Pacemaker programming:
All patients underwent different programming modes for their devices and
were thereby represented as 3 groups: group I (AS-VP mode): in atrial
sensed and ventricular paced mode; the device sense the intrinsic atrial
activity and pace the ventricles accordingly to maintain A-V synchrony,
group II (AP-VP mode): in atrial paced and ventricular paced mode; the
device was programmed to initiate atrial pacing at a rate of 100 b/min
followed by ventricular pacing “maintaining A-V synchrony” and group
III (VVI mode): in this mode, the atrial lead is switched off and the
device functions as a single chamber pacemaker delivering ventricular
pacing at 100 b/min dissociated from the intrinsic atrial activity i.e.
asynchronous ventricular pacing mode.
2-D STE was used to measure the global and segmental systolic
longitudinal strain of the LV walls in order to compare them between
controls and patients during AS-VP mode (group I). We also compared LV
LSS in the patients in the three pacing modes; group I (AS-VP mode),
group II (AP-VP mode) and group III (VVI mode). The comparison of LV LSS
between group (AS-VP) and group (AP-VP) was done to study the indirect
effects of atrial pacing on LV LSS. The comparison of LV LSS between
group (AP-VP) and group (VVI) was done to study the effects of A-V
synchrony on LV LSS at the same heart rate of 100 b/min.