Fibrinolysis with intrathrombic injection of urokinase and tissue-type plasminogen activator. Results in a new model of subacute venous thrombosis.

The efficacy of intrathrombic deposition vs. parathrombic infusion of urokinase (UK) and tissue-type plasminogen activator (t-PA) was investigated in a canine model. Gianturco coils were placed by transcatheter techniques into the iliac veins of 12 dogs. Venography obtained 48 hours later showed formation of large thrombi. After heparinization, UK (24,000-48,000 IU/ml) or t-PA (12,500-25,000 IU/ml) was spray-injected at high pressure throughout test clots every half-hour using a steel catheter with multiple side holes. Between injections, the agent was infused below the clots. The contralateral thrombi received an equivalent dose of fibrinolytic agent by continuous infusion. In six cases, plasminogen was injected into test clots prior to activator treatment. Thrombi spray-injected with either activator lysed in 64 +/- 26 minutes. Four of six thrombi treated with parathrombic urokinase infusion showed partial lysis after 133 +/- 50 minutes. After parathrombic infusion of t-PA, three clots showed complete lysis, one showed partial lysis, and two demonstrated no lysis. There was no significant difference in lysis rate between intrathrombic UK and t-PA nor did prior intrathrombic injection of plasminogen accelerate lysis. In summary, intrathrombic injection of highly concentrated UK or t-PA lysed subacute thrombi more effectively than parathrombic infusion.