Vascular and stromal features in the skin of the lower limb in patients with chronic critical limb ischaemia (CLI) and oedema

Objective: periphral oedema is often observed in limbs affected by chronic critical limb ischaemia (CLI) and is mainly subcutaneous in distribution. Previous work has shown that capillary filtration coefficient (CFC) in limbs with CLI and oedema was twice as great as that in the contralateral a limb. These changes might be due to morphological changes. Transmission electron microscopy (TEM) was used to examine the morphological features of the capillary walls and surrounding stromal tissues in the skin of these limbs. Material and methods: eight patients with unilateral CLI and peripheral pitting oedema (four men, four women, a mean ge of 81 +/- 6.9 years) was studied. Skin biopsies were taken from the pulp of the first toe, interdigital space between the first and second digits and dorsal part of forefoot just prior to amputation. Results: stromal oedema and dilated capillaries were most prominent in the distal part of the foot. Some of the capillaries were filled with blood cells and some were empty. The endothelium of th dilated vessels was elongated and distended. In some patients a number of capillaries were collapsed with degenerate endothelial cells. "Gaps", i.e. large openings, were found between the elongated oedematous endothelial cells. The basal lamina was thickened in all patients. Stromal haemorrhage and degeneration were seen in approximately 50% of patients. Conclusion: CLI causes ultrastructural changes in the capillary endothelium and surrounding stroma. The presence of large gaps between endothelial cells as well as an increased capillar pressure may enhance transcapillary transudation, and are most likely the causative factors in the formation of the ischaemic oedema. The stromal haemorrhage as well as degeneration probably signifies a terminal stage of CLI.