(9)
Conventional echocardiographic examination:
M-Mode measurements included the inter-ventricular septal thickness in diastole (IVSd), the posterior wall thickness in diastole (PWd), the LV end-diastolic diameter (LVEDD), the LV end-systolic diameter (LVESD), LV ejection fraction (EF %) and fractional shortening (FS %). As this method is inaccurate due to paradoxical septal motion caused by RV pacing; we assessed the EF using the modified biplane Simpson’s method. The LVEDV and LVESV were calculated from the apical 2- and 4-chamber views. The LV ejection fraction (EF %) was automatically calculated as follows (10) : Ejection fraction (EF %) = (EDV−ESV)/EDV×100.
2-D speckle tracking echocardiography (STE):
Apical views were adjusted at a frame rates that range from 70–100 frame/s. The patients were asked to hold breath at the end of expiration and three cardiac cycles were taken consecutively. Images were stored on the hard drive digitally for off-line analysis later. Pulsed-wave Doppler was used to record mitral and aortic velocities to determine the cardiac events timing.
The endocardial lining of these chambers was traced manually by two-dimensional strain Echo Pac software. Eventually a region of interest (ROI) involving the entire transmural wall was created automatically by the computer. The software divided each wall into three segments (basal, mid and apical). Regional and global LV longitudinal systolic strain (LSS) values were calculated.