Valvular density alone cannot account for sites of chronic venous insufficiency and ulceration in the lower extremity

Objective: Class 6 chronic venous stasis is associated with abnormal venous hemodynamics and ulceration. Ulcers primarily occur over bones and tendon prominences but very rarely over muscular compartments. We hypothesized tha t the anatomical distribution of venous stasis ulcers in the lower extremit y is related to a lower density of venous valves. Methods: The venous vasculature of six normal human legs was cast with resi n, and their microvenous valvular anatomy was examined. Skin samples were o btained from the skin overlying the 1) Achilles' tendon, 2) anterior tibia, 3) medial malleolus, 4) lateral malleolus, 5) dorsal surface of the foot, 6) planta pedis, 7) dorsal aspect of the great toe; and from the skin regio ns overlying the 8) gastroenemius, 9) tibialis anterior, and 10) peroneus m uscles. The valvular and venous densities were determined in a scanning ele ctron microscope, normalized to the size of specimens, and the valvular ind ex was calculated. Analysis of variance with Bonferroni t-test was used to compare the valvular index between the regions. Results: Venous valves were observed in all tissue regions. The diameter of veins with valves ranged from 18 mum to 803 mum. The valvular index for re gions overlying bones/tendons (i.e., regions 1-7) was significantly higher versus those overlying muscular regions (i.e., regions 8-10) (p < 0.05). Th e valvular index was not different (p = 0.51) when regions 1 and 2 (where u lcers almost never occur) were compared to regions 3, 4, 5, 6, and 7 (where ulcers frequently occur): nor were there differences between the vascular indexes of regions overlying muscle. The largest venous valves were observe d in the plantar region, and the smallest-sized ones were present in the pe roneal region. Conclusions: This study shows that the density of venous valves is actually higher in regions of the human lower extremity overlying bones and tendons , where venous stasis ulcers are common, than those overlying muscular area s, where ulcers are rarely seen. Thus, valvular quantity alone cannot accou nt for the higher clinical incidence of ulceration. It is likely that muscu lar pumping and/or valvular quality are important factors in preventing the development of venous stasis and ulceration in the lower extremity.