Pulmonary stenosis (pulmonary valve stenosis) is a constricted blood flow condition caused by an obstruction (deformity) near or on the pulmonary valve. This creates a significant problem because the valve influences the flow of blood to the lungs from the heart. The obstruction can cause mild to severe symptoms, or no symptoms at all.
The condition is congenital, meaning it was present at birth and caused by an abnormal development of the heart during its development stage in the womb. This usually occurred within the first two months of pregnancy.
The pulmonary valve is located between the right ventricle and the pulmonary artery and has three leaflets to push blood in one direction to ensure it flows ahead to the pulmonary artery. However, the defect can make the blood flow back up into the right ventricle.
There are four distinct forms of pulmonary stenosis that include:
- Valvar Pulmonary Stenosis develops by narrowing or thickening the valve leaflets.
- Subvalvar Pulmonary Stenosis is caused by the thickening of the muscle under the valve that narrows the outflow of blood from the right ventricle.
- Supravalvar Pulmonary Stenosis creates a narrowing of the pulmonary artery above the valve.
- Branch Peripheral Pulmonary Stenosis causes a narrowing of the left or right pulmonary artery or both.
Problems associated with pulmonary stenosis make it difficult for the leaflets of the valve to open normally and allow the flow of blood to move into the lungs. Congenital conditions involving pulmonary stenosis can include:
- A fusing of the valve leaflets
- A narrowing below or above the pulmonary valve
- Thick leaflets of the valve that cannot open completely
The severity of pulmonary stenosis is determined by the level of obstruction in the flow of blood to the lungs. Some children never experience a symptom or develop symptoms later in life. Moderate obstructions can become significantly worse with time.
- Who Is at Risk for Pulmonary Stenosis?
- Common Symptoms
- What Causes Pulmonary Valve Stenosis?
- Diagnosing Pulmonary Stenosis
- Pulmonary Stenosis Treatments
Who Is at Risk for Pulmonary Stenosis?
Because pulmonary valve stenosis is a congenital defect, meaning it developed before the child was born, scientists have yet to find many risk factors. However, specific conditions have been associated with pulmonary valve stenosis that develops later in life. These include:
- Noonan Syndrome
- Rheumatic Fever – This condition involves a streptococcus bacterium infection like scarlet fever or strep throat that could injure the valves of the heart.
- Carcinoid Syndrome – This syndrome involves the flushing of the skin due to a release of serotonin, from carcinoid tumor growths in the digestive tract.
What Causes Pulmonary Valve Stenosis?
Pulmonary valve stenosis is a defect involving the abnormal growth of the pulmonary valve when the baby is in the womb. Often, the baby will have other congenital heart abnormalities. The pulmonary valve is comprised of three cusps (thin layers of tissue) that form a circle. As the heart beats, the pulmonary valve opens to allow the flow of blood in one direction that leads out to the pulmonary artery and into the lungs.
The pulmonary heart valve then closes blocking the backward flow of blood into the right ventricle. However, the defect causes the cusps to become too thick or malformed causing a restricted flow of blood when the valve is not functioning properly. The defect or malformation may affect one, two or all three cusps. Other risk factors may cause pulmonary stenosis, especially later in life. This includes Noonan syndrome, rheumatic fever, and carcinoid syndrome.
Depending on the level of obstruction or defect, the symptoms associated with pulmonary valve stenosis can range from no symptoms at all to severe. The most common pulmonary valve stenosis symptoms include:
- Shortness of breath, especially after physical activity
- Fainting (loss of consciousness)
- Chest pain
- Heart murmur detected by a stethoscope as an abnormal whooshing sound produced by the turbulent flow of blood.
Any serious heart problem, including pulmonary valve stenosis, usually requires a prompt evaluation and effective treatment to ensure the risks of the complications associated with the condition are reduced or eliminated.
Diagnosing Pulmonary Stenosis
Doctors usually diagnose pulmonary valve stenosis during the patient's childhood years. However, sometimes it cannot be identified until the patient reaches late adulthood. The diagnostician may be suspicious of a heart defect if a heart murmur is detected when listening through a stethoscope during a routine checkup. When this occurs, the doctor typically recommends a variety of tests to accurately diagnose and verify the condition. These tests include:
- Electrocardiogram (ECG) – This test measures the heart's electrical activity and can determine a thickening of the right ventricle wall caused by ventricular hypertrophy.
- Echocardiography – This test uses sound waves to generate a moving image of the heart in motion that can be seen on a video screen. The results of the test can identify stenosis (narrowing) of the right ventricle, along with its severity, location, and function.
- Imaging Scans – The doctor may recommend a CT (computerized tomography) scan, or MRI (magnetic resonance imaging) scan to accurately confirm a diagnosis of the defect.
- Cardiac Catheterization – By inserting a flexible, thin catheter (tube) into a Weiner artery in the groin, the doctor can weave the catheter into the heart through blood vessels. If a dye is used, it is injected through the catheter to make the blood vessels highly visible after an x-ray has been taken. Cardiac catheterization measures blood pressure in blood vessels and heart chambers to verify a diagnosis of pulmonary stenosis.
In some rare cases, the doctor may recommend a balloon valvuloplasty in conjunction with a cardiac catheterization when necessary.
Pulmonary Stenosis Treatments
After a diagnosis of pulmonary valve stenosis has been verified, the doctor will determine if the defect is mild, moderate, or severe. This can be done by measuring blood pressure differences between the pulmonary artery and the right ventricle. Usually, treatment is not necessary for mild cases of pulmonary stenosis.
However, the patient should follow up with routine checkups to detect any worsening of the condition before it progresses too far. More serious cases often require open-heart surgery or balloon valvuloplasty.
- Open-Heart Surgery – Typically the doctor will perform a balloon valvuloplasty procedure before recommending open-heart surgery. During the surgical procedure, the doctor will repair the defect or replace the body's valve with an artificial one. The doctor can also use an open-heart surgical procedure to repair a congenital heart defect. However, like all surgeries, there is often a minimal risk of infection, bleeding, or blood clots.
- Balloon Valvuloplasty – During this procedure, the doctor will insert a small tube through a vein in the leg and threaded through blood vessels into the heart as a part of a cardiac catheterization. The threat contains an uninflated balloon that is positioned in the narrowed pulmonary valve. The balloon is then inflated and widens the narrowed valve to increase the flow of blood to the area. The balloon is then removed by reversing the procedure.
In addition to the above procedures, the doctor may prescribe preventative antibiotics to prevent infectious endocarditis prior to surgical and dental procedures that are known to cause bacterial infections. Healthy lifestyle choices like quitting smoking, consuming a healthy diet, exercising on a routine basis, and maintaining a healthy weight are effective in minimizing many of the risk factors associated with pulmonary valve stenosis.