Use of Heparin during Cardiopulmonary Bypass in Patients with a History of Heparin-Induced Thrombocytopenia

To the Editor: Patients with heparin-induced thrombocytopenia are at high risk for thromboembolic complications. Heparin-induced thrombocytopenia is caused by heparin-related and platelet-activating antibodies.1 These antibodies, referred to as HIT antibodies, are usually undetectable 100 days after the cessation of heparin therapy.2 Avoidance of a secondary immune response and the use of alternative anticoagulants are strongly recommended in patients who have had heparin-induced thrombocytopenia to avoid another bout. If such patients require cardiopulmonary bypass, danaparoid and hirudin are available.3,4 Both treatments, however, carry the risk of potentially life-threatening hemorrhage, because their anticoagulant actions cannot be neutralized at the end of . . .