| Effect of continuous vagal enhancement on concealed conduction and refractoriness within the atrioventricular node. | |
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MedLine Citation:
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PMID: 8607405 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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This study examined the complex interaction between vagal enhancement and how a concealed atrial impulse alters atrioventricular (AV) nodal function. In theory, vagal augmentation could increase or decrease the effect that a premature atrial beat has on the subsequent beat. In 10 patients we established the AV nodal effective refractory period (ERP) without and with a conditioning atrial stimulus (Sc); the stimulation protocol was then repeated after enhancing reflex vagal tone with a continuous phenylephrine infusion. During phenylephrine infusion, the sinus cycle length prolonged from 827 +/- 99 to 1,029 +/- 223 ms (p < 0.001) and AV nodal ERP increased from 331 +/- 51 to 425 +/- 64 ms (p < 0.005). At control, AV nodal ERP in the presence of Sc prolonged to 536 +/- 69 ms (p < 0.001), and during phenylephrine infusion increased to 579 +/- 57 ms (p < 0.01), a change significantly less than during control (58 +/- 14% vs 31 +/- 14%, respectively, p < 0.01). Further experiments suggest that the effect of Sc was reduced because it occurred earlier relative to the vagally prolonged AV nodal ERP. In conclusion, this study demonstrates a complex relation between the timing of a premature atrial beat causing concealed conduction and the degree of vagal tone. The concealed beat, as related to the AV node ERP, has a substantial effect on subsequent AV nodal conduction. These data give insights into clinical AV nodal function. |
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Authors:
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R L Page; J M Wharton; E N Prystowsky |
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Publication Detail:
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Type: Journal Article; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: The American journal of cardiology Volume: 77 ISSN: 0002-9149 ISO Abbreviation: Am. J. Cardiol. Publication Date: 1996 Feb |
Date Detail:
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Created Date: 1996-05-21 Completed Date: 1996-05-21 Revised Date: 2007-11-14 |
Medline Journal Info:
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Nlm Unique ID: 0207277 Medline TA: Am J Cardiol Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 260-5 Citation Subset: AIM; IM |
Affiliation:
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Department of Medicine, University of Texas Southwestern Medical Center, Dallas 75235-9047, USA. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adrenergic beta-Agonists
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pharmacology Adult Aged Atrioventricular Node / drug effects, innervation, physiopathology* Electric Conductivity Electrophysiology Female Humans Male Middle Aged Phenylephrine / pharmacology Reflex Regression Analysis Time Factors Vagus Nerve / drug effects, physiopathology* |
| Grant Support | |
ID/Acronym/Agency:
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5T32 HL07101/HL/NHLBI NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Adrenergic beta-Agonists; 59-42-7/Phenylephrine |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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