Between December 1, 1986 and October 30, 1987, balloon aortic valvuloplasty was performed in 492 patients with aortic stenosis (mean age 79 +/- 8.4 years) enrolled in the Mansfield Scientific Aortic Valvuloplasty Registry. All procedures were performed from a femoral approach (92%), brachial approach (6%) or transseptal approach (2%) and utilized either a single balloon technique (72%) or a double balloon technique (28%). Valvuloplasty resulted in a significant improvement in aortic valve area (0.50 +/- 0.18 cm2 to 0.82 +/- 0.30 cm2), mean aortic valve gradient (60 +/- 23 mm Hg to 30 +/- 13 mm Hg) and cardiac output (3.86 +/- 1.26 to 4.05 +/- 1.31 liters/min). Serial aortography demonstrated a moderate or severe increase in aortic insufficiency in only 2.1% of patients. Statistical analysis of the procedural factors affecting acute valvuloplasty results demonstrated significant correlations of single versus double balloon technique, total number of balloon inflations and total number of balloon exchanges with respect to the absolute change in mean aortic valve gradient occurring during the valvuloplasty procedure. In addition, there was a significant correlation between the maximal time of valvuloplasty balloon inflation with aortic valve area measured after valvuloplasty, and there were significant correlations of the total number of balloon inflations and total number of balloon exchanges with the aortic valve mean gradient measured after valvuloplasty. The overall complication rate for the procedure was 20.5%, including vascular injury in 11%, embolic phenomenon in 2.2%, ventricular perforation resulting in tamponade in 1.8%, massive aortic insufficiency in 1%, nonfatal arrhythmia in 0.8% and myocardial infarction in 0.2%. Death occurred within 24 h of the procedure in 4.9%, and within 7 days in an additional 2.6%. The results of this multicenter study suggest that balloon aortic valvuloplasty can result in acute hemodynamic improvement in patients with aortic stenosis, with only a minimal risk of increasing aortic insufficiency. Single versus double balloon technique, the total number of balloon inflations, the length of balloon inflation, and the total number of balloon exchanges are all procedural factors that may affect the immediate efficacy of the procedure. At the time of this study, complication rates for the procedure are significant, with one in five patients experiencing a complication.