What is the purpose of anticoagulation during the CABG procedure?

• A. To reverse anticoagulation after cardiopulmonary bypass.
• B. To prevent thrombus in the machine and patient due to reduced blood flow (stasis) with heparin.
• C. To maintain normal blood viscosity during surgery.
• D. To promote clot formation in the bypass circuit.

Answer: (B)

During CABG with cardiopulmonary bypass, blood encounters artificial surfaces and non-physiologic flow, which can trigger the coagulation system and platelet activation. Anticoagulation with heparin is used to blunt this response, preventing clot formation both in the bypass circuit and in the patient. Heparin works by enhancing antithrombin III, which inhibits thrombin and factor Xa, reducing fibrin formation and the risk of circuit thrombosis and systemic clots while on bypass. After the bypass is finished, the anticoagulation is reversed with protamine to allow normal clotting afterward. The purpose is not to reverse anticoagulation during bypass, not to maintain blood viscosity as the primary goal, and certainly not to promote clotting in the bypass circuit.