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.