Abstract 3180: Underestimation of the Proximal Isovelocity Surface Area by Conventional Flow Convergence Method in Functional Mitral Regurgitation: Comparison Between Hemispheric and 3D Hemi-ellipsoidal Assumption
Background: The geometry of the proximal isovelocity surface area (PISA) in functional mitral regurgitation (FMR) is elongated, leading to the underestimation of the effective regurgitant orifice area (ERO) by the conventional PISA method. This underestimation could be corrected by hemi-ellipsoidal assumption.
Methods: 23 patients with FMR were examined by real-time color 3D echocardiography. After optimizing aliasing velocity (Va), PISA length (l), radius (r), and short length (s) were measured for calculating hemi-ellipsoidal surface area in the frame of the largest PISA as Fig. 1⇓. The radius-length ratio was calculated as (the largest r)/l. We calculated 2 EROs by 3D PISA methods with hemispheric and hemi-ellipsoidal assumptions:
Hemispheric ERO = 2π×(the largest r)2×Va/(peak regurgitant velocity: Vp),
Hemi-ellipsoidal ERO = (3D hemi-ellipsoidal area)×Va/Vp. Each ERO was compared with that by 2D quantitative Doppler method (2D method).
The rate of underestimation of hemispheric ERO was calculated as (hemispheric ERO)/(ERO by 2D method).
Results: The rate of underestimation of hemispheric ERO correlated with the radius-length ratio (Fig. 2⇓). 3D hemi-ellipsoidal ERO was significantly larger than hemispheric one (0.30±0.11 vs. 0.21±0.10cm2, P<0.001). The hemispherical method underestimated ERO by 23% (0.09cm2), compared with 2D method (Fig. 3⇓). The underestimation by the 3D hemi-ellipsoidal method was only 11% (0.04cm2) (Fig. 3⇓).
Conclusion: The more flattened shaped PISA leads the underestimation of ERO by the conventional PISA method with hemispheric assumption. This underestimation is significantly corrected by 3D hemi-ellipsoidal method in FMR.