Use of plasma exchange in patients with heparin-induced thrombocytopenia: a report of two cases and a review of the literature.

Heparin-induced thrombocytopenia (HIT), which is characterized by thrombocytopenia and potentially serious thromboses, may develop in patients exposed to heparin anticoagulation. HIT is caused by antibodies to the heparin/platelet factor 4 (PF4) complex. Management of HIT involves discontinuation of heparin and anticoagulation with a nonheparin alternative such as a direct thrombin inhibitor (DTI). This poses a challenge in the management of patients who need to undergo cardiopulmonary bypass surgery (CPB), because CPB requires anticoagulation with heparin and standardized protocols for use of DTIs are not widely available. We report two patients with HIT who underwent successful CPB with heparin anticoagulation following plasma exchange (PE) to reduce heparin/PF4 antibody titers. Case 1 is a 46-year-old male with cardiac amyloidosis who needed urgent placement of a left ventricular assist device. Case 2 is a 34-year-old woman with acute myocarditis who needed placement of a biventricular assist device. Both patients had positive enzyme-linked immunosorbent assay assays for heparin/PF4 antibodies and clinical evidence of HIT before PE. Following PE and subsequent CPB, neither patient had clinical or laboratory evidence of HIT. The literature regarding the use of PE for the treatment of complications of HIT and as prophylaxis before CPB is reviewed.