Pulmonary Stenosis

What is pulmonary stenosis?

Pulmonary stenosis is a congenital (present at birth) defect that occurs due to abnormal development of the fetal heart during the first 8 weeks of pregnancy.

The pulmonary valve is found between the right ventricle and the pulmonary artery. It normally has 3 leaflets that function like a one-way door, allowing blood to flow forward into the pulmonary artery, but not backward into the right ventricle.

With pulmonary stenosis, problems with the pulmonary valve make it harder for the leaflets to open and permit normal blood flow from the right ventricle to the lungs in a normal fashion. In children, these problems can include:

A valve that has leaflets that are partially fused together.

A valve that has thick leaflets that do not open all the way.

Narrowing of the area above or below the pulmonary valve.

There are four different types of pulmonary stenosis:

Valvar pulmonary stenosis. The valve leaflets are thickened and/or narrowed

Supravalvar pulmonary stenosis. The portion of the pulmonary artery just above the pulmonary valve is narrowed

Subvalvar (infundibular) pulmonary stenosis. The muscle under the valve area is thickened, narrowing the outflow tract from the right ventricle

Branch peripheral pulmonic stenosis. The right or left pulmonary artery is narrowed, or both may be narrowed

Pulmonary stenosis may be present in varying degrees, classified according to how much obstruction to blood flow is present. A child with severe pulmonary stenosis could be quite ill, with major symptoms noted early in life. A child with mild pulmonary stenosis may have few or no symptoms, or perhaps none until later in adulthood. A moderate or severe degree of obstruction can become worse with time.

Pulmonary stenosis is a component of half of all complex congenital heart defects.

Isolated pulmonary stenosis accounts for 5% to 10% of all congenital heart defect cases.

What causes pulmonary stenosis?

Congenital pulmonary stenosis occurs due to improper development of the pulmonary valve in the first 8 weeks of fetal growth. It can be caused by a number of factors, though most of the time this heart defect occurs by chance, with no clear reason evident for its development.

Some congenital heart defects may have a genetic link that causes heart problems to occur more often in certain families.

Why is pulmonary stenosis a concern?

Mild pulmonary stenosis may not cause any symptoms. Problems can occur when pulmonary stenosis is moderate to severe and the right ventricle has to work harder to try to move blood through the tight pulmonary valve. Eventually, the right ventricle is no longer able to handle the extra workload, and it fails to pump forward efficiently. Pressure builds back into the right atrium, and then in the veins bringing blood back to the right side of the heart. Fluid retention and swelling may occur.

What are the symptoms of pulmonary stenosis?

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

• Heavy or rapid breathing

• Shortness of breath

• Fatigue

• Rapid heart rate

• Swelling in the feet, ankles, face, eyelids, and/or abdomen

The symptoms of pulmonary stenosis may look like other medical conditions or heart problems. Always consult your child's doctor for a diagnosis.