Validation of quantitative parameters of evaluation of paraprosthetic mitral regurgitation by the study of the zone of convergence by transthoracic echocardiography.

The study of the convergence zone by echocardiography is a validated method of quantification of native valve mitral regurgitation. However, there is little data concerning its applications to paraprosthetic mitral regurgitat ion. The aim of this study was to evaluate the method in this indication. Thirty consecutive patients (21 mechanical and 9 bioprostheses) with parapr osthetic mitral regurgitation quantified by transoesophageal echocardiograp hy were included : 4 mild, 13 moderate and 13 severe. The regurgitant volum e RV) and the regurgitant surface area (RSA) were calculated by the followi ng formulae : RV = 2 pi .r(2).Va.t.alpha /180 and RSA = RV / VTI (r:. mid s ystolic radius of the convergence zone, Va : aliasing velocity, t: regurgit ation time, alpha /180 :the angular correction due to parietal stress, VTI : velocity time integral of the regurgitant flow). The feasibility of the c alculation of the RV and RSA was 93 and 63% respectively. There was a stati stically significant correlation between the RV and transoesophageal echoca rdiography (r : 0.85, p < 0.001), between RSA and transoesophageal echocard iography (r : 0.67, p < 0.05) and between RV and RSA (r : 0.95, p < 0.001). When severe paraprosthetic regurgitation was defined by a RV greater than 60 mi and RSA greater than 40 mm(2), the concordance between RV, RSA and tr ansoesophageal echocardiography was 75% and 74% respectively. Therefore, the study of the convergence zone provides an accurate evaluatio n of paraprosthetic mitral regurgitation by transthoracic echocardiography.