The effect of subcutaneously administered low-molecular-weight heparin on microarterial thrombosis in the rat.

OBJECTIVE To examine the effect of administration of a low-molecular-weight heparin derivative, enoxaparin, on the rate of arterial thrombosis in a rat model. STUDY DESIGN Prospective, randomized, blinded study. METHODS A standard microarterial anastomosis tuck injury was created in both femoral arteries of 25 Long Evans retired breeder rats. Thirteen animals received a subcutaneous injection of 50 IU/kg of enoxaparin 2 hours before the procedure, while 12 control animals received vehicle (isotonic sodium chloride solution) alone. Sites of injury/repair were assessed 2 hours after the procedure for anastomotic patency or thrombosis. RESULTS Six (23%) of 26 vessels in the drug-treated group developed an arterial thrombosis at the site of repair, while 6 (25%) of 24 vessels in the control group developed thrombosis. There was no statistically significant difference at the 95% confidence limit between the 2 groups based on a comparison-of-proportions test. CONCLUSION The preoperative subcutaneous administration of 50 IU/kg of enoxaparin did not alter the rate of arterial thrombosis following the creation of a thrombogenic tuck injury/repair of the rat femoral artery.