Until recently the hemodynamic severity of valvular aortic stenosis (AS) was evaluated only by cardiac catheterization. Now, Doppler echocardiography allows a noninvasive and accurate assessment of AS severity and can be used to study its progression with time. The progression of AS was assessed during a follow-up period of 6 to 45 months (mean 18) by serial Doppler examinations in 45 adult patients (21 men and 24 women, mean age 72 +/- 10 years) with isolated AS. The following parameters were serially measured: left ventricular outflow tract diameter and velocity by pulsed Doppler, peak velocity of aortic flow by continuous-wave Doppler, to calculate peak gradient by the modified Bernoulli equation, and aortic valvular area by the continuity equation. At the initial observation, 13 of 45 patients (29%) were symptomatic (1 angina, 1 syncope and 11 dyspnea); during follow-up, 25 (55%) developed new symptoms or worsening of the previous ones (5 angina, 3 syncope and 17 dyspnea); 11 underwent aortic valve replacement and 3 died from cardiac events. Baseline peak velocity and gradient ranged between 2.5 and 6.6 m/s, and 25 and 174 mm Hg, respectively; aortic area ranged between 0.35 and 1.6 cm2. With time, mean peak velocity and gradient increased significantly from 4 +/- 0.7 to 4.7 +/- 0.8 m/s (p less than 0.01), and 64 +/- 30 to 88 +/- 30 mm Hg (p less than 0.01), respectively. A concomitant reduction in mean aortic area occurred (0.75 +/- 0.3 to 0.6 +/- 0.15 cm2; p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)