Evaluating Left Ventricular Systolic Synchrony And Torsion Of Right Ventricular Pacing Using Echocardiography

PartⅠEvaluating left ventricular systolic synchrony of different right ventricular pacing sites by tissue Doppler imagingObjective Using Tissue Doppler Imaging(TDI) to evaluate the effects of different right ventricular pacing sites on left ventricular systolic synchrony. Methods A total of sixty-nine patients with indications for permanent pacemaker implantation were enrolled sequentially by Pace-ROAD study(Pacemaker-Right ventricular Outflow tract and Apex study,a randomized control study).They were randomized to RVOT pacing group(group A) or RVA pacing group(group B). Echocardiographic study with routine Echocardiographic technologies and TDI was performed before and after 3 month follow up,and the data were analysed off-line.The routine echocardiographic parameters and TDI parameters,such as the peak velocity(Vs),the time to the peak of S wave(Ts) of all 12 basal and middle segments of left ventricle were measured,and then the standard deviation of Ts (Ts-SD),the average ofVs(Vs-M),were calculated.Results Thirty-six patients were randomized to group A,while the other 33 patients to group B.In each group,one patient was excluded due to non-pacing rhythm during follow-up.(1) There were no statistical differences between group A and group B in all the parameters(including the routine echocardiographic parameters and TDI parameters) before pacemaker implantation.(2) After 3 month pacing,no significant differences in inner diameters of left atrium and ventricule and volumetric parameters of left ventricule were showed in the two groups between the baseline and follow up.Neither were there signficant differences between the two groups.The PPET and APET of the follow up were all signficantly longer than the baseline in the two groups,as well as the IVMD,but there were no signficant differences between the two groups.(3) After 3 month pacing,the Ts-SD of group A was significantly shorter than that of group B(23.63±2.32ms vs 31.54±2.93ms,P=0.0387).(4) In the patients with the basal Ts-SD longer than 32.6ms(group A2 and group B2), the Ts-SD was significantly shortened than the baseline in group A2 during follow-up, while no significant difference was found in group B2.And the follow-up Ts-SD of group B2 was significantly longer than that of group A2(38.19±18.34ms vs 28.55±16.93ms P=0.0290).Conclusions(1) Tissue Dopier Imaging may provide a noninvasive,sensitive,quick and exact tool for evaluating left ventricular systolic synchrony.(2) The RVOT pacing is associated with favorable left ventricular systolic synchrony than RVA pacing,especially in patients with worsened baseline systolic synchrony.PartⅡEvaluating left ventricular torsion of different right ventricular pacing sites by speckle tracking imagingObjective It remains unknown whether right ventricular(RV)pacing could affect left ventricular(LV) torsion and whether there are differences between the right ventricular apex pacing and the right ventricular outflow tract pacing.The aim of this study was to use sparkle tracking imaging to evaluate the LV torsion in patients with permanent pacemaker implantation. Methods Twenty-two patients(13 male,mean age 60±11years) with permanent pacemaker implantation were enrolled.Four of them had VVI pacing and 18 of them had DDD pacing.Eleven of them had the pacing electrodes placed in the RV apex(right ventricular apex,RVA Group) and the others had the pacing electrodes placed in the RV outflow tract(right ventricular outflow tract,RVOT Group). Thirteen healthy subjects(7 male,mean age 58±7years,Control Group ) were studied as controls.Echocardiographic studied were performed 5±2months after the implantation.The basal and apical short-axis views of the left ventricle were acquired and analyzed using EchoPAC 7.0 station.The parameters for LV torsion included the peak twist(Ptw),twist at aortic valve closure(AVCtw),twist at mitral valve opening(MVOtw),untwisting rate(UntwR),peak twist velocity(Ptv),peak untwisting velocity(Putv),time to peak twist(TPtw),time to peak twist velocity(TPtv),time to peak untwisting velocity(Tutv),total twist(TW),torsion,the peak twist of the base(Ptw-m),the peak twist of the apex(Ptw-a),the time to peak twist of the base(Tptwm) and the time to peak twist of the apex(Tptwa).Results(1) The curves of LV torsion in the pacing groups were generally lower and notched than those in the control group.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°;AVCtw:11.76±4.22°VS 10.57±6.83°VS 18.28±6.06°,MVOtw: 9.09±4.24°VS 8.53±6.01°VS 14.98±4.29°,the p values are all less than 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.(2) The values of Tptwa were gradually declined among RVOT Group,RVA Group and Control Group.There was statistical difference in Tptwa between RVOT Group and Control Group(7.40±4.27°VS 12.70±6.82°,p=0.0364).(3) The curves of torsion velocity in the pacing groups were obviously disorganized compared with control Group.But there were no statistical differences in Ptv,Putv, Tptv and Tutv among the three groups.Conclusions(1) The RV pacing tends to depress LV torsion,though it doesn't change the timing of LV torsion.It may impair LV systolic and diastolic function.(2) The differences in the effects on LV torsion between RVA pacing and RVOT pacing need further investigation.