Effects of cod-liver oil on intimal hyperplasia in vein grafts used for arterial bypass.

Cod-liver oil rich in eicosapentaenoic acid, an unsaturated fatty acid, has been shown to inhibit platelet aggregation. To determine the effect of this acid on vein-graft intimal hyperplasia, 46 segments of undistended external jugular vein were interposed between the bilaterally divided femoral arteries of 26 mongrel dogs. The animals received a 2% cholesterol diet for 1 week before and 6 weeks after the operation. Eight control animals received the diet alone, eight received cod-liver oil containing 1.8 g of eicosapentaenoic acid daily, for 1 week before and 6 weeks after operation, and seven animals received 1.8 g of eicosapentaenoic acid daily for 6 weeks after operation. Intimal thickness was measured at 6 weeks with a Zeiss computerized interactive image analysing system from multiple cross-sections of vein graft; 395 +/- 10 measurements were made from each graft. The intima measured 4 +/- 0.2 micron (SEM) before implantation and increased to 83 +/- 10 micron in the controls. Eicosapentaenoic acid administered before and after operation reduced intimal hyperplasia to 24 +/- 2.5 micron (p less than 0.001) and to 30 +/- 5 micron in animals receiving eicosapentaenoic acid after operation only (p less than 0.001). These results indicate that the acid inhibits intimal hyperplasia of canine vein grafts but that it is more effective when given before operation (p less than 0.01).