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.     

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.     

Clinical outcomes of left bundle branch pacing compared to right ventricular apical pacing in patients with atrioventricular block

BackgroundLeft bundle branch pacing (LBBP) can produce near normalization of QRS duration. This has recently emerged as alternative technique to right ventricular pacing and His bundle pacing.HypothesisThe purpose of this study is to evaluate clinical outcomes of LBBP compared to right ventricular apical pacing (RVAP).MethodsA total of 70 AVB patients with indications for ventricular pacing were retrospectively studied. LBBP was attempted in 33 patients, classified as LBBP group. The other patients were classified as RVAP group. Pacing parameters, electrocardiogram and echocardiogram characteristics, heart failure hospitalization (HFH), and atrial fibrillation (AF) were evaluated perioperatively and at follow‐ups. Patients were followed in the device clinic for a minimum of 12 months and up to 24 months at a 3–6 monthly interval.ResultsLBBP was successful in 29 of 33(87.9%) patients while all 37 of the remaining patients successfully underwent RVAP. Paced QRS duration was significantly narrower in the LBBP group compare to RVAP(110.75 ± 6.77 ms vs. 154.29 ± 6.96 ms, p = .000) at implantation, and the difference persisted during follow‐ups. Pacing thresholds (at implantation: 0.68 ± 0.22 V in the LBBP group and 0.73 ± 0.23 V in the RVAP group, p = .620) remained low and stable during follow‐ups. The cardiac function in the LBBP group remained stable during follow‐ups (LVEF%:55.08 ± 4.32 pre‐operation and 54.17 ± 4.34 at the end of follow‐up, p = .609), and better than RVAP group (LVEF%: 54.17 ± 4.34 vs. 50.14 ± 2.14, p = .005). Less HFH was observed in the LBBP group (2/29,6.89%) compared to RVAP group (10/37,27.03%).ConclusionsThe present investigation demonstrates the safety and feasibility of LBBP that produces narrower paced QRS duration than RVAP. LBBP is associated with reduction in the occurrence of pacing‐induced left ventricular dysfunction and HFH compared to RVAP in patients requiring permanent pacemakers.     

Myocardial systolic activation delay in patients with left bundle branch block and either normal or impaired left ventricular function

AIM OF THE STUDY: to evaluate determinants of myocardial activation delay of both left (LV) and right (RV) ventricle in patients with left bundle branch block (LBBB) and either normal or impaired LV ejection fraction (EF). METHODS: From an initial cohort of patients with LBBB, 42 patients with dilated cardiomyopathy (group A) and 33 with normal global LV systolic function (group B), all comparable in age and sex, underwent standard Doppler echo, pulsed Doppler myocardial imaging (DMI), and coronary angiography. Using DMI, the following regional parameters were evaluated in five different basal myocardial segments (LV anterior, inferior, septal, lateral walls-RV lateral wall): systolic (Sm), early- and late-diastolic (Em and Am) peak velocities. As index of myocardial systolic activation was calculated: precontraction time (PCTm) (from the beginning of Q-wave of ECG to the onset of Sm). Intraventricular systolic dyssynchrony was analyzed by difference of PCTm in different LV myocardial segments. Interventricular activation delay was calculated by the difference of PCTm between the most delayed LV segment and RV lateral wall. RESULTS: Patients of group A showed increased heart rate (HR), QRS duration and LV end-diastolic diameter, and reduced LV EF. By DMI, patients of group A showed reduced myocardial peak velocities and a significant intraventricular delay in activation of LV lateral wall, with increased regional PCTm (P < 0.001). In addition, patients with dilated cardiomyopathy showed a more pronounced interventricular dyssynchrony, even after adjustment for HR and QRS duration. By receiver operating characteristic (ROC) curve analysis, a cut-off value of 55 msec of interventricular delay showed 86% sensitivity and 92% specificity in identifying patients with impaired EF. In the overall population, by use of stepwise forward multivariate linear regression analyses, LV end-diastolic diameter (beta coefficient = 0.52; P < 0.001) and LV EF (beta coefficient =-0.58; P < 0.0001) were the only independent determinants of interventricular activation delay. CONCLUSIONS: Pulsed DMI is an effective noninvasive technique for assessing the severity of regional delay in activation of LV walls in patients with LBBB. The impairment of interventricular systolic sychronicity is strongly related to LV dilatation and to the degree of global systolic dysfunction. Therefore, patients with dilated cardiomyopathy suitable for cardiac resynchronization therapy may be better selected.     

Radiofrequency catheter ablation of upper septal idiopathic left ventricular tachycardia exhibiting left bundle branch block morphology

Idiopathic left ventricular (LV) tachycardia usually exhibits right bundle branch block morphology. There are only a few sporadic cases that exhibit left bundle branch block (LBBB) morphology. We report a patient whose QRS complex during ventricular tachycardia (VT) was relatively narrow (100 msec) and exhibited LBBB (precordial R wave transition between V3 and V4) and a normal frontal plane axis. This VT was ablated successfully by radiofrequency current applied to the LV upper septum, where the earliest endocardial activation was recorded.     

Body surface mapping criteria for diagnosis of left ventricular hypertrophy associated with complete right bundle branch block

The standard electrocardiographic (ECG) criteria for left ventricular hypertrophy are unreliable in patients with complete right bundle branch block. This study was undertaken to formulate criteria for diagnosing these patients by using body surface mapping. The echocardiographic left ventricular mass was calculated by the Penn method from M-mode measurements. Of 56 patients, 27 were defined as having left ventricular hypertrophy with a left ventricular mass of 215 g or more. Isopotential and isointegral maps of the QRS complex were observed. The QRS isointegral maps were separated into two parts at the end of the downstroke of the initial R wave of vector spatial magnitude. The body surface mapping criteria with the highest sensitivity were EPmax (maximum of early part of the QRS) 45 μV·s or greater (sensitivity 93%, specificity 90%), EPmax/d (EPmax averaged by EP duration) 0.8 mV or greater (sensitivity 93%, specificity 97%), and Max (initial maximum) 2.2 mV or greater (sensitivity 89%, specificity 90%). These results suggest that body surface mapping is a useful technique in diagnosing patients with left ventricular hypertrophy and right bundle branch block.     

束支折返性室性心动过速射频消融后左心室功能的变化

目的 观察扩张性心肌病合并束支折返性室性心动过速(bundle branch reentry ventricular tachycardia,BBRVT)患者消融右束支后左心室功能的变化,探讨该消融方法治愈室速后对左心功能的长期影响.方法 自2007年12月至2010年2月,12例扩张性心肌病合并阵发性室速,电生理检查证实为BBRVT,标测右束支电位后予以消融,比较术前及术后12个月患者左室射血分数(left ventricular ejection fraction,LVEF);左室舒张末内径(left ventricular end distolic diameter,LVEDD);左室收缩末容量(left ventricular end systolic volume,LVESV);主动脉瓣口速度时间积分(velocity time integral,VTI);主动脉与肺动脉瓣开放时间差(QAO-QP);纽约心功能分级(NYHA);6分钟步行距离(6 minutes walk test,6-MWT);血浆脑钠肽前体(NT-proBNP)变化;心电图QRS宽度变化.结果 12例患者射频消融后随访1年均未再发作室速,与术前相比,术后12个月LVEF,VTI,NYHA,6-MWT均显著降低;LVEDD,LVESV,QAO-QP,NT-proBNP及QRS宽度均增加.结论 束支折返性室速消融右束支后可造成左右室间以及左室内收缩的不同步,可能是术后左室功能进一步减低的机制,但不能完全排除扩张性心肌病自身发展的影响.     

Differential diagnosis of tachycardia with a typical left bundle branch block morphology

The evaluation of wide QRS complex tachycardias (WCT)remains a common dilemma for clinicians.Numerous algorithms exist to aid in arriving at the correct diagnosis.Unfortunately,these algorithms are difficult to remember,and overreliance on them may prevent cardiologists from understanding the mechanisms underlying these arrhythmias.One distinct subcategory of WCTs are those that present with a"typical"or"classic" left bundle branch block pattern.These tachycardias may be supraventricular or ventricular in origin and arise from functional or fixed aberrancy,bystander or participating atriofascicular pre-excitation,and bundle branch reentry.This review will describe these arrhythmias,illustrate their mechanisms,and discuss their clinical features and treatment strategies.     

Relationship of QRST isointegral maps during simulated left bundle branch block to impairment of left ventricular function due to myocardial infarction

The clinical usefulness of QRST isointegral maps for assessing left ventricular (LV) dysfunction due to myocardial infarction (MI) in patients with MI in the setting of simulated left bundle branch block (LBBB) was investigated. Isointegral maps were recorded during sinus rhythm and right ventricular pacing, which simulated LBBB, in 62 patients with MI and 26 patients without MI. An abnormal decrease in the QRST value in the isointegral map was assessed by the difference map that indicated a "-2 SD area" where the QRST integral value was less than the normal range (mean - 2 SD) calculated from 608 normal individuals. The isointegral maps during the two activation sequences were similar in patients with and without MI (r = 0.87 and 0.92, respectively). The sum of QRST integral values less than the normal range (sigma DM) during simulated LBBB correlated significantly with the asynergy index, derived from left ventriculographic data (r = 0.81, p < 0.01). LV dysfunction (asynergy index > or = 2) was diagnosed in simulated LBBB with a sensitivity of 81%, specificity of 77%, and diagnostic accuracy of 80% when the criterion that LV dysfunction is present if the number of lead points in the -2 SD area exceeds 4, and a sensitivity of 71%, specificity of 81%, and diagnostic accuracy of 74% if sigma DM exceeds 200 mVms was used. The findings demonstrate that isointegral maps may be useful in assessing LV dysfunction due to MI in patients with MI and LBBB in addition to detecting the presence and site of MI in these patients.     

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。     

定量组织速度成像对左束支传导阻滞左室收缩和舒张活动的评价

目的利用定量组织速度成像(QTVI)技术评价左束支传导阻滞左心室整体和局部收缩、舒张活动。方法测量20例完全性左束支传导阻滞(LBBB)患者和20名健康人于标准心尖四腔、两腔及心尖左室长轴切面获得的左心室6个室壁(后室间隔、侧壁、下壁、前壁、后壁、前间隔)基底段、中间段及心尖段同一心动周期各时相时间(ICT、IRT、ET等)以及长轴方向收缩期峰值速度(VS),舒张早期峰值速度(VE)、舒张晚期峰值速度(VA)。结果左束支传导阻滞患者ICT、IRT较正常对照组明显延长(P<0.01),ET缩短(P<0.05);SMPI、DMPI、MPI较对照组明显增高(P<0.01);同一室壁运动虽然存在一定梯度,但VS、VE明显减低。结论LBBB时,左心室内电机械活动不同步,收缩协同失调,引起局部心肌收缩舒张功能减低。     

老年高血压病人左室肥厚与左室舒张功能的关系

目的：研究老年高血压病人左室肥厚与左室舒张功能各参数的关系,探讨在老年人左室肥厚对左室舒张功能的影响。方法：用彩色多普勒超声心动图测量101例老年高血压病人左心室结构及舒张功能参数。结果：101例高血压病人中,左室肥厚组（48例）的左房内径指数（LADI）、等容舒张时间（IVRT）、舒张期二尖瓣E波减速时间（EDT）显著大于左室正常组（53例,P〈0．05～〈0．01）．多元逐步回归分析发现,左室质量指数（LVMI）与左房射血分数（LAEF）、LADI、IVRT和EDT有明显的相关关系（r分别为0．213,0．251．0．450．0．338．P〈0．05～0．001）结论：老年高血压病人的左室增厚可进一步降低左室舒张功能。     

Remarkable response to cardiac resynchronization therapy via left bundle branch pacing in patients with true left bundle branch block

BackgroundLeft bundle branch pacing (LBBP) has been suggested as an alternative means to deliver cardiac resynchronization therapy (CRT).HypothesisLBBP may deliver resynchronization therapy along with an advantage over traditional biventricular (BiV) pacing in clinical outcomes.MethodsHeart failure patients who presented LBBB morphology according to Strauss''s criteria and received successful CRT procedure were enrolled in the present study. Propensity score matching was applied to match patients into LBBP‐CRT group and BiV‐CRT group. Then, the electrographic data, the echocardiographic data and New York heart association (NYHA) class were compared between the groups.ResultsTwenty‐one patients with successful LBBP procedure and another 21 matched patients with successful BiV‐CRT procedure were finally enrolled in the study. The QRS duration (QRSd) was narrowed from 167.7 ± 14.9 ms to 111.7 ± 12.3 ms (P < .0001) in the LBBP‐CRT group and from 163.6 ± 13.8 ms to 130.1 ± 14.0 ms (P < .0001) in the BiV‐CRT group. A trend toward better left ventricular ejection fraction (LVEF) was recorded in the LBBP‐CRT group (50.9 ± 10.7% vs 44.4 ± 13.3%, P = .12) compared to that in the BiV‐CRT group at the 6‐month follow‐up. A trend toward better echocardiographic response was documented in patients receiving LBBP‐CRT procedure (90.5% vs 80.9%, P = .43) and more super CRT response was documented in the LBBP‐CRT group (80.9% vs 57.1%, P = .09) compared to that in the BiV‐CRT group.ConclusionsLBBP‐CRT can dramatically improve the electrical synchrony in heart failure patients with LBBB. Meanwhile, compared with the traditional BiV‐CRT, it has a tendency to significantly improve LVEF and enhance the NYHA cardiac function scores.     

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.     

完全性左束支阻滞81例临床分析

目的分析完全性左束支阻滞(CLBBB)病例的临床特点。方法回顾性分析81例完全性左束支阻滞患者的病因、动态心电图、超声心动图、冠状动脉造影结果。结果60岁以上男性43例,占53%。病因以冠心病、高血压、心功能不全多见。本组冠脉造影的28例完全性左束支阻滞患者中确诊为冠心病者16例,占57.14%。超声心动图结果:55%患者心房、心室增大或心房心室同时增大。左室射血分数(LVEF)<50%者22例,占33.8%。动态心电图检查可见左束支阻滞常合并各种类型心律失常。结论完全性左束支阻滞常发生在老年男性患者,常见于器质性心脏病,尤其是冠心病、高血压、扩张型心肌病。完全性左束支阻滞可导致不良的心脏血流动力学效应,导致左心室功能受损。     

Aging and left ventricular mass and function in people with end-stage renal disease

OBJECTIVES: To identify the main age‐related factors responsible for cardiomyopathy in people with end‐stage renal disease (ESRD). DESIGN: Cross‐sectional. SETTING: Dialysis unit. PARTICIPANTS: Two hundred fifty‐four individuals undergoing chronic dialysis. MEASUREMENTS: Left ventricular (LV) systolic function (assessed according to midwall fractional shortening (mwFS)) and LV mass index (LVMI). RESULTS: At echocardiography, 196 (77%) participants displayed LV hypertrophy (LVH) and 123 (48%) had LV systolic dysfunction. On univariate analysis, age was related directly to LVMI (correlation coefficient (r)=0.33, P<.001) and inversely to mwFS (r=?0.23, P<.001) and a 10‐year increase in age was associated with 4.2‐g/m^2.7 greater LVMI and 0.5% lower mwFS. Albumin, pulse pressure, cardiovascular comorbidities, and C‐reactive protein were age‐related risk factors for LVMI and mwFS, whereas hemoglobin was an age‐dependent risk factor only for LVMI and heart rate and diabetes mellitus only for mwFS. After adjusting for age‐related risk factors, the predictive value of age for cardiomyopathy was substantially less (–67%) and the age‐dependent variability in LVMI and mwFS was much attenuated (?61%), and neither was significant. CONCLUSION: This study suggests that in people with ESRD, the relationship between age and cardiomyopathy is largely dependent on age‐related risk factors and that interventions focused on modifiable risk factors linked to age (e.g., malnutrition and inflammation) could attenuate the detrimental effect of aging on cardiovascular risk in the dialysis population.     

ACE inhibition with ramipril improves left ventricular function at rest and post exercise in patients with stable ischaemic heart disease and preserved left ventricular systolic function.

AIMS: To assess the effects of 6 months intervention with +ramipril on resting and post exercise left ventricular function in patients with stable ischaemic heart disease and preserved left ventricular systolic function. METHODS and RESULTS: Patients (n=98, age 65+/-9 years, 37% women) were randomized to double-blind treatment with ramipril 5 mg. day(-1)(n=32), ramipril 1.25 mg. day(-1)(n=34), or placebo (n=32). Resting and post maximum exercise echocardiography/Doppler examinations were performed at baseline and after 6 months. Changes over 6 months in resting transmitral E-wave deceleration time (Edt) and Edt adjusted for heart rate (Edt/RR) differed between the ramipril 5 mg, ramipril 1.25 mg, and placebo groups: Edt 24+/-82, -1+/-69, and -29+/-64 ms, respectively, P=0. 012; Edt/RR 30+/-105, 2+/-61, and -28+/-69 ms, respectively, P=0.015. Changes in the difference between resting and post exercise Edt/RR also varied between groups: -53+/-137, -28+/-118, and 35+/-101 ms, respectively, P=0.029. No differences in E/A indices were noted. Resting atrioventricular plane displacement improved in the combined ramipril groups vs the placebo group: 0.2+/-0.8 vs -0.2+/-1.3 mm, P<0.05.Conclusion Six months ramipril treatment in patients with stable ischaemic heart disease and preserved left ventricular systolic function improved resting left ventricular function and reduced the exercise induced diastolic filling abnormalities usually seen in these patients.