Pulmonary stenosis, or pulmonic stenosis, is a heart condition characterized by narrowing at or near the pulmonary valve. (Stenosis means narrowing of a bodily passage.) This restricts blood flow from the right ventricle—the heart’s lower right chamber—to the pulmonary artery, the vessel that carries blood to the lungs for oxygenation. As a result, the heart must work harder to pump blood to the lungs. Though mild cases of pulmonary stenosis often do not cause symptoms, moderate to severe cases can result in fatigue, shortness of breath, chest pain, and fainting. In more severe cases, heart failure may occur.

The majority of cases of pulmonary stenosis are congenital (present at birth), though less commonly, it can be acquired during a person’s life as a result of rheumatic heart disease, heart tumors, previous heart or chest surgeries, infective endocarditis, and other causes.

Congenital pulmonary stenosis accounts for approximately 7% to 12% of all congenital heart defects. Although it is one of the more common types of heart defect, pulmonary stenosis is a rare condition. It can occur in both sexes, though it is slightly more common in females. The condition is often diagnosed in infancy or childhood, but in some cases, it may not be detected until adulthood.

Fortunately, pulmonary stenosis can be managed effectively with treatments. With the right care, many individuals with this condition can lead healthy, active lives.

The pulmonary valve has three leaflets and sits between the heart’s right ventricle and the pulmonary artery. When the right ventricle contracts, the pulmonary valve’s leaflets open, allowing blood to flow from the ventricle into the pulmonary artery and onward to the lungs, where it becomes oxygenated. The pulmonary valve then closes to prevent blood from flowing backward into the right ventricle.

In pulmonary stenosis, part of the pathway through which blood flows from the right ventricle to the pulmonary artery becomes narrowed. This narrowing can occur at the pulmonary valve, below it in the right ventricle, or above it in the pulmonary artery. There are different types of pulmonary stenosis, each named for where the narrowing occurs:

• Valvular pulmonary stenosis: The narrowing occurs at the pulmonary valve itself. It is the most common type of pulmonary stenosis, accounting for 80% to 90% of cases.
• Subvalvular pulmonary stenosis: The narrowing occurs below the pulmonary valve, in the part of the right ventricle that directs blood to the pulmonary valve.
• Supravalvular pulmonary stenosis: The narrowing is above the pulmonary valve, in the pulmonary artery or branches of the pulmonary artery.

Pulmonary stenosis is primarily a congenital condition. Congenital pulmonary stenosis occurs before birth, during early development in the womb. In most cases, the cause of congenital pulmonary stenosis is unknown, though genetic factors may be involved.

The condition can also be acquired later in life, though this is less common. Causes of acquired pulmonary stenosis include rheumatic heart disease, infective endocarditis, cardiac tumors, the degeneration of a replacement pulmonary valve, and previous heart or chest surgery.

Symptoms can range from mild to severe, depending on the extent of the narrowing of the pulmonary valve. In mild cases, individuals usually do not have any symptoms, while those with moderate or severe pulmonary stenosis may experience symptoms, including:

• Shortness of breath
• Fatigue
• Chest pain
• Fainting
• Bluish discoloration of the skin (cyanosis)
• Abdominal swelling
• Failure to thrive (in infants)
• Poor weight gain (in infants)

Symptoms may worsen during or after physical activity.

To diagnose pulmonary stenosis, the doctor will review the patient’s medical history, conduct a physical exam, and order one or more diagnostic tests.

The doctor will ask about symptoms, such as shortness of breath, fatigue, or chest pain, and inquire about any family history of congenital heart disease. During the physical exam, the doctor will listen for heart murmurs, check for signs of bluish discoloration of the skin or lips, and look for other signs of pulmonary stenosis and syndromes that have been associated with it.

Diagnostic tests may include:

• Echocardiogram, an ultrasound of the heart used to confirm the diagnosis and assess the severity and location of the stenosis, the size and function of the right ventricle, and the structure of the pulmonary valve. In general, echocardiography is the primary diagnostic test for pulmonary stenosis. In some cases, however, additional tests are necessary, for example, if the echocardiogram image is of poor quality or the location of the narrowing is unclear.

The following tests provide doctors with additional information about the structure, location, and severity of the narrowing:

• Cardiac magnetic resonance imaging (MRI), an imaging test that helps doctors assess the location and anatomy of the narrowed pulmonary valve or pulmonary artery.
• Cardiac computed tomography (CCT), an imaging test that helps doctors evaluate the pulmonary arteries, location of the narrowing, and the size and function of the right ventricle.
• Cardiac catheterization, a minimally invasive procedure in which a catheter is inserted into a vein or artery in the groin, arm, or neck and then guided through blood vessels to the heart. Though rarely used for a diagnosis, this procedure may be used to assess the severity and location of the narrowing. Cardiac catheterization is typically performed on people who are undergoing balloon pulmonary valvuloplasty (more below) for pulmonary stenosis.

Though they cannot be used to make a definitive diagnosis, the following tests may also be ordered by the doctor as part of the evaluation:

• Electrocardiogram (ECG), a test that records the electrical activity of the heart. Certain abnormal findings may be indicative of pulmonary stenosis.
• Chest X-ray, an imaging test may be used to assess the size of the heart and pulmonary artery.

Treatments for pulmonary stenosis include catheterization procedures, surgery, medications, monitoring, and physical activity restrictions.

Catheterization procedures:

• Balloon pulmonary valvuloplasty (BPV): This is the first-line treatment for pulmonary stenosis. A catheter—a small tube—with a balloon is inserted through a vein in the groin and guided to the heart. The balloon is then inflated to widen the narrowed valve, improving blood flow. It is less invasive than surgical treatment options and has a high success rate, often reducing the pressure significantly. BPV may not be as effective for very thick or stiff valves, or abnormal valves associated with specific genetic syndromes, such as Noonan syndrome or other RASopathies. (RASopathies are a group of genetic disorders caused by changes in genes involved in the Ras/MAPK cell signaling pathway, which plays a crucial role in regulating cell growth and other cellular processes that are fundamental to normal development. Changes in certain genes can disrupt this pathway, resulting in a number of RASopathies including Noonan syndrome, Costello syndrome, and neurofibromatosis type 1 among others.) It is generally well-tolerated with minimal complications.

• Pulmonary artery angioplasty with or without stenting: This procedure is used to treat narrowing in the pulmonary artery or branches of the pulmonary artery, rather than narrowing of the valve itself. In pulmonary artery angioplasty, a catheter with a balloon at its tip is inserted into a blood vessel in the groin or arm. It is then guided through the blood vessels to the pulmonary artery. Once in position, the balloon is inflated to stretch and widen the narrowed section of the artery. Sometimes, a stent—a tube made of mesh wire—may be inserted and left in place to hold the artery open. At the end of the procedure, the balloon is deflated and removed.
• Pulmonary valve replacement: This procedure may be an option when there is significant pulmonary valve regurgitation (leakage of blood backward into the heart through the pulmonary valve) after BPV or surgical treatment, if previous treatments have failed, or for those who are not good candidates for BPV. In this procedure, the pulmonary valve is replaced with a new one. The replacement valve may be inserted via a surgical procedure or through a minimally invasive procedure known as transcatheter valve replacement.

Surgery:

• Surgical valvotomy: This procedure may be an option if BPV is not suitable or successful. In a surgical valvotomy, the surgeon makes an incision in the chest to access the heart, then makes one or more incisions in the pulmonary valve to widen it, thereby improving blood flow. It may result in higher rates of pulmonic valve regurgitation compared to BPV.

Medications:

• Medications may be used to manage symptoms or other heart issues. In newborns with severe pulmonary stenosis, prostaglandins, a drug that widens blood vessels, may be given intravenously to help keep the ductus arteriosus open in newborns. The ductus arteriosus is a blood vessel that remains open in a fetus but closes shortly after birth. In newborns with pulmonary stenosis, the closure of this blood vessel may result in severe symptoms. Prostaglandins are used to keep the blood vessel open until BPV can be performed.

Monitoring:

• Regular check-ups are important to monitor the heart and pulmonary valve. This may include echocardiograms and other heart tests.

Activity Restrictions:

• People with mild stenosis can usually participate in normal activities and exercise without restrictions. Those with more severe stenosis may need to limit intense physical activities until treatment is completed. People with pulmonary stenosis should discuss any potential physical activity and exercise restrictions with their health care provider.

People with pulmonary stenosis are at increased risk for certain complications, including:

• Thickening of the right ventricle (impairing its function)
• Heart arrhythmias
• Heart failure
• Pulmonary valve regurgitation
• Infective endocarditis
• Tricuspid valve regurgitation
• Sudden death (rare)

The outlook for people with pulmonary stenosis is generally good, though it can vary based on several factors, including the severity of the condition, the presence of other congenital heart defects, the association with certain genetic syndromes, and the success of any interventions. For those with mild pulmonary stenosis and many people with moderate forms of the condition, the outlook is generally excellent, with many individuals leading normal lives without any symptoms or significant progression of the condition. For some people with moderate pulmonary stenosis and those with severe stenosis, however, the condition can worsen over time. In these cases, treatment is often necessary. Fortunately, with successful treatment, the outlook for moderate and severe pulmonary stenosis is typically good to excellent.

The presence of other congenital heart conditions can also influence the outlook, as they may complicate treatment and management. People with pulmonary stenosis who have had their pulmonary valve replaced with one from a donor or animal tissue may require multiple replacements in a lifetime. Because these valves deteriorate over time, they need to be replaced after 10 to 20 years. Technology has evolved and it is more common that these valves can be replaced in a minimally invasive cardiac catheterization than in older eras when surgery would have been required.

People with pulmonary stenosis should see their health care provider regularly throughout their lives to monitor their heart and pulmonary valves.

This article was medically reviewed by Britton Keeshan, MD, MPH, a Yale Medicine pediatric cardiologist who treats congenital heart disease in adults and children.