Document Detail

Characterization of responses of neonatal sinus and AV nodes to critically timed, brief vagal stimuli.
MedLine Citation:
PMID:  1996689     Owner:  NLM     Status:  MEDLINE    
We studied the responses of sinus cycle length and atrioventricular (AV) nodal conduction to brief, critically timed vagal stimuli in 25 neonatal (9.6 +/- 3.1 days) canines. Vagal stimuli were delivered to the right or left decentralized cervical vagosympathetic trunk as either a single, brief stimulus train or a repetitive, phase-coupled train with both stimulation paradigms programmed to scan the entire cardiac cycle. The effects of brief vagal stimuli on cardiac cycle length were measured while the heart was beating spontaneously, and the vagal effects on AV nodal conduction were measured while the cycle length was held constant by atrial pacing at 300 ms. Neither changes in sinus cycle length nor AV nodal conduction demonstrated classical phase dependency, i.e., a gradual increase in the magnitude of the vagal response as stimuli are delivered progressively later in the cardiac cycle until the latency period (that point in the cardiac cycle at which vagal stimulation no longer affects the next cardiac cycle) is reached. Phase-response curves (PRCs) to single and repetitive stimuli typically exhibited either a flat response or a small decrease in magnitude as the latency period of the PRC was approached. Thus the neonatal sinus and AV node PRCs exhibit a different configuration than that reported in the adult.
S Yamasaki; A Stolfi; A S Pickoff
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The American journal of physiology     Volume:  260     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1991 Feb 
Date Detail:
Created Date:  1991-03-22     Completed Date:  1991-03-22     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  H459-64     Citation Subset:  IM    
Department of Pediatrics, Tulane University School of Medicine, New Orleans, Louisiana 70112.
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MeSH Terms
Animals, Newborn
Atrioventricular Node / physiology*
Electric Stimulation / methods
Neural Conduction
Sinoatrial Node / physiology*
Time Factors
Vagus Nerve / physiology*
Grant Support

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