Neointimal hyperplasia in a porcine model of vein graft disease: comparison between organ culture and coronary artery bypass grafting
BACKGROUND: Neointima formation is a crucial problem in the early phase after coronary artery bypass grafting which may result in vein graft stenosis and occlusion 10 years after surgery. METHODS: Six pigs underwent aortocoronary bypass surgery by grafting the left internal mammary vein to the left anterior descending coronary artery (LAD). The remnants of internal mammary veins were cultured for 14 days under standardized conditions. Pigs were sacrificed two weeks after surgery. Histological and immunohistological investigations were performed with special regard to morphometric analysis, differences of the vein wall structure and connective tissue changes. RESULTS: Histological examination revealed similar amounts of collagen, elastic and reticulin fibers in intima and media of native and cultured vein segments with an accumulation in the neointima of vessel specimens after bypass surgery (p<0.01). Moreover, veins at day 14 after bypass surgery showed a significant increase of the intima (220.74 µm vs. 1.91 µm in native and 2.14 µm in cultured veins; p<0.01) and a thickening of the media (334.07 µm vs. 52.44 µm in native and 76.29 µm in cultured veins; p<0.01). CONCLUSIONS: Contrary to cultured vessel specimens, venous conduits are characterized by the development of neointima formation, thickening of the media and a higher percentage of elastic, collagen, reticulin fibers and vascular smooth muscle cells in the intima.
Ch. M. Steger, J. Bonatti, J. Nagiller, D. Wiedemann, W. Sterlacci, G. Laufer, Th. Schachner, European Surgery 3/2011