Intimal thickness associated with endothelial dysfunction in human vein grafts.

backgroundIntimal hyperplasia is a complex process thought to be initiated by injury and is the leading cause of vein graft failure. In the present investigation, we hypothesized that the basal intimal thickness in the human saphenous vein is a predictor of endothelial dysfunction and, potentially, intimal hyperplasia.

methodsHuman saphenous veins were obtained during coronary artery bypass surgery. The segments were contracted with phenylephrine and relaxed with carbachol to determine the endothelial-dependent relaxation. The vein segments were fixed in 10% buffered formalin and grown for 14 d in high-serum culture and then fixed in formalin. The fixed tissues were stained with Verhoeff-Van Gieson, and the average intimal and medial thicknesses were calculated using light microscopy and a computerized image analysis system.

resultsThe human saphenous veins displayed varying amounts of basal intimal thickness (range 18.80-241.3 μm). The endothelial-dependent relaxation of the veins was highly variable, with values ranging from 0% to 27.59%. Human saphenous veins with a basal intimal thickness greater than 120 μm had significantly less endothelial-dependent relaxation (8.90% ± 6.32%) than those with a basal intimal thickness less than 120 μm (21.97% ± 10.64%). Endothelial dysfunction correlated with a basal intimal thickness greater than 120 μm (P = 0.02). The basal intimal thickness also correlated with increased intimal thickness after 14 d in organ culture (P = 0.0001).

conclusionsA basal intimal thickness greater than 120 μm is a predictor of endothelial dysfunction. Also, because a greater basal intimal thickness correlated with an increased intimal thickness after organ culture, the basal intimal thickness might predict vein graft failure owing to intimal hyperplasia.