ABSTRACT
Objective To evaluate the left ventricular(LV)torsion in patients with permanent pacemaker implantation by speckle tracking imaging(STI).Methods Twenty-two patients with permanent pacemaker implantation were enrolled.Eleven of them had the pacing electrodes placed in the right ventricular(RV)apex(RVA group)and the others had the pacing electrodes placed in the RV outflow tract (RVOT group).Thirteen healthy subjects were studied as controls.The basal and apical shortaxis views of the left ventricle were acquired and analyzed using EchoPAC 7.0 station.Results ①The curves of LV torsion in the pacing groups were generally lower than those in the control group and notched.The torsion parameters of RVA group and RVOT group were all less than those of control group(Ptw:12.57±4.19°vs 12.43±5.46°vs 18.98±5.73°,all P＜0.05),but there were no significant differences between RVA group and RVOT group.The time of torsion was not changed in the pacing groups because there were no significant differences among the three groups.②The values of Ptw-a(peak twist of the apex)were gradually declined among control group,RVA group and RVOT group.There was statistical difference in Ptw-a between RVOT group and control group(7.40±4.27°vs 12.70±6.82°,P=0.0364).③The basal Tp-SD(standard deviation of times to peak twist)of RVOT group was significantly longer than that of control group[14.1(7.97～22.70)%vs 4.87(3.03～7.79)%,P=0.0298].And total Tp-SD of RVA group was significantly longer than that of control group[(7.6±6.5)%vs 2.26(1.62～3.51)%,P=0.0423].④The curves of torsion velocity in the pacing groups were obviously disorganized compared with control group.But there were no statistical differences in Ptv(peak twist velocity),Putv(peak untwisting velocity),Tptv(time to peak twist velocity)and Tutv(time to peak untwisting velocity)among the three groups.Conclusions The RV pacing tends to impair torsional synehrony of LV and depress LV torsion,though it doesn't change the timing of LV torsion.It may impair LV systolic and diastolic function.
