To assess right ventricular (RV) diastolic filling in children with pulmonary stenosis (PS), 14 patients (mean age 5.1 years) were examined immediately before and after pulmonary balloon valvuloplasty. Fourteen normal children (mean age 4.8 years) were also studied. From the tricuspid valve inflow Doppler study, the following measurements were made at peak inspiration: peak velocities at rapid filling (peak E) and during atrial contraction (peak A), ratio of peak E to peak A velocities, RV peak filling rate normalized for stroke volume, total area under the Doppler curve, percent of the total Doppler area occurring in the first third of diastole (0.33 area fraction), percent of the total area occurring under the E wave (E area fraction), percent of the total area occurring under the A wave (A area fraction) and the ratio of E area to A area. Before balloon valvuloplasty, the patients with PS had higher peak A velocity (0.64 +/- 0.28 vs 0.39 +/- 0.08 m/s), lower E/A velocity ratio (1.11 +/- 0.52 vs 1.76 +/- 0.45), lower 0.33 area fraction (0.34 +/- 0.14 vs 0.49 +/- 0.08), higher A area fraction (0.45 +/- 0.21 vs 0.27 +/- 0.09) and lower E/A area ratio (1.73 +/- 1.05 vs 2.96 +/- 1.14) than the normal subjects (p less than 0.01). In patients before and after balloon valvuloplasty, there was a significant difference in RV outflow gradient (71 +/- 35 vs 28 +/- 15 mm Hg), but there was no change in any Doppler index. Thus, patients with PS have abnormal diastolic filling with decreased filling in early diastole and increased filling during atrial contraction.(ABSTRACT TRUNCATED AT 250 WORDS)