Effects of right ventricular outflow septal pacing on cardiac functions in patients with complete atrioventricular block

AIM;To compare the effect of right ventricular outflow tract septum(RVS) pacing and right ventricular apical(RVA) pacing on contraction synchrony,ventricular remodeling and cardiac functions.METHODS:Sixty-one patients(39 males,22 females) with III atrium ventricular conduction block(AVB) were randomly divided into RVS group(n=33) and RVA group(n=28).The parameters of the pacing leads on implantation and post-implantation and changes of QRS duration of pre- and post-implantation were observed.The ventricular synchrony was evaluated by tissue Doppler and left ventricular end-diastolic diameter(LVEDD) and left ventricular ejection fraction(LVEF) were compared between groups.RESULTS;No statistical differences were observed in the pacing parameters between groups(P 0.05).Post-implantation QRS duration was significantly prolonged in both groups(P 0.01),especially in the RVA group(P 0.01).Ts(time to peak systolic velocity) of the left lateral wall to the right wall was(27 ± 14) ms for RVS pacing and(90 ± 22) ms for RVA pacing(P 0.01).LVEDD of post-implantation significantly increased compared with pre-implantation in RVA group[(54 ± 5) mm vs.(50 ±4) mm,P0.05].LVEF statistically decreased in both groups[RVS:(0.58 ±0.14) ts.(0.63 ±0.09),P0.01;RVA:(0.51 ±0.12) vs.(0.64 ±0.13),P 0.01].CONCLUSION:RVS pacing achieves a better effect on cardiac contraction synchrony and ventricular remodeling than RVA pacing.