Right ventricular pacing: the best site is yet to be defined

The right ventricular (RV) apex is the traditional site to provide stable and reliable chronic ventricular pacing. Interest in alternate site pacing has grown since RV apical pacing has been associated with increased mortality and morbidity compared to normal atrio-ventricular conduction. 1-4 Alternate pacing sites include the RV septum and outflow tract.

Does Minimizing Ventricular Pacing Reduce the Incidence of Atrial Fibrillation ? A Systematic Review and Meta-analysis of Randomized Controlled Trials

Background:Right ventricular pacing disrupts atrioventricular synchrony and increases the risk of atrial fi brillation(AF).However,whether algorithms for minimizing ventricular pacing reduce the incidence of AF remains controversial.Therefore,we conducted a systematic review and meta-analysis to compare the incidence of AF between minimizing ventricular pacing and conventional pacing protocols in patients with pacemakers implanted.Methods:The PubMed,Embase,and Cochrane Library databases were searched up to August 1,2017,for randomized controlled trials that reported the incidence of AF in patients with and without the use of algorithms for minimizing ventricular pacing.Results:Eleven studies comprising 5705 participants(61%males,mean age 71 years[standard deviation 11 years])were fi nally included in the analysis.The mean follow-up duration was 24 months.Use of algorithms for minimizing ventricular pacing signifi cantly reduced the incidence of AF,with an odds ratio of 0.74(95%confi dence interval 0.55–1.00;P<0.05).There was moderate heterogeneity among studies(I 2=63%).Conclusions:The incidence of AF was reduced by 26%with use of algorithms for minimizing ventricular pacing.The incorporation of such algorithms in routine clinical practice should in theory lead to a decrease in AF-related morbidity and mortality.

Rapid right ventricular pacing for balloon valvuloplasty in congenital aortic stenosis:A systematic review

BACKGROUND Balloon aortic valvuloplasty(BAV)is a well-established treatment modality for congenital aortic valve stenosis.AIM To evaluate the role of rapid right ventricular pacing(RRVP)in balloon stabilization during BAV on aortic regurgitation(AR)in pediatric patients.METHODS A systematic review of the MEDLINE,Cochrane Library,and Scopus databases was conducted according to the PRISMA guidelines(end-of-search date:July 8,2020).The National Heart,Lung,and Blood Institute and Newcastle-Ottawa scales was utilized for quality assessment.RESULTS Five studies reporting on 72 patients were included.The studies investigated the use of RRVP-assisted BAV in infants(>1 mo)and older children,but not in neonates.Ten(13.9%)patients had a history of some type of aortic valve surgical or catheterization procedure.Before BAV,58(84.0%),7(10.1%),4(5.9%)patients had AR grade 0(none),1(trivial),2(mild),respectively.After BAV,34(49.3%),6(8.7%),26(37.7%),3(4.3%),patients had AR grade 0,1,2,and 3(moderate),respectively.No patient developed severe AR after RRVP.One(1.4%)developed ventricular fibrillation and was defibrillated successfully.No additional arrhythmias or complications occurred during RRVP.CONCLUSION RRVP can be safely used to achieve balloon stability during pediatric BAV,which could potentially decrease AR rates.

The Prevalence and Short-Term Outcomes of Ventricular Dyssynchrony after Right Ventricular Pacing

Objective: Long-term right ventricular pacing has been associated with an increased risk of heart failure and cardiomyopathy. The pathophysiology of cardiomyopathy associated with right ventricular pacing remains unclear. We aim to evaluate the burden and short-term outcomes of ventricular dyssynchrony after immediate permanent pacemaker implantation. Materials and Methods: This prospective cohort study examined consecutive patients who had permanent pacemaker implantation at Vajira Hospital in 2019. Left ventricular systolic function, specifically left ventricular ejection fraction (LVEF) and echocardiographic ventricular dyssynchrony parameters were assessed. The endpoints included the prevalence of ventricular dyssynchrony, new-onset cardiomyopathy, heart failure, and death. The correlation between QRS complex duration, the burden of ventricular pacing, and echocardiographic ventricular dyssynchrony was measured. Results: Thirty-six consecutive patients underwent pacemaker implantation. The prevalence of mechanical ventricular dyssynchrony was 22.2% using the interventricular conduction delay method, 41.7% using LV pre-ejection period method, and 11.1% using the septal posterior wall motion abnormality method. Electrical ventricular dyssynchrony was 86.1% and new-onset cardiomyopathy was 17.1% after 3 months of permanent pacemaker implantation. The right ventricular pacing of more than 20% was significantly associated with cardiomyopathy (p < 0.022) and heart failure (log-rank, p = 0.049) within 3 months. But heart failure was not associated with mechanical ventricular dyssynchrony parameters (log-rank, p = 0.610;hazard ratio [HR], 1.53;95% confidence interval [CI], 0.29 - 7.96;p = 0.613 for IVMD and log-rank, p = 0.398;HR, 0.04;95% CI, 0.01 - 3316.7 for SPWMD). Conclusion: Mechanical and electrical ventricular dyssynchrony are common findings in right ventricular pacing. High-burden right ventricular pacing after 3 months of permanent pacemaker implantation is often associated with cardiomyopathy and heart failure, but mechanical and electrical ventricular dyssynchrony does not predict a short-term decline in left ventricular systolic function and heart failure.

Effects of different pacing algorithms on cumulative ventricular pacing proportion in patients with pacemakers

Background It is welt known that increased cumulative ventricular pacing proportion （CumVP%） is one of the most important causes for adverse cardiovascular events. Therefore, how to reduce CumVP% has been a treatment issue in recent years. This study aimed to investigate the effects of different pacing algorithms on CumVP% in patients with pacemakers. Methods Pacemakers with three pacing algorithms, i.e., conventional dual chamber rate adaptive pacing （DDDR）, search atrioventricular conduction plus （SAV＋） and managed ventricular pacing （MVP）, were implanted in 42 patients including 41 with bradycardia arrhythmias and one with ventricular tachycardia. Pacemakers were programmed to work in conventional DDDR, SAV＋ and MVP during the follow-up periods of the first, the second and the third month. In each pacing algorithm, the time percentages of four pacing and sense status including atrial sense-ventricular sense （AS-VS）, atrial sense-ventricular pacing （AS-VP）, atrial pacing-ventricular sense （AP-VS） and atrial pacing-ventricular pacing （AP-VP） were calculated. Cumulative ventricular pacing proportions were compared in the three pacing algorithms in the first, the second and the third month postoperatively. Results In the DDDR algorithm AS-VS, AS-VP, AP-VS and AP-VP were 2.4%, 52.3%, 2.5% and 42.8% respectively, while in SAV＋ they were 19.3%, 34.9%, 33.9% and 12.0%, in MVP they were 38.9%, 13.2%, 41.6% and 6.4%. In the above the DDDR, SAV＋ and MVP algorithms, cumulative ventricular pacing proportions were 95.1%, 46.9% and 19.6%, respectively （P〈0.05） and the percentages of CumVP% 〈40% in patients were 0, 23.8% and 95.2.0% （P〈0.05）. Conclusions Compared with the conventional DDDR algorithm, both SAY＋ and MVP significantly reduced the CumVP%, especially the MVP algorithm. Patients may benefit from MVP algorithm due to reduced CumVP%.

Feasibility analysis of rapid right ventricular pacing in thoracic endovascular aortic repair under local anesthesia

Background Rapid right ventricular pacing is one of the methods for counteracting the ＂wind sock＂ effect in the thoracic endovascular aortic repair （TEVAR）. Most of the doctors are to complete this operation under general anesthesia. Now, our operation has been performed under local anesthesia. No related reports were found as to whether can the patient tolerate rapid fight ventficular pacing under local anesthesia. Methods From 2009 January to 2010 January, in our hospital all the DeBakey llI aortic dissection patients who underwent TEVAR were randomly divided into general anesthesia group （n = 50） and local anesthesia group （n = 51）. All the data were compared between two groups including the hemodynamic indexes, the graft positioning accuracy, rapid pacing duration, operation time, intraoperative discomfort and postoperative neurological understanding function changes and the complications. Results The success rate were 100% in the two groups. The duration of rapid pacing, operation time, the accuracy of graft localization and the intraoperative discomfort scores of Numerical Pain Rating Scale showed no significant difference between the two groups （P 〉 0.05）. There were no rapid fight ventricular pacing-related complications in the two groups. Conclusion During thoracic endovascular aortic repair procedure, rapid fight ventricular pacing under local anesthesia is safe and feasible. Thus it is worthy to be popularized in clinical practice.

Right Ventricular Outflow Tract Septal Pacing versus Apical Pacing: A Prospective, Randomized, Single-blind 5-Years Follow-up Study of Ventricular Lead Performance and Safety

Summary： Lead placement for ventricular pacing variably impacts the physiological benefit of the pa- tient. This study evaluated the ventricular lead performance and safety of right ventricular outflow tract septal pacing in patients with bradyarrhythmia in South China over 60-month follow-up. Totally, 192 patients （108 males, and 84 females, 63-4-21 years old） with bradyarrhythmia were randomly divided into two groups. The right ventricular outflow tract septum （RVOTs） group had lead placement near the sep- tum （n=97）, while the right ventricular apex （RVA） group had a traditional apical placement （n=95）. RV septal lead positioning was achieved with a specialized stylet and confirmed using fluoroscopic projec- tion. All patients were followed up for 60 months. Follow-up assessment included stimulation threshold, R-wave sensing, lead impedance and lead complications. The time of electrode implantation in both the ROVTs and RVA groups were significantly different （4.29±0.61 vs. 2.16±0.22 min; P=0.009）. No dif- ferences were identified in threshold, impedance or R-wave sensing between the two groups at 1 st, 12th, 36th and 60th month during the follow-up period. No occurrence of electrode displacement, increased pacing threshold or inadequate sensing was found. The long-term active fixation ventricular electrode performance in RVOTs group was similar to that in RVA group. RVOTs pacing near the septum using active fixation electrodes may provide stability during long-term follow-up period.

Cardiac resynchronization therapy improved the clinical outcomes in pacemaker patients upgraded to biventricular device

The right ventricular pacing （RVP） is the standard treat- ment for patients with severe bradyarrhythmias; however, it may cause and exacerbate heart failure symptoms in a long run under some circumstances.{1] In fact, significant left ventricular （LV） systolic dysfimction and symptomatic heart failure （HF） is commonly found in patient population with pacemaker implantations.

Analysis of Incidence of Atrial Fibrillation after Implantation of VVI Pacemaker-Long-term Observation of 154 Patients

Incidence of occurrence of atrial fibrillation (Af) after implantation of VVI was examined and the possible mechanism was explored. Eighty cases of atriouentricular block (AVB) and 74 cases of sick sinus syhdrome (SSS) were studied and followed up for 1-14 years after implantation of VVI. The endpoint was the occurrence of permanent Af. The results showed that the incidence of Af among the 154 patients was 14.3 % (22/154). And the incidence was 2. 5 % among patients with AVB (2/80), and 27 % among patients with SSS (20/74). Significant significance was found between patients with AVB and those with SSS (P<0. 01). Among the patients with SSS, the incidence was 33. 3 % (9/27) in type I, 38.1 % (8/21) in type Ⅲ and 11. 5 % (3/26) in type Ⅱ. Significant differences were revealed among patients with Ⅱ, Ⅲ and Ⅱ type SSS (P<0. 05). It is concluded that retrograde conduction of pure ventricular pacing may play the chief role of occurrence of Af.

Left ventricular endocardial pacing predicts the reduction of left ventricular outflow tract pressure gradient immediately after percutaneous transseptal myocardial ablation in patients with hypertrophic obstructive cardiomyopathy refractory to medicatio

Background Hypertrophic obstructive cardiomyopathy （HOCM） carries an increased risk for sudden cardiac death. No data regarding the percutaneous transseptal myocardial ablation （PTSMA） and epicardial left ventricular pacing （LVP） were reported. Methods Seven patients with recurrent symptoms and increased resting left ventricular outflow tract pressure gradient （LVOTG） after PTSMA and another 14 patients with HOCM without history of PTSMA were studied. Both resting and dobutamine stress echocardiography, PTSMA and LVP were routinely performed. Results In patients without previous PTSMA procedure, mild reduction of resting LVOTG was detected at 5 minutes after left ventricular pacing, and this reduction became significant at 10 minutes. All patients were divided into successful and unsuccessful groups according to their response to LVP. In contrary to patients in unsuccessful group, resting and R-S2 stimuli-induced LVOTG during PTSMA procedure were decreased dramatically （（9±5） mmHg vs （58±12） mmHg, （12±2） mmHg vs （113±27） mmHg, P〈0.001）. Analysis of Logistic regression demonstrated that only LVOTG level dudng left ventdcular pacing was an independent factor predicting the reduction of LVOTG immediately after PTSMA （odds ratio （OR）, 0.59; 95% CI 2.67 to 5.82; P=0.0002）. Conclusion Left ventricular endocardial temporary pacing plays a critical role in predicting acute effect on the reduction of LVOTG immediately after PTSMA procedure.

Olmesartan Reduces New-onset Atrial Fibrillation and Atrial Fibrillation Burden after Dual-chamber Pacemaker Implantation in Atrioventricular Block Patients

Background： Atrial fibrillation （AF） is the rnost frequent tachyarrhythmia in patients with a permanent pacemaker. Angiotensin II receptor antagonists have a protective effect against the occurrence of AF in patients with heart diseases. This study aimed to assess the effectiveness of olmcsartan in the prevention of new-onset AF and AF burden in atrioventricular block （AVB） patients with dual-chamber （DDD） pacemaker implantation. Methods： This was a single-center, prospective, randomized, single-blind, controlled clinical study. A total of 116 AVB patients, who received DDD pacemakers implantation with the percentage of ventricular pacing （VP%） _〉40% from April 22, 2011 to December 24, 2012, were prospectively randomized to olrnesartan group （20 mg per day; n - 57） or control group （n = 59）. Patients were lbllowed up using pacernaker prograrnming± 12-lead electrocardiography in the intrinsic sinus rhythm, laboratory examinations, and transthoracic echocardiography at 24 months. Atrial high rate events （AHREs） were defined as 180 beats/min over a minimum of 5 min. AF burden was calculated by the number of hours with AHREs divided by the number of measurement hours. Results： Ten （17.5%） patients in the olmesartan group and 24 patients （40.7%） in the control group occurred new-onset AF, and the difference between two groups was statistically significant （P = 0.04）. AF burden was lower in olmesartan group than that in control group （8.02 ± 3.10% vs. 13.66 ± 6.14%, P = 0.04）. There were no significant differences in mean days to the first occurrence of AHREs and mean cumulative numbers of AHREs between two groups （P = 0.89 and P = 0.42, respectively）. Moreover, olmesartan group had smaller values of maximal P-wave durations and P-wave dispersion （PD） after 24 months follow-up compared with the control group （ 109.5 ± 7.4 ins vs. 113.4 ± 7.1 ms, P = 0.00; and 40.6 ± 4.5 ms vs. 43.3 ± 4.4 ins, P - 0.02, respectively）. Left ventricular end-diastolic diameter and left ventricular qiection traction were not significantly diiTerent between two groups （both P 〉 0.05）. Conclusion： This study suggested that 24-month ofolmesartan therapy could reduce new-onset AF and AF burden in patients with DDD pacemakers.

Prognostic factors of pacing-induced cardiomyopathy

Background:The detrimental outcomes of right ventricular pacing on left ventricular electromechanical function ultimately result in heart failure,a phenomenon termed pacing-induced cardiomyopathy(PICM)in clinical research.This study aimed to validate prognostic factors that can be used to identify patients with higher susceptibility to progress to the stage of cardiomyopathy before pacemaker implantation.Methods:This observational analysis enrolled 256 patients between January 2013 and June 2016,23(8.98%)of whom progressed to PICM after 1 year of follow-up.A Cox proportional hazard model was used to analyze the prognostic factors associated with PICM.Dose-response analysis was used to evaluate the relationship between significant indicators in multifactor analysis and PICM.Results:The mean values of left ventricular ejection fraction before and after pacemaker implantation in 23 patients diagnosed with PICM were 62.3%and 42.7%,respectively.Univariate analysis showed that sex,atrio-ventricular block,paced QRS duration,and ventricular pacing percentage were significantly associated with PICM.In the multivariate analysis,male sex(hazard ratio:1.20,95%confidence interval[CI]:1.09-1.33,P<0.005),paced QRS duration(hazard ratio:1.95 per 1 ms increase,95%CI:1.80-2.12,P<0.001),and ventricular pacing percentage(hazard ratio:1.65 per 1%increase,95%CI:1.51-1.79,P<0.001)were independent prognostic factors associated with the development of PICM.The ventricular pacing percentage and paced QRS duration level defined by the dose-response analysis were positively associated with PICM(P<0.05).Conclusions:Our findings indicated that paced QRS duration and ventricular pacing percentage were the most sensitive prognostic factors for PICM.

Application of permanent left bundle branch pacing in patients with bradycardia after cardiac surgery

Background The study was to access the feasibility and effectiveness of permanent left bundle branch pacing(LBBP)in patients with bradycardia after cardiac surgery,in comparison with conventional right ventricular outflow tract septal pacing(RVOSP).Methods A total of 50 patients with cardiac surgery who underwent permanent pacemaker implantation(PPI)were enrolled,21 patients underwent LBBP(LBBP group)and 29 patients underwent RVOSP(RVOSP group).Pacing electrical parameters,QRS duration(QRSd),echocardiographic measurements,lead and device related complications were obtained at procedure and during follow-ups.Results There were no statistically significant differences between the LBBP group and the RVOSP group at procedure and at the twelfth month’s follow-up in pacing thresholds(0.64±0.16 V vs.0.63±0.22 V)and(0.91±0.28 V vs.0.85±0.20 V),R-wave amplitude(16.68±4.52 mV vs.15.09±4.53 mV)and(14.41±8.65 mV vs.12.65±6.17 mV),pacing impedances(719.24±152.65Ωvs.639.13±177.04Ω)and(534.01±96.92Ωvs.499.18±77.87Ω).But the average ventricular pacing percentage(VP%)at the first month’s follow-up(81.96±32.06%vs.58.37±42.96%)and at the twelfth month’s follow-up(84.65±35.84%vs.53.57±38.47%)showed significant difference between two groups(P<0.05);The LBBP group produced narrower QRSd(121.13±23.91 ms)than the RVOSP group(158.00±9.69 ms)(P=0.011).There were no significant differences between the LBBP group and the RVOSP group at pre-procedure and at the twelfth month’s follow-up in echocardiographic parameters,which included left ventricular end-diastolic dimension(LVEDD)(48.76±7.08 mm vs.47.34±6.91 mm)and(50.58±10.33 mm vs.45.97±7.11 mm),left ventricular ejection fraction(LVEF)(58.33±12.64%vs.61.50±8.40%)and(55.85±16.35%vs.61.50±10.52%),and area of tricuspid regurgitation(TR)(2.79±3.65 cm2 vs.2.85±2.26 cm2)and(3.09±2.34 cm2 vs.2.95±1.92 cm2).No lead and device related complication was observed during follow-ups.Conclusions LBBP is feasible and effective in patients with bradycardia after cardiac surgery.LBBP produces narrow QRSd,which may be a preferred pacing strategy for patients after cardiac surgery.[S Chin J Cardiol 2021;22(1):13-20]