Determination of regurgitant orifice area with the use of a new three-dimensional flow convergence geometric assumption in functional mitral regurgitation.

Geometry of the proximal isovelocity surface area (PISA) in functional mitral regurgitation (MR) is elongated, leading to underestimation of the effective regurgitant orifice (ERO) area. This underestimation could be corrected by a new hemiellipsoidal method. Thirty patients with functional MR were examined by real-time 3-dimensional (D) echocardiography. Two ERO areas were calculated from 3D measurements: ERO area by the hemispheric method and that by the new hemiellipsoidal method with our customized program. Each ERO area was compared with that by the 2D quantitative Doppler method. Color 3D images showed an elongated PISA geometry including 2 geometric types ("mountain" or "valley") in all patients with functional MR. Our hemiellipsoidal method could be adapted for all geometric types of PISA and underestimated ERO area by only 26%, whereas the underestimation by the hemispheric PISA method was 49%. The underestimation by the hemispheric PISA method can be significantly corrected by our hemiellipsoidal method.