| Effects of an acute increase in atrial pressure on atrial refractoriness in humans. | |
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MedLine Citation:
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PMID: 1279534 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Contraction-excitation feedback has been studied extensively in mammalian ventricles. In contrast, little is known about contraction-excitation feedback in mammalian atria. The objective of this study was to investigate the effect of acute alterations in atrial pressure, induced by varying the atrioventricular (AV) interval, on atrial refractoriness. Twenty patients without structural heart disease participated in the study. In each patient the atrial effective (ERP) and absolute refractory periods (ARP) were measured during AV pacing at a cycle length of 500 msec and an AV interval of 120 msec. Acute increases in atrial pressure were induced by pacing the atrium and ventricle simultaneously for the final two beats of the drive train. The ERP was defined as the longest extrastimulus coupling interval that failed to capture with an extrastimulus current strength of twice the stimulation threshold. The ARP was defined in a similar manner with an extrastimulus current strength of 10 mA. The ERP and ARP were determined using the incremental extrastimulus technique. A subset of patients had the pacing protocol performed during autonomic blockade. As the AV interval of the final two beats of the drive train was shortened from 120 msec to 0 msec, the peak right atrial pressure increased from 7 +/- 3 mmHg to 15 +/- 5 mmHg (P < 0.001). The increase in atrial pressure associated with simultaneous pacing of the atrium and ventricle resulted in shortening of the atrial ERP and ARP by 7.3 +/- 5.2 and 6.2 +/- 3.5 msec, respectively (P < 0.001). Similar results were obtained during autonomic blockade. these findings confirm the presence of contraction-excitation feedback in normal human atria. |
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Authors:
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H Calkins; R el-Atassi; S Kalbfleisch; J Langberg; F Morady |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Pacing and clinical electrophysiology : PACE Volume: 15 ISSN: 0147-8389 ISO Abbreviation: Pacing Clin Electrophysiol Publication Date: 1992 Nov |
Date Detail:
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Created Date: 1992-12-11 Completed Date: 1992-12-11 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 7803944 Medline TA: Pacing Clin Electrophysiol Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 1674-80 Citation Subset: IM |
Affiliation:
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Division of Cardiology, University of Michigan Medical Center, Ann Arbor. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Adult Atrial Function / physiology* Atrioventricular Node / physiology* Atropine / diagnostic use Cardiac Pacing, Artificial / methods* Feedback / physiology Female Humans Male Myocardial Contraction / physiology Pressure Propranolol / diagnostic use Refractory Period, Electrophysiological / physiology |
| Chemical | |
Reg. No./Substance:
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51-55-8/Atropine; 525-66-6/Propranolol |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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