Biologic valves

Suri RM, Schaff HV. Selection of aortic valve prostheses contemporary reappraisal of mechanical versus biologic valve substitutes. Circulation 2013 128 1372-80. 

Since the success of Professor Cribier, there have been some limitations to the percutaneous technologies used. One of the major limitations relates to valve tissue, which is fragile material when associated with the metallic stent. The biological valve tissue, which when mounted on a rigid stent... 

The main problems so far found for the practical applications of the prosthetic heart valves in cardiovascular surgery seem to be related to the short life exhibited by the biological valves and to the unsatisfactory hemodynamic behaviour and thrombogenic properties shown by the mechanical ones. In attempt to alleviate the above problems, a study has been undertaken to design a new type of prosthetic leaflet heart valve entirely manufactured in polymeric materials. ... 

When any one of the four heart valves requires replacement, the transplanted valve may be from a cow, pig, or deceased human, or it may be mechanical. Biological valves of animal tissue last only about ten years and are better suited for use in older, less-active patients. Mechanical valves are typically fashioned from plastic, carbon, or metal. Although they last longer than tissue valves and seldom require replacement, blood clots may form on their surface, so the recipient must take an anticoagulant for the rest of his or her life. 

Kunadian, B. et al.. Should the tricuspid valve be replaced with a mechanical or biological valve Interact Cardiovasc Thorac Surg, 2007. 6(4) p. 551-7. 

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