Effective orifice area (EOA) is the standard index for assessing aortic stenosis (AS) severity. However, EOA varies during ejection and a single measurement at 1 ejection time point may not fully describe the hemodynamic severity of a stenotic aortic valve. We investigated whether the dynamic change in EOA during ejection differs between patients with severe AS (EOA ≤ 1.0 cm²) (n = 15) and age-/sex-matched control patients (n = 15), and whether the ejection pattern varies with AS severity (n = 45). In patients with severe AS, maximum left ventricular outflow tract velocity (V_LVOT) and transvalvular velocity (V_AS) occurred later in the ejection period (EP) when compared with control patients (V_LVOT 47 ± 8 vs 29 ± 8%, P = .0001; V_AS 36 ± 7 vs 27 ± 8%, P = .003). Maximum V_LVOT occurred later than maximum V_AS in patients with severe AS (47 ± 8 vs 36 ± 7%, P = .0005), but simultaneously in control patients (29 ± 8 vs 27 ± 8%, P = NS). Patients with severe AS had a slower EOA opening rate than control patients (4 ± 1 vs 41 ± 38 cm²/s, P = .002) and reached 80% and 100% of maximum EOA later in the EP (43 ± 26 vs 15 ± 6%, P = .001; 70 ± 20 vs 48 ± 30%, P = .03). EOA tended to increase between 10% and 90% of the EP in patients with severe AS, but had a plateau in control patients (slope 0.38 ± 0.26 vs 0.02 ± 0.25% change in EOA per 1% change of EP, P = .0006). In patients with severe AS, EOA was ≥80% of maximum EOA for a shorter duration during ejection compared with control patients (49 ± 25 vs 64 ± 14%, P = .05). EOA opening rate, time to maximum V_LVOT, time to maximum V_AS, and time to 80% of maximum EOA correlated with mean pressure gradient (r = −0.80, 0.63, 0.42, and 0.54, respectively, n = 45). Indices of ejection dynamics and valve kinetics differ in patients with AS and may provide further insight into the hemodynamic or physiologic severity of a stenotic aortic valve.