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Management of bleeding complications in redo cardiac operations
1Division of Cardiothoracic Surgery, Columbia-Presbyterian Medical Center, New York, New York 10032, USA.
Insights
This review explores strategies to reduce bleeding during complex cardiac surgery, including preoperative assessments and perioperative interventions. It highlights the safety and efficacy of aprotinin and discusses novel factor IXa inhibitors for managing blood loss.
Area of Science:
- Cardiovascular Surgery
- Hematology
- Pharmacology
Background:
- Bleeding is a significant complication in complex cardiac surgeries, especially those involving prolonged bypass times and hypothermia.
- Reducing the need for blood transfusions is a key clinical challenge in these procedures.
Purpose of the Study:
- To review clinical and experimental strategies for minimizing bleeding and transfusion requirements in cardiac surgery.
- To discuss the perioperative management of coagulopathies and the role of pharmacologic agents.
Main Methods:
- Review of preoperative patient assessment for coagulation defects.
- Discussion of perioperative interventions: erythropoietin, autologous donation, autotransfusion, and anemia tolerance.
- Analysis of pharmacologic agents like aprotinin and novel factor IXa inhibitors.
Main Results:
- Aprotinin is effective in managing excess bleeding, inhibiting plasma enzyme systems, and preserving platelet function without evidence of inducing a prothrombotic state.
- Novel factor IXa inhibitors show promise in animal studies for reducing blood loss post-bypass.
Conclusions:
- Comprehensive strategies, including preoperative optimization and perioperative interventions, can effectively manage bleeding in complex cardiac surgery.
- Aprotinin is a safe and effective agent for reducing bleeding, and new molecular therapies are emerging.
Abstract:
Bleeding remains a complication of certain complex surgical procedures, particularly those cardiac operations associated with long bypass times and profound hypothermia. Clinical and novel experimental strategies to reduce bleeding and the need for blood and blood-product transfusions are the focus of this review. Preoperative assessment of the patient will identify drug-induced, acquired, or inherited coagulation defects that may contribute to this problem. The main attention is directed to the perioperative period, and broad areas discussed include the preoperative use of erythropoietin to increase red blood cell mass, autologous donation either preoperatively or before bypass, autotransfusion/hemofiltration, and acceptance of relative anemia both during the operation and into the postoperative period. A further, often overlooked, management strategy in treating major coagulopathies is the consideration of the cost and half-lives of the coagulation factors in individual blood components. Prevention of bleeding has become possible both by manipulation of the control of coagulation and inflammatory processes and by the introduction of pharmacologic agents such as aprotinin. Aprotinin is widely used and has proven efficacy in the management of excess bleeding. It is a serine protease inhibitor and has several possible mechanisms of action, including inhibition of the plasma enzyme systems activated by contact with the foreign surface of the bypass circuit and preservation of platelet function. Safety issues include the possibility of hypersensitivity and anaphylactic reaction on a second exposure. Concerns that aprotinin may induce a prothrombotic or coagulant state have no basis in theory or any good evidence in the current literature. A recent study specifically sought to identify the presence of disseminated microvascular platelet-fibrin thrombi present at autopsy in patients who had received aprotinin therapy. The study concluded that diffuse platelet-fibrin thrombi were not a direct complication of aprotinin therapy. Finally, modern molecular biology has led to the recent development of an inhibitor for factor IXa that competitively replaced IXa in the intrinsic complex and blocked the conversion of factor X to factor Xa. This compound is under investigation in animal studies. These have so far shown efficacy in reducing blood loss after bypass in comparison with standard heparin anticoagulation.