Document Detail

Steep fall in cardiac output is main determinant of hypotension during drug-free and nitroglycerine-induced orthostatic vasovagal syncope.
MedLine Citation:
PMID:  19084808     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: How much of the hypotension occurring during postural syncope is cardiac output-mediated and how much can be ascribed to a fall in systemic vascular resistance are unknown. The contribution of both determinants may be influenced by the use of vasoactive drugs. OBJECTIVE: The purpose of this study was to assess the determinants of hypotension during drug-free and nitroglycerine (NTG)-induced vasovagal presyncope in routine tilt table testing. METHODS: In this retrospective study, a total of 56 patients (37 female; age 36 +/- 19 years) with suspected vasovagal syncope and a positive tilt test at two clinical centers were selected. In 29 patients, presyncope was provoked by 0.4 mg sublingual NTG, administered in the 60 degrees head-up tilt position. In the other 27 patients, presyncope was provoked by passive tilt alone. Finger arterial pressure was monitored continuously, and left ventricular stroke volume was computed from pressure pulsations. RESULTS: After NTG administration, heart rate rose, and peak heart rate was similar in all patients. Use of NTG did not affect circulatory patterns precipitating a vasovagal response. On average in all patients, marked hypotension was mediated by an approximately 50% fall in cardiac output, whereas systemic vascular resistance was well maintained until presyncope. CONCLUSION: Hypotension during routine tilt testing is cardiac output-mediated, and the mechanism appears independent of the use of 0.4 mg sublingual NTG. The study data challenge the conventional idea of systemic vasodilation as the overriding cause of hypotension during postural syncope.
Bart Verheyden; Jiexin Liu; Nynke van Dijk; Berend E Westerhof; Tony Reybrouck; André E Aubert; Wouter Wieling
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't     Date:  2008-09-05
Journal Detail:
Title:  Heart rhythm : the official journal of the Heart Rhythm Society     Volume:  5     ISSN:  1556-3871     ISO Abbreviation:  Heart Rhythm     Publication Date:  2008 Dec 
Date Detail:
Created Date:  2008-12-16     Completed Date:  2009-04-07     Revised Date:  2009-10-27    
Medline Journal Info:
Nlm Unique ID:  101200317     Medline TA:  Heart Rhythm     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1695-701     Citation Subset:  IM    
Laboratory of Experimental Cardiology, University Hospital Gasthuisberg, KU Leuven, Leuven, Belgium.
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MeSH Terms
Blood Pressure / drug effects,  physiology
Body Mass Index
Follow-Up Studies
Heart Ventricles / physiopathology*
Hypotension, Orthostatic / etiology,  physiopathology*
Nitroglycerin / diagnostic use*
Retrospective Studies
Stroke Volume / physiology*
Syncope, Vasovagal / chemically induced,  complications,  physiopathology*
Tilt-Table Test / methods*
Vascular Resistance / physiology
Vasodilator Agents / diagnostic use
Ventricular Function, Left / physiology*
Reg. No./Substance:
0/Vasodilator Agents; 55-63-0/Nitroglycerin
Comment In:
Heart Rhythm. 2008 Dec;5(12):1702-3   [PMID:  18996054 ]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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