Temporal variations in effective orifice area during ejection in patients with valvular aortic stenosis

Abstract

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 cm 2) (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 cm 2/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.