With the current trend to performing surgical valvotomy for infantile aortic stenosis without cardiac catheterization, there is a need to develop echocardiographic criteria for adequacy of left ventricular size. The echocardiograms and catheterization data of all 25 infants less than 3 months of age undergoing aortic valvotomy for isolated aortic valve stenosis from September 1980 through July 1990 were reviewed. Significant differences (p less than 0.05) between the survivors and nonsurvivors were noted for age at operation (30 +/- 28 vs. 3 +/- 1.5 days), mitral valve diameter (10.1 +/- 1.7 vs. 7.7 +/- 1.5 mm), left ventricular end-diastolic dimension (18.4 +/- 6.4 vs. 11.4 +/- 3 mm), left atrial dimensions (15.3 +/- 3.8 vs. 10 +/- 2.4 mm), left ventricular cross-sectional area on the parasternal long-axis echocardiogram (4 +/- 1.9 vs. 2 +/- 1.9 cm2) and angiographically determined left ventricular end-diastolic volume (43 +/- 23 vs. 11 +/- 5 ml/m2). There was no difference with respect to patient weight, body surface area, aortic root dimension or left ventricular ejection fraction. Left ventricular cross-sectional area less than 2 cm2 as measured on the parasternal long-axis echocardiogram was found in 5 of 7 nonsurvivors and 0 of 12 survivors, making this a risk factor for perioperative death (p less than 0.05). Left ventricular end-diastolic dimension less than 13 mm was found in 5 of 6 nonsurvivors and 2 of 17 survivors, making this another risk factor for early mortality (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)