The Surface Electrocardiogram Predicts Risk of Heart Block During Right Heart Catheterization in Patients With Preexisting Left Bundle Branch Block: Implications for the Definition of Complete Left Bundle Branch Block

LBBB and Heart Block . Background: Patients with left bundle branch block (LBBB) undergoing right heart catheterization can develop complete heart block (CHB) or right bundle branch block (RBBB) in response to right bundle branch (RBB) trauma. We hypothesized that LBBB patients with an initial r wave (≥1 mm) in lead V1 have intact left to right ventricular septal (VS) activation suggesting persistent conduction over the left bundle branch. Trauma to the RBB should result in RBBB pattern rather than CHB in such patients. Methods: Between January 2002 and February 2007, we prospectively evaluated 27 consecutive patients with LBBB developing either CHB or RBBB during right heart catheterization. The prevalence of an r wave ≥1 mm in lead V1 was determined using 118 serial LBBB electrocardiographs (ECGs) from our hospital database. Results: Catheter trauma to the RBB resulted in CHB in 18 patients and RBBB in 9 patients. All 6 patients with ≥1 mm r wave in V1 developed RBBB. Among these 6 patients q wave in lead I, V5, or V6 were present in 3. Four patients (3 in CHB group and 1 in RBBB group) developed spontaneous CHB during a median follow‐up of 61 months. V1 q wave ≥1 mm was present in 28% of hospitalized complete LBBB patients. Conclusions: An initial r wave of ≥1 mm in lead V1 suggests intact left to right VS activation and identifies LBBB patients at low risk of CHB during right heart catheterization. These preliminary findings indicate that an initial r wave of ≥1 mm in lead V1, present in approximately 28% of ECGs with classically defined LBBB, may constitute a new exclusion criterion when defining complete LBBB. (J Cardiovasc Electrophysiol, Vol. pp. 781‐785, July 2010)     

Total Masquerading Bundle Branch Block

We report a case of 82‐year‐old female with total masquerading bundle branch block. We discuss the problems with ECG analysis.     

急性心肌梗死合并完全性左束支传导阻滞的心电图诊断

当心肌梗死合并左束支阻滞时,心电图诊断变得困难.近半个世纪以来出现了一些针对这类患者的心电图诊断标准,现就此作一综述.     

左束支区域起搏可改善右束支阻滞的心电图表现

目的:旨在观察左束支区域起搏(LBBAP)纠正右束支阻滞(RBBB)的临床效果及心电图特点.方法:本研究为单中心、前瞻性观察性研究,纳入2018年4月至2019年12月间入院有心室起搏指征,存在基线RBBB图形且QRS波群时限≥120 ms、左心室射血分数>50％并接受LBBAP的患者,分析LBBAP纠正RBBB的临床...     

Underuse of Thrombolytic Therapy in Acute Myocardial Infarction and Left Bundle Branch Block

Thrombolytic therapy reduces mortality in patients with acute myocardial infarction (AMI) and left bundle branch block (LBBB). The difficulty in accurately diagnosing AMI in patients with LBBB, however, might result in their undertreatment. Among 3,890 patients hospitalized with chest pain, 241 (6.2%) had LBBB at presentation. The only variable independently associated with AMI among patients with LBBB was in‐hospital left ventricular failure (odds ratio [OR]: 4.32, 95% confidence interval [CI]: 1.95–9.57, p < 0.0005). Only 16 (29%) of the LBBB patients with AMI received thrombolytic therapy compared with 583 (78%) of the 747 patients with ST‐elevation AMI (p < 0.0005). A further 19 (10%) LBBB patients without AMI also received thrombolysis. Difficulty in making an accurate early diagnosis in patients with LBBB ensures that the majority of those with AMI fail to receive thrombolytic therapy while others without AMI are treated inappropriately. Improved diagnostic and therapeutic strategies are needed for patients with acute coronary syndromes and LBBB. Copyright © 2010 Wiley Periodicals, Inc.     

急性心肌梗死与束支传导阻滞新认识

束支传导阻滞是急性心肌梗死的心电图常见合并情况。由于束支传导阻滞显著干扰急性心肌梗死患者的心电图表现,易导致临床识别困难和误诊;且束支传导阻滞对心肌梗死患者预后具有重要的预测价值。本综述详细阐明了急性心肌梗死时合并束支传导阻滞的诊断及预后意义。     

Intermittent Left Bundle Branch Block and Myocardial Ischemia in Patient Without Coronary Artery Stenosis:A Case Report

Left bundle branch block （ LBBB ）, traditionally viewed as an electrophysiologic abnormality, is increasingly recognized for its effects on hemodynamics and patient＇s prognosis^[1]. Exercise nuclear studies frequently show reversible perfusion defects in the absence of obstructive coronary artery disease^[2] and some patients with intermittent LBBB develop angina coincident with the onset of LBBB^[3]. We report a case of intermittent LBBB with abnormal stress technetium 99m TC single-photon emission computed tomography （SPECT） study and normal coronary artery angiography.     

Continuous ST‐segment Monitoring of Patients with Right Bundle Branch Block and Suspicion of Acute Myocardial Infarction

Background: Patients with right bundle branch block comprise 5–9% of all patients with acute myocardial infarction. In spite of this, limited data exist on early diagnosis or the usefulness of continuous electrocardiographic monitoring in these patients. Methods: A prospective multicenter study with 14 Swedish coronary care units. Patients with right bundle branch block and suspicion of acute myocardial infarction with less than 6 hours symptom duration were included. All patients were monitored with continuous vectorcardiography for 12–24 hours. Results: Seventy‐nine patients were included, 43% had acute myocardial infarction. Patients with acute myocardial infarction had significantly higher initial ST‐vector magnitude values (P = 0.0014) compared to patients without acute myocardial infarction. Patients with acute myocardial infarction also showed gradual regression of ST‐vector magnitude over time that was not seen for patients without acute myocardial infarction (P = 0.005). ST‐vector magnitude measured at the J‐point differentiated best between patients with and without acute myocardial infarction. A cutoff value of 125 μV for initial ST‐vector magnitude resulted in 55% sensitivity and 87% specificity for the diagnosis of acute myocardial infarction. Over time, patients with acute myocardial infarction showed greater changes in QRS‐vector difference compared to patients without acute myocardial infarction (P = 0.052). Conclusion: Vectorcardiographic monitoring shows good diagnostic abilities for patients with right bundle branch block and clinical suspicion of acute myocardial infarction and could be useful for continuous monitoring of these patients.     

Pulsus Alternans Caused by 2:1 Left Bundle Branch Block

Pulsus alternans was caused by 2:1 left bundle branch block in a patient with a left ventricular ejection fraction of 50% and normal coronary arteries. The observations documented the profound depressant hemodynamic effect of complete left bundle branch block in the setting of minimal systolic left ventricular function.     

急性心肌梗死新出现的束支传导阻滞与30天全因死亡率的关系

【摘要】目的：这篇文章的目的是为了探索急性心肌梗死的患者，心电图上出现束支传导阻滞的时间和持续时间与其30天全因死亡率之间的关系。方法：从2015年01月至2015年12月，我们共收集了1000例急性心肌梗死的患者，使用多元回归的方法分析了其30天全因死亡率与束支传导阻滞出现时间和持续时间之间的关系。结果：和右束支阻滞比较起来，左束支阻滞有更高的共病患病率和死亡率。暂时性束支传导阻滞30天全因死亡率更低。结论：急性心肌梗死的患者，新出现的永久性束支传导阻滞是30天全因死亡率的独立危险因素。     

Optimal QT/JT Interval Assessment in Patients with Complete Bundle Branch Block

Background: Prolonged ventricular repolarization duration confers increased risk for malignant ventricular arrhythmias. We sought to clarify the optimal method of QT/JT interval assessment in patients with complete bundle branch block (BBB). Methods: Study patients (n = 71) were dual‐chamber device recipients with baseline left or right BBB who preserved intrinsic ventricular activation during incremental atrial pacing. Patients were classified according to the presence or not of structural heart disease. The former group received chronic amiodarone therapy. QT and JT intervals were recorded at baseline heart rate of 51 ± 4 beats/min and during atrial pacing at 60, 80, and 100 beats/min. We used linear mixed‐effects models to assess the effect of heart rate on the derived QTc and JTc values with the use of six different heart rate correction formulae. Results: Heart rate had a significant effect on the QTc and the JTc intervals regardless of the correction formula used (P < 0.001 for all formulae). The formula of Hodges demonstrated the least variability in QTc and JTc measurements across the different heart rates in both patients groups without (F = 15.05 and F = 13.53, respectively) and with structural heart disease (F = 5.71 and F = 7.69, respectively), followed by the Nomogram and Framingham methods, whereas the uncorrected QT and JT intervals showed comparable heart rate–dependency. The application of Bazett's JTc and QTc led to the most pronounced interval variations in any case with BBB. Conclusions: The Hodges, Nomogram and Framingham correction methods provide best assessment of QT/JT intervals in BBB, whereas Bazett's formula exaggerates heart rate–dependency of ventricular repolarization intervals.     

The Mischievous Bundle: A Case of Varying Degrees of Right Bundle Branch Block on Alternate Beats during Exercise Stress Testing

A 78‐year‐old male was referred for exercise stress testing. He developed incomplete right bundle branch block during first stage of exercise and later on developed incomplete and complete right bundle branch block on alternate beats (2:1). During first minute of recovery he developed complete right bundle branch block on all beats (1:1). At 3 minutes of recovery, baseline electrocardiographic pattern was resumed. Variable degree of right bundle branch block on alternate beats is a rare phenomenon. The plausible mechanisms responsible for this phenomenon are being discussed.