Quantitative echocardiographic assessment of native mitral regurgitation: two- and three-dimensional techniques

Abstract

Chronic mitral regurgitation (MR) is a common valvular lesion. During recent years, it has become increasingly evident that moderate to severe MR, even in the absence of left ventricular dilatation and dysfunction, may have adverse prognostic consequences. Thus, the accurate quantification of MR, using echocardiography, is vitally important in clinical medicine. Because of the mitral valve's structural complexity, MR is often difficult to define, especially with two-dimensional (2D) imaging methods. Both qualitative and quantitative approaches to the quantification of MR are widely used. Color Doppler imaging allows measurement of the regurgitant jet area and vena contracta (VC) width; these two qualitative methods are simple to apply in daily practice but often are inaccurate, especially in patients with eccentric MR. 2D quantitative methods include the calculation of regurgitant fraction, regurgitant volume, and proximal isovelocity surface area. While these parameters are well-established indicators of MR severity, they require tailored image acquisition and additional calculations; moreover, their accuracy may be compromised in the setting of eccentric MR or aortic insufficiency. With three-dimensional (3D) echocardiography, many of the geometric assumptions necessary with 2D imaging are obviated. A realistic depiction of the VC, which often is non-circular, and of the anatomic regurgitant orifice area, which usually is non-planar, becomes possible with 3D zoom-mode imaging. Ongoing efforts to characterize MR in asymptomatic or minimally symptomatic patients include investigations into stress echocardiography and strain rate imaging. The distinct geometry of the mitral valve, and the various mechanisms of MR, will continue to challenge cardiac research teams during the coming years.