Prophylactic gamma radiation of unaffected vein grafts failed to prevent vein graft disease in a chronic hypercholesterolemic porcine model.

OBJECTIVE

The value of prophylactic brachytherapy on vein graft disease is unknown.

METHODS AND RESULTS

Vein bypass grafts in 23 hypercholesterolemic pigs after ex vivo gamma irradiation of the vein grafts (10, 20, and 40Gy) and 16 control veins were analyzed regarding: (1) expression of platelet-derived growth factor (PDGF-AA and -BB, ELISA); (2) smooth muscle cell (SMC) proliferation/cell death (double-immunohistochemistry Mib-1/TUNEL/SMC alpha-actin); and (3) vessel wall dimensions. Planimetric data on vessel wall dimensions revealed no positive effect of gamma radiation on neointima formation and inner lumen diameter. On the contrary, vein grafts subjected to 40Gy were significantly more likely to be occluded and to have reduced inner lumen and increased neointima formation. Radiation therapy had no effect on PDGF expression and SMC proliferation/cell death. The mean inner lumen diameter decreased as PDGF-AA expression increased.

CONCLUSIONS

Prophylactic gamma radiation of unaffected vein grafts failed to prevent vein graft disease in a hypercholesterolemic porcine model. High-dose radiation (40Gy) resulted in more frequent graft occlusion and vein sclerosis.