Abstract 13438: Aortic Valve Adaptation to Aortic Root Dilatation: Insights into the Mechanism of Functional Aortic Regurgitation From Three-Dimensional Cardiac Computed Tomography
Background: The three-dimensional (3D) relationships between aortic root and leaflets are essential to understand the mechanism of potentially repairable functional aortic regurgitation (AR) due to aortic root dilatation (ARD), including whether the stretched leaflets enlarge in compensation.
Methods: Computed tomography imaged 92 patients, 57 with ARD: 29 with moderate to severe AR, 28 without significant AR, 35 normal controls. Specialized 3D software measured individual leaflet surface areas (LSAs) relative to maximal mid-sinus cross-sectional area and minimal 3D annular area, coapted Leaflet fraction (CoaptFrn), and asymmetry of sinus volumes and intercommissural distances.
Results: Total open LSA increased (p<0.001) from 7.6±1.4 cm2/m2 in normals to 12.9±2.2 in AR(–) and 15.2±3.3 in AR(+) patients, who had the largest roots. However, the ratio of closed LSA to maximal mid-sinus area, reflecting leaflet adaptation, decreased from normals to AR(–) to AR(+) patients (1.38±0.20 to 1.15±0.15 to 0.88±0.15, p<0.001), creating the lowest CoaptFrn.). Regurgitant orifice area correlated inversely with CoaptFrn (r=-0.60). Leaflet distensibility (closed diastolic versus open area) decreased from 20% in controls and AR(–) patients to 5% in AR(+) patients (p<0.001). Multivariate determinants of AR and CoaptFrn reflected both sinus size and leaflet-to-annular adaptation. ARD was also progressively asymmetric with root size, and individual LSAs failed to match this asymmetry.
Conclusions: Aortic leaflet enlargement occurs in ARD, but leaflet adaptation and distensibility become limited in prominent, asymmetric ARD, leading to AR. Optimal AR repair tailored to individual patient anatomy can benefit from appreciating valve adaptation and 3D valvular-aortic relationships; understanding leaflet adaptation mechanisms may ultimately provide therapeutic opportunities to improve such compensation.
- © 2013 by American Heart Association, Inc.