Conventional echocardiographic measurements
In our study, a GE Vivid E9 doppler ultrasound instrument equipped with an M5S-D probe (1.5-4.5 MHz) was introduced to obtain 2-dimensional images. The ultrasound examination was conducted when the subjects lay in the left lateral decubitus position and keep steady breathing with connecting a three-lead electrocardiography (ECG). Three groups of participants completed an assessment of echocardiography from multiple views including the LV long-axis, apical 4-chamber and apical 2-chamber. We measured the conventional parameters which included interventricular septal thickness and LV posterior wall thickness at end-diastolic (IVSTd and PWTd), LV end-diastolic diameter (LVDd) and LV end-systolic diameter (LVDs), transmitral peak early and late inflow diastolic velocity (E and A) , early-diastolic tissue velocity of septal and lateral mitral annulus (Sept e’ and Lat e’), then computed respectively E/A and E/mean e’. We used the views of apical 2-chamber and 4-chamber to measure the left atrial maximum volume at the LV end-systole by modified Simpson’s rule, then calculated left atrial maximum volume index (LAVImax).