Thrombolytic therapy is used for myocardial infarctions, stroke, and venous thromboembolic disease. This chapter discusses the agents and management of bleeding. The third type of anticoagulant therapy–besides inhibiting coagulation or platelets–is lysing a formed thrombosis (Table 27.1). In normal fibrinolysis, tPA binds to fibrin and then converts plasminogen to plasmin, which lyses the clot. The ability of tPA to cleave plasminogen to plasmin is far greater when plasminogen and tPA are both bound to the fibrin clot. Moreover, when plasmin is bound to fibrin, plasmin is protected from the action of circulating alpha 2–antiplasmin. Any excess tPA that escapes into the plasma is rapidly inactivated by plasminogen activator inhibitor–1 (PAI–1). Any plasmin that escapes into the plasma is rapidly snuffed out by alpha 2–antiplasmin. Thus, active fibrinolysis is confined to the thrombus itself.
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