Three-dimensional echocardiographic planimetry of maximal regurgitant orifice area in myxomatous mitral regurgitation: Intraoperative comparison with proximal flow convergence

Objectives. We sought to validate direct planimetry of mitral regurgitant orifice area from three-dimensional echocardiographic reconstructions. Background. Regurgitant orifice area (ROA) is an important measure of the severity of mitral regurgitation (MR) that up to now has been calculated from hemodynamic data rather than measured directly. We hypothesized that improved spatial resolution of the mitral valve (MV) with three-dimensional (3D) echo might allow accurate planimetry of ROA. Methods. We reconstructed the MV using 3D echo with 3°rotational acquisitions (TomTec) using a transesophageal (TEE) multiplane probe in 15 patients undergoing MV repair (age 59 ± 11 years). One observer reconstructed the prolapsing mitral leaflet in a left atrial plane parallel to the ROA and planimetered the two-dimensional (2D) projection of the maximal ROA. A second observer, blinded to the results of the first, calculated maximal ROA using the proximal convergence method defined as maximal flow rate (2πr²v(a), where r is the radius of a color alias contour with velocity v(a)) divided by regurgitant peak velocity (obtained by continuous wave [CW] Doppler) and corrected as necessary for proximal flow constraint. Results. Maximal ROA was 0.79 ± 0.39 (mean ± SD) cm² by 3D and 0.86 ± 0.42 cm² by proximal convergence (p = NS). Maximal ROA by 3D echo (y) was highly correlated with the corresponding flow measurement (x) (y = 0.87x + 0.03, r = 0.95, p < 0.001) with close agreement seen (ΔROA (y - x) = 0.07 ± 0.12 cm²). Conclusions. 3D echo imaging of the MV allows direct visualization and planimetry of the ROA in patients with severe MR with good agreement to flow- based proximal convergence measurements.