| Elevated parasympathetic nerve tone in isoproterenol-induced neurally mediated syncope during head-up tilt testing. | |
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MedLine Citation:
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PMID: 11316131 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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To clarify the autonomic nerve mechanisms whereby isoproterenol induces vasovagal reaction, 32 patients with recurrent syncopal episodes of unknown origin underwent head-up tilt testing. Syncope was induced in 11 patients by a control tilt (control/+ group). The remaining 21 patients (control/- group) underwent the procedure during isoproterenol infusion. Syncope was induced in 13 (isoproterenol/+ group), but not in the remaining 8 patients (isoproterenol/- group). High-frequency component (HF) and low-frequency component (LF)/HF, which are indices of heart rate variability, were assessed for 2-min intervals at baseline (T1) during the initial phase (T2) and at the end (T3) of tilting in each test. The ratios of HF and LF/HF at T2/T1 and T3/T2 were calculated. The HF value at T3 in the control/+ group was greater than that in the control/- group (1.47+/-0.91 vs 0.75+/-0.34; p<0.05). The HF value at T3 in the isoproterenol/+ group was significantly greater than those in the isoproterenol/- group (1.19+/-1.04 vs 0.43+/-0.23; p<0.05). The HF value at T2 in the isoproterenol/+ tended to be greater than in the isoproterenol/- group (1.30+/-0.85 vs 0.66+/-0.53; p=0.07). The ratio of HF for T2/T1 in isoproterenol/+ was greater than in the other groups (2.04+/-1.26 in isoproterenol/+ vs 0.58+/-0.39 in control/-, 0.47+/-0.18 in control/+ and 0.71+/-0.45 in isoproterenol/-; p=0.0001), whereas that of HF for T3/T2 in the control/+ group was greater than in the other groups (1.48+/-0.62 in control/+ vs 0.97+/-0.33 in control/-; p<0.05, 0.79+/-0.35 in isoproterenol/- and 0.88+/-0.37 in isoproterenol/+; p<0.01). No difference was observed in either LF/HF or the ratio of LF/HF among the groups. The early and persistent increase in parasympathetic nerve tone provoked by isoproterenol plays an important role in enhancing the vasovagal reaction during head-up tilt testing. |
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Authors:
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A Takei; Y Ohnishi; M Yokoyama |
Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Japanese circulation journal Volume: 65 ISSN: 0047-1828 ISO Abbreviation: Jpn. Circ. J. Publication Date: 2001 Apr |
Date Detail:
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Created Date: 2001-04-23 Completed Date: 2001-09-20 Revised Date: 2004-11-17 |
Medline Journal Info:
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Nlm Unique ID: 7806868 Medline TA: Jpn Circ J Country: Australia |
Other Details:
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Languages: eng Pagination: 320-4 Citation Subset: IM |
Affiliation:
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First Department of Internal Medicine, Kobe University School of Medicine, Japan. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adolescent Adrenergic beta-Agonists / diagnostic use* Adult Afferent Pathways / physiopathology Blood Pressure / drug effects Echocardiography Electrocardiography Electrocardiography, Ambulatory Female Heart Rate* / drug effects Humans Isoproterenol / diagnostic use* Male Mechanoreceptors / physiology Middle Aged Parasympathetic Nervous System / physiopathology* Recurrence Sympathetic Nervous System / drug effects, physiopathology Syncope, Vasovagal / chemically induced, diagnosis, etiology, physiopathology*, ultrasonography Tilt-Table Test* Vagus Nerve / physiopathology |
| Chemical | |
Reg. No./Substance:
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0/Adrenergic beta-Agonists; 7683-59-2/Isoproterenol |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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