[Microangiopathy in chronic venous insufficiency].

Skin in the medial malleolar region was examined in 15 patients with moderately severe venous insufficiency (9 women, 6 men; mean age 57 [35-76] years), using intravital fluorescence microscopy, transcutaneous pO2 measurement and laser Doppler flowmetry. The findings were compared with those in a healthy control group (8 women, 7 men; mean age 53 [35-73] years). The arteriolar vasoconstriction response was tested by comparing laser Doppler flowmetry readings in the recumbent and sitting positions. Transcutaneous pO2 was likewise measured in both positions. Capillary morphology and microangiodynamics were investigated before and after injection of Na-fluorescein. The microangiopathy of moderately severe venous insufficiency was characterised fluorescence microscopically by greatly dilated, elongated and winding (glomerulus-like) capillaries, and by an increase in the pericapillary leakage diameter (halo). However, the vasoconstrictive response to change in posture remained largely intact, and there was little alteration in the spontaneous rhythmic flow waves. In contrast, flow in the recumbent position was significantly increased (P less than 0.001), since laser Doppler flowmetry also measures the flow in deeper (1-6 mm), non-nutrient skin vessels. In spite of a normal capillary count, the mean transcutaneous pO2 was reduced, in keeping with the microangiopathy observed in the superficial nutrient capillaries. These pronounced morphological and dynamic changes explain the development of trophic lesions.