Pliable plastic aortic substitutes have enjoyed an increasing extension of use since the introduction of Vinyon N by Voorhees, Jaretzki, and Blakemore.23Complications have, in general, been meager; however, the many experimental studies concerning this subject include very few reports in which the follow-up period was as long as two years.1,2,4-17,19-22,24Recent evidence indicates a loss of as much as 80% of the strength of nylon six months after implantation.8The importance of the synthetic fabric itself as a part of the newly formed artery is emphasized by Shumacker's experience18in which removal of the plastic tube from a newly formed vessel was followed by aneurysm formation. The fibrous sheath alone was unable to maintain the integrity of the vessel wall when subjected to the pressure of the arterial system. In another instance, following resection of a large aortic aneurysm with insertion of a nylon graft,