| Detection of rapid changes in ventricular refractoriness in human studies. | |
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MedLine Citation:
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PMID: 11990659 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Conventional determination of the ventricular effective refractory period (VERP) is unsuitable for detection of rapid fluctuations in the effective refractory period (ERP). A programmed stimulation system was developed that adapts continuous atrioventricular sequential pacing, incremental extrastimulus interval (S1S2) scanning, and automatic detection of extrastimulus capture which is followed by shortening of S1S2 to execute repeated scanning. The accuracy of ERP determination was tested using variable incremental (2 and 4 ms) and decremental (4-16 ms) steps of the S1S2 interval. Based on a mean of 82 determinations in eight patients, the average VERP values stayed at 249.8-251.0 ms except during the highest capture frequency. Standard deviation of ERP values ranged from 1.1 to 2.5 ms on average at the tested incremental and decremental steps. One determination was accomplished within 7.8-15.6 seconds on average. The ability to track changes in ERP was tested by changing the drive cycle length. Time constants for the adaptation rate of VERP and ventricular monophasic action potential duration at a 90% level of repolarization were determined from each test, and were similar, 51 +/- 8 seconds (mean +/- SEM) for ERP and 51 +/- 6 seconds for the action potential duration. Thus, the developed method provides accurate ERP measurements during rapid variation in ventricular refractoriness. It allows studying the recovery of excitability and the action potential duration simultaneously, and would be valuable particularly in pathological conditions and pharmacologic interventions where these electrophysiological variables become dissociated. |
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Authors:
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Lauri Toivonen; Eija Kettunen; Kim Simelius; Hannu Parikka |
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Publication Detail:
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Type: Comparative Study; Journal Article |
Journal Detail:
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Title: Pacing and clinical electrophysiology : PACE Volume: 25 ISSN: 0147-8389 ISO Abbreviation: Pacing Clin Electrophysiol Publication Date: 2002 Mar |
Date Detail:
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Created Date: 2002-05-06 Completed Date: 2002-12-12 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: 300-7 Citation Subset: IM |
Affiliation:
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Division of Cardiology, Helsinki University Hospital, Finland. lauri.toivonen@hus.fi |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Action Potentials Adult Aged Cardiac Pacing, Artificial / methods* Electrophysiology Female Heart Conduction System / physiology* Humans Male Middle Aged Myocardial Contraction / physiology* Ventricular Function / physiology* |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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