Real-time 3-Dimensional Color Doppler Flow of Mitral and Tricuspid Regurgitation: Feasibility and Initial Quantitative Comparison with 2-Dimensional Methods

Abstract

Visualization of valvular regurgitation using 3-dimensional (3D) echocardiography has been attempted but not routinely performed to date because of technical limitations. With the recent development of a fully sampled matrix-array probe, real-time color flow imaging allows display and analysis of regurgitant jets. Accordingly, the aim of this study was 2-fold. We: (1) investigated the feasibility of transthoracic, real-time visualization of 3D color flow jets; and (2) compared conventional 2-dimensional (2D) Doppler/color flow methods of quantitation (ie, 2D jet/left atrial [LA] area, flow convergence, and vena contracta [VC]) to 3D-derived measurements (3D jet/LA volume, flow convergence, and VC). In all, 56 patients with good acoustic windows and varying degrees of mitral regurgitation (MR) (n = 32) and tricuspid regurgitation (TR) (n = 24) scheduled for a routine echocardiogram were studied. Using a broadband transducer, 2D color Doppler imaging of TR and MR jets was performed to obtain jet/atrial area ratio, effective regurgitant orifice area, and VC measurements. Subsequently, real-time 3D echocardiography imaging of these jets was performed and analyzed offline using software, resulting in jet/atrial volume ratio, effective regurgitant orifice area, and VC (major and minor axes). Of the 56 patients recruited into the study, 86% had sufficient data quality for analysis (87.5% in patients with MR and 83% in patients with TR). Both LA and right atrium were adequately visualized in all patients. Manually traced 3D MR and TR volumes had good agreement when compared with proximal isovelocity surface area-derived volumes (r = 0.7, y = 0.4x + 6.4; and r = 0.8, y = 1.1x + 5.1; respectively) with minimal underestimation and overestimation of volumes for MR and TR (8 and 7 mL, respectively), but with relatively wide limits of agreement for MR (28 mL) versus TR (12 mL). When comparing 3D MR jet/LA volume ratios and TR jet/right atrial volume ratios to 2D MR jet/LA area and 2D TR jet/right atrial area ratios, the former were significantly smaller. The 3D minimum and maximum VC diameter for MR were significantly different compared with those measured with 2D (minimum diameter = 0.7 +/- 0.1 cm, P < .01; maximum diameter = 1.1 +/- 0.5 cm, P < .02 vs 2D = 0.8 +/- 0.3 cm). Conversely, the TR VC minimum diameter was similar but maximum diameter measurements were larger in 3D compared with 2D (3D = 1.3 +/- 0.6 cm vs 2D = 0.7 +/- 0.2 cm, P < .001). Three-dimensional echocardiography of color flow Doppler of MR and TR jets was feasible. Quantitative methods using 3D echocardiography such as MR and TR volumes correlated well with 2D flow convergence methods. TR VC has more of an elliptic shape, whereas MR is more circular or oval when visualized in 3D. Regurgitant/atrial volume ratios provide a new method of assessing the severity of regurgitant lesions; however, 3D volume-derived ratios were comparatively smaller than those measured with 2D echocardiography.