Background Percutaneous balloon valvuloplasty has been the accepted first-line treatment for congenital pulmonic stenosis in children. Its efficacy in adolescents and adults is less well defined. Methods Between December 1985 and July 1995 we performed percutaneous pulmonic valvuloplasty with a single Inoue balloon catheter in 53 adolescent or adult patients 13 to 55 years of age (mean [+/-SD], 26+/-11). Follow-up studies were performed 0.2 to 9.8 years after the procedure (mean, 6.9+/-3.1) by Doppler echocardiography (in all the patients) and by cardiac catheterization and angiography (in nine patients). Results After balloon valvuloplasty, the systolic pressure gradient across the pulmonic valve decreased from 91+/-46 mm Hg to 38+/-32 mm Hg (P<0.001), and the diameter of the pulmonic-valve orifice increased from 8.9+/-3.6 mm to 17.4+/-4.6 mm (P<0.001). In the nine patients catheterized at followup, the systolic gradient decreased from 107+/-48 mm Hg before valvuloplasty to 50+/-29 mm Hg after valvuloplasty and to 30+/-16 mm Hg at follow-up (P<0.001 for the comparison of the gradient before and after valvuloplasty; P<0.001 for the comparison before valvuloplasty and at follow-up; and P<0.05 for the comparison after valvuloplasty and at followup). In the same nine patients, the diameter of the pulmonic valve, as measured by right ventricular angiography, increased from 8.3+/-1.4 mm before valvuloplasty to 17.2+/-2.0 mm after valvuloplasty (P<0.001) and to 18.4+/-1.4 mm at follow-up (P=0.08). Incompetence of the pulmonic valve was noted in 7 of the 53 patients (13 percent) after balloon valvuloplasty, but it had disappeared at followup in all of them. Conclusions Patients with congenital pulmonic stenosis who present in late adolescence or adult life can be treated with percutaneous balloon valvuloplasty with excellent short-term and long-term results that are similar to those in young children. (C)1996, Massachusetts Medical Society.