Determination of aortic valve area by two-dimensional and Doppler echocardiography in patients with normal and stenotic bioprosthetic valves.

To assess the feasibility and accuracy of determining bioprosthetic aortic valve area from two-dimensional and Doppler echocardiographic measurements, three partially overlapping groups were selected from 55 patients with such bioprosthetic valves and adequate Doppler studies. These were Group 1, 37 patients with recent aortic valve replacement surgery and no clinical or echocardiographic evidence of valve dysfunction; Group 2, 12 patients with prosthetic valve stenosis documented by cardiac catheterization; and Group 3, 22 patients with both Doppler and catheterization studies in whom noninvasive and invasive determinations of aortic valve area could be directly compared. Left ventricular outflow tract diameter was measured from two-dimensional still frame images. Flow velocity proximal to the aortic valve, transvalvular velocity and acceleration time were determined from pulsed and continuous wave Doppler spectra. Aortic valve gradient was calculated with the modified Bernoulli equation and valve area by the continuity equation. In the 37 patients with a normally functioning valve, the calculated mean gradient ranged from 5 to 25 mm Hg (average 13.6 +/- 5.2) and valve area from 1.0 to 2.3 cm2 (mean 1.6 +/- 0.31). Linear regression analysis of prosthetic aortic valve area determined by Doppler imaging and cardiac catheterization demonstrated a high correlation (r = 0.93) between the two techniques. Comparison of the patients with and without prosthetic valve stenosis revealed statistically significant differences in mean gradient (42.8 +/- 12.3 versus 13.6 +/- 5.2 mm Hg; p = 0.0001), acceleration time (116 +/- 15 versus 80 +/- 13 ms; p = 0.0001) and valve area by the continuity equation (0.80 +/- 0.16 versus 1.6 +/- 0.31 cm2; p = 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)