Danger of urokinase as an anticoagulant with left ventricular assist devices

The sole administration of urokinase causes no initial prolongation of activated partial thromboplastin time (A-PTT), but thereafter produces serious progressive prolongation of A-PTT; it also causes a progressive, severe decrease in fibrinogen levels and alpha 2-plasmin inhibitor activity by depletion. The antithrombogenicity of urokinase is not caused by prevention of blood coagulation system activation by antithrombin effect, but by secondary fibrinolysis by plasmin. Consequently, the administration of urokinase as a sole anticoagulant results in activation of coagulation and fibrinolysis, and, as a result, induces disseminated intravascular coagulation. Therefore, it is concluded that administration of urokinase is an inadequate anticoagulation therapy unless it is combined with other antithrombin agents.