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Current Cardiology Reviews 2021RBBB, a pattern seen on the 12-lead ECG, results when normal electrical activity in the His-Purkinje system is interrupted for some reason. The normal sequence of... (Review)
Review
RBBB, a pattern seen on the 12-lead ECG, results when normal electrical activity in the His-Purkinje system is interrupted for some reason. The normal sequence of activation is altered in RBBB, with a resultant characteristic appearance on the ECG manifest by a widened QRS complex and changes in the directional vectors of the R and S waves. This ECG pattern is often seen in clinical practice and generally regarded as benign. The anatomy, epidemiology, causes, symptoms, ECG findings and diagnosis, differential diagnosis in ECG, treatment, complications, prognosis, with respect to RBBB are outlined here, demonstrating some typical ECGs of RBBB.
Topics: Bundle-Branch Block; Electrocardiography; Female; Humans; Male
PubMed: 32640959
DOI: 10.2174/1573403X16666200708111553 -
Circulation. Arrhythmia and... Apr 2020Left bundle branch block may be due to conduction system degeneration or a reflection of myocardial pathology. Left bundle branch block may also develop following aortic... (Review)
Review
Left bundle branch block may be due to conduction system degeneration or a reflection of myocardial pathology. Left bundle branch block may also develop following aortic valve disease or cardiac procedures. Patients with heart failure with reduced ejection fraction and left bundle branch block may respond positively to cardiac resynchronization therapy. Lead placement via the coronary sinus is the mainstay approach of cardiac resynchronization therapy. However, other options, including physiological pacing, are being explored. In this review, we summarize the salient pathophysiologic and clinical aspects of left bundle branch block, as well as current and future strategies for management.
Topics: Action Potentials; Bundle of His; Bundle-Branch Block; Cardiac Resynchronization Therapy; Heart Rate; Humans; Recovery of Function; Risk Factors; Treatment Outcome
PubMed: 32186936
DOI: 10.1161/CIRCEP.119.008239 -
Cardiology Clinics Aug 2023Left bundle branch block (LBBB) and right bundle branch block (RBBB) are classic manifestations of bundle branch conduction disorders. However, a third form that is... (Review)
Review
Left bundle branch block (LBBB) and right bundle branch block (RBBB) are classic manifestations of bundle branch conduction disorders. However, a third form that is uncommon and underrecognized may exist that has features and pathophysiology of both: bilateral bundle branch block (BBBB). This unusual form of bundle branch block exhibits an RBBB pattern in lead V1 (terminal R wave) and an LBBB pattern in leads I and aVL (absence of S wave). This unique conduction disorder may confer an increased risk of adverse cardiovascular events. BBBB patients may be a subset of patients that respond well to cardiac resynchronization therapy.
Topics: Humans; Bundle-Branch Block; Electrocardiography; Cardiac Conduction System Disease; Heart Conduction System; Cardiac Resynchronization Therapy
PubMed: 37321689
DOI: 10.1016/j.ccl.2023.03.011 -
The American Journal of Cardiology Mar 2011Cardiac resynchronization therapy (CRT) has emerged as an attractive intervention to improve left ventricular mechanical function by changing the sequence of electrical... (Review)
Review
Cardiac resynchronization therapy (CRT) has emerged as an attractive intervention to improve left ventricular mechanical function by changing the sequence of electrical activation. Unfortunately, many patients receiving CRT do not benefit but are subjected to device complications and costs. Thus, there is a need for better selection criteria. Current criteria for CRT eligibility include a QRS duration ≥ 120 ms. However, QRS morphology is not considered, although it can indicate the cause of delayed conduction. Recent studies have suggested that only patients with left bundle branch block (LBBB) benefit from CRT, and not patients with right bundle branch block or nonspecific intraventricular conduction delay. The authors review the pathophysiologic and clinical evidence supporting why only patients with complete LBBB benefit from CRT. Furthermore, they review how the threshold of 120 ms to define LBBB was derived subjectively at a time when criteria for LBBB and right bundle branch block were mistakenly reversed. Three key studies over the past 65 years have suggested that 1/3 of patients diagnosed with LBBB by conventional electrocardiographic criteria may not have true complete LBBB, but likely have a combination of left ventricular hypertrophy and left anterior fascicular block. On the basis of additional insights from computer simulations, the investigators propose stricter criteria for complete LBBB that include a QRS duration ≥ 140 ms for men and ≥ 130 ms for women, along with mid-QRS notching or slurring in ≥ 2 contiguous leads. Further studies are needed to reinvestigate the electrocardiographic criteria for complete LBBB and the implications of these criteria for selecting patients for CRT.
Topics: Animals; Bundle-Branch Block; Cardiac Resynchronization Therapy; Dogs; Electrocardiography; Electrophysiologic Techniques, Cardiac; Humans; Patient Selection; Randomized Controlled Trials as Topic
PubMed: 21376930
DOI: 10.1016/j.amjcard.2010.11.010 -
Annals of Noninvasive Electrocardiology... Mar 2019In left bundle branch block (LBBB), the ventricles are activated in a sequential manner with alterations in left ventricular mechanics, perfusion, and workload resulting... (Review)
Review
In left bundle branch block (LBBB), the ventricles are activated in a sequential manner with alterations in left ventricular mechanics, perfusion, and workload resulting in cardiac remodeling. Underlying molecular, cellular, and interstitial changes manifest clinically as changes in size, mass, geometry, and function of the heart. Cardiac remodeling is associated with progressive ventricular dysfunction, arrhythmias, and impaired prognosis. Clinical and diagnostic notions about LBBB have evolved from a simple electrocardiographic alteration to a critically important finding affecting diagnostic and clinical management of many patients. Advances in cardiac magnetic resonance imaging have significantly improved the assessment of patients with LBBB and provided additional insights into pathophysiological mechanisms of left ventricular remodeling. In this review, we will discuss the epidemiology, etiologies, and electrovectorcardiographic features of LBBB and propose a classification of the conduction disturbance.
Topics: Aged; Bundle-Branch Block; Cardiac Resynchronization Therapy; Electrocardiography; Female; Humans; Magnetic Resonance Imaging, Cine; Male; Middle Aged; Prognosis; Risk Assessment; Severity of Illness Index; Treatment Outcome; Vectorcardiography
PubMed: 29932265
DOI: 10.1111/anec.12572 -
Progress in Cardiovascular Diseases 1984
Review
Topics: Adult; Aged; Bundle of His; Bundle-Branch Block; Canada; Death, Sudden; Electrocardiography; Electrophysiology; Female; Heart Block; Heart Conduction System; Humans; Male; Middle Aged; Myocardial Infarction; United States
PubMed: 6364217
DOI: 10.1016/0033-0620(84)90009-4 -
Circulation. Cardiovascular Imaging Nov 2022
Topics: Humans; Cardiac Resynchronization Therapy; Bundle-Branch Block; Defibrillators, Implantable; Electric Countershock; Heart Failure; Treatment Outcome; Electrocardiography
PubMed: 36330794
DOI: 10.1161/CIRCIMAGING.122.014849 -
Europace : European Pacing,... Aug 2017Left bundle branch block (LBBB) results in an altered pattern of left ventricular (LV) activation and subsequent contraction, causing remarkable changes in LV mechanics,... (Review)
Review
Left bundle branch block (LBBB) results in an altered pattern of left ventricular (LV) activation and subsequent contraction, causing remarkable changes in LV mechanics, perfusion and workload and ultimately leading to pathologic cardiac remodelling. Clinical and diagnostic notions about the LBBB phenomenon had evolved from just an electrocardiographic pattern to a critically important finding affecting diagnostic and clinical management of many patients and adversely influencing their outcomes. Recent advances in imaging techniques significantly improved the assessment of patients with LBBB and provided additional insights into pathophysiological mechanisms of LV remodelling. In the current review we summarized currently available data on the LBBB epidemiology, diagnosis, its impact on clinical management and prognosis, and the role and place of various imaging modalities in assessing cardiac mechanics and perfusion abnormalities, as well as their potential implications for diagnostic and treatment strategies.
Topics: Action Potentials; Aged; Aged, 80 and over; Animals; Bundle of His; Bundle-Branch Block; Electrocardiography; Female; Heart Rate; Humans; Male; Middle Aged; Myocardial Contraction; Predictive Value of Tests; Prognosis; Risk Factors; Ventricular Function, Left; Ventricular Remodeling
PubMed: 28444180
DOI: 10.1093/europace/eux061 -
JAMA Internal Medicine Nov 2022
Topics: Humans; Bundle-Branch Block; Electrocardiography
PubMed: 36066887
DOI: 10.1001/jamainternmed.2022.3703 -
Cardiac Electrophysiology Clinics Jun 2022Current electrocardiogram (ECG) criteria for left bundle branch block (LBBB) are largely based on early work in animal models or on mathematical models of cardiac... (Review)
Review
Current electrocardiogram (ECG) criteria for left bundle branch block (LBBB) are largely based on early work in animal models or on mathematical models of cardiac activation. The resulting criteria have modest specificity, and up to one-third of patients who meet current ECG criteria for LBBB may have intact conduction through their His-Purkinje systems. Intracardiac tracings offer the ability to accurately discriminate between LBBB and other causes of delayed activation, which may facilitate the development of more accurate ECG criteria. Assessing these distinctions are particularly salient to applications for conduction system pacing.
Topics: Animals; Bundle of His; Bundle-Branch Block; Cardiac Pacing, Artificial; Electrocardiography; Heart Conduction System; Humans
PubMed: 35715078
DOI: 10.1016/j.ccep.2021.12.015