[Anticoagulant therapy and cardiopulmonary bypass]

Cardiac surgery is an area in which coagulation monitoring has vital applications. Cardiopulmonary bypass (CPB) procedures could not be performed without an effective method of preventing blood from clotting in the extracorporeal circuit. In the early part of the twentieth century, heparin was discovered to have anticoagulant properties; it remains the anticoagulant most commonly used during CPB. Reversal of heparin effect is most frequently performed using protamine; however a number of different pharmacologic agents and reversal techniques can be utilized. CPB itself induces a "whole body inflammatory response" due to contact of blood and cellular elements whit the extracorporeal circuit. This complex interplay of systems induces a coagulopathy characterized by microvascular coagulation, platelet dysfunction, and enhanced fibrinolysis. The need to monitor anticoagulation during and after surgery is the reason that the cardiac surgical arena has evolved into a major site for the evaluation and utilization of hemostasis monitor. Heparin-induced thrombocytopenia (HIT) is a serious, immune system-mediated complication of heparin therapy often resulting in devastating thromboembolic outcomes. Alternative anticoagulation must be initiated immediately (argatroban, lepirudin and danaparoid). Lepirudin and bivalirudin has been used for on-pump cardiopulmonary bypass surgery.