Effect of external stenting and systemic hypertension on intimal hyperplasia in rat vein grafts

OBJECTIVE: Overdistention of vein grafts in arterial circulation and system ic hypertension are thought to be influential risk factors contributing to vein graft failures. This study tested the effects of external stenting in preventing systemic hypertension and overdistention of the rat vein graft i n the long term. METHODS: Jugular vein grafts were interposed into the carotid artery of nor motensive (n = 39) and two-kidney, one-clip hypertensive (n = 30) rats. Jug ular vein grafts wrapped with 1.5-mm-diameter polyester stents were used in normotensive (n = 26) and hypertensive (n = 25) rats. The vein grafts were harvested at 1, 2, 4, 8, 12, and 24 weeks after the grafting procedure. Th e neointimal area and wall thickness were measured by computerized planimet ry, and Ki-67 immunohistochemistry was used to detect replicative smooth mu scle cells in the graft wall. RESULTS: In each group, intimal hyperplasia was apparent at 1 week and incr eased gradually to 24 weeks. The number of Ki-67-positive cells was most in creased at 2 weeks after the grafting procedure and gradually decreased the reafter. The numbers of Ki-67-positive cells and the extent of intimal hype rplasia were not significantly different between normotensive and hypertens ive rats. Both neointima formation and cell proliferation in the graft wall were significantly reduced by external stenting as compared with the resul ts with unstented grafts. CONCLUSION: Systemic hypertension by itself is not a risk factor for intima l hyperplasia and experimental vein graft failure in the long term. Externa l stenting is effective against intimal hyperplasia, and it is possible to reduce the subsequent atherosclerotic change of the vein graft wall and imp rove the long-term patency of the vein graft with external stenting.