Capillary underperfusion in chronic venous insufficiency: a cause for leg ulceration?

Dermal capillaries in the goiter area of the lower leg were examined by video-microscopy before and after the administration of intravenous fluorescein in 13 patients with chronic venous insufficiency (CVI) who were at risk of developing leg ulceration, and in 13 normal controls. The influence of posture on capillary perfusion was determined by viewing the same area of skin with the leg in both the supine and dependent positions. Capillary density was lower in patients than in controls, irrespective of the position of the leg (P < 0.01). Fluorescence angiography studies in normal controls showed a reduction in capillary density with dependency (P < 0.01), but patients with CVI showed no significant change. Fluorescence angiography revealed a greater number of capillaries than seen during native capillaroscopy (P < 0.05). The decreased capillary density, and the loss of the postural vasoconstrictor reflex in patients with chronic venous incompetence may play a role in the pathogenesis of ulceration.