GROWTH-FACTOR PRODUCTION BY ARTERIAL AND VEIN GRAFTS - RELEVANCE TO CORONARY-ARTERY BYPASS-GRAFTING

Background. Occlusion caused by myotintimal hyperplasia, atheroscleros is, or both is the main reason for late failure of saphenous vein coro nary artery bypass grafts. On the other hand, internal mammary artery grafts are usually spared from atherosclerosis. Evidence exists that p latelet-derived growth factor (PDGF) and basic fibroblast growth facto r (bFGF) are involved in the genesis of myointimal hyperplasia and ath erosclerosis. The aim of this study was to assess the production of PD GF and bFGF by arterial and vein grafts. Methods. In 20 inbred Lewis r ats a 1 cm long segment of arterial graft was interposed at the level of the abdominal aorta. In a control group of 20 Lewis rats a 1 cm lon g segment of vein graft was implanted at the level of the abdominal ao rta. Animals were killed 4 weeks after operation, and the grafts were studied in serum-free organ culture to assess the production of PDGF a nd bFGF. Results. Arterial grafts produced a smaller quantity of PDGF and bFGF than vein grafts (p < 0.01). Higher mitogenic activity was pr esent in the conditioned media from vein grafts than in the conditione d media from arterial grafts (p < 0.001). A large amount of myointimal hyperplasia was present in all vein grafts. Conclusions. This phenome non could explain the rarity of atherosclerotic changes in internal ma mmary coronary bypass grafts.