Patients with a history of type II heparin-induced thrombocytopenia with thrombosis requiring cardiac surgery with cardiopulmonary bypass: a prospective observational case series.

Heparin-induced thrombocytopenia with thrombosis (HITT) type II is a life-threatening complication of heparin therapy that most often occurs after 5-10 days of exposure to heparin. Anticoagulation is a significant concern for patients with HITT type II being prepared for cardiac surgery requiring cardiopulmonary bypass (CPB). We report a case series of 12 patients with a history HITT type II who underwent CPB and cardiac surgery. Six patients did not express the antibody that mediates HITT type II immediately before surgery. Heparin was used as the anticoagulant for the duration of CPB only, and all these patients did well without thrombotic complications. Six patients expressed the antibody that mediates HITT type II immediately before surgery. Hirudin was used as the anticoagulant for CPB in these patients. The ecarin clotting time was used to guide hirudin therapy during CPB. The patients receiving hirudin did well, but they had a large amount of bleeding, required transfusions of multiple allogeneic blood products, and had a frequent rate of reexploration of the mediastinum after CPB.