DR ROSENBERG: Studies on the preparation of a chemically modified heterologous artery and its performance as an arterial graft were begun in 1954, at a time when arterial allografts were in widespread use and when work on the first plastic arterial prosthesis had already begun. The collagen tube, which resulted from enzymatic removal of immunoreactive proteins from the bovine carotid wall and subsequent tanning with dialdehyde starch, has since been subjected to extensive long-term testing in both laboratory and clinical situations. Indeed, some 25,000 such grafts have probably been implanted to date, with some applications other than its original use as a peripheral arterial substitute. Our panel was selected for its expertise in one or more of these applications, and the questions are directed to problems encountered and results achieved.
Question 1: What has been your long-term patency rate, using the bovine graft as (a) a femoropopliteal bypass above the