Association between plasma levels of tissue plasminogen activator and postoperative deep vein thrombosis--influence of prophylaxis with a low molecular weight heparin. The Venous Thrombosis Group

In a prospective, randomized controlled study, tissue plasminogen activator (t-PA) and tissue plasminogen activator antigen (t-PA:ag) were measured pre- and postoperatively in 40 consecutive patients undergoing total hip replacement. Patients received either a subcutaneous injection of low molecular weight heparin or placebo once daily. Deep vein thrombosis was diagnosed by bilateral phlebography. Patients who developed postoperative thromboembolic complications had significantly lower preoperative t-PA activity levels than patients who did not develop such complications. No difference was observed between the two groups with respect to t-PA:ag. Thromboprophylaxis with low molecular weight heparin did not cause any significant changes in t-PA activity and t-PA:ag. This study in high risk patients indicates that impaired fibrinolysis may be associated with development of thromboembolic complications after operation.