Document Detail


Determinants of QRS alternans during narrow QRS tachycardia.
MedLine Citation:
PMID:  3819196     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
This study was designed to prospectively determine the incidence of QRS alternans during various types of narrow QRS tachycardia and to clarify the determinants of QRS alternans. An electrophysiologic study was performed in 28 consecutive patients with a narrow QRS tachycardia. Persistent QRS alternans was observed in 6 (43%) of 14 patients during orthodromic reciprocating tachycardia, 5 (71%) of 7 patients during atrial tachycardia and 3 (43%) of 7 patients during atrioventricular (AV) node reentrant tachycardia. Incremental atrial pacing during sinus rhythm resulted in QRS alternans in patients who had QRS alternans during tachycardia, unless the shortest pacing cycle length associated with 1:1 AV conduction exceeded the tachycardia cycle length. In patients without QRS alternans during narrow QRS tachycardia, incremental atrial pacing during sinus rhythm resulted in persistent QRS alternans in five patients in whom the shortest pacing cycle length associated with 1:1 AV conduction was 60 to 180 ms less than the tachycardia cycle length. In an additional 20 patients without a narrow QRS tachycardia, persistent QRS alternans was observed during incremental atrial pacing in 11 (55%) of the patients. In six of six patients who had QRS alternans during abrupt rapid atrial pacing, QRS alternans was not observed when the same pacing rates were achieved gradually. Among the patients with narrow QRS tachycardia, the mean tachycardia cycle length in those who had QRS alternans (mean +/- SD 288 +/- 44 ms) was significantly shorter than in those who did not (369 +/- 52 ms, p less than 0.001). The presence of QRS alternans was not related to the tachycardia mechanism, relative or functional refractory period of the His-Purkinje system (at a drive cycle length of 500 ms), age, presence of structural heart disease, direction of input into the AV node or concealed retrograde conduction in the His-Purkinje system. In conclusion, QRS alternans during narrow QRS tachycardias is a rate-related phenomenon that depends on an abrupt increase to a critical rate and is independent of the tachycardia mechanism.
Authors:
F Morady; L A DiCarlo; J M Baerman; M de Buitleir; W H Kou
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of the American College of Cardiology     Volume:  9     ISSN:  0735-1097     ISO Abbreviation:  J. Am. Coll. Cardiol.     Publication Date:  1987 Mar 
Date Detail:
Created Date:  1987-03-30     Completed Date:  1987-03-30     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  8301365     Medline TA:  J Am Coll Cardiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  489-99     Citation Subset:  AIM; IM    
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MeSH Terms
Descriptor/Qualifier:
Cardiac Pacing, Artificial
Electrocardiography*
Heart Rate / drug effects
Humans
Isoproterenol / pharmacology
Tachycardia, Atrioventricular Nodal Reentry / physiopathology*
Tachycardia, Supraventricular / physiopathology*
Chemical
Reg. No./Substance:
7683-59-2/Isoproterenol

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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