Pulmonary stenosis (PS) is a common congenital heart disease, accounting for about 8-12% of the total. Pathologic anatomy] 1, pulmonary stenosis can be divided into pulmonary valve stenosis, pulmonary valve stenosis (i.e., funnel part) and pulmonary valve stenosis. 2, in the pulmonary valve stenosis, can be seen in the thickening of the pulmonary valve, the three valve leaflet junction fused with each other or no junction between the valve leaflets, the valve mouth is narrow, only the center to leave a small hole. Severe pulmonary stenosis (near atresia) in infancy is often associated with dysplasia, although the right ventricle is normal in size. In the dysplastic form, the pulmonary valve is often thickened, irregular, stiff, and has a small annulus, as seen in Noonan syndrome. 3. Simple funnel pulmonary stenosis is rare; it is often combined with a large ventricular septal defect, as seen in tetralogy of Fallot. 4. Suprapulmonary stenosis, also known as main pulmonary stenosis, is occasionally seen in rubella syndrome and Williams syndrome. Pathophysiology] At 6-9 weeks of gestation, the common trunk of the artery separates into the aorta and pulmonary artery, and the pulmonary valve begins to develop. Pulmonary valve stenosis is due to fusion of the valve leaflets in the middle and late stages of pregnancy. Pulmonary valve stenosis during fetal life does not have much effect on circulation. After birth, due to pulmonary valve stenosis, the right ventricle is obstructed from discharging blood, the systolic load is increased, and thus the right ventricular pressure is elevated. In the long term, this leads to right ventricular hypertrophy, which narrows the right ventricular cavity, followed by obstruction of the right ventricular outflow tract, which increases right ventricular pressure further, and excretory difficulty is aggravated, resulting in failure of the right ventricle to function and the occurrence of heart failure. In severe stenosis, the right atrial pressure rises, and if there is an unclosed patent foramen ovale or atrial septal defect, blood flow can flow from the right atrium to the left atrium, resulting in cyanosis. With the different degree of stenosis, the right ventricle and the pulmonary artery between the different degrees of pressure step difference, blood flow from the high-pressure right ventricle through the stenotic orifice, into the low-pressure pulmonary artery, resulting in jet turbulence, so that the main trunk of the pulmonary artery after the formation of stenosis dilatation, which is mainly seen in the valvular type stenosis. Clinical manifestations] 1. Symptoms Children with mild stenosis may be completely asymptomatic; those with moderate to severe stenosis may have exertional dyspnea and fatigue. In severe stenosis, there may be heart failure or chest pain during activity. 2, neonatal severe pulmonary stenosis, feeding difficulties, shortness of breath, cyanosis and heart failure. 3.Physical examination Most of the sick children are well developed without cyanosis, and neonates with severe pulmonary valve stenosis have shortness of breath and cyanosis. The precordial area is full, and the right ventricular lifting beat can be touched on the left side of the sternum, and systolic tremor can be detected above the left edge of the sternum. A grade 2-5/6 jet systolic murmur can be heard superior to the left sternal border, traveling dorsally; the intensity and duration of the murmur are proportional to the severity of the stenosis. Early systolic clicks may be heard in mild and moderate stenosis. The click is due to the sudden tightening of the thickened but still elastic valve at the onset of contraction. The second tone in the pulmonary valve region is split and attenuated to varying degrees. 4.When accompanied by congestive heart failure, there may be hepatomegaly. Electrocardiogram (ECG): In mild stenosis, the ECG is normal; in moderate stenosis, the electrical axis is deviated to the right, and the right ventricle is hypertrophied. The degree of right ventricular hypertrophy is proportional to the severity of stenosis. X-ray examination The heart size is normal, but the pulmonary artery segment is bulging (i.e. the pulmonary artery is dilated after stenosis). In the presence of heart failure, the heart is markedly enlarged, mainly the right ventricle and right atrium. The pulmonary angiogram is usually normal, but in severe pulmonary stenosis, there is a decrease in pulmonary blood. In neonates with severe pulmonary stenosis, there is less pulmonary blood and the heart is enlarged to varying degrees. 3. Echocardiography A 2-dimensional echocardiogram may show thickening of the pulmonary valve and a rounded bulge with restricted systolic opening; measure the pulmonary valve annulus; and show dilatation of the main pulmonary arteries (i.e., dilatation of the pulmonary arteries after stenosis). Doppler ultrasound can estimate the transvalvular pressure order difference across the pulmonary valve based on the modified Bernoulli equation, and thus the severity of pulmonary stenosis. Dysplastic valves show significant thickening, leaflet stiffness, and annular dysplasia. 4. Cardiac catheterization grades pulmonary stenosis according to the pressure gradient between the right ventricular systolic pressure and the pulmonary artery. A pressure gradient between 10-30 mmHg is considered mild, 30-60 mmHg is considered moderate, and greater than 60 mmHg is considered severe. Prognosis and Complications】 1. Mild pulmonary stenosis is usually not aggravated; however, moderate and severe stenosis will worsen with age. 2. Heart failure may occur in severe pulmonary stenosis. 3. Occasionally, infective endocarditis may occur. 4.Children with severe pulmonary stenosis have the potential for sudden death during heavy physical activity. 5.Most newborns with severe pulmonary stenosis can die if not treated appropriately. [Treatment] For children with moderate or severe pulmonary stenosis, it is generally recognized that when the right ventricular systolic pressure exceeds 50 mmHg, treatment should be instituted. Transcatheter balloon pulmonary valvuloplasty is the treatment of choice for most children. It is low-risk, painless, less expensive than open-heart surgery, has a shorter hospital stay, and is also effective in the dysplastic type of valve. If balloon pulmonary valvuloplasty fails, surgical open-heart valvulotomy is used. Transcatheter balloon valvuloplasty or surgical valvulotomy is necessary for severe pulmonary stenosis in the neonatal period. Mild pulmonary stenosis in childhood requires prevention of endocarditis.