A three-dimensional insight into the complexity of flow convergence in mitral regurgitation: adjunctive benefit of anatomic regurgitant orifice area

Abstract

Chandra S, Salgo IS, Sugeng L, Weinert L, Settlemier SH, Mor-Avi V, Lang RM. A three-dimensional insight into the complexity of flow convergence in mitral regurgitation: adjunctive benefit of anatomic regurgitant orifice area. Am J Physiol Heart Circ Physiol 301: H1015-H1024, 2011. First published June 17, 2011 doi:10.1152/ajpheart.00275.2011.-Mitral effective regurgitant orifice area (EROA) using the flow convergence (FC) method is used to quantify the severity of mitral regurgitation (MR). However, it is challenging and prone to interobserver variability in complex valvular pathology. We hypothesized that real-time three-dimensional (3D) transesophageal echocardiography (RT3D TEE) derived anatomic regurgitant orifice area (AROA) can be a reasonable adjunct, irrespective of valvular geometry. Our goals were to 1) to determine the regurgitant orifice morphology and distance suitable for FC measurement using 3D computational flow dynamics and finite element analysis (FEA), and (2) to measure AROA from RT3D TEE and compare it with 2D FC derived EROA measurements. We studied 61 patients. EROA was calculated from 2D TEE images using the 2D-FC technique, and AROA was obtained from zoomed RT3DE TEE acquisitions using prototype software. 3D computational fluid dynamics by FEA were applied to 3D TEE images to determine the effects of mitral valve (MV) orifice geometry on FC pattern. 3D FEA analysis revealed that a central regurgitant orifice is suitable for FC measurements at an optimal distance from the orifice but complex MV orifice resulting in eccentric jets yielded nonaxisymmetric isovelocity contours close to the orifice where the assumptions underlying FC are problematic. EROA and AROA measurements correlated well (r ϭ 0.81) with a nonsignificant bias. However, in patients with eccentric MR, the bias was larger than in central MR. Intermeasurement variability was higher for the 2D FC technique than for RT3DE-based measurements. With its superior reproducibility, 3D analysis of the AROA is a useful alternative to quantify MR when 2D FC measurements are challenging.three-dimensional echocardiography; Doppler echocardiography; mitral valve; proximal isovelocity surface area TWO-AND THREE-DIMENSIONAL (2D and 3D) echocardiography combined with Doppler interrogation plays a crucial role in the identification of the mechanisms, in the accurate quantification of the severity of mitral regurgitation (MR), and in the assessment of the suitability for repair. The severity of MR has been used to determine the progression of disease (9), identify patients at the highest mortality risk without surgical intervention, (8,13,14,16,20, 33), and guide the timing of surgery (4,23,32,35). Effective regurgitant orifice area (EROA) based on 2D methods of flow convergence (FC) estimation is currently one of the standards used to assess the severity of MR.Unlike 2D planimetry of mitral and aortic stenotic valves, planimetry of the regurgitant orifice area in patients with MR is not feasible because of the complex, nonplanar 3D geometry ...

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