Intravascular fibrinolysis of small-vessel thrombosis

The effect of intraarterial fibrinolysin infusion on the prevention and treatment of vascular thrombosis in arterial and venous systems of large and small dogs was studied by use of a free groin flap model. Vessel patency and clot lysis after microvascular repair of the superficial caudal epigastric artery and vein were compared in 14 dogs that received prophylactic infusion of fibrinolysin and in 10 control dogs that did not. In 22 additional dogs, after the formation of a standard fibrin clot, arterial infusion of fibrinolysin was performed to determine its therapeutic effect on fibrin clot lysis. The results demonstrate that, after blunt trauma to peripheral vessels in the dog, prophylactic infusion of fibrinolysin has no significant effect on either vessel patency or percentage of local thrombus formation at the anastomatic site. From a therapeutic standpoint, fibrinolysin was effective in fibrin clot lysis in the large vessels (internal diameter 1.8 to 3.0 mm) of 7 of 10 dogs infused within 48 hours after thrombus formation, but was not effective in the small vessels (internal diameter 0.8 to 1.5 mm) of 11 of 12 small dogs with infusion as early as 1 hour after thrombus formation. The therapeutic effectiveness of the fibrinolytic agents to lyse preformed thromboses in small vessels appears doubtful.