Document Detail


Optical mapping of the atrioventricular junction.
MedLine Citation:
PMID:  16226086     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
In the normal heart, the atrioventricular node (AVN) is part of the sole pathway between the atria and ventricles, and is responsible for the appropriate atrial-ventricular delay. Under normal physiological conditions, the AVN controls appropriate frequency-dependent delay of contractions. The AVN also plays an important role in pathology: it protects ventricles during atrial tachyarrhythmia, and during sinoatrial node failure the atrioventricular (AV) junction assumes the role of pacemaker. Finally, the AV junction provides an anatomic substrate for AV nodal reentrant tachycardia, which is the most prevalent supraventricular tachycardia in humans. Using fluorescent imaging with voltage-sensitive dye and immunohistochemistry, we have investigated the structure-function relationship of the atrioventricular (AV) junction during normal conduction, reentry, and junctional rhythm. We identified the site of origin of junctional rhythm at the posterior extension of the AV node (AVN) in 78% (n=23) of the studied hearts and we found that this pacemaker is sensitive to autonomic control. For instance, when the autonomic nervous system was activated using subthreshold stimulation, a transient accelerated junctional rhythm was observed when subthreshold stimulation was terminated. A very similar phenomenon is observed clinically during slow pathway ablations treating AV nodal reentrant tachycardia (AVNRT). The autonomic control of the AV junction was investigated using immunohistochemistry, showing that the AV junction of the rabbit is very densely innervated with both cholinergic and adrenergic neurons. The posterior AV nodal extension was similar to the compact AVN as determined by morphologic and molecular investigations. In particular, both the posterior extension and the compact node express the pacemaking channel HCN4 (responsible for the IF current) and neurofilament 160. In the rabbit heart, AV junction conduction, reentrant arrhythmia, and spontaneous rhythm are governed by heterogeneity of expression of several isoforms of gap junctions and ion channels, and these properties are regulated by the autonomic nervous system. Uniform neurofilament expression suggests that AV nodal posterior extensions are an integral part of the cardiac pacemaking and conduction system.
Authors:
William J Hucker; Vladimir P Nikolski; Igor R Efimov
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Review    
Journal Detail:
Title:  Journal of electrocardiology     Volume:  38     ISSN:  0022-0736     ISO Abbreviation:  J Electrocardiol     Publication Date:  2005 Oct 
Date Detail:
Created Date:  2005-10-17     Completed Date:  2006-04-13     Revised Date:  2009-11-11    
Medline Journal Info:
Nlm Unique ID:  0153605     Medline TA:  J Electrocardiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  121-5     Citation Subset:  IM    
Affiliation:
Department of Biomedical Engineering, Washington University, St. Louis, MO 63130, USA.
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MeSH Terms
Descriptor/Qualifier:
Action Potentials
Animals
Atrial Function
Atrioventricular Node / anatomy & histology,  innervation*,  pathology*,  physiopathology
Autonomic Nervous System / pathology,  physiopathology
Electrophysiologic Techniques, Cardiac
Humans
Immunohistochemistry
Tachycardia, Atrioventricular Nodal Reentry / pathology,  physiopathology
Grant Support
ID/Acronym/Agency:
R01-HL58808/HL/NHLBI NIH HHS

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


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