| Background Mitral regurgitation (MR) is common valvular lesion that ultimately progresses to irreversible heart failure with high morbidity and mortality. Consequently, timely diagnosis and accurate assessment of severity of MR are of significant importance for appropriate decision making and timing of surgical intervention. Mitral regurgitant volume (MRvol) is a useful and important index of the severity of MR, but MRvol measurement remains challenging. MRvol calculation using effective regurgitant orifice area (EROA) by real-time3-dimensional color Doppler echocardiography multiplied by the velocity time integral of the mitral regurgitant jet on the continuous-wave Doppler has been recently documented as an accurate method. With the development of probe technology and software, General Imaging3-dimensional Quantification (GI3DQ) allows direct measurement of MRvol.Objectives The aim of this study was to evaluate feasibility and accuracy of GI3DQ method for quantification of MRvol comparison with MRvol using EROA by real-time3-dimensional (3D) color Doppler echocardiography multiplied by the velocity time integral of the mitral regurgitant jet on the continuous-wave Doppler.Methods1) Ninety-three patients were included,61with functional MR and32with mitral valve prolapse (MVP). The MR was also divided into central MR (n=41) and eccentric MR (n=52).2) EROA by real-time3-dimensional color Doppler echocardiography. To measure EROA, the3D color Doppler datasets were manually cropped by an image plane that was perpendicularly oriented to the jet direction and the cropping plane was then moved along the jet direction as far as the smallest cross-sectional area. The EROA was measured by manual planimetry of the color Doppler signal, tilting the image in an "en face" view and selecting the systolic frame with the most relevant lesion size;the MRvol was calculated as EROA multiplied by the MR time-velocity integral. The MRvol derived from EROA by real-time3D color Doppler echocardiography was used as reference method.3) Direct measurement Of MRvol By GI3DQ. In QLAB workstation, we entered the analysis plug-in of GI3DQ and clicked the initial position and the terminal position of the mitral regurgitant jet to display15slices in the systolic frame with the most relevant lesion size. For each slice in the volume, select one end slice of the regurgitant jet contour and draw along the boundary of the regurgitant jet. The same procedure was performed one after the other until the last slice. Pressed Enter to end the measurement and the MRvol calculation appeared in the results.4) MRvol by PISA. The proximal isovelocity surface of the mitral regurgitant jet was visualized in an image from the apical4-chamber view, using a zoom mode. The position of the transducer was modified to minimize the angle between the centerline of the PISA and the ultrasound beam. We optimized the appearance of the PISA by shifting the color Doppler aliasing velocity from20to40cm/s. For each cardiac cycle, the frame with the largest flow convergence region was selected as coinciding with maximal regurgitant flow. The maximal velocity of the regurgitant jet was determined by continuous-wave Doppler. Effective regurgitant orifice area was calculated by the PISA method as (2×π×r2×Vr)/Vmax, where r is the isovelocity radius measured as the maximal radial distance between the first aliasing contour and the center of the regurgitant orifice at mid-systole, Vr is the aliasing velocity, and Vmax is the maximal velocity of the regurgitant jet. Two-dimensional PISA MRvol was calculated as2D PISA-derived EROA multiplied by the MR time-velocity integral.4)MRvol by Doppler method. Mitral inflow and aortic outflow were calculated as the time-velocity integral of the mitral or aortic inflow multiplied by the cross-sectional area of the mitral annulus (estimates of mitral annulus cross-sectional area were obtained as circular:πa2/4as well as biplane elliptical:πab/4) or aortic annulus(πr2/4),where a is the mitral annular dimension in the four-chamber view,b is the mitral annular dimension in the apical two-chamber view, and r is the left ventricular outflow tract diameter in the parasternal long-axis view(1cm proximal to the aortic annulus). Mitral Rvol was calculated as the difference between mitral and aortic forward stroke volumes.Results.1. MRvol by the GI3DQ Method Compared with RT3DE MethodIn all cases, MRvol measured by GI3DQ was well correlated with MRvol measured by3D color Doppler echocardiography (r=0.921), but with a significant difference between these techniques (mean difference=-6.07ml). Functional MRvol measured by GI3DQ showed better excellent correlation with MRvol measured by3D color Doppler echocardiography (r=0.948) with a lower underestimation (mean difference=-3.18ml). The correlation of MVP MRvol measured by GI3DQ and by3D color Doppler echocardiography was also good(r=0.911), but with a severe underestimation (mean difference=-11.56ml), similar to the result of the eccentric MR (r=0.914, mean difference=-10.55ml). Central MR provided the best correlation and agreement of GI3DQ estimates with3D color Doppler echocardiography (r=0.956, mean difference=-0.38ml).2. MRvol by the PISA Method Compared with RT3DE MethodIn all cases, MRvol measured by PISA was well correlated with MRvol measured by3D color Doppler echocardiography (r=0.911, p<0.001), but with a difference between these techniques (mean difference=-4.64ml). In eccentric MR group, the correlation of MRvol measured by PISA and by3D color Doppler echocardiography was:r=0.871,but with a severe underestimation (mean difference=-7.58ml).Central MR group provided the best correlation and agreement of PISA estimates with3D color Doppler echocardiography(r=0.964, mean difference=-0.92ml).3. MRvol by the Doppler Methods Compared with RT3DE Method①Estimates of mitral annulus cross-sectional area as circular.In all cases,eccentric MR group and central MR group, the correlation of MRvol measured by Doppler method and by3D color Doppler echocardiography was respectively:0.813;0.759;0.725. However, the Bland-Altman analysis demonstrated varying degrees of overestimation between these techniques: mean difference (Doppler-RT3DE),respectively,9.82ml;12.79ml;6.06ml (all p values were less than0.05).②Estimates of mitral annulus cross-sectional area as biplane elliptical.In all cases, eccentric MR group and central MR group, MRvol measured by Doppler method was well correlated with MRvol measured by3D color Doppler echocardiography (r=0.906;0.889;0.844; all p values were less than0.0001) in these three groups and the Bland-Altman analysis demonstrated a slight overestimation between these techniques, mean difference (Doppler-RT3DE)=1.34ml;1.64ml;0.96ml,but no statistical meanings.4. MRvol by GI3DQ Method Compared with PISA and Doppler Methods①GI3DQ and PISA method. In all cases, eccentric MR group and central MR group, the t test revealed that there was no significant difference in the measurement of MRvol between these methods in these three groups. In the former two groups, the Bland-Altman analysis demonstrated a slight underestimation between these techniques, mean difference (GI3DQ-PISA), respectively,1.43ml;2.97ml; but no statistical meanings. In the central group, the Bland-Altman analysis demonstrated a slight overestimation between these techniques, mean difference (GI3DQ-PISA)=0.54, p=0.0587>0.05.②GI3DQ and Doppler method (biplane elliptical).In all cases and eccentric MR group, the t test revealed that there was significant difference in the measurement of MRvol between these methods in these two groups and the Bland-Altman analysis demonstrated a significant underestimation between these techniques,mean difference(GI3DQ-Doppler), respectively,7.41ml;12.19ml.In central group, the t test revealed that there was no significant difference in the measurement of MRvol between these methods and the Bland-Altman analysis demonstrated a slight underestimation between these techniques, mean difference(GI3DQ-PISA)=1.34, p=0.0564>0.05.Conclusion Quantification of MRvol with GI3DQ was feasible and correlated well with MRvol by3D color Doppler echocardiography. Quantification of central MRvol with GI3DQ was accurate as compared with MRvol by3D color Doppler echocardiography. |
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