Abstract 10662: Variability in Normal Mitral Annular Geometry and its Impact on Annuloplasty Ring Selection and Design
Introduction: The objective of this study was to assess mitral annular geometry in subjects with normal mitral valve (MV) function using 3D transesophageal echocardiography (3D TEE). Hypothesis: 3D TEE image analysis and statistical shape modeling can identify features of normal mitral annular geometry and optimize annuloplasty ring selection and design.
Methods: Full-volume 3D TEE images of the MV were acquired from 13 human subjects with normal MV structure and function and normal ejection fraction. 3D patient-specific shape models of the mitral annulus were semi-automatically generated at midsystole using active contour segmentation and shape modeling with medial representation. Total annular circumference (AC), posterior and anterior annular circumferences (PAC, AAC), annular height (AH), septolateral diameter (SLD), and intercommissural width (ICW) were measured. A mean 3D annular shape was computed by generalized Procrustes analysis.
Results: Mean ± standard deviations were obtained from 3D TEE image analysis: 109.6 ± 16.0 mm (AC), 66.0 ± 12.0 mm (PAC), 43.6 ± 7.5 mm (AAC), 9.5 ± 3.0 mm (AH), 29.0 ± 4.3 mm (SLD), 33.3 ± 4.7 mm (ICW). Of the six measurements, AH had the largest coefficient of variation (31.5%) and ICW, AC, and SLD had the smallest (14.1%, 14.6%, 15.0%). The mean annular model, illustrated below, had a distinct saddle shape with peaks at the anterior aortic peak and midpoint of the posterior annulus and troughs at the commissures. In all subjects, annular height measured with respect to the anterior commissure was larger than that measured with respect to the posterior commissure, indicating a consistent asymmetry in annular saddle shape.
Conclusion: 3D TEE-based modeling of the human MV predicts consistent normal annular shape and size with the most variable parameter being AH. These results suggest that annuloplasty ring selection should be based in part on AH, rather than solely on annular diameter, to optimally restore normal annular geometry.
- © 2012 by American Heart Association, Inc.