Minute vascular replacements.

Glutaraldehyde-tanned, mesh-reinforced, mandrel-grown ovine collagen conduits were compared with tanned human umbilical arteries and polytetrafluoroethylene (PTFE) grafts in the aorta of rat recipients. All grafts had 100% patency and became lined by a cellular neointima. The mean maximum thickness of the neointima of the tanned human umbilical artery, ovine collagen graft, and the PTFE grafts was 68, 57, and 13 micrometer, respectively. Neointimal proliferation was complete for the two biosynthetic grafts, but none was seen in the center of the PTFE grafts as late as ten weeks. The mean increase in lumen cross-sectional area was 49% for the umbilical artery grafts, 23% for ovine collagen conduits, and 4% for the PTFE grafts. Longer follow-up periods will be required before unqualified support can be given to clinical trials of these small-diameter prostheses; however, long-term patency for synthetic grafts of such a small caliber is encouraging for future microvascular applications and for study of host-prosthesis interactions.