The influence of nifedipine on microvascular vein graft intimal thickening.

The influence of high-dose Nifedipine on the intimal thickening seen in experimental vein grafts was studied in an established rat model. The iliolumbar vein was grafted to the common iliac artery in 28 control and 30 Nifedipine-treated animals. There was one death in the control group and 10 deaths due to drug aspiration in the treated group; a further six control and four treated grafts were excluded from analysis due to occlusion or histological artefact. Animals were killed at 3 weeks, at which time a Nifedipine assay was performed. Longitudinal sections of the graft were prepared and the intimal thickness in the proximal, mid and distal graft measured using an eyepiece graticule. Median (range in brackets) intimal thicknesses for the control group were as follows: proximal 50 microns (10-120), mid 30 microns (10-70), and distal 30 microns (10-100). Results for the treated group were: proximal 65 microns (10-110), mid 30 microns (5-90), and distal 35 microns (20-120). There was no statistically significant difference between the two groups suggesting that Nifedipine is not of value in the inhibition of early vein graft intimal thickening.