Verapamil reduces intimal hyperplasia in a sheep carotid artery patch graft model

Background: The current study investigated the effect of verapamil on the development of intimal hyperplasia (IH) using a sheep model. Methods: A gelatin-sealed Dacron patch graft was implanted into the left common carotid artery in 40 adult Merino sheep. Sheep were then randomly allocated to four groups. Group 1 were controls given no treatment (n = 10). Groups 2-4 were treated with intravenous verapamil 0.5 mg/kg per day in two divided doses for different lengths of time. Group 2 (n = 10) received treatment for 1 week, group 3 (n = 10) received treatment for 2 weeks and group 4 (n = 10) received treatment for 4 weeks. All sheep were killed at 4 weeks and the grafted segments of artery were harvested for IH assessment by an image analysis system. Results: The IH index from the three groups treated with verapamil was significantly less than that of the control (group 1, 0.287 +/- 0.077; group 2, 0.205 +/- 0.064, P < 0.05; group 3, 0.193 +/- 0.059, P < 0.01; group 4, 0.171 +/- 0.036, P < 0.01). Conclusion: The present study suggests that verapamil inhibits the development of IH even when treatment is given for only 1 week.