A refined hemispheric model of normal human aortic valve and root geometry.

BACKGROUND: Better understanding of aortic root geometry could improve diagnosis and reconstruction of pathologic aortic valves. In this study, a previous model of hemispheric aortic valve leaflets nested within a cylindrical aorta was refined in humans with normal aortic valves.
METHODS: Using 1-mm axial slices, high-resolution computed tomographic angiograms from 10 normal aortic roots were used to generate high-density X-, Y-, and Z-coordinates of valve structures using Mathematica software. Three-dimensional least squares regression analyses of leaflet and sinus coordinates were employed to compare multiple geometric models of aortic valve and root geometry. Shapes and dimensions of all root structures were evaluated and compared.
RESULTS: Aortic valve geometry was roughly hemispherical, but the valve base was elliptical (minor-major diameter ratio = .66). Dimensional fits of the leaflet-sinus complexes also were better using ellipsoidal geometry, with taller leaflets than predicted by hemispheres. The commissure between the left and noncoronary cusps was located uniformly at the posterior junction of the base minor diameter and circumference, with the center of the right coronary cusp opposite. The subcommissural post areas flared outward by 5° to 10°, and the volume of the right coronary leaflet-sinus complex was 12.4% and 10.7% larger than the noncoronary cusps and left cusps, respectively.
CONCLUSIONS: The normal human aortic valve is an elliptical structure, and ellipsoidal refinements improve representation of leaflet geometry. The left and noncoronary cusps commissure is located posteriorly; the right coronary cusp is located anteriorly. This model could be useful in quantifying pathologic geometry and in engineering devices for aortic valve reconstruction.