Abstract 3184: Dynamics of Mitral Complex Geometry During Left Ventricular Pressure Overload: in Vivo Experimental Study by Real-time 3D Echocardiography

Abstract

Background: Functional mitral regurgitation (MR) occurs as a consequence of regional or global left ventricular (LV) dysfunction despite a structurally normal mitral valve (MV). Degree of MV coaptation should be an important parameter in the assessment of functional MR. Purpose: We sought to investigate the change of MV coaptation and to clarify relationship between MV coaptation and development of MR in LV pressure overload. Methods: Using a canine model, LV pressure overload was induced by staged aortic banding (60 to 120mmHg). Echocardiographic examinations were performed before and during the banding. Degree of MR was evaluated by tracing the color jet MR area (MR area). By using a novel software system (RealView TM ) for 3D quantification, mitral annulus (MA) area, tenting volume, tenting length and 3D tenting surface area were analyzed. MA and surface of MV was manually traced both at the onset of MV closure [O] and at the maximum MV closure [M]. Coaptation index was calculated by the difference in 3D tenting surface area at O and at M devided by that at O. Results: MA area was gradually increased during banding ( p < 0.01). Tenting length and tenting volume tended to increase during banding but they did not reach statistical significance (tenting length; p = 0.17, tenting volume; p = 0.12). MR area increased with decrease in coaptation index (Figure ). The best cutoff value of the coaptation index to predict presence of MR was calculated as 0.24, giving a sensitivity of 82 % and specificity of 86 %. Conclusions: During aortic banding, MA dilated and coaptation of the MV decreased with apparent leaflet tenting. Coptation index might be able to predict the appearance of functional MR.