Abstract

LOMBARDERO, Martín; PEREA, Gabriel  and  TINETTI, Matías. Where is the Effective Mitral Orifice?: Echocardiographic Divergence Between Mitral Inflow Volume and Left ventricular Outflow Tract Volume. Rev. argent. cardiol. [online]. 2014, vol.82, n.2, pp.118-125. ISSN 1850-3748.

Introduction Two-dimensional transthoracic echocardiography (2DTTE) is not a reliable method for estimating regurgitatant volume in mitral insufficiency due to inadequate measurement of the mitral annulus (MA). Three-dimensional transesophageal echocardiography (3DTEE) offers better tools for measuring the MA. Objectives The aim of this study was to compare the MA area and the difference in mitral inflow (MI) volume and left ventricular out-flow tract (LVOT) volume determined by 2DTTE and 3DTEE in normal hearts, and to evaluate at what level of the mitral valve apparatus the mitral effective orifice is actually located. Methods A total of 13 consecutive and prospective patients with indication of transesophageal echocardiography (9 to rule out cardioembolic source and 4 due to febrile syndrome) were included in the study. Their mean age was 42 (29-47) years and 7 were women. All the patients had normal 2DTTE, were in sinus rhythm and had normal blood pressure at the moment of the study. 2DTTE and 3DTEE were simultaneously performed. LVOT area and MA area were calculated by 2DTTE and 3DTEE. Mitral valve (MV) area distal to the MA was estimated by 3DTEE. Mitral inflow and LVOT volume were calculated as the product between the area and flow velocity time integral (VTI). The effective mitral valve area (EMVA) was hypothetically estimated by dividing the LVOT (3DTEE) volume by MI VTI. Results Correlation (rs), concordance and 95% CI between MA area by 2DTTE vs. 3DTEE: 0.506, 1.97 (-0.40 to 4.34), EMVA vs. 3DTEE: 0.549, 2.41 (-4.03 to -0.79) and EMVA vs. MV at 11 mm (8-12) of the MA: 0.982, 0.079 (-0.26 to 0.42). The difference between MI volume and LVOT volume (ml) was: 2DTTE: 12.8 (7.5-19), 3DTEE: 32.8 (25.9-48) and 3DTEE (from the MV distal to the MA) 1.8 (1.25-3.6). Conclusions The better the technique for measuring the mitral annulus, the farther we are from the mitral effective orifice. The mitral valve area measured at one centimeter of the highest point of the mitral annulus is the best approximation to the effective mitral orifice.

Keywords : Echocardiography; Mitral Regurgitation; Three-dimensional Echocardiography.

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