[Microangiopathies in chronic venous insufficiency (CVI)]

The degree of cutaneous microangiopathy at the medial ankle correlates with the severity of chronic venous insufficiency, most probably it is the trigger factor for development of trophic skin lesions. Using intravital fluorescence videomicroscopy, microlymphography, transcutaneous oxygen tension measurement and laser Doppler flowmetry, the microangiopathy is characterized by morphological alterations of blood and lymph capillaries and by dynamic changes (decreased transcutaneous oxygen tension reflecting microvascular ischemia, increased skin perfusion). Microangiopathy in patients with chronic venous insufficiency is recognized by the presence of dilated, elongated and tortuous (glomerulus-like) capillaries and by an increase in diameter of the pericapillary space (halo) filled by Na-fluorescein. In severe CVI a reduction of the capillary number can be observed, probably as a result of previous capillary thrombosis. Lymphatic drainage is disturbed and lymph capillaries are obliterated in part. Laser Doppler flowmetry, which detects flux in deeper, non-nutrient skin vessels, shows increased blood flow. However, the postural vasoconstrictive response remains intact and there is little alteration in the spontaneous rhythmic flux waves. In contrast to deeper skin flux transcutaneous oxygen tension is reduced, in keeping with the microangiopathy observed in the superficial nutrient capillaries. These pronounced morphological and dynamic changes explain the development of trophic skin lesions.