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).

Cod-liver oil in the prevention of intimal hyperplasia in autogenous vein grafts used for arterial bypass.

Cod-liver oil, rich in eicosapentaenoic acid, an unsaturated fatty acid, was administered to 14 mongrel dogs to determine if this acid would prevent platelet-mediated intimal hyperplasia. Twenty-eight 1 cm segments of undistended jugular vein were interposed between bilaterally divided femoral arteries. Seven control animals were fed a 2% cholesterol diet 1 week before and for 6 weeks after the operation. A further seven animals received cod-liver oil capsules containing 1.8 gm of eicosapentaenoic acid daily 1 week before and for 6 weeks after autogenous vein implantation, in addition to the lipid-supplemented diet. Baseline serum cholesterol was 4.6 +/- 0.4 mmol/L. The rise in serum cholesterol was similar in the two groups and increased to 7.4 +/- 0.6 mmol/L (control group) and to 6.8 +/- 0.2 mmol/L (eicosapentaenoic acid group) (p less than 0.001). Prothrombin time, partial thromboplastin time, bleeding time, and platelet counts were unchanged in the two groups. Vein grafts, harvested at 6 weeks, were fixed in formaldehyde. Mean intimal thickness was measured from multiple vein graft cross sections with a Zeiss computerized interactive image analyzing system. A mean of 140 +/- 11 measurements were computed from each graft. Marked intimal hyperplasia occurred in the control group and increased from 4.3 +/- 0.3 to 86.4 +/- 14 micron. In contrast, a high eicosapentaenoic acid diet inhibited intimal hyperplasia, with intimal thickness only increasing from 4.0 +/- 0.4 to 24.8 +/- 2.7 micron (p less than 0.001). These data indicate that eicosapentaenoic acid inhibits platelet-mediated intimal hyperplasia and suggest that cod-liver oil could be used to prevent intimal hyperplasia in vein grafts used for myocardial revascularization.