Early Effect of Right Ventricular Apical Pacing On Left Ventricular Twist

Abstract

Objective: The study aimed to assess the short-term effects of apical RV pacing on LV function and twist mechanics using speckle tracking echocardiography.

Background: The myofibers of the heart has geometric orientation that induces its characteristic wringing motion around its long axis during contraction leading to the systolic LV twist. This motion is created by the apical and basal rotations that are oppositely directed and has an important role in regulation of LV function. Several studies have demonstrated that LV systolic function and mechanics had delayed deterioration after RV apical pacing with limited data regarding the acute effects.

Methods: This study was conducted on Twenty-Four patients who were indicated for pacemaker insertion due to complete heart block. Echocardiographic examination was done to measure the LV dimensions and ejection fraction (EF) before and 24 hours after RV apical pacing. LV twist changes were assessed by using speckle tracking imaging modality.

Results: Our study showed that the LV end diastolic dimension has a significant reduction acutely after RV apical pacing (p value=0.001) while the end systolic dimension significantly increased (p value=0.003). EF significantly decreased after pacing (p value=0.001).Also there was a significant reduction in LV apical rotation (p value=0.001), basal rotation (p value=0.012) and torsion (p value=0.034).

Conclusion: Pacing of RV apex impairs the LV rotational mechanics acutely which subsequently have a detrimental effect on LV function.