Abstract 3186: Right Ventricular Apical Pacing Impairs Left Ventricular Apical and Basal Rotation and Induces Apical-Basal Rotation Dyssynchrony
Backgrounds: Although right ventricular apical (RVA) pacing has been reported to result in asynchronous patterns of left ventricular (LV) contraction reducing the LV ejection fraction (EF), LV torsion in RVA pacing has been unknown. We hypothesized that RVA pacing impairs rotation of LV apex and base and synchrony between LV apical and basal rotation, leading to the reduction of LV torsion.
Methods: We studied 30 adult patients with sick sinus syndrome who had undergone DDD pacemaker implantation. Right ventricular pacing leads were positioned at the right ventricular apex. Changing from the intrinsic AV conduction to RVA pacing, we assessed the acute effect on echocardiac parameters; LV EF, tissue Doppler imaging (TDI) derived intraventricular delay, LV rotation and torsion, and LV apical-basal rotation dyssynchrony.
Results: Results were shown in a table⇓. Changing from the intrinsic AV conduction to RVA pacing, LV EF reduced (P=0.0003) and TDI derived intraventricular delay prolonged (P<0.0001). During RVA pacing, values of peak rotation in LV apex and LV base were significantly lower than those during intrinsic AV conduction (P=0.007 and 0.003, respectively). Correspondingly, LV torsion decreased significantly (P<0.0001). During the intrinsic AV conduction, LV apex and base rotated at the almost same time, while, during RVA pacing, LV basal rotation was delayed as compared to LV apical rotation. Consequently, apical-basal rotation dyssynchrony during RVA pacing was significantly longer than that during the intrinsic AV conduction (P=0.02).
Conclusion: RVA pacing decreases LV rotation and torsion and induces LV apical-basal rotation dyssynchrony, resulting in partially LV systolic dysfunction.