Document Detail

Differentiation between left bundle branch block and left ventricular hypertrophy: Implications for cardiac resynchronization therapy.
MedLine Citation:
PMID:  23022304     Owner:  NLM     Status:  Publisher    
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 120ms conventionally used to diagnose LBBB. New strict criteria for diagnosing complete LBBB have been proposed that utilize longer QRS duration thresholds (130ms in women and 140ms 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.
David G Strauss
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-9-27
Journal Detail:
Title:  Journal of electrocardiology     Volume:  -     ISSN:  1532-8430     ISO Abbreviation:  J Electrocardiol     Publication Date:  2012 Sep 
Date Detail:
Created Date:  2012-10-1     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0153605     Medline TA:  J Electrocardiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Published by Elsevier Inc.
Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, Silver Spring, MD, USA. Electronic address:
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