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Sympathetic autoregulation in peripheral vascular disease.
K T Delis1, A F Lennox, A N Nicolaides
1Irvine Laboratory, Regional Vascular Unit, 10th Floor QEQM Wing, St Mary's Hospital, Praed Street, London W2 1NY, UK. k.delis@ic.ac.uk
The British Journal of Surgery
|April 12, 2001
Summary
Patients with leg ischaemia have impaired venoarteriolar response (VAR). Successful revascularization restores normal VAR, indicating improved sympathetic autoregulation. This study evaluated VAR in claudication and post-revascularization.
Area of Science:
- Vascular Physiology
- Autoregulation
- Sympathetic Nervous System
Background:
- Lower limb venous pressure increases with dependency, triggering a sympathetic reflex causing vasoconstriction.
- This venoarteriolar response (VAR) reduces arterial calf inflow and is impaired in critical leg ischaemia.
- The study investigated VAR in non-critical leg ischaemia and after revascularization.
Purpose of the Study:
- To evaluate the venoarteriolar response (VAR) in patients with symptomatic non-critical leg ischaemia.
- To assess VAR following successful revascularization in patients with severe leg ischaemia.
- To compare VAR in normal subjects, claudication patients, and post-revascularization patients.
Main Methods:
- Foot skin blood flow (flux) was measured in horizontal and sitting positions using laser Doppler fluxmetry.
- The venoarteriolar response (VAR) was calculated as (horizontal blood flow - sitting blood flow)/horizontal blood flow x 100%.
- The pressure eliciting the reflex (pVAR) was determined in the horizontal position.
Main Results:
- The median VAR was significantly lower in patients with stable claudication (29.1%) compared to normal subjects (59.5%) and post-revascularization patients (63.9%).
- Similar significant differences were observed for pVAR (22 mmHg in claudication vs. 45 mmHg in normal and 40 mmHg in post-revascularization).
- No significant difference in VAR or pVAR was found between normal individuals and patients after successful revascularization.
Conclusions:
- Patients with intermittent claudication exhibit impaired orthostatic sympathetic autoregulation.
- Successful revascularization restores normal venoarteriolar response and sympathetic autoregulation, despite underlying vascular disease.
- The findings highlight the reversibility of autoregulation impairment after restoring leg perfusion.