Treatment of Microcirculation Disorders in Venous Leg Ulcer

摘要

Venous ulceration occurs when the muscle pumping mechanisms of the leg are impaired due to disease in the superficial or deep venous systems [1]. This may be simply a consequence of varicose veins which account for 20-50% of venous leg ulcers [2, 3], or from incompetence of the valves of the deep veins. This may arise from a previous deep vein thrombosis or be due to primary valve failure, in a manner similar to that which results in incompetence of the superficial veins in patients with varicose veins [4]. The consequence of incompetent lower limb vein valves is that the pumping mechanism no longer reduces the pressure in the veins to low levels during walking. A cannula placed in the dorsal foot vein usually shows a reduction in the resting pressure from 80-100 to 10-20 mm Hg in a fit person. Patients with severe calf muscle pump impairment may not be able to reduce the foot vein pressure below the resting level [5] (fig. 1). The presence of substantial venous reflux will result in rapid refilling of the veins of the calf after exercise, which is shown as a rapid rise in foot vein pressure after the end of exercise. Some patients seem to tolerate severe muscle pump impairment without ulceration, while others suffer ulcers of the leg with only moderate venous impairment. Clearly, other factors are important in the pathogenesis of this disease, but it remains unclear what leads to increased or decreased susceptibility of certain patients to ulcers of the leg. Hypotheses have been proposed since the Middle Ages, but more recently have revolved around the proposal that ulceration is attributable to skin hypoxia [6].