus arteriosus from closing. By keeping the ductus arteriosus open, blood can flow from the right side of the heart to the left side and pass through the left ventricle to the lungs to pick up oxygen.

Cardiac catheterization, which is used to diagnose heart problems, may also be used to enlarge the opening in the septum (the wall between the right atrium and left atrium). The procedure, which is called balloon atrial septostomy, improves blood flow to the lungs. A catheter is inserted into the heart through a blood vessel and is guided through the foramen ovale. The balloon at the tip of the catheter is inflated and the catheter is quickly removed to make an opening in the atrial septum. Oxygen-poor blood can then flow from the right to the left atrium and into the left ventricle and aorta.

Medication and balloon atrial septostomy are short-term treatments. Your baby will probably need additional surgery to improve blood flow to the lungs over the long term. The type of surgery will depend on several factors, including the size of the right ventricle and the pulmonary artery and the ability of the right ventricle to pump blood. If the right ventricle and pulmonary artery are normal and the right ventricle functions properly, open heart surgery can be performed.

Types of operations

If your child has a ventricular septal defect, it may be surgically repaired by placing a homograft conduit (an artery and valve from another person) between the right ventricle and pulmonary artery. The conduit lets blood flow through the right ventricle into the pulmonary artery and to the lungs.

If there is no ventricular septal defect, a series of three operations is usually performed during the first few years of the child’s life. The operations are open heart surgeries designed to redirect the flow of oxygen-poor blood directly to the pulmonary artery and lungs.

• The first operation involves the placement of a shunt or tube (B-T shunt) directly from the right ventricle to the pulmonary artery. The procedure ensures that enough blood is flowing to the lungs during the first few months of life.
• When the child is about 4 to 8 months old, a second operation, called the bi-directional Glenn or hemi-Fontan procedure, is performed. The shunt inserted during the first operation is removed, and a connection is formed between the superior vena cava (a major vein that carries deoxygenated blood from the upper body to the heart) to the right pulmonary artery. This allows blood to flow from the superior vena cava directly to the pulmonary artery and the lungs.
• The third and final operation, known as the Fontan procedure, is usually performed when the child is between 3 and 6 years old. During this surgery, both the superior vena cava and inferior vena cava (the vein that carries deoxygenated blood from the lower body to the heart) are connected to the pulmonary artery.

What is the prognosis (outlook) after surgery for pulmonary atresia?

Your child will need to spend some time in the intensive care unit after the surgery. He or she will be placed on a ventilator (breathing machine) and heart monitor. In addition, medications will be given through one or more intravenous (IV) catheters to provide pain relief and lessen the work of the heart.

Some infants may experience feeding problems or might be too weak after surgery to bottle- or breastfeed. Feedings through a nasogastric tube or high-calorie formula can be used instead of or along with bottle- or breastfeeding.

Your child will have regular follow-up appointments with the pediatric cardiologist. Some children may need additional heart catheterization or surgical procedures as they grow older, or will need special medications. People who have been diagnosed with pulmonary atresia must remain under the care of a cardiologist throughout their lives.

Long-term complications may include abnormal heart rhythms, heart failure, or narrowing of the pulmonary artery. These complications can be reduced or prevented through regular follow-up care.

References

National Heart, Lung, and Blood Institute:
1) Heart valve disease. Updated April 2011. Accessed May 2, 2011
2) Congenital heart defects. Updated August 2009. . Accessed May 2, 2011.

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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. This document was last reviewed on: 5/2/2011…#14779