Heparin-associated thrombocytopenia and thrombosis : Implications for perioperative management

SINCE its discovery 80 yr ago, heparin has become a valuable component of medical therapeutics. Lack of an alternative, rapidly acting, and reversible anticoagulant makes heparin one of the most widely prescribed pharmaceutical agents in hospitalized patients. Unfortunately, a subpopulation of patients exposed to heparin develop antibodies that induce thrombocytopenia and, almost paradoxically in some cases, thrombosis. This clinical syndrome of immune complex-mediated thrombocytopenia, thrombosis, or both after heparin therapy comprises the condition of heparin-associated thrombocytopenia (HAT). Lack of standardized diagnostic criteria and limited availability of screening tests contribute to the misconception that HAT rarely occurs in patients having surgery. However, recent evidence suggests that heparin-associated antibodies are more prevalent than previously suspected and may even contribute to perioperative morbidity.