Heparin-induced vascular occlusion in vasculosurgical patients - An evaluation of the disease in 13 cases

Objective. To describe the diagnosis and treatment of adverse reaction to h eparin (heparin-induced thrombocytopenia [HIT]) administered prophylactical ly for thrombosis and embolism. Experimental design: case series, Setting: vascular surgical division in a University hospital. Patients: thirteen pat ients treated for HIT type II between October 1994 and June 1997. Measures/ Interventions: diagnosis of heparin-induced complications is based bn exact medical history and regular measurement of platelet counts. Confirmation c an be obtained with the aggregation test, serotonin-release test, heparin-i nduced platelet release (HIPA) test, and platelet factor 4/heparin ELISA. V asculosurgical reconstruction is usually required to eliminate vessel occlu sion, Results. In our series, HIT was confirmed by HIPA test (11 patients) and ag gregation test (2 patients). All patients had positive cross reaction with low-molecular-weight heparin, and six had cross reaction with heparinoid da naproid sodium (Orgaran(R)). Occlusions occurred between day 2 and 22 after the start or resumption of heparin administration (mean, 11 days), Anticoa gulation treatment with hirudin or danaproid sodium was given to 5 patients , in conjunction with vasculosurgical reconstruction. Three of those patien ts died and the other two required amputation. Conclusions. Heparin-induced vascular occlusion is a rare but severe advers e effect of heparin treatment. When HIT is suspected, heparin administratio n must be stopped, with substitution of dextran and acetylsalicylic acid. L aboratory tests must be used for confirmation or exclusion. However, the di agnosis can be obscured by a normal platelet count due to pre-existing poly cythemia and by false-negative test results. Surgery is usually warranted, depending on the degree and localization of ischemia.