The pulmonary or pulmonic valve is the valve between the right ventricle and the pulmonary artery. It opens to allow blood to flow from the right ventricle to the lungs. A defective pulmonary valve that doesn't open properly is called stenotic. That means the right ventricle must pump harder than normal and reach a higher than normal pressure to overcome the obstruction. If the stenosis is very severe, especially in babies, not enough blood crosses the valve to reach the lungs to become oxygenated. This is called critical pulmonary valve stenosis. Therefore cyanosis (blueness) may occur as the blood finds other pathways to get from the veins returning to the heart back to the body (“right to left” shunt).
Sometimes the valve does not open at all, in which case it is called pulmonary atresia. In those cases, the tricuspid valve may be underdeveloped and the right ventricle may also not be well formed and is small or hypoplastic. In other cases, the stenosis is very mild and causes minimal obstruction to blood flow.
What Are the Symptoms of Pulmonary Stenosis?
Depending on the severity, no symptoms may be present with mild stenosis. Severe cyanosis may be the feature which calls attention to the patient with pulmonary stenosis.
How Is Pulmonary Stenosis Diagnosed?
The physical examination provides the first clues to the underlying heart defect. There may be an abnormal murmur to suggest abnormal blood flow across the abnormal valve. With critical stenosis or atresia, there may be no abnormal murmur, but cyanosis should be present to provide the clue of the heart defect. The definitive diagnosis is made with an echocardiogram.
How Is Pulmonary Stenosis Treated?
With very severe pulmonary stenosis or pulmonary atresia, which is noted in newborns, a medicine is sometimes given to stabilize the infant and improve oxygenation. This medication is called “prostaglandin” and helps to open the ductus arteriosus and provide more blood flow to the lungs. In cases where the right ventricle is normal in size, treatment of critical stenosis or atresia is performed soon after birth.
Treatment options include open-heart surgery and interventional cardiac catheterization. Attempts to relieve the obstruction are usually successful by putting a balloon across the valve and dilating the narrowed area (opening up the valve when the balloon is blown up). This is called balloon valvuloplasty and is an interventional procedure performed in the cardiac catheterization laboratory. Not all patients with pulmonary stenosis require an intervention. The indication to intervene depends on whether or not the pressure in the right ventricle is higher than normal as well as the size of the right ventricle and other factors, which can be determined by your cardiologist.
Almost all surgical operations and cardiac catheterizations have the risk of bleeding, infection and sedation. Open-heart surgery has special risks of cardiopulmonary bypass. Special risks of valvuloplasty in the catheterization laboratory include rupture of one of the blood vessels as the balloon is inflated. Both procedures will end up with some amount of pulmonary valve regurgitation. This is usually well tolerated, though may need to be treated in the long term.
What Are the Long-term Effects of Pulmonary Stenosis?
Untreated significant pulmonary stenosis can lead to abnormal right ventricular function, rhythm abnormalities and a shortened lifespan. The outlook after balloon valvuloplasty or surgery is favorable, but follow-up is required to determine if heart function returns to normal. With a good result from surgery or cardiac catheterization, a normal lifestyle and lifespan is possible. Preventive measures against bacterial endocarditis may be indicated.