732 Accurate timing of mitral valve opening by tissue Doppler imaging for an all in one beat analysis

Background: Echocardiographic indices of diastolic function are largely dependent on accurate timing of mitral valve opening (MVO). Determination of MVO in the same heart beat as other derived echocardiographic measures is crucial to avoid inaccuracies caused by beat to beat variation. The aim of the study was to investigate if tissue Doppler imaging (TDI) information can be used to determine MVO. Methods: In anaesthetised mongrel dogs (n=4) with left atrial (LA) and LV micromanometers, MVO was defined as the time of first diastolic LA/LV pressure crossover (MVOPCO), which is when the pressure gradient starts separating the valve leaflets. In apical projections, the TDI signal from a sample volume positioned at the mitral leaflet tips was used to define MVOTDI as the time of onset of rapid increase of positive velocity in early diastole (figure, left panel). MVO was measured by the two methods and compared during different loading conditions, increased inotropy, and during ischaemia. In 6 patients with acute myocardial infarction and in 6 healthy subjects we compared MVOTDI with timing of onset of mitral flow by Doppler (MVODoppler). Results: In the experimental study MVOTDI showed very good agreement with MVOPCO: mean difference: 1.7±9.8 ms (2SD); correlation: r=0.99, p<0.0001. MVOTDI showed excellent agreement with MVODoppler in the clinical study: mean difference: -0.3±8.1 ms; correlation: r=0.99, p<0.0001. Conclusions: The proposed marker in the mitral valve leaflet TDI signal showed excellent agreement with MVO as defined both by pressure crossover and onset of Doppler flow. MVOTDI thus provides a new method for accurate timing of MVO in the same heart beat as other TDI measurements. 734 Early diastolic mitral annulus velocity at onset of fillinga new marker of cardiac suction