Influence of dexamethasone on intimal thickening in experimental vein graft

The influence of dexamethasone on vein graft intimal hyperplasia was studied in a rat model. The iliolumbar vein was grafted to the common iliac artery in 42 rats. Twenty animals were treated with dexamethasone 0.1 mg/kg per day by injection for 3 weeks; 22 control animals received saline injections. Grafts were harvested at 3 weeks and longitudinal sections prepared. Five deaths and considerable morbidity was seen in the dexamethasone-treated animals. All grafts in the surviving animals in both groups were patent at 3 weeks. Intimal thickening, measured in the proximal, mid and distal graft, was found to be maximal in the proximal graft and least in the mid-portion of the graft. Dexamethasone reduced intimal thickening throughout the graft; the median thickness of the proximal graft was 30 microns (control 50 microns), in the mid-graft 10 microns (control 30 microns) and in the distal graft 20 microns (control 30 microns). This reduction was statistically significant in the mid-graft only (P < 0.05; Mann-Whitney U test). The small effect on anastomotic intimal thickening suggests that dexamethasone is of limited use in the prevention of vein graft intimal hyperplasia in clinical practice.