What is pulmonary stenosis? Pulmonary stenosis is a condition that results in restriction of blood flow from the right ventricle to the pulmonary artery due to a pulmonary valve lesion. Stenosis in one or more different locations from the right ventricle to the pulmonary artery can cause restriction of blood flow, including: subpulmonary muscular hypertrophy, stenosis of the valve itself, and supravalvular stenosis. The most common type of disease in this category is obstruction of the pulmonary valve itself, called pulmonary stenosis. The normal pulmonary valve consists of three thin, pliable leaflets. When blood is ejected from the right ventricle into the pulmonary artery, the normal pulmonary valve leaflets open freely and do not cause obstruction of blood flow. Pulmonary valve stenosis occurs when a pulmonary valve lesion causes narrowing or obstruction between the right ventricle and the pulmonary artery. Pulmonary stenosis is often associated with leaflet thickening and junctional fusion. Leaflet thickening can make the valve less flexible and produce obstruction. Sometimes, the pulmonary valve itself is poorly developed and has a small annulus. When the pulmonary valve is stenosed, the right ventricle must work harder to eject blood flow, and as compensation, the right ventricular muscle gradually hypertrophies. Therefore, thickening of the right ventricular muscle (myocardial hypertrophy) may not be a problem in itself and often indicates the presence of pulmonary valve stenosis. When pulmonary valve stenosis is very severe, especially if present in a newborn, the right ventricle is not able to shoot enough blood into the pulmonary artery. In such cases, instead of passing through the right ventricle, non-oxygenated blood passes from the right to the left atrium through the foramen ovale (the traffic between the two ventricles, which is present in all normal newborns), mixing with oxygenated blood and causing a decrease in the oxygen content of arterial blood, which manifests itself as purple lips of the mouth and nail beds of the fingers (toes). Pulmonary stenosis rarely presents with right heart failure. What are the signs and symptoms of pulmonary stenosis? Children with pulmonary stenosis are usually asymptomatic and in normal health. A heart murmur is usually the most common positive sign on physical examination. In mild to moderate pulmonary stenosis, a heart murmur can be easily detected but is usually asymptomatic. Clinical signs are most often seen in children with severe pulmonary stenosis. Newborns with severe pulmonary stenosis may present with cyanosis within the first few days of life. This is due to a decrease in blood flow to the lungs combined with a right-to-left shunt. This condition requires urgent management, balloon dilation or surgery. In an older child, a child with severe pulmonary stenosis may have chest pain, dizziness, or fainting, especially during activity. Severe pulmonary stenosis rarely leads to right heart failure or sudden death. How is the diagnosis made? Pulmonary stenosis is usually first suspected because the doctor hears a heart murmur during an examination. The heart murmur in pulmonary stenosis is a rough sound caused by the passage of ejected blood through the narrowed valve. It is often combined with a slapping sound when the thickened valve opens. A physician with good cardiac diagnostic training can detect these sounds with careful testing. Other tests can determine the presence of pulmonary stenosis and help detect its severity. An electrocardiogram is usually routine. In mild to moderate pulmonary stenosis, the ECG is usually normal. In severe pulmonary stenosis, the ECG may suggest an enlarged left ventricle or even left ventricular strain. Echocardiography is the most important noninvasive means of detection and evaluation. Echocardiography accurately depicts stenosis at the valve level, and color Doppler is used to estimate the degree of valve stenosis. It is also important in that echocardiography also rules out other problems that can accompany pulmonary valve stenosis, such as possible combined atrial septal defects and ventricular septal defects. If your child has pulmonary stenosis, your child’s doctor may also perform an exercise tolerance test. An exercise tolerance test provides information about the effect of pulmonary stenosis on cardiac function in the non-resting state, i.e., during daily activities. Cardiac catheterization is an invasive technique that allows physicians to accurately quantify the severity of pulmonary stenosis. The severity of obstruction can be measured by measuring distal and proximal valve pressures with cardiac catheterization techniques, and the motion pattern of the inferior valve can be photographed to show the possible presence of valve obstruction. echocardiography has largely replaced cardiac catheterization as a tool for detecting pulmonary stenosis for more than 15 years. Cardiac catheterization is generally rarely used to diagnose pulmonary stenosis, but is performed in conjunction with balloon dilation. Commonly used treatments? Mild pulmonary stenosis in children generally does not require treatment. Children with mild pulmonary stenosis can participate in a variety of sports and have no problems with daily living. However, pulmonary stenosis rarely progresses after one year of age, but can gradually worsen up to one year of age and requires observation and follow-up. For those with moderate to severe pulmonary stenosis requiring treatment, there is generally no strict time limit. The treatment depends on the specific type of valve abnormality. The most common case of pulmonary stenosis is a normal-sized valve with stenosis due to varying degrees of leaflet junction fusion. This “classic” lesion is well suited for balloon dilation. Balloon dilation can be performed at the same time as cardiac catheterization and does not require an open procedure. Balloon dilatation is challenging in newborns because they are very sick and have unstable circulation. More commonly, older children undergo balloon dilatation on an outpatient basis. For more complex valvular lesions, simple balloon dilation is not indicated and open cardiac surgery must then be used for treatment. In such children, the valve leaflets themselves may be poorly developed, with thickened tissue (as in Noonan syndrome), and in some patients the annulus diameter is small. In these cases, surgery may take the form of a leaflet junctional dissection, partial leaflet resection, or trans-pulmonary annular patching. Treatment Outcomes Balloon dilatation is highly effective. This technique was developed in the mid-1980s, and most major medical centers have accumulated some experience with it. This technique does not completely normalize the pulmonary valve, but for most patients it reduces severe pulmonary stenosis to a mild degree. In children or adolescents with typical pulmonary stenosis, balloon dilation may be the only appropriate treatment, and the chance of restenosis after successful balloon dilation is low. Neonates and small infants with severe pulmonary valve stenosis who do not have dysplasia of the valve receive excellent results with balloon dilation. However, in neonates and small infants, despite satisfactory initial dilatation, 20% have significant restenosis requiring re-dilation or surgery. Children whose lesions do not improve effectively with balloon dilation usually have more complex problems, such as valve calcification or a small annulus. The long-term results of direct cardiac surgery are also quite satisfactory. For most patients, balloon dilation alone may be required, and the procedure is only used in children with more complex problems. However, in patients with leaflet thickening and poor valve development, the long-term results of the procedure are quite satisfactory, and these children will lead normal lives in the absence of other co-morbid cardiac disorders. It is important that any patient treated, whether by balloon dilation or surgery, should be followed up regularly. Long-term follow-up, with regular evaluation by a qualified cardiologist, is a guarantee of further improvement of the treatment outcome.