The Use of Arterial Implants Prepared by Enzymatic Modification of Arterial Heterografts

In a previous report1the use of enzyme-digested heterografts as arterial substitutes was described. Bovine arteries were stripped of most of their parenchymatous proteins by controlled enzyme action, leaving a tubular prosthesis composed mostly of collagen. These tubes were implanted into dogs as aortic substitutes with the hope that, with most of their immunologically reactive proteins removed, the implants would be better tolerated by the host while yet maintaining their effectiveness as arterial substitutes. Short-term observations (up to one year) seemed to corroborate this hypothesis. Since the advent of arterial grafting and the blood vessel bank, the concept has gained acceptance that the integrity of the elastica greatly contributes to the strength of a graft. However, much of the older literature is opposed to that hypothesis. In 1939, by ingeniously calculating Young's modulus * for different weight applications, Krafka2,3was able to show that moduli obtained for the collagen