Abstract 10890: A Simplified Method for Correction of Effective Regurgitant Orifice and Flow Underestimation by Pisa in Non-Circular Orifices: An in vitro Study

Abstract

Introduction: The proximal isovelocity surface area (PISA) method has been validated for quantifying severity of mitral regurgitation (MR) in orifices with circular geometry. However, functional MR often has an elliptical orifice, which alters the proximal isovelocity contour from a hemisphere to a hemi-ellipsoid. Studies have previously shown that PISA underestimates regurgitant flow (RF) and effective regurgitant orifice (ERO) in functional MR. Hypothesis: The application of a simplified hemi-ellipsoid formula based on biplane color Doppler improves accuracy in calculating RF and ERO across elliptical orifices. Methods: An in vitro model for flow quantification was used for all experiments. Multiple size orifices with minor to major ratios ranging from 1:1 to 1:9 were constructed by 3D printing. Flow was adjusted at multiple intervals to generate peak flow velocities ranging from 4.1 to 5.5 m/s and aliasing velocities from 12 to 18 cm/s. Isovelocity contours were evaluated by biplane color Doppler (Figure 1A). RF and ERO were estimated using the traditional hemispheric PISA (HS-PISA) formula and a simplified hemiellipsoid formula (HE-PISA) based on two orthogonal diameter measurements (Figure 1A and 1B). The estimated RF and ERO values were compared and validated against those derived from a magnetic flowmeter (FM). Results: Isovelocity contours changed from hemisphere to hemi-ellipsoid orifices with increasing ellipticity ratios. HS-PISA significantly underestimated RF (116 ± 27 vs FM 155 ± 20 ml/s) and ERO (26 ± 4 vs FM 34 ± 1 mm 2 ). Underestimation was significantly reduced by HE-PISA (135 ± 17 ml/s and 30 ± 2.5 mm 2 , both p<0.001). Conclusions: A simplified hemi-ellipsoid PISA method provides more accurate assessment of RF and ERO in regurgitant orifices with non-circular geometries.