Prevention of femoral vein occlusion by local injection of Thrombolysin in the rat

Thrombosis and altered expression of intercellular adhesion molecule-1 (ICAM-1) after avulsion injury in rat vessels

This study was undertaken to characterize the relative degrees of arterial and venous trauma after graded avulsion injuries. Rat femoral arteries and veins were subjected to reproducible avulsion injuries using forces of between 60 and 220g. Thrombotic occlusion occurred at lower avulsion forces in veins than in arteries. Histologic and scanning electron microscopic analysis indicated increased endothelial disruption and exposed elastic lamina with increasing avulsion force in both vessels, but more prominently in arteries. Intercellular adhesion molecule-1 (ICAM-1) mRNA expression was evident at 3 and 6 hours after avulsion injury in veins, but only with higher avulsion-force injuries in arteries. ICAM-1 mRNA expression was not found in either vessel before or after this 3 to 6 hour post-injury interval. These results indicate that the amount of avulsion force to which traumatized extremity vessels are subjected has a direct effect on the degree of intimal injury and subsequent thrombosis.

Evaluation of the effect of pharmacologic agents on crush-avulsion arterial injuries: a scanning electron microscopy study

This study was designed to investigate the short-term formation and composition of thrombus occurring at sites of arterial intimal injury in rabbits. Anti-coagulants, platelet anti-aggregation agents, and fibrinolytic agents were evaluated for their influence upon the developing thrombus, utilizing scanning electron microscopy to determine thrombus surface composition. These agents included: heparin, aspirin, dextran 40, streptokinase, and prostacyclin. The results are consistent with the known nature of each of these agents. When two agents were given simultaneously, each acting on different aspects of thrombogenesis (platelets vs. fibrin), the outcome appeared synergistic, with substantial reduction in thrombus accumulation; clear inhibition of both platelet aggregation and fibrin polymerization was noted. These findings support the clinical use of two agents used simultaneously, one inhibiting fibrin strand formation and the other inhibiting platelet adherence aggregation, for the prevention of micro-arterial thrombosis.

Selective heparinization of venous anastomosis in latissimus dorsi free flaps to cover lower-extremity soft-tissue defects

Two groups of consecutive patients treated with latissimus dorsi free myocutaneous flaps to cover lower-extremity soft-tissue defects were compared for postoperative vascular occlusion. In the first group of 13 patients (group I), there were five (38%) venous occlusions and no arterial occlusions. The second group of 15 patients (group II) was treated with selective heparinization of each venous anastomosis via a 0.35" catheter sutured into the serratus branch of the donor vein. In this group one patient suffered an arterial occlusion, but no patient suffered a venous occlusion. Statistical analysis using the Fisher exact probabilities test showed a significant decrease in vascular occlusion rate in group II, proving that selective heparinization had a beneficial effect on the venous patency rate.

The effects of intravenous prostacyclin in a model of microsurgical thrombosis

Numerous agents have been administered in an attempt to achieve specific biochemical antiplatelet activity. A model of microsurgical trauma was utilized to create a nonocclusive thrombus, similar to what occurs in the postoperative period. Prostacyclin (PGI2) was given in a high intravenous dose which caused in vitro inhibition of platelet aggregation in rats and rabbits. Although hematological and cardiovascular side effects of PGI2 were tolerated, in vivo platelet thrombus formation persisted and constituted 25-75% of the postoperative thrombus. Even though platelets were inhibited by PGI2, other significant stimuli remained at the site of injury for activation and participation of platelets in the formation of a thrombus.

Experimental models for evaluating antithrombotic therapies in replantation microsurgery

A variety of anticoagulation and antiplatelet aggregation agents are in use clinically, and in applications to microvascular surgery, a clear choice for the most effective therapy has not been determined. Models of vascular trauma combined with microvascular anastomosis have been developed for comparing the efficacy of these agents in maintaining vascular patency. In a rat model of microvascular thrombosis, heparin effectively prevents occlusion in both arteries and veins, at clinical levels of administration. Aspirin helps prevent thrombosis, but not as well as heparin. These results support the beneficial effect of antithrombotic drug therapies, and suggest a more potent role of the heparin-inhibited fibrin clot over platelet aggregation in creating thrombotic occlusion of small vessels.

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.

Comparison of efficacy of thrombolysin, streptokinase, and urokinase in a femoral vein clot model in rats

A venous clot model in rats was used to compare the ability of locally infused thrombolytic agents to lyse clots. Urokinase and a combination of streptokinase and human plasminogen (Thrombolysin) proved to be equally effective in lysing clots. In comparison, streptokinase alone was not as effective a thrombolytic agent in this model.