Pathomechanism of chronic venous insufficiency and leg ulcer.

Uniform view of chronic venous diseases has been formed in the last 3 decades. Chronic venous insufficiency (CVI) is a functional disorder of the venous system of the lower limb. The basis of the pathology is always the venous hypertension caused by valvular insufficiency and reflux with or without venous outflow obstruction. Epifascial, subfascial and transfascial forms of CVI can be distinguished. In the practice these forms are almost always combined. The consistent venous hypertension is the initiating factor in alterations in the microcirculation which leads to skin changes and venous ulceration. The precise mechanism of the development of venous leg ulcer is still uncertain. A recent hypothesis suggests that leukocytes are trapped in the capillaries and attaching to the endothel they become activated and release proteolytic enzymes, free radicals which have destructive effects on lipid membranes, proteins as well as on many connective tissue compounds. The endothelium plays active role in the complex mechanism. Increased expression of tissue metalloproteinases has been observed in the periulcer skin. The presence of perivascular leukocyte infiltration and fibrin cuff is a reflexion of an inflammatory process. The clinical stages of CVI are likely to be the results of a systemic inflammatory response to a period of venous hypertension.