A Study Of Optimizing Pacing Site For Improving Prognostic

Objectives To evaluate the prognostic of patients with right atrial septum and high right ventricular septum pacing,and to investigate the necessity and feasibility of optimizing pacing site and technological details of locating screw-in leads. Methods During January 2005-October 2007,Eighty-six patients(48 male,38 female,average age is 65 years old)were randomly enrolled in this study,who received DDD(dicavity demand pacing)pacemaker implantation in the department of cardiology of the First Affiliated Hospital of Kunming Medical College.Forty-six patients were randomly divided into right atrial appendage-high right ventricular septum(RAA-RVS)pacing group(n=32)and interatrial septum-high right ventricular septum(IAS-RVS)pacing group(n=14)as optimized group.Forty patients with right atrial appendage-right ventricular apex(RAA-RVA)pacing were chosen randomly as control.Active-fixation leads(screw-in leads)were used in interatrial septum and high right ventricular septum pacing.Passive leads were used in atrial appendage and right ventricular apex pacing.A series of comparisons were made between the two groups,which included operational duration,cost,technical details,the structure and function of heart,Aft(atrial fibrillation)incidence rate,AF burden,pacing-related complications and the quality of life(QOL).The correlation between above-mentioned and EF(ejection fraction)/AF had also been analyzed.Results 1.IAS-RVS pacing and RAA-RVS pacing subsets consumed a little longer X-ray exposure time(8.31±1.32 & 6.03±1.26 vs.4.13±1.34min)and more expense of leads than RAA-RVA pacing(P＜0.01).The inter-operational complications and parameters of leads(pacing threshold,sensing threshold,impedance and rate setting) were similar between the two groups.However,3 patients in control appeared sensing and pacing dysfunction respectively at 10,12 and 18 months after pacemaker implantation.They have been reseted active-fixation screw-in leads onto high right ventricular septum instead of ROA pacing.One patient with IAS-RVS pacing occurred ventricular lead dislodging and have been reseted it in RVA again. 2.In optimized group,the diameter of left atrium(LA)(32.13±5.99 vs. 30.38±6.21mm)and tricuspid valve regurgitation(TR)(220.47±45.49 vs. 197.64±39.66cm/s)were increased after operation(P＜0.01).And left ventricular fractional shortening(FS)(37.42±6.47%vs.37.90±6.56%)and ejection fraction(EF) (65.98±7.33 vs.66.96±7.19%)were decreased after implantation(P＜0.01). Compared with the control,left ventricle at the end of diastole diameter(LVDd),LA and TR in optimized group were lower(P＜0.01).Furthermore,it's FS and EF were higher than the control(P＜0.01).Constituent ratio of regurgitation degree(mild, moderate and severe)in optimized group has no statistical difference than that before operation.However,seven patients appeared severe tricuspid valve regurgitation and two appeared moderate tricuspid valve regurgitation in control.After pacing,the mean QRS duration was significantly shorter during RVS pacing than during RVA pacing(107.71±20.31 vs.140.88±23.68 ms,P＜0.01).No patient emerged left bundle branch block(LBBB)during RVS pacing.But fifteen patients occurred LBBB during RVA pacing(P＜0.01).Ventricular pacing ratios were similar in both groups. Moreover,by multiple linear regression analysis,optimized group showed negative correlation between ventricular pacing ratio,follow-up period and EF,whereas control group indicated negative correlation between TR,LVDd,ORS duration, LBBB and EF after pacing.3.In interatrial septum pacing,Pmax and Pd were shorter than fight atrial appendage pacing(P＜0.01).After IAS pacing,seizure frequency of paroxysmal atrial fibrillation(PAF)decreased(P＜0.05)and one patient did not occurred PAF again.After RAA pacing,seizure frequency of PAF increased(P＜0.01)and ten patients occurred PAF.Furthermore,six PAF patients transformed to sustained atrial fibrillation.By Logistic regression analysis,during RAA pacing,PAF before pacing, high value of Pd after pacing,sick synchronous syndrome,high value of LA after pacing and great age were the risk factors of Aft by turns.During IAS pacing,PAF before pacing and sick synchronous syndrome were the risk factors of AF.4.Mean follow-up(12.84±8.27 vs.13.08±7.96 months,range 3～32)are similar between the two groups.And no stroke or death happened.Proportion of NYHAⅠ/Ⅱwas high in optimized group and NYHAⅢ/Ⅳis high in control group. The former got higher scores in physiology,psychology,society,environment and subjective feelings than the latter but no statistical difference was showed in the last three aspects.Conclusions①RVS pacing preserves synchronous ventricular activation and prevents the long-term deleterious effects of RVA pacing on myocardial perfusion and function in patients implanted with a permanent pacemaker.②IAS pacing, minimizing the conduction delay of the atria,decreases PAF burden and sustained atrial fibrillation incidence.Furthermore,it is advantageous for atria synchronization which could improve the function of atria as an auxiliary pump.③Patients implanted with WI pacemakers could get much benefit from RVS pacing by better sequence of ventricular activation.④IAS-RVS pacing could improve synchronous activation of atriums and ventricles,decrease deleterious effects with artificial pacing from electrical-mechanical activity and hemodynamics.It can greatly avoid harmful influence of RAA-RVA pacing and preserve modest but significant haemodynamic beneficial effect.OActive fixation electrodes could be firmly fixed in precise sites. Parameters of electrodes are stable and normal during follow up.Time of patients lying in bed is shorter than before.Along with the enhancement of operators' ability X-ray exposure time will be shortened.Patients can obtain much more profit from these techniques in long-term than that they have paid for active fixation electrodes.⑥There is no special contraindication with inclusion criteria.⑦IAS-RVS pacing,as a new physiological technique,has evoked great attention and discussion at home and abroad.Due to the characteristics of safe and easy operate,IAS-RVS pacing has a pleasant generalize and application prospect.