Effects of antithrombogenic agents on microvenous anastomoses in a rat model.

Objective: To compare venous thrombosis rates among animals treated with aspirin, clopidogrel bisulfate, and ketorolac tromethamine using an anastomotic "tuck" model.

Design: Single-blind randomized animal study.

Setting: An animal laboratory at a tertiary care academic referral center.

Subjects: Forty-two retired Lewis breeder rats divided into 3 equal groups.

Interventions: Before surgical intervention, 1 group received aspirin (10 mg/kg) through gavage; 1 group, clopidogrel bisulfate (5 mg/kg) through gavage; and the final group, ketorolac tromethamine (3 mg/kg) through intramuscular injection. Each rat was then anesthetized, and the femoral veins were prepared bilaterally. A 180° venotomy was made, and the vessels were anastomosed with the tuck model set-up for anastomotic failure. The vessels were checked for patency every 15 minutes for 2 hours after clamp removal.

Main Outcome Measures: The rate of venous thrombosis and the time to thrombosis.

Results: In both the aspirin and clopidogrel groups, 2 of 28 vessels (7%) were thrombosed. Thrombosis occurred in 3 of 28 vessels (11%) in the ketorolac group (P = .86). All thromboses in the aspirin and clopidogrel groups took place at 7.5 minutes after clamp removal. In the ketorolac group, the mean time to thrombosis was 7.5 minutes (range, 0-22.5 minutes). There was no difference in time to thrombosis among the 3 groups (P = .86).

Conclusion: Using a microvenous tuck model set-up for anastomotic failure, we found no difference in the rate of thrombosis or the time to thrombosis in rats pretreated with aspirin, clopidogrel, or ketorolac.