Real-Time 3D Transesophageal Echocardiography for the Evaluation of Rheumatic Mitral Stenosis
In patients with rheumatic mitral stenosis (MS), is mitral valve area (MVA) determined using three-dimensional transesophageal echocardiography (3DTEE) feasible, accurate, and comparable to conventional techniques?
A group of 43 consecutive patients referred for echocardiographic evaluation of MS and suitability for percutaneous mitral balloon valvotomy were assessed using two-dimensional (2D) transthoracic echocardiography and real-time 3DTEE. MVA on 3DTEE (MVA3D), on 2D echocardiography (MVA2D), from pressure half-time (MVAPHT), and from continuity equation (MVACON) were evaluated, as was the degree of commissural fusion.
MVA3D assessment was possible in 41 patients (95%). MVA3D measurements were significantly lower compared with MVA2D (mean difference –0.16 ± 0.22 cm2; n = 25, p < 0.005) and MVAPHT (mean difference –0.23 ± 0.28 cm2; n = 39, p < 0.0001), but marginally greater than MVACON (mean difference 0.05 ± 0.22 cm2; n = 24, p = 0.82). MVA3D demonstrated best agreement with MVACON (intraclass correlation coefficient [ICC] 0.83), followed by MVA3D (ICC 0.79) and MVAPHT (ICC 0.58). Interobserver and intraobserver agreement was excellent for MVA3D, with ICCs of 0.93 and 0.96, respectively. Excellent commissural evaluation was possible in all patients using 3DTEE. Compared with 3DTEE, underestimation of the degree of commissural fusion using 2D transthoracic echocardiography was observed in 19%, with weak agreement between methods (κ < 0.4).
MVA planimetry is feasible in the majority of patients with MS using 3DTEE, with excellent reproducibility, and compares favorably with established methods. 3DTEE allows excellent assessment of commissural fusion.
This study demonstrates the feasibility of measuring mitral valve orifice area using planimetry on 3DTEE among patients with rheumatic MS; there was reasonably good correlation with measures of MVA from 2D echocardiography/Doppler. The significant digits reported might be a bit optimistic (it is doubtful that mitral valve orifice area by any technique is either accurate or clinically meaningful to 0.01 cm.2) The absence of an external reference standard (surgical pathology) leaves open to debate whether assessment of commissural fusion was accurate, and whether 3DTEE is better than 2D echo/Doppler measures or simply another way to accomplish the same thing.
Keywords: Echocardiography, Three-Dimensional, Pathology, Surgical, Mitomycin, Mitral Valve Stenosis, Echocardiography, Transesophageal
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