The Journal of Thoracic and Cardiovascular Surgery, Vol 98, 788-791, Copyright © 1989 by The American Association for Thoracic Surgery and The Western Thoracic Surgical Association
Effects of low-dose marine oils on intimal hyperplasia in autologous vein grafts
RW Landymore, MS Manku, M Tan, MA MacAulay and B Sheridan
Dalhousie University, Department of Surgery, Halifax, Nova Scotia, Canada.
The effects of low-dose cod-liver oil on intimal hyperplasia of vein grafts
were examined in 45 adult mongrel dogs undergoing peripheral arterial
reconstruction. Fifteen animals served as the control group, 15 animals
were fed a fish-oil supplement containing 240 mg of eicosapentaenoic acid
daily, and a further 15 animals received 480 mg of eicosapentaenoic acid
daily. Segments of undistended external jugular vein were anastomosed to
bilaterally divided femoral arteries. The grafts were harvested at 6 weeks
and intimal thickness was measured with a computerized interactive image
analyzing system. Serum cholesterol level, prothrombin time, partial
thromboplastin time, bleeding time, and platelet counts were measured
before the operation and at 2, 4, and 6 weeks after the operation. Plasma
levels of thromboxane B2 and prostaglandin F1 alpha and serum levels of
eicosapentaenoic acid were measured before and 4 weeks after the operation.
Serum cholesterol level increased similarly and significantly in all
animals. Serum levels of eicosapentaenoic acid rose proportionately with
the oral ingestion of fish oil but did not affect coagulation parameters.
Plasma thromboxane B2 and prostaglandin F1 alpha were not significantly
affected by the ingestion of marine oils. Intimal thickness was 39 +/- 5
microns in the control dogs. Ingestion of 240 mg of eicosapentaenoic acid
reduced intimal thickness to 24 +/- 3 microns at 6 weeks (p less than
0.01). Increasing the dose by a factor of 2 did not decrease intimal
thickness further, the intima being 23 +/- 2 microns (p less than 0.005).
Our data indicate that small doses of fish oil will reduce intimal
proliferation in autologous vein grafts and that marine oils may exert
their beneficial effects on intimal hyperplasia by a mechanism other than
their known effects on prostanoid metabolism.