ABSTRACT
Objective: To asses the risk of acquired antithrombin III (AT III) deficit before heart surgery and consider countermeasures. Patient: A 50-year-old gentleman who suffered from congestive heart failure due to mitral valve regurgitation. Methods: We replaced the mitral valve with cardiopulmonary bypass. Activated clotting time (ACT) was not long enough even after general heparinization (300 U/Kg) for cardiopulmonary bypass. We measured the activity of antithrombin III and added a total 50000 units of heparin until ACT was over 400 sec. We noted low AT III activity (36.8%) and transfused 4 U of fresh frozen plasma (FFP) during surgery. Results: After administration of protamine (0.3 ml/Kg), ACT reached 137 sec. The hemostasis procedure was uneventful and the patient recovered well without a bleeding incident. Conclusion: Measurement of AT III activity just before the initiation of cardiopulmonary bypass is necessary to avoid insufficient anticoagulation such as antithrombin III deficit.