Heparin-induced thrombocytopenia with thrombotic complications.

Heparin-induced thrombocytopenia with thrombotic complications is a serious clinical problem. The diagnosis is confirmed by a positive heparin-induced platelet aggregation test and/or detection of white clots upon pathological exam after a presumptive diagnosis based on these criteria: (1) Development of thrombocytopenia of less than 100,000 mm3 while receiving heparin therapy; (2) Normalization of the platelet count after an interruption in heparin therapy; (3) The presence of thrombotic complications; and (4) Exclusion of other causes of thrombocytopenia. Eight patients with heparin-induced thrombocytopenia were encountered at the Charleston Area Medical Center, Memorial Division, in a recent 20-month period. Various types of heparin, routes of administration, and indications were implicated. The mean platelet nadir was 25,750 mm3 and the mean time to onset of of heparin-induced thrombocytopenia was 4.9 days. Thrombotic complications included seven patients with arterial occlusions of the legs, six with deep-vein thrombosis of the legs (three had pulmonary embolism), and five with combined arterial and venous thrombosis. Treatment strategies included discontinuation of heparin in all patients; intravenous infusion of dextran in five patients, followed by arterial thrombectomy in three patients; urokinase therapy in two patients for arterial thrombotic complications; and insertion of Greenfield filters in four patients for venous thrombotic complications. All surviving patients were given warfarin. The mortality rate was 25 percent and the morbidity rate was 38 percent. In conclusion, an initial platelet count should be obtained on all patients prior to receiving heparin, followed by repeat platelet counts every two to three days. Once thrombocytopenia or thrombosis is diagnosed, heparin should be discontinued and other therapeutic modalities considered.