Where is the Effective Mitral Orifice? Echocardiographic Divergence Between Mitral Inflow Volume and Left ventricular Outflow Tract Volume;
¿Dónde está el Orificio Mitral Efectivo? Divergencia entre el volumen del tracto de salida y el tracto de entrada del ventrículo izquierdo por ecocardiografía

Two-dimensional transthoracic echocardiography (2DTTE) is not a reliable methodfor estimating regurgitatant volume in mitral insufficiency due to inadequate measurementof the mitral annulus (MA). Three-dimensional transesophageal echocardiography(3DTEE) offers better tools for measuring the MA.ObjectivesThe aim of this study was to compare the MA area and the difference in mitral inflow(MI) volume and left ventricular outflow tract (LVOT) volume determined by2DTTE and 3DTEE in normal hearts, and to evaluate at what level of the mitralvalve apparatus the mitral effective orifice is actually located.MethodsA total of 13 consecutive and prospective patients with indication of transesophagealechocardiography (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 bloodpressure at the moment of the study. 2DTTE and 3DTEE were simultaneously performed.LVOT area and MA area were calculated by 2DTTE and 3DTEE. Mitralvalve (MV) area distal to the MA was estimated by 3DTEE. Mitral inflow and LVOTvolume were calculated as the product between the area and flow velocity time integral(VTI). The effective mitral valve area (EMVA) was hypothetically estimated bydividing the LVOT (3DTEE) volume by MI VTI.ResultsCorrelation (rs), concordance and 95% CI between MA area by 2DTTE vs. 3DTEEwere: 0.506, 1.97 (-0.40 to 4.34), EMVA vs. 3DTEE: 0.549, 2.41 (-4.03 to -0.79) andEMVA vs. MV at 11 mm (8-12) of the MA: 0.982, 0.079 (-0.26 to 0.42). The differencebetween 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).ConclusionsThe better the technique for measuring the mitral annulus, the farther we are fromthe mitral effective orifice. The mitral valve area measured at one centimeter of thehighest point of the mitral annulus is the best approximation to the effective mitralorifice.

Introducción: El cálculo del volumen (vol) regurgitante en la insuficiencia mitral por EcoTranstorácico 2D (ETT2D) es poco confiable y está relacionado con inadecuada medición del anillo mitral (AM). El EcoTransesofágico 3D (ETT3D) posee mejores herramientas de medición del AM. OBJETIVOS Comparar el área del AM y la diferencia de vol del Tracto de Entrada y Salida del VI (TSVI y TEVI) por ETT2D y ETE3D en corazones normales. Evaluar en que nivel del aparato mitral se encuentra el orificio mitral efectivo. METODO A 13 pacientes se les realizó simultáneamente ETT2D y ETE3D. El área del TSVI y del AM fue medida por ETT2D y ETE3D. Se estimó por ETE3D el área de la válvula mitral (VM) distal al AM. El vol se calculó como el producto del área por la Integral de flujo (VTI) de cada tracto. Se estableció una Hipotética Área Mitral Efectiva (AME) como el cociente entre el vol del TSVI (ETE3D) y el VTI del TEVI (área prestablecida como referente) RESULTADOS Correlación (rs), concordancia y 95% de IC entre área del AM por ETT2D vs ETE3D: 0.506, 1.97 (-0.40 a 4.34), AME vs ETE3D 0.549, 2.41 (- 4.03 a -0.79) y AME vs VM a 11 mm (8-12) del AM: 0.982, 0.079 (-0.26 a 0.42). La diferencia de vol (ml) entre ambos tractos fue: ETT2D: 12.8 (7.5-19), ETE3D: 32.8 (25.9-48) y ETE3D (desde VM distal al AM) 1.8 (1.25 -3.6). CONCLUSIONES Cuanto mejor medimos el anillo mitral mas lejos estamos del orificio mitral efectivo.