Document Detail

Ventricular echo beats during ventricular pacing or junctional bradycardia: studies in the normal canine heart.
MedLine Citation:
PMID:  3953388     Owner:  NLM     Status:  MEDLINE    
In 15 adult dogs ventricular echoes were elicited during sinus rhythm by incremental ventricular pacing and during atrioventricular (AV) junctional rhythm by depressing simultaneously AV junctional automaticity and retrograde AV nodal conduction. Concomitant slowing of AV junctional automaticity and conduction was achieved by selective intranodal administration of verapamil. In three dogs incremental pacing from either ventricle failed to retrogradely activate the atria, and in each case the site of block was found to be in the AV node. In two dogs with retrograde atrial capture there was little or no rate-dependency of retrograde ventriculoatrial (VA) conduction. During incremental ventricular pacing a single ventricular echo beat was observed in 10 of the 12 dogs that had atrial capture, and the atrium appears to be an essential link in the production of each ventricular echo. Ventricular echo occurred when the time allotted for retrograde VA conduction amounted to 70 +/- 4% of the duration of the ventricular pacing cycle length. During AV junctional rhythm, a single ventricular echo was elicited in half of the dogs and in each of those cases intranodal verapamil produced a profound depression of retrograde VA conduction. These experiments suggest that retrograde AV nodal longitudinal dissociation occurs in the slow current-dependent cells of the AV node.
F Urthaler
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  American heart journal     Volume:  111     ISSN:  0002-8703     ISO Abbreviation:  Am. Heart J.     Publication Date:  1986 Apr 
Date Detail:
Created Date:  1986-04-18     Completed Date:  1986-04-18     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0370465     Medline TA:  Am Heart J     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  672-8     Citation Subset:  AIM; IM    
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MeSH Terms
Atrioventricular Node / drug effects,  physiology*
Cardiac Pacing, Artificial*
Heart Conduction System / physiology*
Heart Rate* / drug effects
Ventricular Function
Verapamil / pharmacology
Grant Support
Reg. No./Substance:

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

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