New concepts in the design and use of biological prosthetic valves.

The natural aortic valve is a structure that has thus far eluded all attempts at duplication with synthetic materials. Real success in the replacement of the aortic valve has come about primarily through the use of biological devices, such as the porcine aortic valve xenograft. In the future, bioprostheses based more closely on the natural aortic valve may ultimately succeed where synthetic approaches have failed. Some recent advances in the design and development of bioprosthetic heart valves, such as the absence of a stent and the better preservation of the valve's natural biomechanical properties, show considerable promise in improving the long term durability of these devices. With a greater understanding of the structure/function relationship of the aortic valve at the micromechanical level, the future of bioprostheses may be even more biologically oriented than it is today.