Investigations on the pathogenesis of venous leg ulcers.

Based on a prospective study of 92 patients with DVT initiated in 1979, including a follow-up every year, the following investigations were performed: phlebography, Doppler-ultrasound, plethysmography (strain gauge and PPG) and foot-volumetry. In ulcer-patients skin blood flow was measured by Laser-Doppler and local oxygen supply by measurement of transcutaneous oxygen. Transcapillary protein-leakage was assessed by isotopic methods, local lymph-drainage by isotopic lymphography and indirect x-ray lymphography. From the results of these investigations the following course of events, which may be of importance for the development of venous ulceration, can be outlined: 1. Venous refluxes penetrating into the venules of the skin. 2. Chronic venous ambulatory hypertension (lack of pressure-fall during walking), waves of high pressure in the capillaries. 3. Protein-rich oedema. 4. Failure of fibrin clearance from the pericapillary space due to inadequate (exhausted?) fibrinolysis and deficient local lymph drainage. 5. Resulting changes in the ground substance, proliferation of fibres. 6. Local hypoxia due to a diffusion block by the impermeable pericapillary cuffs, partially due to a reduction of capillaries in the superficial layers.