Dynamic recording of vasoconstrictor response to increased vascular transmural pressure. A study in patients with lower limb atherosclerosis.

Ultrasound Doppler flowmetry during local exposure to subatmospheric pressure (limb negative pressure exposure--LNPE) was used to study the effect of increased transmural pressure on femoral artery blood flow. Twelve healthy controls and patients with lower limb atherosclerosis--before (n = 11) and after (n = 18) femoropopliteal reconstruction were included in the study. One minute after onset of LNPE blood flow in the common femoral artery was reduced by 46% in controls, which implies increased arterial tone at increased transmural pressure (veno-arteriolar vasoconstrictor response). In patients with lower limb atherosclerosis the average blood flow during LNPE was not different from blood flow at rest. In 3 patients with pain at rest blood flow increased 25% during exposure, indicating reduced arterial tone. This finding is consistent with the clinical experience that patients with ischemic pain find relief by lowering their legs. Following femoropopliteal reconstruction the vasoconstrictor response was absent during the first days; but appeared approximately one week postoperatively. Thus impaired arteriolar regulatory mechanisms may be one causative factor for the initial formation of local edema frequently observed after arterial reconstruction.