| Influence of respiratory instability during neurocardiogenic presyncope on cerebrovascular and cardiovascular dynamics. | |
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MedLine Citation:
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PMID: 17947365 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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OBJECTIVE: To analyse the influence of breathing activity on cerebrovascular dynamics during presyncope. DESIGN: Retrospective study. SETTING: University hospital. PATIENTS: 38 subjects developing neurocardiogenic syncope (syncope group), and 61 age-matched control subjects with negative tilt. INTERVENTIONS: Middle cerebral artery mean blood flow velocity (MCFV), continuous non-invasive blood pressure (BP), end-tidal CO(2) (CO(2)-et) and minute ventilation were measured before and during 45' 60 degrees tilting. MAIN OUTCOME MEASURES: Respiratory and cerebrovascular variability, cerebrovascular resistance (CVR)-absolute and corrected for CO(2)-et at 40 mm Hg (CVR-40)-and dynamic cerebrovascular regulation (CVR-dyn: transfer function phase analysis between MCFV and BP), obtained during supine rest (baseline), first 5 minutes of tilt (early tilt), early- and late presyncope (first and second half, respectively, of 4 minutes preceding syncope in syncope group, and equivalent time in controls). RESULTS: Tilting induced a mean (SE) CVR decrease in controls (baseline 1.20 (0.04); late presyncope 1.12 (0.06) mm Hg x s/cm, p<0.05) but not in the syncope group (baseline 1.09 (0.04); late presyncope 1.09 (0.06) mm Hg x s/cm, p = NS). However, CVR-40 showed similar reduction in both groups (controls: from 1.15 (0.04) to 0.96 (0.04) mm Hg x s/cm; syncope group: from 1.01 (0.04) to 0.83 (0.04) mm Hg x s/cm, p = NS). CVR-dyn of the two groups was also similar (p = NS). Respiratory variability increased in the syncope group, from early tilt to late presyncope (p<0.05 or better), preceding hyperventilation and being significantly correlated with an increase in MCFV and BP variability (p<0.01). CONCLUSIONS: During presyncope, the development of respiratory instability and hypocapnia impairs MCFV, thus facilitating the onset of syncope despite preserved cerebrovascular regulation. |
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Authors:
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C Porta; G Casucci; S Castoldi; A Rinaldi; L Bernardi |
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Publication Detail:
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Type: Journal Article Date: 2007-10-18 |
Journal Detail:
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Title: Heart (British Cardiac Society) Volume: 94 ISSN: 1468-201X ISO Abbreviation: Heart Publication Date: 2008 Nov |
Date Detail:
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Created Date: 2008-10-20 Completed Date: 2008-12-10 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 9602087 Medline TA: Heart Country: England |
Other Details:
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Languages: eng Pagination: 1433-9 Citation Subset: AIM; IM |
Affiliation:
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Department of Internal Medicine, University of Pavia and IRCCS Ospedale S Matteo, Pavia, Italy. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Adult Blood Pressure / physiology* Carbon Dioxide / physiology Cardiovascular System / physiopathology* Cerebrovascular Circulation / physiology Female Hemodynamics / physiology Humans Hypocapnia / complications, physiopathology* Male Oxygen Consumption / physiology Retrospective Studies Syncope / complications, physiopathology* Syncope, Vasovagal / complications, physiopathology Tilt-Table Test / methods |
| Chemical | |
Reg. No./Substance:
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124-38-9/Carbon Dioxide |
| Comments/Corrections | |
Comment In:
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Heart. 2008 Nov;94(11):1372-3
[PMID:
18931152
]
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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