Time domain analysis of the signal averaged electrocardiogram in patients with a conduction defect or a bundle branch block

Doubts have been expressed about the clinical usefulness oftime domain analysis of the signal averaged electrocardiogramin patients with prolonged QRS complex duration. We studied147 patients using a signal averaged ECG (40–250 Hz) whoseQRS complex was longer than 100 ms. A baseline electrophysiologystudy was also performed in 128 of these patients. Seventy-sevenpatients had a minor (QRS <120 and >100 ms) conductiondefect. Thirty-seven of these 77 had either induced or spontaneoussustained ventricular tachycardia (group I) and 40 had no sustainedventricular tachycardia (group II). Seventy patients had a major(QRS120 and >100 ms) conduction defect, 44 of whom had sustainedventricular tachycardia (group A). The remaining 26 withoutthis condition formed Group B. Group I compared to group IIpatients had a longer filtered QRS duration (120.8 ±14 vs 104.5 ± 9.5 ms, P<0.001), a longer low amplitudesignal duration (41 ± 12.1 vs 31 ± 12.6 ms, P<0.0001)and a lower root mean square of the last 40 ms of the filteredQRS complex (27 ± 29.8 vs 35 ± 25.3 µV,P=ns). Group A compared to group B had a longer filtered QRSduration (157.7±20.2 vs 140.7± 15.7 ms, P<0.001),a longer low amplitude signal duration (57.3 ±24.9 vs37.8 ± 20.3 ms P<0.001) and a lower root mean squareof the last 40 ms of the filtered QRS complex (14.3 ±11.2 vs 22.0 ± 10.5 1 P<0.01). Using conventionallate potential criteria, the sensitivity and specificity ofthe signal averaged ECG for the detection of sustained ventriculartachycardia patients with a minor conduction defect were 89%and 75%, respectively. The same criteria applied to patientswith a major conduction defect were sensitive (sensitivity:87%) but non-specific (specificity: 50%). However, by usingmodified late potential criteria, such as the presence of twoof any of the following three signal averaged parameters: filteredQRS duration 145 ms, low amplitude signal duration 50 ms,root mean square of the last 40 ms of the filtered QRS complex17.5µV, we derived a non-optimal but still acceptablecombination of sensitivity (68%) and specificity (73%). We concludethat traditional late potential criteria can be applied in patientswith a minor conduction defect, but modification of these criteriais necessary to derive useful clinical information for riskstratification of patients with a QRS complex duration 120ms.     

Association of right bundle branch block or intraventricular conduction delay with recurrence of atrial fibrillation after catheter ablation

Background

The association between bundle branch block (BBB) and recurrence of atrial fibrillation (AF) after catheter ablation is unclear. The aim of this study was to determine whether AF combined with BBB is associated with AF recurrence after catheter ablation.

Methods

A total of 477 consecutive AF patients who underwent catheter ablation were included. The AF patients were divided into three groups according to BBB: AF without BBB (n = 427), AF with right bundle branch block (AF with RBBB) (n = 16), and AF with intraventricular conduction delay (AF with IVCD) (n = 34).

Results

Of the 477 AF patients (mean age 57 years, 81% men, median CHA₂DS₂-VASc score of 1), 16 (3.4%) patients had RBBB, and 34 (7.1%) patients had IVCD. During a mean follow-up of 15.2 ± 6.7 months, 119 patients (24.9%) had recurrence of AF. Of these, 111 (26%) patients were in the AF without BBB group, with 2 (12.5%) and 6 (17.6%) patients in the RBBB and IVCD groups, respectively. The Kaplan–Meier estimate of the rate of recurrent AF was not significantly different among the three groups (p = .39). Multivariable analysis showed that persistent AF (HR 1.7, 95% CI 1.15–2.50, p = .007), chronic kidney disease (HR 2.94, 95% CI 1.20–7.17, p = .01), and left atrial diameter (HR 1.04, 95% CI 1.009–1.082, p = .01) were significantly associated with AF recurrence.

Conclusion

AF with BBB was not significantly associated with the recurrence of AF after catheter ablation in middle-aged patients with low-risk cardiovascular profile.     

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。     

完全性左束支阻滞和右束支阻滞心电图结果分析

目的 了解完全性左束支阻滞和右束支阻滞不同性别、不同年龄的发生率情况.方法 分析108 610例常规心电图检测结果,分别统计完全性左束支阻滞和右束支阻滞不同性别、不同年龄的发生率情况.结果 108 610例门诊及住院患者资料,完全性左束支阻滞19例,占0.18％;右束支阻滞3 794例,占3.49％;完全性左束支阻滞发生率在不同性别之间差异无统计学意义（Х^2=1.707,P=0.191）,不同年龄之间比较差异有统计学意义（Х^2=209.874,P＜0.05）;右束支阻滞发生率在不同性别之间、不同年龄之间比较,差异均有统计学意义（Х^2=986.046,P＜0.05;Х^2=1 483.286,P＜0.05）.结论 60岁以上老年人的完全性左束支阻滞和右束支阻滞发生率较高,应定期进行常规心电图检查,及时发现异常情况并进行相应的处理.     

早搏揭示位相型束支阻滞的心电图分析

目的探讨早搏对位相型束支阻滞的揭示作用和诊断价值。方法利用早搏的回归周期明显长于基础周期这一特征,对17例患者早搏后第1次窦性搏动形态改变进行分析,间接诊断位相型束支阻滞,并确定其类型。结果 17例患者早搏后的QRS形态均发生改变,依据位相型束支阻滞诊断标准,共发现3相右束支阻滞8例、3相左束支阻滞5例、3相左前分支阻滞1例、4相右束支阻滞1例、4相左束支阻滞2例。结论位相型束支阻滞多呈一过性改变,较难扑捉,借助于早搏后回转周期长于基础窦性周期来间接诊断是一种简洁、可靠的方法,无疑对基础疾病的预后判断以及对心律失常机制的理解是十分有益的。     

心电向量图诊断伪装性束支传导阻滞的优势

伪装性束支传导阻滞(masquerading bundle branch block,MBBB)不同于单纯的左前分支阻滞(left anterior fascicular block,LAFB)合并右束支阻滞(right bundle branch block,RBBB),其心脏传导系统的病变程度严重且多呈进行性恶化;诊断依赖心电图但往往漏诊较多。结合临床实例,就其束支阻滞实质和心电向量图表现特征进行分析和论述。由于左束支后分支纤维传导障碍时,在心电向量图上表现为QRS环体中部泪点密集,而该图形的表达方式较心电图类本位曲折时间(或称室壁激动时间)更加直观,因此心电向量图有助于临床早期发现心电图难以诊断的伪装性束支传导阻滞。     

Right bundle branch block and long-term mortality in patients with acute congestive heart failure

OBJECTIVES: Risk stratification in acute congestive heart failure (ACHF) is poorly defined. The aim of the present study was to assess the impact of right bundle brunch block (RBBB) on long-term mortality in patients presenting with ACHF. METHODS AND RESULTS: The initial 12-lead electrocardiogram was analysed for RBBB in 192 consecutive patients presenting with ACHF to the emergency department. The primary endpoint was all-cause mortality during 720-day follow-up. This study included an elderly cohort (mean age 74 years) of ACHF patients. RBBB was present in 27 patients (14%). Age, sex, B-type natriuretic peptide levels and initial management were similar in patients with RBBB when compared with patients without RBBB. However, patients with RBBB more often had pulmonary comorbidity. A total of 84 patients died during follow-up. Kaplan-Meier analysis revealed that mortality at 720 days was significantly higher in patients with RBBB when compared with patients without RBBB (63% vs. 39%, P = 0.004). In Cox proportional hazard analysis, RBBB was associated with a two-fold increase in mortality (hazard ratio 2.18, 95% CI 1.26-3.66; P = 0.003). This association persisted after adjustment for age and comorbidity. CONCLUSIONS: RBBB is a powerful predictor of mortality in patients with ACHF. Early identification of this high-risk group may help to offer tailored treatment in order to improve outcome.     

Significance of QRS morphology in determining the prevalence of mechanical dyssynchrony in heart failure patients eligible for cardiac resynchronization: particular focus on patients with right bundle branch block with and without coexistent left-sided conduction defects

Aims: The aim of this study was to assess the significance of QRSmorphology in determining the prevalence of mechanical dyssynchronyin heart failure (HF) patients considered eligible for cardiacresynchronization. Methods and results: A total of 200 consecutive HF patients (158 males, mean age56 ± 13.5 years) with standard indications for cardiacresynchronization therapy (CRT) were evaluated prospectively.The prevalence of an interventricular mechanical delay 40 mswas lower in patients with pure right bundle branch block (RBBB)than that in those with RBBB plus left fascicular hemiblock(RBBB-LFH) and those with left bundle branch block (LBBB) (33vs. 50 vs. 54%, P = 0.05). A maximal difference in peak myocardialsystolic velocity among all 12 segments (Ts)>100 ms was foundin 63% of the patients with LBBB, whereas it was present in31% of the patients with pure RBBB and in 42% of those withRBBB-LFH (P < 0.001). A standard deviation of Ts (Ts-SD)>34ms was present in 58% of the LBBB subjects, but in only 29%and 42% of the patients with pure RBBB and RBBB-LFH, respectively(P < 0.001). Intraventricular dyssynchrony, however, wasnot different in patients with pure RBBB and in those with RBBB-LFHin terms of maximal difference in Ts (P = 0.25) and Ts-SD (P= 0.17). Conclusions: Although LBBB was more often associated with intraventriculardyssynchrony, ECG sign of additional left ventricular (LV) conductiondelay is not a helpful tool for the identification of intra-LVmechanical dyssynchrony in HF patients with RBBB who would benefitfrom CRT.     

Distinct left bundle branch block pattern in ischemic and non-ischemic dilated cardiomyopathy

BACKGROUND: A high percentage of patients with dilated cardiomyopathy have the electrocardiographic (ECG) pattern of advanced left bundle branch block (LBBB). In the present study we sought to investigate whether patients with dilated cardiomyopathy of ischemic or non-ischemic etiology can be differentiated on the basis of LBBB pattern. METHODS AND RESULTS: The study population included 41 patients with dilated cardiomyopathy of non-ischemic (NIC) (n=26) or ischemic origin (IC) (n=15) and LBBB on surface ECG. ECG duration and voltage were digitally measured. The presence of notching of S wave in right precordial leads (V1-V3) was not statistically different between the groups. The voltages of precordial leads V2, V3 and the Sigma(V1+V2+V3 voltages) were significantly more prominent in patients with NIC (P=0.002, P<0.001 and P=0.002, respectively). The discriminative power of receiver operating characteristic analysis was best at voltages of V3 of 2100 microV (area under the curve, 0.805; standard error, 0.001). The sensitivity and specificity of V3 voltage >2100 microV on surface ECG in the presence of LBBB to identify a cardiomyopathy of non-ischemic origin were 85 and 73%, respectively. CONCLUSIONS: A single ECG criteria, voltage of lead V3, appears to be a useful parameter to identify patients with dilated cardiomyopathy of ischemic or non-ischemic origin in the presence of advanced LBBB.     

Left-sided intraventricular conduction delay concealed by right bundle branch block

The electrocardiograms of a 69-year-old woman with severe heart failure showed a left-sided nonspecific intraventricular conduction delay (QRS duration, 0.13 seconds) characterized by notches and slurrings in the descending part of the R waves in the left precordial leads and in the ascending parts of the S waves in the right precordial leads. Subsequently, a complete right bundle branch block with wider QRS complexes (0.17 seconds) appeared. It is possible to consider that the left-sided nonspecific intraventricular conduction delay was concealed by the greater conduction delay occurring when the complete right bundle branch block was present. This would be in keeping with a previous study using Doppler tissue imaging in which this was postulated but where the corresponding electrocardiograms were not shown.     

Left bundle branch block associated with propoxyphene hydrochloride poisoning

Described is the case of a patient who developed left bundle branch block following acute propoxyphene hydrochloride overdosage. The left bundle branch block was transient and associated with no permanent sequelae. Previously documented cardiac abnormalities, specific narcotic antagonist therapy, and animal studies correlating cardiac toxicity of propoxyphene hydrochloride with its potent local anesthetic action are discussed.     

预激综合征并发房室阻滞和束支阻滞PJ间期的分析

目的探讨预激综合征并发传导阻滞心电图PJ间期的变化。方法选经导管射频消融术（RFCA）治愈的显性预激综合征并发传导阻滞者10例,分为3组,即旁路（AP）位于束支阻滞（BBB）同侧组,旁路位于BBB异侧组及并发Ⅰ°房室阻滞（AVB）组。分别测量各组术前、术后的PJ间期并比较PJ间期变化。结果①6例旁路与BBB位于同侧的患者,术前PJ间期明显短于术后[（230±27）ms比（285±27）ms,P<0.01],但其中1例术前PJ间期为270ms（>260ms）;②2例AP与BBB位于异侧的患者,术前PJ间期短于术后（P<0.01）;③2例并发Ⅰ°AVB的患者,术前PJ间期明显短于术后PJ间期（P<0.01）。结论①预激综合征并发BBB时,PJ间期的变化取决于AP与正路的时差,AP与BBB的位置及AP距离心室最晚激动部位的远近,不能仅从AP的位置与BBB部位的关系来反映PJ的长短;②PJ间期的延长有可能为并发室内阻滞或AVB,宜进一步作食管心房调搏检查以明确诊断。     

Reduced high-frequency QRS components in electrocardiogram leads facing an area of the heart with intraventricular conduction delay due to bundle branch block

Background

The mechanisms underlying high-frequency QRS components (HF-QRS) are incompletely understood. One theory is that HF-QRS are related to the conduction velocity of the heart. The purpose was to test this hypothesis by comparing HF-QRS in patients with left or right bundle branch block (LBBB and RBBB, respectively) to those in healthy subjects and in patients with ischemic heart disease (IHD).

Methods

Twenty-two patients with LBBB, 19 patients with RBBB, 63 normal subjects, and 64 patients with IHD were included. Twelve-lead electrocardiograms were analyzed in the frequency interval 150 to 250 Hz.

Results

The study showed reduced HF-QRS in patients with LBBB compared with healthy subjects and patients with IHD. The difference, however, was small in lead V₁ and V₂. In patients with RBBB, no differences in HF-QRS could be detected except in few leads; among those is lead V₁.

Conclusion

The results support the theory that HF-QRS are related to the conduction velocity of the heart.     

Tissue Doppler evaluation of intraventricular asynchrony in isolated left bundle branch block

BACKGROUND: The aim of this study was to evaluate normal subjects with isolated left bundle branch block (LBBB) using tissue Doppler imaging (TDI) for the presence of intraventricular asynchrony. METHODS AND RESULTS: For this purpose, 23 subjects with isolated LBBB were compared with age-matched asymptomatic healthy subjects without LBBB with respect to global ejection fraction (EF) and isovolumic contraction time (ICTm) in separate left ventricular segments. TDI evaluation revealed prolongation of the ICTm in all of the segments in the LBBB group. Moreover, the ICTm differed significantly in each segment in the LBBB group. The ICTm in the lateral segments were shown to be longer compared to the anteroseptal segments. CONCLUSION: Our results indicate the presence of intraventricular asynchrony in isolated LBBB. This fact may play a role in the decreased global EF and increased cardiac mortality in patients with isolated LBBB.     

Spectral turbulence analysis of the signal-averaged electrocardiogram for predicting inducible sustained monomorphic ventricular tachycardia in patients with and without bundle branch block

Spectral turbulence analysis of the signal-averaged electrocardiogramis a new method for identifying patients prone to sustainedmonomorphic ventricular tachycardia. In contrast to analysisin the time domain, it has been claimed to be applicable inpatients with bundle branch block. The aim of this study wasto assess the predictive value of spectral turbulence analysis,in relation to the inducibility of sustained monomorphic ventriculartachycardia, in patients with and without bundle branch block.One hundred and sixty nine patients, of whom 120 had a QRS duration 120 ms, were studied Forty-seven patients had inducible sustainedmononwrphic ventricular tachycardia and were compared to 122control patients. The overall sensitivity of the spectral turbulenceanalysis for predicting inducible ventricular tachycardia was77%, the spectficity 35% and the total predictive accuracy 47%.The limited predictive accuracy was mainly due to a lack ofd between patients with and without ventricular tachycardiain patients with a QRS duration 120 ms. In patients with QRS 120 ms, however, there were significant differences in allspectral turbulence parameters and the method had a sensitivityof 75%, a specificity of 72% and a total predictive accuracyof 73%. The diagnostic usefulness of spectral turbulence analysis isdependent upon normal QRS duration and the method is applicableonly to patients without bundle branch block.     

Spectral turbulence analysis of the signal-averaged electrocardiogram for predicfing inducible sustained monomorphic ventricular tachycardia in patients with and without bundle branch block

Spectral turbulence analysis of the signal-averaged electrocardiogramis a new method for identifying patients prone to sustainedmonomorphic ventricular tachycardia. In contrast to analysisin the time domain, it has been claimed to be applicable inpatients with bundle branch block. The aim of this study wasto assess the predictive value of spectral turbulence analysis,in relation to the inducibility of sustained monomorphic ventriculartachycardia, in patients with and without bundle branch block.One hundred and sixty nine patients, of whom 120 had a QRS duration 120 ms, were studied Forty-seven patients had inducible sustainedmononwrphic ventricular tachycardia and were compared to 122control patients. The overall sensitivity of the spectral turbulenceanalysis for predicting inducible ventricular tachycardia was77%, the spectficity 35% and the total predictive accuracy 47%.The limited predictive accuracy was mainly due to a lack ofd between patients with and without ventricular tachycardiain patients with a QRS duration 120 ms. In patients with QRS 120 ms, however, there were significant differences in allspectral turbulence parameters and the method had a sensitivityof 75%, a specificity of 72% and a total predictive accuracyof 73%. The diagnostic usefulness of spectral turbulence analysis isdependent upon normal QRS duration and the method is applicableonly to patients without bundle branch block.     

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。