| abstract |
In making artificial arteries from extruded synthetic resin tubes or woven, knitted or braided tubes made from polytetrafluorethylene or similar fibres, the tube is corrugated by placing it on a rod, wrapping a thread or wire helically around it, compressing it longitudinally to form corrugations between the turns of the thread, and setting the corrugations such as by heating or by chemical means. The finished tube is preferably bleached and shrunk by boiling in a bath of nitric, sulphuric and perchloric acids, this process rendering it less reactive to body tissues and less porous. A final product of laminated construction may be formed by superimposing a number of tubes on the former prior to wrapping and in this case the various layers may be of different physical characteristics. Specification 892,981 is referred to. |