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.
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Research Article|
July 12 2011
Dissection of carotid sinus hypersensitivity: the timing of vagal and vasodepressor effects and the effect of body position
C. T. Paul Krediet;
*Department of Medicine, Academic Medical Center at the University of Amsterdam, Amsterdam, The Netherlands
Correspondence: Dr C. T. Paul Krediet (email [email protected]).
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David L. Jardine;
David L. Jardine
†Department of General Medicine, Christchurch Hospital, University of Otago, Christchurch, New Zealand
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Wouter Wieling
Wouter Wieling
*Department of Medicine, Academic Medical Center at the University of Amsterdam, Amsterdam, The Netherlands
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Publisher: Portland Press Ltd
Received:
December 20 2010
Revision Received:
May 13 2011
Accepted:
May 20 2011
Accepted Manuscript online:
May 20 2011
Online ISSN: 1470-8736
Print ISSN: 0143-5221
© The Authors Journal compilation © 2011 Biochemical Society
2011
Clin Sci (Lond) (2011) 121 (9): 389–396.
Article history
Received:
December 20 2010
Revision Received:
May 13 2011
Accepted:
May 20 2011
Accepted Manuscript online:
May 20 2011
Citation
C. T. Paul Krediet, David L. Jardine, Wouter Wieling; Dissection of carotid sinus hypersensitivity: the timing of vagal and vasodepressor effects and the effect of body position. Clin Sci (Lond) 1 November 2011; 121 (9): 389–396. doi: https://doi.org/10.1042/CS20100607
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