Document Detail

Hemodynamic significance of heart rate in neurally mediated syncope.
MedLine Citation:
PMID:  15562934     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Vasovagal and vasodepressor syncope are used interchangeably in the literature to describe the common faint syndrome, now collectively named neurally mediated syncope. The significance of heart rate (HR) in these reflex-induced reactions remains unclear.
HYPOTHESIS: The study was undertaken to investigate the hemodynamic significance of HR in tilt-induced neurally mediated syncope.
METHODS: In all, 113 patients with syncope of unknown etiology were studied by head-up tilt test with invasive hemodynamic monitoring. Thirty-five patients (15 women, 20 men, age range 21 to 72 years) developed syncope and were enrolled for analysis. The hemodynamic data were compared between patients who developed bradycardia (vasovagal group, n = 15) and those without bradycardia (vasodepressor group, n = 20).
RESULTS: The baseline hemodynamic data (mean +/- standard deviation) and the hemodynamic responses after 10-min headup tilt were similar between patients in the vasovagal and vasodepressor groups. During syncope, patients with vasovagal reaction developed hypotension and paradoxical bradycardia (HR = 52.4 +/- 5.9 beats/min), while patients with vasodepressor reaction developed a precipitous drop in arterial blood pressure with inappropriate HR (105 +/- 21 beats/min) compensation. Patients with vasovagal syncope manifested a significantly lower cardiac index and a significantly higher systemic vascular resistance index than patients with vasodepressor syncope (1.47 +/- 0.29 vs. 1.97 +/- 0.41 1/min/m2, p < 0.001 and 2098 +/- 615 vs. 1573 +/- 353 dynes x s x cm(-5) x m2, p < 0.003, respectively). A positive correlation existed between HR and cardiac index (r = 0.44, p = 0.008) during syncope in the patients studied.
CONCLUSIONS: These findings suggest that the hemodynamic characteristics of vasovagal and vasodepressor reactions are different, and that HR plays a significant role in neurally mediated syncope.
Wan Leong Chan; Tse Min Lu; Jiann Jong Wang; Shyi Shiaw Jiau; Chi Woon Kong
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Publication Detail:
Type:  Comparative Study; Journal Article    
Journal Detail:
Title:  Clinical cardiology     Volume:  27     ISSN:  0160-9289     ISO Abbreviation:  Clin Cardiol     Publication Date:  2004 Nov 
Date Detail:
Created Date:  2004-11-25     Completed Date:  2005-03-01     Revised Date:  2014-07-29    
Medline Journal Info:
Nlm Unique ID:  7903272     Medline TA:  Clin Cardiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  635-40     Citation Subset:  IM    
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MeSH Terms
Heart Rate / physiology*
Middle Aged
Syncope, Vasovagal / physiopathology*
Tilt-Table Test

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

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