The Managed Ventricular pacing versus VVI 40 Pacing (MVP) Trial: clinical background, rationale, design, and implementation

Background: Implantable cardioverter defibrillators (ICDs) reduce mortality among appropriately selected patients who have had or are at risk for life‐threatening ventricular arrhythmia. Right ventricular apical (RVA) pacing has been implicated in worsening heart failure and death. The optimal pacemaker mode for bradycardia support while minimizing unnecessary and potentially harmful RVA pacing has not been determined. Methods: The Managed Ventricular pacing vs. VVI 40 Pacing Trial (MVP) is a prospective, multicenter, randomized, single‐blind, parallel, controlled clinical trial designed to establish whether atrial‐based dual‐chamber managed ventricular pacing mode (MVP?) is equivalent or superior to back‐up only ventricular pacing (VVI 40) among patients with standard indications for ICD therapy and no indication for bradycardia pacing. The MVP Trial is designed with 80% power to detect a 10% reduction in the primary endpoint of new or worsening heart failure or all‐cause mortality in the MVP?‐treated group. Approximately 1,000 patients at 80 centers in the United States, Canada, Western Europe, and Israel will be randomized to MVP? or VVI 40 pacing after successful implantation of a dual‐chamber ICD. Heart failure therapies will be optimized in accordance with evidence‐based guidelines. Prespecified secondary endpoints will include ventricular arrhythmias, atrial fibrillation, new indication for bradycardia pacing, health‐related quality of life, and cost effectiveness. Enrollment began in October 2004 and concluded in April 2006. The study will be terminated upon recommendation of the Data Monitoring Committee or when the last patient enrolled and surviving has reached a minimum 2 years of follow‐up. Conclusion: The MVP Trial will meet the clinical need for carefully designed prospective studies to define the benefits of atrial‐based dual‐chamber minimal ventricular pacing versus single‐chamber ventricular pacing in conventional ICD patients.     

Biventricular vs. left univentricular pacing in heart failure: rationale, design, and endpoints of the B-LEFT HF study.

AIMS: Cardiac resynchronization therapy (CRT) confers sustained therapeutic benefits to patients suffering from congestive heart failure (CHF) due to systolic dysfunction associated with ventricular dyssynchrony. Biventricular (BiV) pacing has, thus far, been the preferred method, as it corrects both electrical and mechanical dyssynchrony. Left ventricular (LV) only pacing, which has conferred similar benefits in pilot studies, may be an alternative treatment method. 'Biventricular vs. left univentricular pacing with ICD back-up in heart failure patients' (B-LEFT HF) is an international, prospective, randomized, parallel-design, double-blind, clinical trial to examine whether LV only pacing is as safe and effective as BiV pacing in patients suffering from CHF. METHODS AND RESULTS: The trial will randomly assign 172 patients to either LV only or BiV pacing. The study has prospectively defined efficacy endpoints to be evaluated at 6 months, which are (i) changes in functional capacity and degree of reverse remodelling (primary) and (ii) changes in the heart failure clinical composite response (secondary). CONCLUSION: Because LV only pacing in CRT is likely to be technically less challenging and costly than BiV, a specifically designed study is needed to compare the safety and effectiveness of the two configurations. B-LEFT HF has been designed to settle this critical issue.     

Left ventricular versus biventricular pacing: a randomized comparative study evaluating mid-term electromechanical and clinical effects

BACKGROUND: Although left ventricular (LV) pacing has been proposed as an alternative to biventricular (BIV) pacing for heart failure (HF) patients, few comparative data are available on the electromechanical effects of these pacing modalities at mid-term follow-up. AIM: To investigate the clinical and echocardiographic effects of LV versus BIV pacing in a mid-term randomized study. METHODS: After implantation of a device with LV/BIV pacing capabilities, 22 patients with chronic HF and left bundle branch block were randomized to LV or BIV pacing. Patients were assessed both preimplantation and after 3 months by clinical examination, ECG and echocardiography with pulsed tissue Doppler imaging. RESULTS: At 3 months LV pacing improved clinical parameters, LV ejection fraction (+5%, range 5-8%, P = 0.007) and intraventricular dyssynchrony (-40 ms, range -50 to -15 ms, in septal to lateral delay, P = 0.008) to a similar extent to BIV pacing. A decrease in interventricular mechanical delay (-25 ms, range -40 to -5 ms, P = 0.008) and QRS duration (-28 ms, range -40 to -5 ms, P = 0.008) was observed in BIV, but not in LV patients. CONCLUSION: In this pilot evaluation, LV pacing appeared to be associated with clinical benefits similar to BIV pacing at mid-term follow-up, and this was combined with an improvement in intraventricular dyssynchrony, regardless of variations in interventricular dyssynchrony and QRS duration. Echocardiographic evaluation of intraventricular dyssynchrony seems to be an appropriate method for assessing the chronic response to LV pacing.     

Biventricular versus right ventricular pacing decreases immune activation and augments nitric oxide production in patients with chronic heart failure

INTRODUCTION: Immune system activation and oxidative stress are involved in the pathogenesis of heart failure (HF). We aimed to test the hypothesis that upgrading from right ventricular pacing (RVp) to biventricular pacing (BiVp) can counteract these phenomena. METHODS: 28 HF patients, with BiVp were switched to RVp for one week, and then returned to BiVp. Immediately prior to, and 48 h after the return to BiVp, left ventricular (LV) systolic function was evaluated by echocardiography, and serum N-terminal pro-brain natriuretic peptide (NTproBNP), C-reactive protein (CRP), tumor necrosis factor alpha (TNF-alpha), interleukin 6 (IL6), nitric oxide metabolites (NO(x)) and malondialdehyde (MDA) were assayed. RESULTS: LV systolic function significantly improved 48 h after switching from RVp to BiVp: Ao-VTI (p<0.001), SV (p<0.001) and CO (p<0.001), and mitral regurgitation significantly decreased (p=0.003). At the same time, indices of peripheral immune activation decreased: TNF-alpha (p=0.02) and IL6 (p<0.001). MDA decreased (p<0.001), whereas NO(x) increased (p=0.04). NTproBNP and CRP did not change. In addition, in "responders" (i.e. CO increase >10% during BiVp vs. RVp) NTproBNP decreased and NO(x) increased. However, during BiVp, the decreases in TNF-alpha, IL6, and MDA occurred both in responders and in non-responders and were accompanied by a reduction in mitral regurgitation. CONCLUSION: The beneficial effect of BiVp compared to RVp extends beyond improving cardiac haemodynamics and comprises a decrease in immune activation accompanied by an increase in serum NO(x) and decrease in serum MDA.     

Avoidance of right ventricular pacing in cardiac resynchronization therapy improves right ventricular hemodynamics in heart failure patients

Background: Cardiac resynchronization therapy (CRT) applied by pacing the left and right ventricles (BiV) has been shown to provide synchronous left ventricular (LV) contraction in heart failure patients. CRT may also be accomplished through synchronization of a properly timed LV pacing impulse with intrinsically conducted activation wave fronts. Elimination of right ventricular (RV) pacing may provide a more physiological RV contraction pattern and reduce device current drain. We evaluated the effects of LV and BiV pacing over a range of atrioventricular intervals on the performance of both ventricles.
Methods: Acute LV and RV hemodynamic data from 17 patients with heart failure (EF = 30 ± 1%) and a wide QRS (138 ± 25 msec) or mechanical dyssynchrony were acquired during intrinsic rhythm, BiV, and LV pacing.
Results: The highest LV dP/dt_max was achieved during LV pre- (LV paced prior to an RV sense) and BiV pacing, followed by that obtained during LV post-pacing (LV paced after an RV sense) and the lowest LV dP/dt_max was recorded during intrinsic rhythm. Compared with BiV pacing, LV pre-pacing significantly improved RV dP/dt_max (378 ± 136 mmHg/second vs 397 ± 136 mmHg/second, P < 0.05) and preserved RV cycle efficiency (61.6 ± 14.6% vs 68.6 ± 11.4%, P < 0.05) and stroke volume (6.6 ± 4.4 mL vs 9.0 ± 6.3 mL, P < 0.05). Based on LV dP/dt_max, the optimal atrioventricular interval could be estimated by subtracting 30 msec from the intrinsic atrial to sensed RV interval.
Conclusions: Synchronized LV pacing produces acute LV and systemic hemodynamic benefits similar to BiV pacing. LV pacing at an appropriate atrioventricular interval prior to the RV sensed impulse provides superior RV hemodynamics compared with BiV pacing.     

Dilated cardiomyopathy following right ventricular pacing for AV block in young patients: resolution after upgrading to biventricular pacing systems

Introduction: Cardiac resynchronization therapy (CRT) has been demonstrated to result in clinical improvement in older adult patients with dilated cardiomyopathy (DCM), specifically those with left bundle branch block and prolonged QRS duration. We sought to demonstrate the benefits of CRT on improvement in cardiac function and clinical outcome in young patients that developed congestive heart failure (CHF) and DCM following cardiac pacing for AV block.
Methods and Results: We reviewed the charts of six patients who developed CHF or low cardiac output symptoms and DCM following implantation of right ventricular (RV)-based pacing systems for AV block, and subsequently underwent CRT. Patients ranged in age from 6 months to 23.7 years (mean: 11.3 ± 3.6 years). AV block was congenital (3), post-surgery (2), and acquired (1). Pacing had been performed for 0.1–14.5 (7.6 ± 2.4) years prior to development of DCM. Two patients required listing for cardiac transplantation. Following CRT: (1) QRS duration shortened from 204 ± 15 to 138 ± 10 msec, P = 0.002, (2) left ventricular ejection fraction improved from 34 ± 6 to 60 ± 2%, P = 0.003, and (3) left ventricular end diastolic dimension shortened from 5.5 ± 0.8 to 4.3 ± 0.5 cm, P =0.03. All patients demonstrated clinical improvement and have been weaned from CHF medications and listing for cardiac transplantation.
Conclusions: CRT can benefit young patients that develop CHF and DCM following RV pacing for AV block. Upgrading to biventricular pacing systems should be considered early in the management of these patients prior to listing for cardiac transplantation.     

Biventricular pacing preserves left ventricular performance in patients with high-grade atrio-ventricular block: a randomized comparison with DDD(R) pacing in 50 consecutive patients

Aims: We aimed to investigate whether biventricular (BiV) pacing minimizesleft ventricular (LV) dyssynchrony and preserves LV ejectionfraction (LVEF) as compared with standard dual-chamber DDD(R)pacing in consecutive patients with high-grade atrio-ventricular(AV) block. Methods and results: Fifty patients were randomized to DDD(R) pacing or BiV pacing.LVEF was measured using three-dimensional echocardiography.Tissue-Doppler imaging was used to quantify LV dyssynchronyin terms of number of segments with delayed longitudinal contraction(DLC). LVEF was not different between groups after 12 months(P = 0.18). In the DDD(R) group LVEF decreased significantlyfrom 59.7(57.4–61.4)% at baseline to 57.2(52.1–60.6)%at 12 months of follow-up (P = 0.03), whereas LVEF remainedunchanged in the BiV group [58.9(47.1–61.7)% at baselinevs. 60.1(55.2–63.3)% after 12 months (P = 0.15)]. Dyssynchronywas more prominent in the DDD(R) group than in the BiV groupat baseline (2.2 ± 2.2 vs. 1.4 ± 1.3 segmentswith DLC per patient, P = 0.10); and at 12 month follow-up (1.8± 1.9 vs. 0.8 ± 0.9 segments with DLC per patient,P = 0.02). NT-proBNP was unchanged in the DDD(R) group duringfollow-up (122 ± 178 pmol/L vs. 91 ± 166 pmol/L,NS) but decreased significantly in the BiV-group (from 198 ±505 pmol/L to 86 ± 95 pmol/L after 12 months, P = 0.02). Conclusion: BiV pacing minimizes LV dyssynchrony, preserves LV function,and reduces NT-proBNP in contrast to DDD(R) pacing in patientswith high-grade AV block.     

Managed ventricular pacing vs. conventional dual-chamber pacing for elective replacements: the PreFER MVP study: clinical background, rationale, and design

Aims: Several clinical studies have shown that, in patients with intactatrioventricular (AV) conduction, unnecessary chronic rightventricular (RV) pacing can be detrimental. The managed ventricularpacing (MVP) algorithm is designed to give preference to spontaneousAV conduction, thus minimizing RV pacing. The clinical outcomesof MVP are being studied in several ongoing trials in patientsundergoing a first device implantation, but it is unknown towhat extent MVP is beneficial in patients with a history ofventricular pacing. The purpose of the Prefer for Elective ReplacementMVP (PreFER MVP) study is to assess the superiority of the MVPalgorithm to conventional pacemaker and implantable cardioverter-defibrillatorprogramming in terms of freedom from hospitalization for cardiovascularcauses in a population of patients exposed to long periods ofventricular pacing. Methods and results: PreFER MVP is a prospective, 1:1 parallel, randomized (MVP ON/MVPOFF), single-blinded multi-centre trial. The study populationconsists of patients with more than 40% ventricular pacing documentedwith their previous device. Approximately, 600 patients willbe randomized and followed for at least 24 months. The primaryendpoint comprises cardiovascular hospitalization. Conclusion: The PreFER MVP trial is the first large prospective randomizedclinical trial evaluating the effect of MVP in patients witha history of RV pacing.     

New-onset heart failure after permanent right ventricular apical pacing in patients with acquired high-grade atrioventricular block and normal left ventricular function

Introduction: Emerging data have suggested that right ventricular (RV) apical pacing results in progressive left ventricular (LV) dysfunction and contributes to the development of heart failure (HF). This study aimed to investigate the prevalence and clinical predictors for the development of new-onset HF after long-term RV apical pacing in patients with acquired atrioventricular (AV) block who require permanent pacing.
Methods: We studied the clinical outcomes after long-term RV apical pacing for acquired AV block in 304 patients without a prior history of HF. All patients had >90% ventricular pacing as determined by device diagnostic data.
Results: After a median follow-up of 7.8 years, 79 patients (26.0%) developed new-onset HF after RV apical pacing. Univariate Cox-regression analysis revealed that older age at the time of pacemaker implantation (P < 0.001), the presence of coronary artery disease (CAD) (P < 0.001) or atrial fibrillation (P = 0.03), VVI pacemaker (P < 0.001), wider paced QRS duration (P < 0.001), and new-onset myocardial infarction (P < 0.001) were predictors for HF. Multivariate analysis revealed that older age at implantation (Hazard ratio [HR] 1.06, 95% confidential interval [CI] 1.04–1.09, P < 0.001), CAD (HR 1.98, 95% CI 1.12–3.50, P < 0.05), and a wider paced QRS duration (HR 1.27 for each 10 ms increment, 95% CI 1.11–1.45, P = 0.001) were independent predictors of HF. Furthermore, cardiovascular mortality was significantly increased in those with HF (36.7% vs. 2.7%, P < 0.001).
Conclusions: After a median follow-up of 7.8 years, permanent RV apical pacing was associated with HF in 26% of patients. Elderly age at the time of implant, a wider paced QRS duration and the presence of CAD independently predicted new-onset HF. More importantly, HF after RV apical pacing was associated with a higher cardiovascular mortality.     

双心室优化程序起搏治疗充血性心力衰竭及短期随访结果

目的报道6例使用双心室优化起搏治疗充血性心力衰竭患者,探讨双心室优化起搏治疗的初步临床经验及V-V起搏间期优化方法。方法自2004年3月起对6例顽固性充血性心力衰竭且药物治疗效果不佳的患者植入了InSyncⅢ(8042型)起搏器。全部患者术前48h之内接受常规超声心动图检查、6min室内平面步行试验(6MHW)、临床心功能评估等作为基础对照。出院前行心室起搏优化确定最佳V-V起搏间期,术后1、3、6个月再次重复上述检查并动态心电图检查,其中第6个月重新优化V-V起搏间期。结果6例患者均顺利完成起搏器植入术。5例患者起搏方式为心房感知并心室起搏,其中总心室起搏数均>90%。1例患者起搏方式为心房感知并心室起搏,其中总心室起搏数为94%。全部患者临床心功能指标(NYHA分级)和6min室内平面步行试验均较术前有显著提高。从双心室优化起搏的即刻效果来看,优化V-V间期使主动脉瓣射血时间-速度积分(VTI)从术前的(20.7±6.6)cm增加至(23.5±6.6)cm。左心室射血分数从术前的0.24±0.09增加至0.29±0.08。结论双心室起搏治疗能改善顽固性充血性心力衰竭且药物治疗效果不佳患者的心功能,提高患者的生活质量,在此基础上进行V-V间期优化可以进一步提高患者的左心室功能。     

Biventricular pacing and left ventricular pacing in heart failure: similar hemodynamic improvement despite marked electromechanical differences

INTRODUCTION: We conducted an acute echocardiographic study comparing hemodynamic and ventricular dyssynchrony parameters during left ventricular pacing (LVP) and biventricular pacing (BVP). We sought to clarify the mechanisms responsible for similar hemodynamic improvement despite differences in electrical activation. METHODS AND RESULTS: Thirty-three patients underwent echocardiography prior to implantation with a multisite pacing device (spontaneous rhythm [SR]) and 2 days after implantation (BVP and LVP). Interventricular dyssynchrony (pulsed-wave Doppler), extent of myocardium displaying delayed longitudinal contraction (%DLC; tissue tracking), and index of LV dyssynchrony (pulsed-wave tissue Doppler imaging) were assessed. Compared to SR, BVP and LVP caused similar significant improvement of cardiac output (LVP: 3.2 +/- 0.5, BVP: 3.1 +/- 0.7, SR: 2.3 +/- 0.6 L/min; P < 0.01) and mitral regurgitation (LVP: 25.1 +/- 10, BVP: 24.7 +/- 11, baseline: 37.9 +/- 14% jet area/left atria area; P < 0.01). LVP resulted in a smaller index of LV dyssynchrony than BVP (29 +/- 10 vs 34 +/- 14; P < 0.05). However, LVP exhibited a longer aortic preejection delay (220 +/- 34 vs 186 +/- 28 msec; P < 0.01), longer LV electromechanical delays (244.5 +/- 39 vs 209.5 +/- 47 msec; P < 0.05), greater interventricular dyssynchrony (56.6 +/- 18 vs 31.4 +/- 18; P < 0.01), and higher%DLC (40.1 +/- 08 vs 30.3 +/- 09; P < 0.05), leading to shorter LV filling time (387 +/- 54 vs 348 +/- 44 msec; P < 0.05) compared to BVP. CONCLUSION: Although LVP and BVP provide similar hemodynamic improvement, LVP results in more homogeneous but substantially delayed LV contraction, leading to shortened filling time and less reduction in postsystolic contraction. These data may influence the choice of individual optimal pacing configuration.     

Right ventricular outflow versus apical pacing in pacemaker patients with congestive heart failure and atrial fibrillation

INTRODUCTION: Prior studies suggest that right ventricular apical (RVA) pacing has deleterious effects. Whether the right ventricular outflow tract (RVOT) is a more optimal site for permanent pacing in patients with congestive heart failure (CHF) has not been established. METHODS AND RESULTS: We conducted a randomized, cross-over trial to determine whether quality of life (QOL) is better after 3 months of RVOT than RVA pacing in 103 pacemaker recipients with CHF, left ventricular (LV) systolic dysfunction (LV ejection fraction < or = 40%), and chronic atrial fibrillation (AF). An additional aim was to compare dual-site (RVOT + RVA, 31-ms delay) with single-site RVA and RVOT pacing. QRS duration was shorter during RVOT (167 +/- 45 ms) and dual-site (149 +/- 19 ms) than RVA pacing (180 +/- 58 ms, P < 0.0001). At 6 months, the RVOT group had higher (P = 0.01) role-emotional QOL subscale scores than the RVA group. At 9 months, there were no significant differences in QOL scores between RVOT and RVA groups. Comparing RVOT to RVA pacing within the same patient, mental health subscale scores were better (P = 0.03) during RVOT pacing. After 9 months of follow-up, LVEF was higher (P = 0.04) in those assigned to RVA rather than RVOT pacing between months 6 and 9. After 3 months of dual-site RV pacing, physical functioning was worse (P = 0.04) than during RVA pacing, mental health was worse (P = 0.02) than during RVOT pacing, and New York Heart Association (NYHA) functional class was slightly better (P = 0.03) than during RVOT pacing. There were no other significant differences between RVA, RVOT and dual-site RV pacing in QOL scores, NYHA class, distance walked in 6 minutes, LV ejection fraction, or mitral regurgitation. CONCLUSION: In patients with CHF, LV dysfunction, and chronic AF, RVOT and dual-site RV pacing shorten QRS duration but after 3 months do not consistently improve QOL or other clinical outcomes compared with RVA pacing.     

Conduction system versus biventricular pacing in heart failure with non-left bundle branch block

Introduction

The benefits of cardiac resynchronization therapy (CRT) with biventricular pacing (BiV) is significantly lower when applied to heart failure (HF) patients with non-left bundle branch block (LBBB) conduction delay. We investigated clinical outcomes of conduction system pacing (CSP) for CRT in non-LBBB HF.

Methods

Consecutive HF patients with non-LBBB conduction delay undergoing CSP were propensity matched for age, sex, HF-etiology, and atrial fibrillation (AF) in a 1:1 ratio to BiV from a prospective registry of CRT recipients. Echocardiographic response was defined as an increase in left ventricular ejection fraction (LVEF) by ≥10%. The primary outcome was the composite of HF-hospitalizations or all-cause mortality.

Results

A total of 96 patients were recruited (mean age 70 ± 11years, 22% female, 68% ischemic HF and 49% AF). Significant reductions in QRS duration and LV dimensions were seen only after CSP, while LVEF improved significantly in both groups (p < 0.05). Echocardiographic response occurred more frequently in CSP than BiV (51% vs. 21%, p < 0.01), with CSP independently associated with four-fold increased odds (adjusted odds ratio 4.08, 95% confidence interval [CI] 1.34–12.41). The primary outcome occurred more frequently in BiV than CSP (69% vs. 27%, p < 0.001), with CSP independently associated with 58% risk reduction (adjusted hazard ratio [AHR] 0.42, 95% CI 0.21–0.84, p = 0.01), driven by reduced all-cause mortality (AHR 0.22, 95% CI 0.07–0.68, p < 0.01), and a trend toward reduced HF-hospitalization (AHR 0.51, 95% CI 0.21–1.21, p = 0.12).

Conclusions

CSP provided greater electrical synchrony, reverse remodeling, improved cardiac function and survival compared to BiV in non-LBBB, and may be the preferred CRT strategy for non-LBBB HF.     

右室心尖部起搏与右室流出道起搏对Ⅲ度房室传导阻滞患者疗效的对比研究

目的:比较右室心尖部起搏与右室流出道起搏对Ⅲ度房室传导阻滞患者心室间运动同步性及左室内运动同步性,以及对患者心功能的影响。方法:选取因Ⅲ度及高度房室传导阻滞患者置入双腔起搏器患者共38例。其中心室电极置入右室流出道者20例(RVOT组),置入右室心尖部18例(RVA组),超声心动图术前测量左室舒张末内径(LVEDD),左室收缩末内径(LVESD)、左室射血分数(LVEF)、E/A值、心室间激动延迟时间(IVMD)、室间隔与左心室后壁间收缩延迟时间(SPWMD)。术后1个月、12个月随访。结果:术后1个月,与RVOT组比较,RVA组IVMD、SPWMD明显延长[IVMD(39.83±6.01)∶(31.95±7.86)ms,P=0.02],[SP-WMD(97.83±20.81)∶(84.6±10.89)ms,P=0.023]。术后12个月,与ROVT组比较,RVA组LVEDD明显增大[(49.11±2.39)∶(47.4±1.96)mm,P=0.02],LVESD明显增大[(34.28±3.41)∶(32.5±1.5)mm,P=0.04];LVEF明显降低[(59.56±3.38)∶(62.8±2.14)%,...     

右心室流出道间隔部起搏对完全性房室传导阻滞患者心功能的影响

目的：比较右心室流出道间隔部（RVS）起搏与右心室心尖部（RVA）起搏对左右心室间收缩同步性、左室重构及心功能的影响。方法：①入选Ⅲ度房室传导阻滞患者61（男39,女22）例,随机分入RVS部起搏组（RVS组,n=33）和RVA部起搏组（RVA组,n=28）。②比较两组患者植入术中及术后12月心室电极导线参数（起搏阈值、R波感知及阻抗）的差异。③观察两组患者术前及术后12月QRS波时限;术后应用组织多普勒同步图（TSI）分别测定两组左、右心室侧壁基底部收缩达峰时间差（△Ts）。评价心室间不同步的程度。④行多普勒超声心动图（UCG）检查,观察两组术前及术后12月左室舒张末期内径（LVEDD）及左室射血分数（LVEF）的变化,比较不同起搏部位对心功能的影响。结果：①两组患者测试的起搏阈值、R波感知及导线阻抗无统计学差异。②两组患者术后QRS波时限均较术前延长（均P〈0．01）,RVA组较RVS组延长更为明显（P〈0．01）。RVS组与RVA组ATs分别为（27±14）ms和（90±22）ms,有统计学差异（P〈0．01）。③术后12／了＇月两组LVEDD均较术前增加,RVA明显大于RVS组[（54±5）mm阮（51±5）mm,P〈0．05]。RVA组术后12月LVEDD较术前明显增加[（54±5）mmvs．（50±4）mm,P〈0．05],术后12月两组LVEF均较术前降低[RVS组：（0．58-4-0．14）傩．（0．63±0．09）,P〈0．01;RVA组：（0．51±0．12）伽．（0．64±0．13）,P〈0．01],组间比差异不显著。结论：RVS起搏对心室问同步性、左室重构的影响要优于RVA起搏。     

Long-term outcomes in patients with atrioventricular block undergoing septal ventricular lead implantation compared with standard apical pacing

Aims: Left ventricular function may be altered by right ventricularapical pacing. The aims of the study were to compare the long-termcourse of different parameters of left ventricular dysfunctionin patients undergoing implantation of a dual-chamber pacemakerwith the ventricular lead in a septal position vs. in a standardapical position. Methods: We randomized 98 patients with atrioventricular block (AV-block)undergoing pacemaker implantation to positioning the ventricularlead in the high or mid septum (n = 53) or in the apex (n =45) of the right ventricle. N-terminal pro-brain natriueticpeptide (BNP) levels, left ventricular ejection fraction (LVEF),and exercise capacity were analysed 3 days, 3 months, and 18months after the implantation. The primary endpoints were thechanges of these parameters from baseline to 18 months. Results: Changes of BNP levels, LVEF, and exercise capacity from baselineto 18 months were statistically not different between septaland apical stimulation. The clinical occurrence or deteriorationof overt heart failure was similar in both treatment arms. Conclusion: With regard to different parameters of congestive heart failure,a septal stimulation site is not superior to conventional apicalpacing in unselected patients undergoing pacemaker implantationfor AV-block.     

Left ventricular septal pacing versus left bundle branch pacing in the treatment of atrioventricular block

BackgroundThis study aimed to evaluate the feasibility and clinical response of LVSP as an alternative to LBBP.MethodsThis was a retrospective study of pacemaker implantation, and 46 consecutive patients with pacemaker implantation were enrolled in the study. The patients were divided into the LBBP and LVSP groups. Electrocardiogram characteristics, pacing parameters, cardiac function, and safety events were assessed during implantation and 12‐month follow‐up.ResultsThe procedure time was significantly increased in the LBBP group compared with the LVSP group (53.52 ± 14.39 min vs. 38.13 ± 11.52 min, respectively, p = .000). The pacing QRS duration (PQRSD) decreased by 14.09 ± 41.80 ms in the LBBP group and increased by 9.70 ± 29.60 ms in the LVSP group (p = .031). Furthermore, the left ventricle activation time (LVAT) was shorter in the LBBP group than in the LVSP group (48.70 ± 13.67 ms vs. 58.70 ± 13.67 ms, p =  .032). During the 12‐month follow‐up, pacing thresholds remained low and stable, and there was no significant decrease in cardiac function. No adverse event was observed during the follow‐up period.ConclusionsBoth LBBP and LVSP are safe and feasible methods. LVSP is a good option when multichannel electrophysiological instruments are not available and when the time available for the procedure is limited.     

Optimized perioperative biventricular pacing in setting of right heart failure.

AIMS: A 78-year-old female with prior atrioventricular junctional ablation for paroxysmal atrial fibrillation and implantation of DDDR pacemaker underwent repair of severe tricuspid insufficiency. Effects of biventricular pacing were tested with temporary wires at the conclusion of cardiopulmonary bypass. METHODS: An ultrasonic flow probe was placed on the ascending aorta for real time cardiac output measurements. Atrioventricular delay optimization was performed and biventricular pacing was initiated while right-left ventricular delays were varied. RESULTS: There was no advantage of biventricular pacing (optimum right-left ventricular delay of +80 ms) compared with existing DDD. CONCLUSIONS: This study confirms the physiological effects of right-left ventricular delay on cardiac output after cardiopulmonary bypass.