HEPARIN-INDUCED THROMBOCYTOPENIA AND THROMBOSIS SYNDROME

Heparin-induced thrombocytopenia and thrombosis syndrome (HITTS) is an immune-mediated response to the administration of heparin that result s in life-threatening thrombosis. The pathophysiology of HITTS remains controversial. The onset of clinical symptoms and laboratory changes is usually delayed 1-2 weeks after exposure to heparin. Thrombosis occ urs in both the arterial and venous circulation with significant morbi dity and mortality. Complications include deep venous thrombosis, pulm onary embolus, stroke, myocardial infarction, chronic venous insuffici ency, extremity ischemia, gangrene, and death. Diagnostic criteria for HITTS include thrombocytopenia during heparin exposure, exclusion of other causes such as sepsis or medications, resolution of thrombocytop enia after withdrawal of heparin, demonstration of in vitro heparin-de pendent platelet antibodies, and development of vascular thrombosis. D espite having several disadvantages, the carbon-14-serotonin release a ssay is the most sensitive and specific test for HITTS. Angiography as an adjunct to other imaging modalities can document the presence, loc ation, and extent of thrombus. Optimal treatment has not yet been defi ned but should include immediate discontinuation of use of all heparin products and heparin-coated catheters. In addition, alternate methods of antithrombotic therapy should be considered. Ln severe cases, thro mbolysis or thrombectomy may be warranted. Familiarity with the pathop hysiology, clinical manifestations, complications, diagnostic criteria , and treatment options associated with HITTS will enable timely recog nition and facilitate prompt and effective treatment.