Experimental evaluation of aortic homograft valves mounted on flexible support frames and comparison with glutaraldehyde-treated porcine valves.

The durability of the aortic homograft valve, when mounted in a rigid support frame, has been limited in some cases by aortic wall detachment from the frame in the commissure buttress area. To investigate the effects of frame flexibility, a stent was designed which was suitable for canine aortic valves of selected sizes. Of the two materials tested, acetal copolymer was found to be superior to polypropylene, as stents made from the latter material were permanently deformed as a result of polymer creep under the action of a cyclic load. Observations of a commercially available glutaraldehyde-treated heterograft mounted on a polypropylene frame indicated that stent flexibility was less important than had been suggested in earlier reports. It is considered that the glutaraldehyde preservation and the method of mounting this valve in the frame are major factors in prolonging the life of the implant.