Reduction of intimal and medial thickening in sheathed vein grafts

Background, Arterial pressures are described as an important factor in the development of graft degeneration and in reduced patency rate in vein bypas s grafts. Sheathing of the graft with a pressure resistant mesh tubing migh t slow down this development. Methods. Saphenous vein grafts were implanted into the carotid arteries of five pigs in order to evaluate the influence on myointimal hyperplasia of a compliant Phynox mesh tubing (a wrought Cobalt-Chromium-Nickel-Molybdenum- Iron Alloy), which surrounded autologous vein grafts that were exposed to a rterial pressure. Each pig was operated on using a sheathed vein graft (bio compound-graft, a hybrid vascular prosthesis) on one side and an untreated saphenous vein on the other. Results. After 4 weeks intimal hyperplastic changes were found in all histo logical sections. The wall thickness (medial and intimal layer) varied from 351 mu m to 432 mu m in the biocompound-graft and from 391 mu m to 1196 mu m in the native vein grafts (p < 0.05, n = 5). Severe myocytial and fibrob last proliferation was only found in the control grafts. Cellularity of the medial layer differed at sites of maximal cellular density and ranged from 11 to 12 cells in the biocompound-graft and from 17 to 18 cells per counti ng field in the native vein grafts (p < 0.05, n 5). Conclusions. External support of vein grafts reduces intimal and medial lay er proliferation. The findings of this study are in accordance with the res ults reported by other research groups. (C) 1999 by The Society of Thoracic Surgeons.