(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.