Background
Pacemakers are considered an effective therapy for symptomatic bradyarrhythmia caused by AV nodal and SA nodal disease.(1) Inspite of the fact that the life quality improved for most patients with a cardiac pacemaker implant, the pacing induced left bundle branch block pattern can result in changes of the structure, function and hemodynamic of the heart.
. (2,3)
In cases with RV apical pacing, the electrical wave front propagates in a slower fashion and induces electrical heterogeneity in the activation of the myocardium similar but not identical to the changes that occur with patients having inherent left bundle branch block. The electrical wave front starts with breakthrough across the interventricular septum and lastly activates the infero-posterior base of the LV.(4,5) This electrical pattern alters the mechanical activation of the LV during pacing of RV apex. Not only the anatomic onset of myocardial activation changes but also the resulting mechanical pattern of contraction appears to be altered.