Abstract 2136: Right Ventricular Apical Pacing Impairs Left Ventricular Torsion as Well as Synchrony
Backgrounds: Newly developed two-dimensional ultrasound speckle tracking imaging (2DST) provided an objective estimation of left ventricular (LV) torsion. Recently, it has reported that right ventricular apical (RVA) pacing induced dyssynchrony and increased morbidity in patients with heart failure. However, LV torsional change caused by RVA pacing is unknown. We assessed the hypothesis that LV dyssynchrony may decrease LV torsion, which may contribute to induce LV dysfunction in the patient with RVA pacing in this study.
Methods: We studied 13 sick sinus syndrome patients with right ventricular apical pacing, showing normal LV function and no structural heart disease. We compared echocardiographic parameters of torsion (a net-difference of LV rotation between apical and basal short-axis planes) using 2DST system (vivid7, GE and EUB-8500, HITACHI), synchronization (tissue Doppler-derived intraventricular delay (TDD)), and cardiac function (ejection fraction) between intrinsic AV conduction (AOO pacing mode) and RVA pacing (DDD pacing mode).
Results: Changing from AOO mode to DDD mode, LV torsion, TDD, and ejection fraction impaired significantly. (Table⇓) The change of LV torsion significantly correlated with the changes of TDD (y = −0.13x+17, r=−0.39, P=0.05) and ejection fraction (y = 0.60x+55, r=0.66; P=0.005).
Conclusion: RVA pacing impaired LV torsion as well as synchrony, that might induce LV dysfunction. Assessing of torsion has a potential to reveal mechanism of disadvantage for RVA pacing.