Abnormalities of the Digital Vasculature as Related to Ulceration and Gangrene

Abstract

Plastic casts were made of digital vessels of 13 extremities amputated for severe atherosclerosis obliterans. Prior to amputation, blood flow averaged 0.02 cc/min/5 cc of digit (normal, 0.5), and digital systolic pressure average 16 mm Hg. There were more occlusions of terminal arteries (<30 µ in diameter) in the first and fifth toes than in the third toes and on the plantar and proximal dorsal surfaces than in the nail bed; this observation suggests relationship to local trauma and shoe pressures. Occlusion was most severe in 30 to 50 µ arteries, decreased with increasing vessel size, and was greater in uninvolved areas of ulcerated toes than in nonulcerated toes. Occluded arteries smaller than the digital artery terminated abruptly; this observation suggests stasis thrombosis; occlusions did not occur preferentially at sites of branchings. In occluded digital arteries, areas of partial occlusion lay adjacent to complete block, reflecting plaque formation. At the rim of an ulcer crater all vessels terminated abruptly which suggests destruction of vasculature secondary to necrosis. The findings suggest the following sequence of events: (1) marked reduction in pressure and flow due to proximal disease, (2) resultant stasis thrombosis accentuated by shoe pressures and local trauma, and (3) death of tissue in ischemic digits leading to further loss of vasculature in the necrotic area.