cardiovascular disorders
Thromboangiitis Obliterans
Introduction
Thromboangiitis obliterans is inflammatory thrombosis of small and medium-sized arteries and some superficial veins, causing arterial ischemia in distal extremities and superficial thrombophlebitis. Tobacco use is the primary risk factor. Symptoms and signs include claudication, nonhealing foot ulcers, rest pain, and gangrene. Diagnosis is by clinical findings, noninvasive vascular testing, angiography, and exclusion of other causes. Treatment is cessation of tobacco use. Prognosis is excellent when tobacco use is stopped, but when it is not, the disorder inevitably progresses, often requiring amputation. Thromboangiitis obliterans occurs almost exclusively in tobacco users (nearly all of them are people who smoke) and predominantly affects men aged 20 to 40 years; it rarely occurs in women. Prevalence is highest in Asia and the Middle East where there is heavy tobacco use. It occurs more commonly in people with human leukocyte antigen (HLA)-A9 and HLA-B5 genotypes. Thromboangiitis obliterans produces segmental inflammation in small and medium-sized arteries and, frequently, in superficial veins of the extremities. In acute thromboangiitis obliterans, occlusive thrombi accompany neutrophilic and lymphocytic infiltration of the intima; endothelial cells proliferate, but the internal elastic lamina remains intact. In an intermediate phase, thrombi organize and recanalize incompletely; the media is preserved but may be infiltrated with fibroblasts. In older lesions, periarterial fibrosis may occur, sometimes affecting the adjacent vein and nerve. The cause is unknown, although cigarette smoking is a primary risk factor. The mechanism may involve delayed hypersensitivity or toxic angiitis. According to another theory, thromboangiitis obliterans may be an Autoimmune Disorders caused by cell-mediated sensitivity to types I and III human collagen, which are constituents of blood vessels. 