Document Detail


Second-degree atrioventricular block revisited.
MedLine Citation:
PMID:  23224264     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Type I second-degree atrioventricular (AV) block describes visible, differing, and generally decremental AV conduction. The literature contains numerous differing definitions of second-degree AV block, especially Mobitz type II second-degree AV block. The widespread use of numerous disparate definitions of type II block appears primarily responsible for many of the diagnostic problems surrounding second-degree AV block. Adherence to the correct definitions provides a logical and simple framework for clinical evaluation. Type II second-degree AV block describes what appears to be an all-or-none conduction without visible changes in the AV conduction time before and after the blocked impulse. Although the diagnosis of type II block requires a stable sinus rate, absence of sinus slowing is an important criterion of type II block because a vagal surge (generally a benign condition) can cause simultaneous sinus slowing and AV nodal block, which can superficially resemble type II block. Furthermore, type II block has not yet been reported in inferior myocardial infarction (MI) and in young athletes where type I block may be misinterpreted as type II block. The diagnosis of type II block cannot be established if the first postblock P wave is followed by a shortened PR interval or the P wave is not discernible. A narrow QRS type I block is almost always AV nodal, whereas a type I block with bundle branch block barring acute MI is infranodal in 60-70 % of cases. A 2:1 AV block cannot be classified in terms of type I or type II block, but it can be nodal or infranodal. A pattern resembling a narrow QRS type II block in association with an obvious type I structure in the same recording (e.g., Holter) effectively rules out type II block because the coexistence of both types of narrow QRS block is exceedingly rare. Concealed (nonpropagated) His bundle or ventricular extrasystoles may mimic both type I and/or type II block (pseudo AV block). All correctly defined type II blocks are infranodal. Infranodal block presenting with either type I or II manifestations requires pacing regardless of QRS duration or symptoms.
Authors:
S Serge Barold; Bengt Herweg
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-12-7
Journal Detail:
Title:  Herzschrittmachertherapie & Elektrophysiologie     Volume:  -     ISSN:  1435-1544     ISO Abbreviation:  Herzschrittmacherther Elektrophysiol     Publication Date:  2012 Dec 
Date Detail:
Created Date:  2012-12-10     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9425873     Medline TA:  Herzschrittmacherther Elektrophysiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
Florida Heart Rhythm Institute, Tampa, FL, USA, USA.ssbarold@aol.com.
Vernacular Title:
Eine erneute Betrachtung des atrioventrikulären Blocks zweiten Grades.
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