Improvement of the PISA method in the setting of mitral regurgitation of complex geometry

Abstract

Doppler echocardiographic methods, such as proximal isovelocity surface area (PISA) are used to quantify mitral regurgitations (MR). However, their accuracy and reproducibility are still discussed, especially in case of MR of complex geometry. The aim of this study was to test in-vitro the accuracy of the PISA method depending on the shape and number of regurgitant flows. Several regurgitant volumes (RV) were produced through various regurgitation severities and shapes in a left heart double activation simulator. Central and oblong MR were performed by suturing the extremity of a bioprosthesis leaflet to the annulus. Multiple jets regurgitation was performed by suturing centrally the two leaflets of an anatomically shaped mitral valve made of hydrogel. A transesophageal echocardiography probe was used to acquire the data. The RV was calculated with the classical PISA method (hemispheric assumption), or by considering the PISA as a hemicylinder or a double hemisphere. It was then compared to a reference value obtained from an electromagnetic flowmeter measurement (accuracy ± 2 ml/min). For a central jet, the hemispheric assumption best estimated the RV (bias − 3.5 ± 14.8 ml, P = 0.10). Oblong MR was underestimated with hemispheric assumption (−18.3 ± 14.9 ml, P < 0.01) whereas hemicylindrical assumption was more accurate (−0.2 ± 5.8 ml, P = 0.85). In case of 2 regurgitant jets, considering only the largest jet led to an important underestimation (−10.9 ± 5.6 ml, P < 0.01), whereas adding the two RV was more accurate (−1.2 ± 8.2 ml, P = 0.50). In case of a single central orifice, the hemispheric assumption correctly quantified the MR. In case of an oblong orifice, the hemicylindrical assumption provided a good quantification with simple measurements. In case of multiple jets of different sizes, it was more accurate to consider both jets for RV calculation.