Disturbed blood flow regulation in venous leg ulcers.

Microangiopathy of the skin has been recognized as an important factor in the development of skin diseases connected with chronic venous insufficiency (CVI). Here the relationship between postcapillary transmural pressure and precapillary vaso-constriction - we call it the postural feedback system - was examined in venous ulcers (n = 12) and compared to blood flow regulation in the inner ankle area of healthy controls (n = 12). Blood flow changes were measured by laser Doppler fluxmetry. Changes in the laser Doppler flux (LDF) minus the biological zero value were measured after 3 min of arterial occlusion, during 3 min of venous occlusion, while the leg was elevated and while it was lowered and expressed relative to the pretest resting value. In venous ulcers the LDF remained nearly unchanged after arterial occlusion (3 vs. 190%, p < 0.001), leg elevation caused an LDF decrease contrary to what was seen in the controls (-17 vs. +80%, p < 0.001), in the lowered leg an LDF decrease was found (-51 vs. -65%) and venous occlusion led to a profound reduction of flux (-78 vs. -84%). In severe CVI the precapillary arterioles seem to be dilated even with the leg at heart level. This finding means that the postural feedback system under resting conditions is upregulated, and 'luxus' hyperperfusion results. The upregulated postural feedback system contributes to the cutaneous microangiopathy due to chronic venous congestion.