Hemostatic and thrombotic issues in cardiac surgery

Cardiac surgery with cardiopulmonary bypass determines a serious imbalance of the hemostatic system. The clinical pattern is multifactorial, involving patient-related, drug-related, and surgery-related factors. As a result, the patient is prone to both hemorrhagic and thrombotic complications. To address the clinical management of a bleeding patient after cardiac surgery, avoiding empirical administration of drugs and blood derivates, it is mandatory to correctly identify the factor(s) responsible for bleeding. Bleeding after cardiac operations can be ascribed to seven basic mechanisms: residual heparin effect; reduced thrombin generation; fibrinogen deficiency; thrombocytopenia; platelet dysfunction; hyperfibrinolysis; and surgical sources. These factors may interact together, creating a complex coagulopathy. Point-of-care coagulation tests are useful to orienteer the clinician in this complex scenario. Viscoelastic coagulation tests find their greater usefulness in the diagnosis of the bleeding mechanism(s), whereas platelet function tests appear more useful for the preoperative assessment of patients under the effects of antiplatelet agents. Thromboembolic complications are the other side of the coin, and their prevention is still a matter of debate. Consumption of natural anticoagulants and endothelial disturbance are important mechanisms underlying this condition. Strategies to limit antithrombin (AT) consumption or to correct low postoperative levels of AT are still a matter of discussion.