Echocardiography
Echocardiographic data obtained using the ultrasound device Profound F 75 Premier (Hitachi Ltd, Tokyo, Japan) with a 1-5 MHz sector probe (UST-52105) were analyzed. Echocardiography was performed by experienced sonographers (T.M., M.K., and C.S.) Standard 2D resting echocardiography was conducted in the lateral decubitus position. Conventional echocardiographic data were collected in accordance using the method recommended by the American Society of Echocardiography (9) (15) (16). The modified Simpson’s biplane method was used to calculate LVEF and the left atrial volume index (LAVI). Transmitral E and A wave peak velocities were obtained in the apical three-chamber view. Diastolic mitral annular velocities (e’ and a’) were obtained using Doppler tissue imaging at the septal side of the mitral annulus from the apical four-chamber view. Peak velocities in the LV outflow tract (LVOT), aortic valve, and tricuspid valve were assessed using continuous Doppler imaging.
Cine loop color images from the apical three-chamber view were acquired for use in the VFM analysis. The colored area of this movies is set to include the entire LV area, LV inflow tract, and LVOT during all cardiac cycles. The Doppler area were optimized in order to achieve the highest frame rate. The Nyquist limit set for 2D color Doppler imaging was 69.3 cm/s.