Document Detail


Dissection of carotid sinus hypersensitivity: the timing of vagal and vasodepressor effects and the effect of body position.
MedLine Citation:
PMID:  21595633     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
We assessed the timing of vagal and sympathetic factors that mediate hypotension during CSM (carotid sinus massage) in patients with carotid sinus hypersensitivity. We hypothesized that a fall in cardiac output would precede vasodepression, and that vasodepression would be exaggerated by head-up tilt. We performed pulse contour analyses on blood pressure recordings during CSM in syncope patients during supine rest and head-up tilt. In a subset we simultaneously recorded muscle sympathetic nerve activity supine. During supine rest, systolic blood pressure decreased from 150±7 to 107±7 mmHg (P<0.001) and heart rate from 64±2 to 39±3 beats/min (P<0.01). Cardiac output decreased with heart rate to nadir (66±6% of baseline), 3.1±0.4 s after onset of bradycardia. In contrast, total peripheral resistance reached nadir (77±3% of baseline) after 11±1 s. During head-up-tilt, systolic blood pressure fell from 149±10 to 90±11 mmHg and heart rate decreased from 73±4 to 60±7 beats/min. Compared with supine rest, cardiac output nadir was lower (60±8 compared with 83±4%, P<0.05), whereas total peripheral resistance nadir was similar (81±6 compared with 80±3%). The time to nadir from the onset of bradycardia did not differ from supine rest. At the onset of bradycardia there was an immediate withdrawal of muscle-sympathetic nerve activity while total peripheral resistance decay occurred much later (6-8 s). The haemodynamic changes following CSM have a distinct temporal pattern that is characterized by an initial fall in cardiac output (driven by heart rate), followed by a later fall in total peripheral resistance, even though sympathetic withdrawal is immediate. This pattern is independent of body position.
Authors:
C T Paul Krediet; David L Jardine; Wouter Wieling
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Clinical science (London, England : 1979)     Volume:  121     ISSN:  1470-8736     ISO Abbreviation:  Clin. Sci.     Publication Date:  2011 Nov 
Date Detail:
Created Date:  2011-07-12     Completed Date:  2011-11-08     Revised Date:  2012-01-05    
Medline Journal Info:
Nlm Unique ID:  7905731     Medline TA:  Clin Sci (Lond)     Country:  England    
Other Details:
Languages:  eng     Pagination:  389-96     Citation Subset:  IM    
Affiliation:
Department of Medicine, Academic Medical Center at the University of Amsterdam, Amsterdam, The Netherlands. C.T.Krediet@amc.nl
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MeSH Terms
Descriptor/Qualifier:
Aged
Aged, 80 and over
Blood Pressure
Bradycardia / pathology
Carotid Sinus / physiopathology*
Female
Heart Rate
Hemodynamics
Humans
Hypersensitivity / physiopathology*
Male
Middle Aged
Posture
Retrospective Studies
Syncope
Vagus Nerve / pathology
Vasodilation

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


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