Left bundle branch pacing set to outshine biventricular pacing for cardiac resynchronization therapy?

The deleterious effects of long-term right ventricular pacing necessitated the search for alternative pacing sites which could prevent or alleviate pacinginduced cardiomyopathy.Until recently,biventricular pacing(BiVP)was the only modality which could mitigate or prevent pacing induced dysfunction.Further,BiVP could resynchronize the baseline electromechanical dssynchrony in heart failure and improve outcomes.However,the high non-response rate of around 20%-30%remains a major limitation.This non-response has been largely attributable to the direct non-physiological stimulation of the left ventricular myocardium bypassing the conduction system.To overcome this limitation,the concept of conduction system pacing(CSP)came up.Despite initial success of the first CSP via His bundle pacing(HBP),certain drawbacks including lead instability and dislodgements,steep learning curve and rapid battery depletion on many occasions prevented its widespread use for cardiac resynchronization therapy(CRT).Subsequently,CSP via left bundle branch-area pacing(LBBP)was developed in 2018,which over the last few years has shown efficacy comparable to BiVP-CRT in small observational studies.Further,its safety has also been well established and is largely free of the pitfalls of the HBP-CRT.In the recent metanalysis by Yasmin et al,comprising of 6 studies with 389 participants,LBBPCRT was superior to BiVP-CRT in terms of QRS duration,left ventricular ejection fraction,cardiac chamber dimensions,lead thresholds,and functional status amongst heart failure patients with left bundle branch block.However,there are important limitations of the study including the small overall numbers,inclusion of only a single small randomized controlled trial(RCT)and a small follow-up duration.Further,the entire study population analyzed was from China which makes generalizability a concern.Despite the concerns,the meta-analysis adds to the growing body of evidence demonstrating the efficacy of LBBP-CRT.At this stage,one must acknowledge that the fact that still our opinions on this technique are largely based on observational data and there is a dire need for larger RCTs to ascertain the position of LBBPCRT in management of heart failure patients with left bundle branch block.

The Impact of Cardiac Pacing Site on Patient's Cardiac Function and Psychological State

With the widespread application of artificial permanent pacemakers in clinical practice,there have been new changes in the indications for pacemaker implantation.The current clinical indications include high atrioventricular block,sick sinus syndrome,cardiac resynchronization therapy for heart failure,and implantation of cardioverter defibrillators for ventricular arrhythmias.The implantation of a pacemaker can improve the quality of life and prognosis of patients with arrhythmia.In the past,permanent pacemaker implantation was performed in clinical practice,and the right ventricular pacing electrode was often fixed at the apex of the right ventricle,which belongs to non physiological pacing.Through long-term clinical follow-up,it was found that apex pacing can easily cause abnormal depolarization of the left ventricle,asynchronous contraction of the myocardium,and ultimately lead to myocardial fibrosis,which has adverse effects on the patient's cardiac function and psychological state.In recent years,Scholars have found that pacing in the right ventricular outflow tract septum is closer to the atrioventricular node and closer to the His bundle Purkinje fibers.The pacing impulse almost simultaneously expands towards both ventricles,closer to the physiological pacing state,thereby reducing the occurrence of cardiovascular events in patients.This article explores the impact of pacing in different parts of the heart on the cardiac function and psychological state of patients based on clinical data from the past three years.

Future easy and physiological cardiac pacing

The right atrial appendage (RAA) and right ventricular apex (RVA) have been widely considered as conventional sites for typical dual-chamber atrio-ventricular cardiac (DDD) pacing. Unfortunately conventional RAA pacing seems not to be able to prevent atrial fibrillation in DDD pacing for tachycardia-bradycardia syndrome, and the presence of a left bundle branch type of activation induced by RVA pacing can have negative effects. A new technology with active screw-in leads permits a more physiological atrial and right ventricular pacing. In this review, we highlight the positive effects of pacing of these new and easily selected sites. The septal atrial lead permits a shorter and more homogeneous atrial activation, allowing better prevention of paroxysmal atrial fibrillation. The para-Hisian pacing can be achieved in a simpler and more reliable way with respect to biventricular pacing and direct Hisian pacing. We await larger trials to consider this "easy and physiological pacing" as a first approach in patients who need a high frequency of pacing.

Predictors of super-response to cardiac resynchronization therapy： the significance of heart failure medication, pre-implant left ventricular geometry and high percentage of biventricular pacing

Background Super-responders （SRs） are defined as patients who show crucial cardiac function improvement after cardiac resynchro- nization therapy （CRT）. The purpose of this study is to identify and validate predictors of SRs after CRT. Methods This study enrolled 201 patients who underwent CRT during the period from 2010 to 2014. Clinical and echocardiographic evaluations were conducted before CRT and 6 months after. Patients with a decrease in New York Heart Association （NYHA） fimctional class 〉 1, a decrease in left ventricular end-systolic volume （LVESV） ≥ 15%, and a final left ventricular ejection fraction （LVEF） ≥ 45% were classified as SRs. Results 29% of the 201 patients who underwent CRT were identified as SRs. At baseline, SRs had significantly smaller left atrial diameter （LAD）, LVESV, left ventricular end-diastolic volume （LVEDV） and higher LVEF than the non-super-responders （non-SRs）. The percentage of patients using angiotensin-converting enzyme inhibitors or angiotensin receptor blockers （ACEI/ARB） was higher in SRs than non-SRs. Most SRs had Biventricular （BiV） pacing percentage greater than 98% six months after CRT. In the multivariate logistic regression analysis, the independ- ent predictors of SRs were lower LVEDV [odd ratios （OR）： 0.93; confidence intervals （CI）： 0.90-0.97], use of ACEI/ARB （OR： 0.33; CI： 0.13~3.82） and BiV pacing percentage greater than 98% （OR： 0.29; CI： 0.16~.87）. Conclusion Patients with a better compliance of ACEI/ARB and a less ectatic ventricular geometry before CRT tends to have a greater probability of becoming SRs. Higher percentage of BiV pacing is essential for becoming SRs.

Left univentricular pacing for cardiac resynchronization therapy using rate-adaptive atrioventricular delay

Objective To evaluate left univentricular （LUV） pacing for cardiac resynchronization therapy （CRT） using a rate-adaptive atrioven- tricular delay （RAAVD） algorithm to track physiological atrioventricular delay （AVD）. Methods A total of 72 patients with congestive heart failure （CHF） were randomized to RAAVD LUV pacing versus standard biventricular （BiV） pacing in a 1 ： 1 ratio. Echocardiography was used to optimize AVD for both groups. The effects of sequential BiV pacing and LUV pacing with optimized A-V （right atrio-LV） delay using an RAAVD algorithm were compared. The standard deviation （SD） of the S/R ratio in lead VI at five heart rate （HR） segments （Rs/R-SD5）, defined as the ＂tracking index,＂ was used to evaluate the accuracy of the RAAVD algorithm for tracking physiological AVD. Results TheQRS complex duration （132 ± 9.8 vs. 138± 10ms, P 〈 0.05）, the time required for optimization （21 ±5 vs. 50±8min, P〈 0.001）, the mitral regurgitant area （1.9 ± 1.1 vs. 2.5 ± 1.3 em2, P 〈 0.05）, the interventricular mechanical delay time （60.7 ± 13.3 ms vs. 68.3 ± 14.2 ms, P 〈 0.05）, and the average annual cost （13,200 ± 1000 vs. 21,600 ± 2000 RMB, P 〈 0.001） in the RAAVD LUV pacing group were significantly less than those in the standard BiV pacing group. The aortic valve velocity-time integral in the RAAVD LUV pacing group was greater than that in the standard BiV pacing group （22.7 ± 2.2 vs. 21.4 ± 2.1 cm, P 〈 0.05）. The Rs/R-SD5 was 4.08 ± 1.91 in the RAAVD LUV pacing group, and was significantly negatively correlated with improved left ventricular ejection fraction （LVEF） （ALVEF, Pearson＇s r = -0.427, P = 0.009）, and positively correlated with New York Heart Association class （Spearman＇s r - 0.348, P 0.037）. Conclusions RAAVD LUV pacing is as effective as standard BiV pacing, can be more physiological than standard BiV pacing, and can de- crease the average annual cost of CRT.

In vivo mechanical study of helical cardiac pacing electrode interacting with canine myocardium

Cardiac pacing is a medical device to help human to overcome arrhythmia and to recover the regular beats of heart. A helical configuration of electrode tip is a new type of cardiac pacing lead distal tip. The helical electrode attaches itself to the desired site of heart by screwing its helical tip into the myocardium. In vivo experiments on anesthetized dogs were carried out to measure the acute interactions between helical electrode and myocardium during screw-in and pull-out processes. These data would be helpful for electrode tip design and electrode/myocardium adherence safety evaluation. They also provide reliability data for clinical site choice of human heart to implant and to fix the pacing lead. A special design of the helical tip using strain gauges is instrumented for the measurement of the screw-in and pull-out forces. We obtained the data of screw-in torques and pull-out forces for five different types of helical electrodes at nine designed sites on ten canine hearts. The results indicate that the screw-in torques increased steplike while the torque-time curves presente saw-tooth fashion. The maximum torque has a range of 0.3-1.9 Nmm. Obvious differences are observed for different types of helical tips and for different test sites. Large pull-out forces are frequently obtained at epicardium of left ventricle and right ventricle lateral wall, and the forces obtained at right ventricle apex and outflow tract of right ventricle are normally small. The differences in pull-out forces are dictated by the geometrical configuration of helix and regional structures of heart muscle.

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.

Prevalence of sleep-disordered breathing in elderly patients with cardiac pacemaker: a case-control study

Objective To investigate the prevalence of sleep-disordered breathing in elderly patients with permanent cardiac pacemaker implantation due to bradyarrhythmias, and the relationship between pacing mode and patients' sleep apnea-hypopnea index.Methods Forty-four elderly patients (＞60 years) with cardiac pacemaker and their 44 controls matched for gender, age, body mass index and cardiovascular morbidity were studied using polysomnography or portable sleep monitoring device. Results Prevalence of sleep-disordered breathing (apnea-hypopnea index ≥5/h) was 44.7% and the mean apnea-hypopnea index was 8.2 ±4.1/h in the cardiac pacemaker group, which were significantly higher than those in control subjects (25% and 4.6±2.4/h, respectively, P＜0.01 and P＜0.05). The mean apnea-hypopnea index of patients with DDD or AAI pacemaker was significantly lower than that of patients with VVI pacemaker. Conclusions Sleep-disordered breathing was more common in patients who had their cardiac pacemaker implanted due to bradyarrhythmias than in their matched controls. Compared with VVI pacing, DDD or AAI pacing may be more beneficial to patients with bradyarrhythmias and sleep-disordered breathing.

THE OPERATION AND FEELINGS OF APPLICATION OF TEMPORARY CARDIAC PACING BESIDE BED WITHOUT FLUOROSCOPY

The endocardial electrodes were placed in endoventriculus beside bed withoutfluoroscopy in 9 patients who required temporary cardiac pacing and theresults were satisfactory.The manipulatory points are below:operatingcarefully with lightly and softly handling,noticing hand’s feeling,tryingagain by roling the electrode and/or changing its top’s direction whenmeeting with venous valves or branches.Judging the position of electrode’stop according to the right ventricular luminal electrogram.As comparedwith the setting of electrode under X ray,our method is superior in savingtime and requires less instrumente,the patients needn’t be moved,bothphysicans and patients are avoided X radiation’s injury.

Effects of atrial septal defects on the cardiac conduction system

The case report presented in this edition by Mu et al.The report presents a case of atrial septal defect(ASD)associated with electrocardiographic changes,noting that the crochetage sign resolved after Selective His Bundle Pacing(S-HBP)without requiring surgical closure.The mechanisms behind the appearance and resolution of the crochetage sign remain unclear.The authors observed the dis-appearance of the crochetage sign post-S-HBP,suggesting a possible correlation between these specific R waves and the cardiac conduction system.This editorial aims to explore various types of ASD and their relationship with the cardiac con-duction system,highlighting the diagnostic significance of the crochetage sign in ASD.

比格犬行传导系统起搏不同位点急性期的心电、血液动力学、左心室流场状态和能量损耗特点

目的:对比比格犬行传导系统起搏不同位点急性期的心电、血液动力学、左心室流场状态和能量损耗特点。方法:选取8只成年健康比格犬。首先在右心耳植入一根主动固定导线,之后将另外一根主动固定导线分别植入右心室心尖、希氏束远端和左束支间隔支。连接双腔起搏器后,分别采集自身窦性心律状态、右心室心尖部起搏(RVAP)、希氏束远端起搏(DHBP)和左束支起搏(LBBP)状态下的心电、急性期血液动力学参数,以及超声心动图血流速度向量模式下采集3个完整心动周期标准心尖三腔心彩色血流动态图像。经脱机分析获得等容收缩期、快速射血期、等容舒张期、快速充盈期、心房收缩期左心室腔内能量损耗等参数。比较不同位点起搏下上述参数的差异及主要参数的线性相关性。结果:基线的自身窦性心律、RVAP、DHBP、LBBP的QRS时限分别为(45.0±4.0)ms、(98.4±6.2)ms、(50.0±4.5)ms、(62.0±4.7)ms。LBBP的起搏QRS时限大于基线的自身窦性心律和DHBP,但小于RVAP(P均<0.01)。与基线的自身窦性心律AOO模式(心房起搏频率快于自身窦性心律10次/min)比,RVAP、DHBP和LBBP的急性期左心室压力最大上升速率(LVdP/dtmax)改变分别为(-7.89±5.67)%、(0.74±2.05)%和(-0.14±3.59)%,DHBP和LBBP的LVdP/dtmax改变差异无统计学意义(P=0.667),但两者均明显优于RVAP的LVdP/dtmax改变(P均<0.01)。RVAP下左心室平均能量损耗在等容收缩期、快速射血期、等容舒张期、快速充盈期和心房收缩期均明显大于基线的自身窦性心律、DHBP和LBBP(P均<0.01)。而基线的自身窦性心律、DHBP和LBBP在以上5个时相的能量损耗方面差异均无统计学意义(P均>0.05)。DHBP及LBBP在各时相左心室总涡流数目、涡流面积及循环强度较基线的自身窦性心律状态均无明显增高,且LBBP涡流面积及循环强度较DHBP均无明显增加(P均>0.05)。结论:尽管比格犬行LBBP的起搏QRS时限明显延长,但其急性期左心室血液动力学、左心室流场状态和能量损耗方面与自身窦性心律下传和DHBP差异并无统计学意义,且优于RVAP。本研究或许有助于揭示LBBP作为生理性起搏治疗的理论依据。

Right ventricular septal pacing: Safety and efficacy in a long term follow up

AIM: To evaluate the safety and efficacy of the permanent high interventricular septal pacing in a long term follow up, as alternative to right ventricular apical pacing. METHODS: We retrospectively evaluated:(1) 244 patients(74 ± 8 years; 169 men, 75 women) implanted with a single(132 pts) or dual chamber(112 pts) pacemaker(PM) with ventricular screw-in lead placed at the right ventricular high septal parahisian site(SEPTAL pacing);(2) 22 patients with permanent pacemaker and low percentage of pacing(< 20%)(NO pacing);(3) 33 patients with high percentage(> 80%) right ventricular apical pacing(RVA). All patients had a narrow spontaneous QRS(101 ± 14 ms). We evaluated New York Heart Association(NYHA) class, quality of life(Qo L), 6 min walking test(6MWT) and left ventricular function(end-diastolic volume, LV-EDV; end-systolic volume, LVESV; ejection fraction, LV-EF) with 2D-echocardiography. RESULTS: Pacing parameters were stable duringfollow up(21 mo/patient). In SEPTAL pacing group we observed an improvement in NYHA class, Qo L score and 6MWT. While LV-EDV didn't significantly increase(104 ± 40 m L vs 100 ± 37 m L; P = 0.35), LV-ESV slightly increased(55 ± 31 m L vs 49 ± 27 m L; P = 0.05) and LV-EF slightly decreased(49% ± 11% vs 53% ± 11%; P = 0.001) but never falling < 45%. In the RVA pacing control group we observed a worsening of NYHA class and an important reduction of LV-EF(from 56% ± 6% to 43% ± 9%, P < 0.0001).CONCLUSION: Right ventricular permanent high septal pacing is safe and effective in a long term follow up evaluation; it could be a good alternative to the conventional RVA pacing in order to avoid its deleterious effects.

The importance of avoiding unnecessary right ventricular pacing in clinical practice

Symptomatic bradycardia is effectively treated with the implantation of a cardiac pacemaker. Although a highly successful therapy, during recent years there has been a focus on the negative effects associated with longterm pacing of the apex of the right ventricle(RV). It has been shown in both experimental and clinical studies that RV pacing leads to ventricular dyssynchrony, similar to that of left bundle branch block, with subsequent detrimental effects on cardiac structure and function, and in some cases adverse clinical outcomes such as atrial fibrillation, heart failure and death. There is substantial evidence that patients with reduced left ventricular function(LVEF) are at particular high risk of suffering the detrimental clinical effects of long-term RV pacing. The evidence is, however, incomplete, coming largely from subanalyses of pacemaker and implantable cardiac defibrillator studies. In this group of patients with reduced LVEF and an expected high amount of RV pacing, biventricular pacing(cardiac resynchronization therapy) devices can prevent the negative effects of RV pacing and reduce ventricular dyssynchrony. Therefore, cardiac resynchronization therapy has emerged as an attractive option with promising results and more clinical studies are underway. Furthermore, specific pacemaker algorithms, which minimize RV pacing, can also reduce the negative effects of RV stimulation on cardiac function and may prevent clinical deterioration.

Biventricular pacing for treating heart failure in children: A case report and review of the literature

BACKGROUND Cardiac resynchronization therapy(CRT) can be used as an escalated therapy to improve heart function in patients with cardiac dysfunction due to long-term right ventricular pacing. However, guidelines are only targeted at adults. CRT is rarely used in children.CASE SUMMARY This case aimed to implement biventricular pacing in one child with heart failure who had a left ventricular ejection fraction < 35% at 4 years after implantation of an atrioventricular sequential pacemaker due to atrioventricular block.Postoperatively, echocardiography showed atrial sensing ventricular pacing and QRS wave duration of 120-130 ms, and cardiac function significantly improved after upgrading pacemaker.CONCLUSION Patients whose cardiac function is deteriorated to a level to upgrade to CRT should be upgraded to reverse myocardial remodeling as soon as possible.

Cardiac resynchronization therapy: Dire need for targeted left ventricular lead placement and optimal device programming

Cardiac resynchronization therapy(CRT) effected via biventricular pacing has been established as prime therapy for heart failure patients of New York Heart Association functional class Ⅱ, Ⅲ and ambulatory Ⅳ, reduced left ventricular(LV) function, and a widened QRS complex. CRT has been shown to improve symptoms, LV function, hospitalization rates, and survival. In order to maximize the benefit from CRT and reduce the number of non-responders, consideration should be given to target the optimal site for LV lead implantation away from myocardial scar and close to the latest LV site activation; and also to appropriately program the device paying particular attention to optimal atrioventricular and interventricular intervals. We herein review current data related to both optimal LV lead placement and device programming and their effects on CRT clinical outcomes.

Cardiac resynchronization therapy in acute pulmonary edema: A case report

We are reporting a case of 71-year old lady with a dual chamber demand pacemaker,who developed acute pulmonary edema due to an acute left ventricular(LV)dysfunction and worsening in mitral valve regurgitation after atrioventricular nodal ablation for uncontrolled atrial fibrillation.This was attributed to right ventricular apical pacing leading to LV dyssynchronization.Patient dramatically improved within 12-24 h after upgrading her single chamber pacemaker to biventricular pacing.Our case demonstrates that biventricular pacing can be an effective modality of treatment of acute congestive heart failure.In particular,it can be used when it is secondary to LV dysfunction and severe mitral regurgitation attributed to significant dyssynchrony created by right ventricular pacing in patients with atrioventricular nodal ablation for chronic atrial fibrillation.

His Bundle Pacing:Rebirth of an Important Technique for Pacing the Intrinsic Conduction System

Permanent pacemaker implant is a commonly performed cardiac procedure for treatment of bradycardia or conduction system abnormality.With conventional right ventricular(RV)pacing a lead is implanted at the RV apex or on the RV septum.However,RV apical or RV septal pacing causes iatrogenic left bundle-branch block and ventricular dyssynchrony and can lead to adverse cardiac remodeling,a pacing-mediated cardiomyopathy,and congestive heart failure.Alternatively,permanent His-bundle pacing uses the intrinsic rapidly-conducting His-Purkinje system to activate the ventricle,thereby maintaining(or sometimes even restoring)ventricular synchrony.Many patients may derive benefit from permanent His-bundle pacing.

Hemodynamic improvement by right ventricular septal pacing in elderly patients with chronic atrial fibrillation and slow ventricular response

Background and objectives Right ventricular apical(RVA)pacing has been reported impairing left ventricular(LV)performance.Alternative pacing sites in right ventricle(RV)has been explored to obtain better cardiac function.Our study was designed to compare the hemodynamic effects of right ventricular septal(RVS)pacing with RVA pacing.Methods Ten elderly patients with chronic atrial fibrillation(AF)and long RR interval or slow ventricular response(VR)received VVI pacing.The hemodynamic difference between RVS and RVA pacing were examined by transthoracic echocardiography(TTE).Results Pacing leads were implanted successfully at the RVA and then RVS in all patients without complication.The left ventricular(LV)parameters,measured during RVA pacing including left ventricular ejection fraction(LVEF),FS,stroke volume(SV)and peak E wave velocity(EV)were decreased significantly compared to baseline data,while during RVS pacing,they were significantly better than those during RVA pacing.However,after 3-6 weeks there was no statistical significant difference between pre-and post-RVS pacing.Conclusions The LV hemodynamic parameters during RVA pacing were significantly worse than baseline data.The short term LV hemodynamic parameters of RVS pacing were significantly better than those of RVA pacing;RVS pacing could improve the hemodynamic effect through maintaining normal ventricular activation sequence and biventricular contraction synchrony in patients with chronic AF and slow ventricular response.

Cardiac Resynchronization Therapy in 2015:Lessons Learned

Over 20 years of research has led to the now widely accepted role of cardiac resynchronization therapy(CRT)in medically refractory,mild to severe systolic heart failure(HF)with increased QRS duration.In addition to conferring a mortality benefi t,CRT has been shown to reduce HF hospitalization rates and improve functional status in this population.However,not all patients consistently demonstrate a positive response to CRT.Efforts to improve response to CRT have focused on improving patient selection and optimizing device implantation and follow-up,thereby correcting electrical and mechanical dyssynchrony.In this article we review the pathobiology of cardiac dyssynchrony,the rationale for the use of CRT,the history and the state of the art of CRT,and guidelines and recommendations for CRT,while also focusing on the areas of controversy and potential future applications.

Epicardial Versus Endocardial Pacemakers in the Pediatric Population:A Comparative Inquiry

Background:Most children in need of cardiac pacemakers remain dependent on the function of the permanent from childhood to adulthood.We sought to evaluate and compare the function between epicardial and endocardial pacemakers in pediatric groups with different conditions.Methods:Between 2012 and 2018,this single-canter study evaluated 44 pediatric patients with indications for epicardial or endocardial pacemakers.Results:The 2 groups,at a median age of 5(0.1–16)years,were compared concerning the characteristics of the leads used(n=80:bipolar,unipolar,steroid-eluting,and non–steroid-eluting),survival data,and complications.The reason for pacemaker implantation was congenital complete heart block in 11(25%)cases and postoperative heart block in 33(75%)cases.The commonest congenital heart disease accompanied by postoperative block was the ventricular septal defect.In the endocardial lead group,the mean ventricular pacing threshold immediately after the implantation and during the follow-up was less than that in the epicardial lead group(0.75 vs.0.81 V;P=0.01 and 0.8 vs.2.4 V;P=0.001).During the follow-up,the mean battery longevity was better in the endocardial group(last visit:6.7 endocardial vs.3.3 years epicardial).Lead failure was commoner in the epicardial pacemaker,and chronic high-pacing threshold pattern was seen in 14 patients in this group.After 3 years,freedom from lead failure was 94%and 63%in the endocardial and epicardial leads.Conclusions:Pacemakers with endocardial bipolar steroid-eluting leads showed better lead characteristics regarding survival and battery longevity than epicardial pacemakers without these lead characteristics.An appropriate pacemaker type should be selected based on the patient’s condition.