Cardiac resynchronization therapy by left bundle branch area pacing in patients with heart failure and left bundle branch block

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不同左束支阻滞型态的心力衰竭患者心脏再同步治疗效果比较

目的 验证符合左束支阻滞(LBBB)新诊断标准的慢性心力衰竭患者是否能从心脏再同步治疗(CRT)中更显著地获益.方法 入选2007年5月至2012年6月符合传统LBBB诊断标准且植入CRT患者,根据术前体表心电图形态分为“真性”LBBB组(真LBBB组:V1、V2导联负向波为主(QS或rS);V1、V2、V5、V6、I、aVL导联中至少有2个以上的导联QRS波中间有切迹或顿挫;QRS时限,男≥140 ms、女≥130ms)和“假性”LBBB组(假LBBB组:符合传统的LBBB标准,但尚未达到“真性”LBBB诊断标准,具体包括上述6个导联中仅有1个或没有导联出现切迹或者顿挫,QRS时限,男＜140 ms、女＜130 ms).术后定期随访,比较两组患者QRS时限、左心室舒张末期内径(LVEDD)、左心室射血分数(LVEF)及心功能(NYHA分级)变化.结果 共入选32例患者(男13例),真LBBB组23例,假LBBB组9例,术前两组患者间性别、年龄、基础疾病、LVEF及心功能等基本情况差异无统计学意义.术后随访显示真LBBB组较假LBBB组LVEF增加显著(0.39±0.11对0.27±0.07,P=0.006),LVEDD缩小明显[(6.3±1.0)cm对(7.6±1.0) cm,P=0.003],提示真LBBB组对CRT治疗反应更佳.结论 符合LBBB新诊断标准的慢性心力衰竭患者从CRT中更显著获益.     

The mechanical and hemodynamic effects of left ventricular pacing in heart failure with preserved ejection fraction and left bundle branch block

Cardiac resynchronization therapy (CRT) has revolutionized the care of patients with heart failure with reduced ejection fraction (HFrEF) and left bundle branch block (LBBB); some hypothesize that electrical resynchronization may also benefit patients with heart failure with preserved ejection fraction (HFpEF) and LBBB. We assessed the acute hemodynamic and mechanical impact of temporary LV pacing in 2 patients with HFpEF and LBBB and a “classic” pattern of echocardiographic dyssynchrony. LV pacing facilitated electrical resynchronization with acute resolution of mechanical dyssynchrony and improvements in invasively and non-invasively measured global cardiac function, due in part to shortening of the isovolumetric contraction period.     

Risk and predictors of dyssynchrony cardiomyopathy in left bundle branch block with preserved left ventricular ejection fraction

BackgroundLeft bundle branch block (LBBB) and left ventricular (LV) dyssynchrony likely contribute to progressive systolic dysfunction. The evaluation of newly recognized LBBB includes screening for structural heart abnormalities and coronary artery disease (CAD). In patients whose LV ejection fraction (EF) is preserved during initial testing, the incidence of subsequent cardiomyopathy is not firmly established.HypothesisThe risk of developing LV systolic dysfunction among LBBB patients with preserved LVEF is high enough to warrant serial imaging.MethodsWe screened records of 1000 consecutive patients with LBBB from our ECG database and identified subjects with an initially preserved LVEF (≥45%) without clinically relevant CAD or other cause for cardiomyopathy. Baseline imaging, clinical data, and follow‐up imaging were recorded to determine the risk of subsequent LV systolic dysfunction (LVEF ≤40%).Results(Data are mean + SD) 784 subjects were excluded, the majority for CAD or depressed LVEF upon initial imaging. Of the remaining 216, 37 (17%) developed a decline in LVEF(≤40%) over a mean follow‐up of 55 ± 31 months; 94% of these patients had a baseline LVEF≤60% and LV end systolic diameter (ESD) ≥ 2.9 cm indicating that these measures may be useful to define which patients warrant longitudinal follow‐up. The negative predictive value of a LVEF>60% and LVESD <2.9 cm was 98%.ConclusionsSeventeen percent of patients with LBBB and initial preserved LVEF develop dyssynchrony cardiomyopathy. We believe the risk of developing dyssynchrony cardiomyopathy is high enough to warrant serial assessment of LV systolic function in this high‐risk population.     

Cardiac and neuromuscular implications of left bundle branch block in left ventricular hypertrabeculation/noncompaction

BACKGROUND:

Left bundle branch block (LBB) is frequently found in left ventricular hypertrabeculation/noncompaction (LVHT).

OBJECTIVES:

To compare LVHT patients with and without LBB regarding LVHT location and extension, left ventricular function, symptoms, electrocardiographic findings, prevalence of neuromuscular disorders (NMDs) and mortality during follow-up.

METHODS:

The charts of patients who underwent transthoracic echocardiographic examination at the Krankenanstalt Rudolfstiftung (Wien, Austria) between June 1995 and November 2006 were examined.

RESULTS:

LVHT was diagnosed in 102 patients (30 women) with a mean (± SD) age of 53±16 years (range 14 to 94 years). A specific NMD was diagnosed in 21 patients and an NMD of unknown etiology was diagnosed in 47. The neurological investigation was normal in 14 patients and 20 patients refused the investigation. The 24 patients with LBB were older (61 versus 51 years of age; P<0.01), and suffered from exertional dyspnea (96% versus 59%; P<0.01) and heart failure (79% versus 46%; P<0.01) more often than patients without LBB. LBB patients had less frequent tall QRS complexes (8% versus 47%; P<0.01) and ST-T wave abnormalities (4% versus 50%; P<0.01) than patients without LBB. Patients with LBB had a larger left ventricular end-diastolic diameter (73 mm versus 61 mm; P<0.01), worse left ventricular fractional shortening (15% versus 26%; P<0.01) and more extensive LVHT (1.8 versus 1.5 ventricular segments; P<0.05). The prevalence of NMDs did not differ between patients with and without LBB. Survival did not differ between patients with and without LBB during follow-up.

CONCLUSIONS:

LBB is associated with increased age, decreased systolic function and increased extension of LVHT. Whether LBB is a prognostic factor in LVHT remains speculative.     

左束支起搏对合并右束支传导阻滞患者的心电学影响

目的探讨左束支起搏对症状性心动过缓合并右束支传导阻滞患者的心电学影响。 方法连续纳入2019年1月1日至2021年12月31日因症状性心动过缓合并完全性右束支传导阻滞并在厦门大学附属心血管病医院心内科拟行左束支起搏的患者,记录标准12导联体表心电图。比较左束支起搏术前与术后V₁导联QRS波形态、QRS时限、右心室延迟激动时间（dRVAT）、左心室达峰时间（LVAT）及心室间延迟时间（IVD）的差异。 结果共入选53例患者,年龄（72.15±9.39）岁,男34例。其中46例（86.79%,46/53）成功完成左束支起搏。术前V₁导联以rsR’型为主38例（38/46,83%）,术后QRS形态以Qr型为主29例（29/46,63%）。左束支起搏可以显著缩短QRS时限［（149.09±12.81）ms对（112.46±9.64）ms,P<0.001）］,其中35例（76.08%,35/46）患者的QRS时限完全纠正,10例（21.73%,10/46）部分纠正,1例（2.17%,1/46）未纠正;IVD显著缩短［（58.28±12.54）ms对（34.34±8.87）ms,P<0.001］;但在dRVAT方面左束支起搏术前与术后差异无统计学意义［（100.47±12.40）ms对（100.86±10.57）ms,P=0.955］。与术前相比,左束支起搏延长LVAT［（42.46±6.95）ms对（66.53±10.83）ms,P<0.001］。 结论左束支起搏可显著缩短完全性右束支传导阻滞患者的QRS时限,并改善其心室间电学同步性,产生以Qr型为主的起搏后QRS波形态。     

Electromechanical coupling, uncoupling, and ventricular function in patients with bundle branch block: a tissue-Doppler echocardiographic study

BACKGROUND: Left bundle branch block (LBBB) is associated with impaired left ventricular (LV) function and increased morbidity and mortality, especially in patients with structural heart diseases. The mechanisms are poorly understood. Subjects and METHODS: Subjects with isolated LBBB (n=20), right bundle branch block (RBBB, n=20), and controls (C, n=20) were studied with standard two-dimensional (2D), and color-encoded tissue-Doppler echocardiography (TDE). Inter- and intraventricular systolic and diastolic coordination were assessed from the TDE velocity profiles. LV function was assessed by 2D echocardiography, by TDE-derived peak systolic velocities, and the atrioventricular (AV) plane displacement. RESULTS: Subjects with LBBB had longer electromechanical delays and longer isovolumic relaxation times than did the C and RBBB groups (P <0.001). For the LBBB subjects compared with the RBBB and C groups, ejection times were shorter, peak systolic velocities and AV plane displacements were lower, they had larger LV end-systolic volumes and lower LV ejection fraction (all P <0.001), and the atrial contribution to A-V plane displacement was higher (P <0.01). There were no differences in diastolic or filling times among the groups. CONCLUSIONS: In patients with LBBB, delayed regional electromechanical coupling and uncoupling leads to generalized intra- and interventricular asynchrony, thereby explaining the depressed regional and global LV functions. Assessment of the electromechanical coupling and uncoupling processes and their consequences on cardiac function in patients with BBB and structural heart diseases may be possible using TDE.     

孤立性左束支传导阻滞的多普勒超声频谱改变

目的:观察孤立性左束支传导阻滞(LBBB)患者左室舒张期的充盈方式。方法:比较LBBB组与正常心脏传导组的超声多普勒参数。结果:发现两组二尖瓣血流频谱的E峰、E／A、E峰减速时间(DT)、E峰下降速率、二尖瓣环的组织多普勒运动频谱e及e／a存在显著差异(P<0.05~<0.01)。结论:与正常心脏传导比较,孤立性左束支传导阻滞患者的左室舒张充盈方式异常。     

完全性左束支传导阻滞SV3》SV2、RV6》RV5对左心室肥大的诊断价值

目的 探讨 左束 支 传导 阻滞 合并 左 心室 肥大 心 电图 诊断 价 值。 方法 对 照 分 析 ５０ 例左 束 支 传 导 阻 滞 合 并 左 心 室 肥 大（ 观 察 组 ）与 ４０ 例 单 纯 完 全 性 左 束 支 传 导 阻 滞（ 对 照 组 ）的 心 电图 。 结 果 观 察 组 Ｒ ＋ＳⅢ、ＳⅢ＞Ｒ 、Ｓｖ３＞Ｓｖ２、Ｒｖ６＞Ｒ ｖ５、Ｓｖ１＋Ｖ５、Ｓｖ３＋Ｒ ｖ６、Ｓｖ１＋Ｓｖ６ 值 与 对 照 组 相 比 差 异 有 Ⅰ Ⅱ非 常显 著 性意 义（Ｐ＜０．０１）。Ｓｖ３＞２．７ｍ Ｖ ，敏感 性 为 ８９．２％ ，准 确性为 ８５．３％ ，特异 性为 ８７．９％ ；其 次 Ｓｖ３＞Ｓｖ２，敏 感性 为 ５８．０％ ，准 确性 为 ６１．０％ ，特 异性 为 ７３．７％ ；　Ｓｖ３＋Ｒｖ６＞４．３ｍ Ｖ，敏 感性 为 ６８．８％ ，准 确 性 为 ６３．７％ 　，特 异 性 为 ７４．１％ 　；　Ｒ ｖ６＞Ｒ ｖ５，敏 感 性 为 ５２．４％ ，准 确 性 为 ６０．４％ ，特 异 性 为 ７０．６％ 。 结 论 Ｓｖ３＞２．７ｍ Ｖ 、Ｓｖ３＋Ｒ ｖ６＞４．３ｍ Ｖ 、Ｓｖ３＞Ｓｖ２、Ｒ ｖ６＞Ｒｖ５、ＱＲ Ｓ 时 间 ＞０．１５ｓ是 合 并左 心室 肥 大的 有效 心 电图 参数 。     

超声评价LBBB对左室整体和局部活动的影响

目的　超声评价LBBB患者左室整体和局部活动。方法　超声测量 15例LBBB患者 (LBBB组 )和 15例正常人 (control组 )各瓣环 ,获得各时相的持续时间 (ICT、ET、IRT、DET) ,评价左室整体和局部Z指数 [(ET DFT) /R R],并测量等容收缩期波峰的加速时间 (IVA)、射血期波峰的加整时间 (Sac)、E波的减速时间 (Edc)。结果　LBBB患者左室整体和局部Z指数明显减低 ,各壁ICT明显延长 ;左室室间隔、下壁的IRT和IVA延长 ,DFT和Edc缩短 ,ICT/ET增加。结论　LBBB时室壁激动的异常 ,影响左室整体和局部舒缩活动     

Relation between electrical and mechanical dyssynchrony in patients with left bundle branch block: An electro‐ and vectorcardiographic study

Background

Current guidelines select patients for cardiac resynchronization therapy (CRT) mainly on electrocardiographic parameters like QRS duration and left bundle branch block (LBBB). However, among those LBBB patients, heterogeneity in mechanical dyssynchrony occurs and might be a reason for nonresponse to CRT. This study assesses the relation between electrocardiographic characteristics and presence of mechanical dyssynchrony among LBBB patients.

Methods

The study included patients with true LBBB (including mid‐QRS notching) on standard 12‐lead electrocardiograms. Left bundle branch block‐induced mechanical dyssynchrony was assessed by the presence of septal flash on two‐dimensional echocardiography. Previously reported electro‐ and vectorcardiographic dyssynchrony markers were analyzed: global QRS duration (QRSD_LBBB), left ventricular activation time (QRSD_LVAT), time to intrinsicoid deflection (QRSD_ID), and vectorcardiographic QRS areas in the 3D vector loop (QRSA_3D).

Results

The study enrolled 545 LBBB patients. Septal flash (SF) is present in 52% of patients presenting with true LBBB. Patients with SF are more frequent female, have less ischemic heart disease and smaller left ventricular dimensions. In multivariate analysis longer QRSD_LBBB, QRSD_LVAT and larger QRSA_3D were independently associated with SF. Of all parameters, QRSA_3D has the best accuracy to predict SF, although overall accuracy remains moderate (59% sensitivity, 58% specificity). The predictive value of QRSA_3D remained constant in both sexes, irrespective of ischemic heart disease, ejection fraction and even when categorizing for QRSD_LBBB.

Conclusion

In LBBB patients, large QRS areas correlate better with mechanical dyssynchrony compared to wide QRSD intervals. However, the overall accuracy to predict mechanical dyssynchrony by electrocardiographic dyssynchrony markers, even when using complex vectorcardiographic parameters, remains low.

     

Differentiation between left bundle branch block and left ventricular hypertrophy: Implications for cardiac resynchronization therapy

Recent clinical trials have demonstrated that cardiac resynchronization therapy (CRT) reduces heart failure hospitalizations and mortality in patients with complete left bundle branch block (LBBB), but potentially not those with right bundle branch block or nonspecific LV conduction delay, such as that due to LV hypertrophy (LVH). Furthermore, endocardial mapping and simulation studies have suggested that one-third of patients diagnosed with LBBB by conventional electrocardiographic criteria are misdiagnosed, and these patients likely have a combination of LVH, LV chamber dilatation and delayed initiation of LV activation (incomplete LBBB). Increase in LV size due to hypertrophy/dilatation and slowed intramyocardial conduction velocity prolong QRS duration in patients with LVH, which can frequently go above the QRS duration threshold of 120 ms conventionally used to diagnose LBBB. New strict criteria for diagnosing complete LBBB have been proposed that utilize longer QRS duration thresholds (130 ms in women and 140 ms in men) and require the presence of mid-QRS notching/slurring in at least 2 of the leads I, aVL, V1, V2, V5 or V6. The emergence of CRT has led to an increased need to differentiate complete LBBB from LVH and other types of intraventricular conduction delay, which should be further studied.     

左束支阻滞激动模式：心功能不良重要的可逆性因素

目的观察左束支阻滞激动模式对心脏功能和结构的影响。方法3例心功能不良和左心室扩大患者,左心室射血分数（LVEF）0．44±0．11,左心室舒张末内径（LVEDD）（56±4）mm,QRS时限增宽（177±15）ms,呈左束支阻滞或左束支阻滞样图形。例1为风湿性心脏病二尖瓣及主动脉瓣置换术后伴左束支阻滞;例2为显性右侧预激综合征;例324h动态心电图示右心室流出道室性早搏（室早）3万次。结果例l成功行心脏再同步治疗,例2和例3成功行右侧显性旁路和右心室流出道室早消融,QRS时限降至（103±25）ms,随访6～30个月,症状明显改善,心功能恢复正常,左心室明显缩小,LVEF为0．65±0．04和LVEDD（48±4）mm。结论左束支阻滞激动模式是心功能不良重要的可逆性因素。     

Long-term outcomes of left bundle branch block in high-risk survivors of acute myocardial infarction: The VALIANT experience

BACKGROUND: In survivors of myocardial infarction (MI), new left bundle branch block (LBBB) is associated with adverse outcomes, but its impact is not well described in post-MI patients with left ventricular (LV) systolic dysfunction and/or heart failure (HF). OBJECTIVES: The aim of this study was to determine if new LBBB is an independent predictor of long-term fatal and nonfatal outcomes in high-risk survivors of MI by reviewing data from the VALsartan In Acute myocardial iNfarcTion (VALIANT) trial. METHODS: In VALIANT, 14,703 patients with LV systolic dysfunction and/or HF were randomized to valsartan, captopril, or both a mean of 5 days after MI. Baseline ECG data were available from 14,259 patients. We assessed the predictive value of new LBBB for death and major cardiovascular outcomes after 3 years, adjusting for multiple baseline covariates including LV ejection fraction. RESULTS: At follow-up, patients with new LBBB (608 [4.2%]) compared with patients without new LBBB had more comorbidities and increased adjusted risk of death (hazard ratio [HR] 1.3, 95% confidence interval [CI] 1.2-1.6), cardiovascular death (HR 1.4, 95% CI 1.2-1.7), HF (HR 1.3, 95% CI 1.1-1.6), MI (HR 1.5, 95% CI 1.2-1.9), and the composite of death, HF, or MI (HR 1.4, 95% CI 1.2-1.6). CONCLUSION: In post-MI survivors with LV systolic dysfunction and/or HF, new LBBB was an independent predictor of all major adverse cardiovascular outcomes during long-term follow-up. This readily available ECG marker should be considered a major risk factor for long-term cardiovascular complications in high-risk patients after MI.     

Reversible left bundle branch block induced congestive heart failure. A case report

Intraventricular conduction delay in the form of left bundle branch block plays an important role in the genesis and the progression of congestive hart failure. We report on the clinical course of a patient and the improvement in functional status after the disappearance of left bundle branch block, despite withholding cardiac resynchronization therapy.     

Variable patterns of septal activation in patients with left bundle branch block and heart failure

INTRODUCTION: Little is known about the septal activation pattern in patients with heart failure and left bundle branch block (LBBB-HF). METHODS AND RESULTS: The right ventricular (RV) and left ventricular (LV) activation patterns of 12 patients (mean age 67 +/- 11 years) with LBBB-HF and 5 patients (mean age 45 +/- 14) with normal hearts were studied during sinus rhythm using a three-dimensional mapping system. The etiology of HF was myocardial infarction (n = 4) or idiopathic dilated cardiomyopathy (n = 8). In patients with LBBB-HF, endocardial activation usually started before the onset of the surface QRS complex on the RV free wall. Latest RV activation occurred in the basal region, and total RV activation time was longer than in patients with normal hearts. In patients with LBBB-HF, the left septum was activated via slowly conducting LBB or via right-to-left transseptal conduction. In both patients with LBBB-HF and those with normal hearts, latest LV activation occurred either in the posterior or posterolateral-basal region. Conduction velocity was slower in the peri-scar region, in patients with previous myocardial infarct and globally slow, in patients with idiopathic dilated cardiomyopathy. CONCLUSION: The two types of left septal activation observed in patients with LBBB-HF may have consequences for biventricular hemodynamic performance. Conduction slowing along the LV, regionally or globally, suggests a contribution outside the specific conduction system in the ECG pattern of LBBB.