Normal Mitral and Aortic Valve Areas Assessed by Three- and Two-Dimensional Echocardiography in 168 Children and Young Adults

Our purpose was to investigate the effects of body size on the sizes of mitral (MV) and aortic valve (AV) areas by three-dimensional (3-D) and two-dimensional (2-D) echocardiography and to create the normal values for 3-D echocardiography. A total of 168 healthy subjects aged 2–27 years were studied by digitized 3-DE, 2-DE, and Doppler echocardiography.

3-D echocardiography was performed by using rotational acquisition of planes at 18° intervals from a parasternal view with electrocardiogram gating and without respiratory gating. The annular levels of MV and AV were identified from short-axis cut planes and their areas were measured by planimetry. The diameters of mitral annulus, left ventricular outflow tract (LVOT), and aortic annulus were measured by 2-DE from the apical and parasternal long-axis views. Flow indices were measured by Doppler from MV inflow and the flow in LVOT and in the ascending aorta. Both MV and AV annular areas increased linearly in relation to body size. In the total study group the estimated areas for MV were 5.2 ± 0.9 cm²/m²by 3-DE, 3.7 ± 0.5 cm²/m² by 2-DE, and 2.0 ± 0.4 cm²/m² by continuity equation. The respective values for AV were 2.7 ± 0.5, 2.1 ± 0.3, and 1.8 ± 0.4 cm²/m². MV velocity time integral (VTI)/ascending aorta VTI increased from 0.80 (0.26) to 0.95 (0.23) with increased body surface area (BSA), whereas MV VTI / LVOT VTI was 1.2 (0.2) in all BSA groups. MV and AV annulus areas increase linearly in relation to body size. 3-DE gives greater estimates for the areas than 2-DE and Doppler equation methods. The data obtained from 168 healthy subjects may serve as a reference for clinical use in patients with various cardiac abnormalities.