Since Kan et al. first reported percutaneous balloon pulmonary valvuloplasty (PBPV) for simple pulmonary stenosis in 1982, an in-depth and comprehensive study on the indications, methodology, pre- and postoperative hemodynamics, mechanism of action, and follow-up of PBPV has been conducted, which concluded that PBPV is a simple, effective, safe, and economical method of choice for the treatment of typical pulmonary stenosis. The best age is 2-4 years old, and the rest can be performed at all ages. (B) Relative indications 1. typical pulmonary stenosis with large right ventricle on electrocardiogram, dilated pulmonary artery on right ventriculography, and presence of ejection sign, but trans-pulmonary valve pressure difference <50 mmHg or ≥35 mmHg on cardiac catheterization. 2. severe neonatal pulmonary stenosis. 3. severe pulmonary stenosis with right-to-left shunt at atrial level. 4. mild to moderate dysplastic pulmonary stenosis. 5. Pulmonary valve stenosis with pre-cardiac disease such as patent ductus arteriosus or atrial septal defect, which can be treated with simultaneous intervention. The selection of the above relative indications depends on the experience, conditions, personnel, equipment, and patient status of each cardiovascular center for interventional cardiac catheterization. (C) Non-indications 1. simple pulmonary inferior funnel stenosis with normal valves. 2. severe dysplastic pulmonary stenosis. 3. severe tricuspid regurgitation with surgical management. (1) Preoperative preparation 1. Preoperative physical examination, electrocardiogram, X-ray chest radiograph and echocardiogram are required to determine the type of pulmonary stenosis and its severity. 2. Preoperative routine preparation for cardiac catheterization. (B) Diagnostic cardiac catheterization Before performing PBPV, right heart catheterization and right ventriculography in the left side position are first performed to determine the trans-pulmonary valve pressure difference and the type of stenosis, and the diameter of the pulmonary valve annulus is measured as a basis for selecting the balloon size. (C) Balloon dilation is performed under general or local anesthesia with left and right femoral vein cannulation and parallel femoral artery cannulation (or noninvasive method) to observe arterial blood pressure. The size of the balloon should be chosen: the ratio of balloon/valve annulus is usually 1.2-1.4. In severe stenosis, the ratio can be small, and in pulmonary stenosis with dysplasia, the ratio of balloon/valve is large. Balloon length: 20-mm-long balloons are suitable for infants; 30-mm-long balloons are suitable for all children except infants; and 30- to 40-mm-long balloons are available for adults. The balloon catheter should be diluted with contrast agent and the balloon should be deflated several times before insertion to check whether the balloon is broken and to expel the air. Single or double balloon dilatation can be used depending on the condition.1. Single balloon valvuloplasty starts with an end-hole catheter or balloon end-hole floating catheter through the femoral vein, inferior vena cava, right atrium, common pulmonary artery, usually to the left pulmonary artery, and finally to the small pulmonary artery, then a straight or elbow wire with a length of 220-260 cm is inserted to the lower lobe pulmonary artery, the end-hole catheter is removed, and the femoral vein is enlarged with a dilatation tube. The end-hole catheter is removed and the femoral vein is enlarged with a dilating tube to allow smooth insertion of the balloon catheter. If the heart rate is slow before balloon expansion, atropine can be used to increase the heart rate to 80 beats/min in adults and more than 100 beats/min in children. After the balloon is inserted and the balloon catheter is pushed to the lower part of the diaphragm of the inferior vena cava, the balloon is dilated again with a dilute contrast agent to check whether the balloon is intact, and if there is no abnormality, the catheter is pushed to the pulmonary valve. If the balloon is in place, the balloon is rapidly dilated with 1:3 diluted contrast agent and the lumbar concavity disappears as the pressure in the balloon cavity increases. Once the balloon is fully dilated and the lumbar concavity disappears, the balloon can be aspirated. The total time from the start of balloon dilation to the deflation of the balloon is usually <10 s. This reduces complications due to prolonged interruption of right ventricular outflow tract blood flow. Usually 2 to 3 repeated dilatations are performed, and sometimes 1 effective dilatation is sufficient to achieve the therapeutic goal. After balloon dilation, the right heart catheterization is repeated, the continuous pressure curve from the pulmonary artery to the right ventricle is recorded, the transvalvular pressure difference is measured, and a left-sided right ventriculogram is performed to observe the effect of balloon dilation and the presence of reactive stenosis in the right ventricular funnel. 2. Double balloon pulmonary valvuloplasty is required in some cases to achieve an adequate balloon valve/annulus ratio. The sum of the two balloon diameters is usually 1.5 times or slightly more than the diameter of the pulmonary annulus. The balloon catheter is inserted by puncturing the right and left femoral veins separately, in the same way as for single-balloon dilation. Two balloons of approximately the same diameter and length were selected, so that the balloon catheter was at the same level, and simultaneous dilatation was performed with dilute contrast agent, to the extent that the lumbar concavity disappeared when the balloon was dilated, and the method was the same as that of single balloon dilation. After balloon dilatation, the pulmonary artery and right ventricular pressure test and right ventricular lateral angiography were repeated. If the postoperative transvalvular pressure difference between the pulmonary artery and the right ventricle (funnel) is less than 25 mmHg, and the right ventriculogram shows that the pulmonary valve stenosis has been released, the PBPV effect is good. In some patients, although the valve obstruction was relieved after PBPV, the pressure drop in the right ventricle was unsatisfactory because of reactive funnel stenosis, but the continuous curve showed that the pressure difference between the pulmonary artery and the funnel was relieved, and there was a pressure step difference between the funnel and the right ventricular inlet, which indicated that PBPV was effective. The reactive funnel stenosis usually recovered within 6 months. Postoperative management and follow-up 1. Patients under general anesthesia should be observed until they are awake, and the local puncture site should be compressed to stop bleeding. If necessary, echocardiography should be repeated within 24 hours. 2. For PBPV with right ventricular outflow tract reactive stenosis, β-blockers should be given orally, usually for 3-6 months. 3. V. Complications Although PBPV is a safe and effective non-open method for the treatment of pulmonary stenosis, there are still about 5% of complications, with an overall mortality rate of <0.5%, mostly in neonates, small infants and severe cases. In addition to the complications of cardiac catheterization, the complications include transient drop in blood pressure during balloon pressure dilation; arrhythmias including bradycardia, conduction block, premature beats and tachycardia; vascular injury; tricuspid valve insufficiency due to tricuspid tendon damage; cardiac perforation and pericardial tamponade.