Progress of interventional therapy for pulmonary stenosis Pulmonary Stenosis (PS) is a congenital cardiac anomaly in which the interventricular septum is intact and there is a narrowing of the pulmonary valve orifice, and its incidence accounts for about 10% of congenital heart disease, which can exist alone or in combination with other congenital anomalies such as arterial ductus arteriosus, interatrial septal defect, ventricular septal defect, and ectopic drainage of the pulmonary veins. (I) Pathological changes pulmonary valve stenosis is mainly manifested as three valve leaflet junction fusion into a dome-shaped thickened diaphragm, protruding into the lumen, the valve mouth was fish mouth, located in the center or eccentric, the small valve diameter of the mouth of the valve is about 1-3mm, the general valve diameter of the mouth of the valve is 5-12mm, most of the valve for the trileaflet valve, a small number of bivalvular valvular, pulmonary arteries trunk was narrow after the dilatation, often combined with the right ventricular outflow tract secondary hypertrophy. The main pathological subtypes are dome-like pulmonary stenosis, dipetalized pulmonary stenosis, annular dysplastic pulmonary stenosis and leaflet dysplastic pulmonary stenosis. 1, valve stenosis: the most common, accounting for 90%, is the junction of the three semilunar valves partially or completely fused, or combined with valve thickening, stenosis of the valve can be located in the center or eccentric, the valve mouth is generally in the range of 5 ~ 12mm, severe stenosis of the valve is only 2 ~ 3mm; can also be due to the development of dysplasia of the pulmonary valve, such as bilobed valves, their junction of the fusion of each other. 2, funnel part of the stenosis: mostly secondary caused by, can be fibrous, muscular or fibromuscular, the structure of the pulmonary valve is mostly normal, no narrowing after expansion. 3.Mixed type: pulmonary valve stenosis with funnel part stenosis, or funnel part stenosis with pulmonary artery branch stenosis. (B) Interventional therapy principles In 1982, Kan et al. first reported the application of percutaneous balloon valvuloplasty (Percutaneous Balloon Valvuloplasty PBPV) for the treatment of pediatric pulmonary stenosis was successful; in 1987, Alkasabs et al. applied the double balloon catheterization technique to its less traumatic, safer and can be used in cases of larger annulus, treatment of pulmonary stenosis. In 1987, Alkasabs et al. applied the double balloon catheter technique with its less traumatic, safer, and available for larger annulus cases to treat pulmonary stenosis with good results. Over the past two decades, through a large number of clinical practices, PBPV has become the preferred method for the treatment of pulmonary stenosis because of its safety, effectiveness, simplicity, and economy. 1, Indications (1) PS alone or combined with interventional therapy can be done in congenital heart disease, trans-pulmonary valve pressure step difference △ P ≥ 35mmHg; (2) Partial dysplasia type pulmonary valve stenosis; (3) Surgery or PBPV after surgery after restenosis. Contraindications (1) Hourglass-like deformity of the pulmonary valve; (2) Pulmonary valve hypoplasia (3) Pulmonary valve annulus stenosis, bilobar deformity of the pulmonary valve; (4) Severe pulmonary stenosis combined with severe heart failure or right ventricular dysplasia. (1) Severe pulmonary valve stenosis (△P ≥ 80 mmHg), PBPV should be performed as soon as possible, preferably within 3 months of age; moderate pulmonary valve stenosis (△P between 50 and 80 mmHg) can be performed at 6 months to 12 months of age; mild pulmonary valve stenosis (50 mmHg ≤ △P) can be done at 1 year of age or older PBPV. (2) In cases of pulmonary valve atresia/intact septum, catheterized radiofrequency perforation followed by PBPV can be performed for radical treatment. (3) For PS in infants under 1 year of age, the size of the single balloon should be 90-100% of the pulmonary valve annulus; for PS patients over 1 year of age, the size of the single balloon should be 120-140% of the pulmonary valve annulus; for PS patients over 14 years of age, the size of the mitral balloon or the double balloon can be selected, and the size of the double balloon should be 150% of the pulmonary valve annulus. (4) The wire should not pass through the tricuspid tendon cords, so that the balloon catheter will not tear the tricuspid tendon cords; the balloon should be inflated quickly, and the balloon should be emptied immediately after the concavity disappears. (5) If right ventricular outflow tract spasm occurs after PBPV surgery, ß-blockers should be taken for 1~3 months and long-term follow-up should be done. 4. Complications (1) Rupture of tricuspid tendon cords The main reason is that the guide wire passes through the tricuspid tendon cords, causing the balloon to tear or damage the tricuspid tendon cords during inflation. The balloon catheter should be stopped when there is resistance while delivering the balloon catheter and it should be determined with the help of echocardiography, whether the balloon catheter has passed through the tricuspid tendon cords or not [1]. (2) Tricuspid valve insufficiency The balloon catheter slips down into the tricuspid valve during inflation, dilating the tricuspid annulus and causing regurgitation. The balloon catheter should be secured during balloon inflation to prevent it from sliding upward and downward. (3) Right ventricular outflow tract spasm Mainly due to increased reactivity of the funnel, secondary hypertrophy of the right ventricular outflow tract, and large or repeated stimulation of the right ventricular outflow tract by the balloon catheter. The appropriate balloon catheter should be selected, the center of the balloon should be positioned at the level of the pulmonary valve, and the balloon should be inflated as much as possible to complete the dilatation procedure 1~2 times to reduce the stimulation of the right ventricular outflow tract. (4) Pulmonary artery and right ventricular outflow tract tears are rare. The main reason is that the balloon catheter is selected too large. An appropriate balloon catheter should be selected, 90-100% of the diameter of the pulmonary valve annulus in cases <1 year of age, and 120-130% of the diameter of the pulmonary valve annulus in cases >1 year of age. (5) Air embolism is rare. The main cause is rupture of the balloon during inflation and escape of gas. The balloon should be completely deflated during preparation of the balloon catheter.