Document Detail

Age-Dependence of Relative Change in Circulating Epinephrine and Norepinephrine Concentrations During Tilt-Induced Vasovagal Syncope.
MedLine Citation:
PMID:  22863884     Owner:  NLM     Status:  Publisher    
BACKGROUND: Although vasovagal syncope (VVS) is preceded by a surge of circulating catecholamines (epinephrine [Epi] and norepinephrine ]NE]) of adrenal/renal and synaptic origin, prevention of VVS with beta-adrenergic blockade has been ineffective except in 'older' VVS patients. OBJECTIVE: We hypothesized that in part, age-related differences of beta-blocker effect may be due to differences in relative magnitudes of epinephrine (Epi) and norepinephrine (NE) release during an evolving faint; specifically, greater Epi/NE ratio in younger fainters compared to older patients. To assess this hypothesis, we measured changes in Epi/NE ratios in younger (<40 years) vs older (≥40 years) patients during head-up tilt-table test induced VVS. METHODS: The study comprised 29 patients (12 pts ≥40: 56±10.7 years and 17 pts <40: 25±5.7 years) with recurrent suspected VVS in whom 70° head-up tilt testing reproduced symptoms. Arterial Epi and NE concentrations were measured at baseline (supine), 2 minutes of head-up tilt, and syncope. RESULTS: Baseline Epi and NE concentrations and the ratio Epi/NE did not differ in younger and older groups (Epi: 90±65 vs 70±32 pg/ml; NE: 226±122 vs 244±183pg/ml). However, Epi/NE ratio increased to a greater extent in younger fainters during head-up tilt, and tended to be greater in younger patients at both 2 min (<40: 1.02±1.29 vs ≥40: 0.40± 0.27, p=0.11), and at symptoms (<40: 2.6±1.26 vs ≥40: 1.6±0.71, p=0.03). At symptoms, an Epi/NE ratio ≥2.5 was observed in 9/17 younger vs 1/12 older patients (p=0.02). CONCLUSIONS: Epi/NE ratios tend to be greater in younger fainters, a finding that may in part account for the observation that beta-blocker therapy is less effective for reducing VVS susceptibility in younger individuals.
David G Benditt; Barry L S Detloff; Wayne O Adkisson; Fei Lu; Scott Sakaguchi; Stefanie Schussler; Erin Austin; Lin Yee Chen
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-7-31
Journal Detail:
Title:  Heart rhythm : the official journal of the Heart Rhythm Society     Volume:  -     ISSN:  1556-3871     ISO Abbreviation:  Heart Rhythm     Publication Date:  2012 Jul 
Date Detail:
Created Date:  2012-8-6     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101200317     Medline TA:  Heart Rhythm     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2012. Published by Elsevier Inc.
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