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Clinical Science (2010) 118, (573–581) (Printed in Great Britain)

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Central and cerebrovascular effects of leg crossing in humans with sympathetic failure

Mark P.M. Harms^*, Wouter Wieling^*, Willy N.J.M. Colier^†, Jacques W.M. Lenders^‡, Niels H. Secher^§ and Johannes J. van Lieshout^*∥¶

*Department of Internal Medicine, AMC Center for Heart Failure Research, Academic Medical Center, Amsterdam, The Netherlands, †Department of Geriatric Medicine, Division of General Internal Medicine, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands, ‡Department of Internal Medicine, Division of General Internal Medicine, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands, §Department of Anaesthesia, The Copenhagen Muscle Research Center, Rigshospitalet, Copenhagen, Denmark, ∥Special Medical Care, AMC Center for Heart Failure Research, Academic Medical Center, Amsterdam, The Netherlands, and ¶Laboratory for Clinical Cardiovascular Physiology, AMC Center for Heart Failure Research, Academic Medical Center, Amsterdam, The Netherlands

Key words: autonomic disease, blood flow velocity, cardiac output, leg crossing, near-IR spectroscopy (NIRS), sympathetic nervous system.

Abbreviations: BP, blood pressure; CA, cerebral autoregulation; CBF, cerebral blood flow; CO, cardiac output; HHb, deoxyhaemoglobin; HR, heart rate; MAP, mean arterial pressure; MAP_heart MAP at the heart level; MCA, middle cerebral artery; MAP_mca; MAP at the brain level; MCA V_mean, MCA flow velocity; NIRS, near-infrared spectroscopy; O₂Hb, oxyhaemoglobin; PETCO₂, end-tidal CO₂; SV, stroke volume; TI, thoracic electrical impedance; TPR, total peripheral resistance.

Correspondence: Dr Johannes J. van Lieshout (email j.j.vanlieshout@amc.uva.nl).

Leg crossing increases arterial pressure and combats symptomatic orthostatic hypotension in patients with sympathetic failure. This study compared the central and cerebrovascular effects of leg crossing in patients with sympathetic failure and healthy controls. We addressed the relationship between MCA V_mean (middle cerebral artery blood velocity; using transcranial Doppler ultrasound), frontal lobe oxygenation [O₂Hb (oxyhaemoglobin)] and MAP (mean arterial pressure), CO (cardiac output) and TPR (total peripheral resistance) in six patients (aged 37–67 years; three women) and age- and gender-matched controls during leg crossing. In the patients, leg crossing increased MAP from 58 (42–79) to 72 (52–89) compared with 84 (70–95) to 90 (74–94) mmHg in the controls. MCA V_mean increased from 55 (38–77) to 63 (45–80) and from 56 (46–77) to 64 (46–80) cm/s respectively (P<0.05), with a larger rise in O₂Hb [1.12 (0.52–3.27)] in the patients compared with the controls [0.83 (−0.11 to 2.04) μmol/l]. In the control subjects, CO increased 11% (P<0.05) with no change in TPR. By contrast, in the patients, CO increased 9% (P<0.05), but also TPR increased by 13% (P<0.05). In conclusion, leg crossing improves cerebral perfusion and oxygenation both in patients with sympathetic failure and in healthy subjects. However, in healthy subjects, cerebral perfusion and oxygenation were improved by a rise in CO without significant changes in TPR or MAP, whereas in patients with sympathetic failure, cerebral perfusion and oxygenation were improved through a rise in MAP due to increments in both CO and TPR.

Received 19 January 2009/8 October 2009; accepted 16 October 2009

Published as Immediate Publication 16 October 2009, doi:10.1042/CS20090038

© 2010 The Author(s)
The author(s) has paid for this article to be freely available under the terms of the Creative Commons Attribution Non-Commercial Licence (http://creativecommons.org/licenses/by-nc/2.5/) which permits unrestricted non-commercial use, distribution and reproduction in any medium, provided the original work is properly cited.