ANIMAL-MODEL OF ACUTE DEEP-VEIN THROMBOSIS

Purpose: To develop an animal model of acute deep vein thrombosis (DVT ). Methods: In part I of the study nine juvenile domestic pigs were us ed. Each external iliac vein was transluminally occluded with a balloo n catheter. Thrombin was infused through a microcatheter in one leg ac cording to one of the following protocols: (1) intraarterial (IA): 125 0 U at 25 U/min in the common femoral artery (n = 3); (2) intravenous (IV): 5000 U in the popliteal vein at 500 U/min (n = 3), or at 100 U/m in (n = 3). Saline was administered in the opposite leg. After the ani mals were killed, the mass of thrombus in the iliofemoral veins was me asured. The pudendoepiploic (PEV), profunda femoris (PF), and poplitea l veins (PV) were examined. Thrombosis in the tributaries of the super ficial femoral vein (SFVt) was graded according to a three-point scale (0, +, ++). In part II of the study IV administration was further inv estigated in nine pigs using the following three regimens with 1000 U at 25 U/min serving as the control: (1) 1000 U at 100 U/min, (2) 250 U at 25 U/min, (3) 250 U at 6.25 U/min. Results: All animals survived. In part I median thrombus mass in the test limbs was 1.40 g as compare d with 0.25 g in the controls (p = 0.01). PEV, PFV and PV were thrombo sed in all limbs infused with thrombin. IV infusion was more effective in inducing thrombosis in both the parent veins (mass 1.32-1.78 g) an d SVFt (++ in 4 of 6 legs), as compared with IA infusion (mass 0.0-1.1 6 g; SFVt ++ in I of 3 legs). In part IT thrombus mass in axial veins ranged from 1.23 to 2.86 g, and showed no relationship with the dose o f thrombin or the rate of infusion. Tributary thrombosis was less exte nsive with 250 U at 25 U/min than with the other regimens. Conclusion: Slow distal intravenous thrombin infusion in the hind legs of pigs co mbined with proximal venous occlusion induces thrombosis in the leg ve ins that closely resembles clinical DVT in distribution.