Carpentier -Edwards Valve (C-E) : This is porcine aortic valve preserved in gluteraldehyde and mounted on flexible stent made of cobalt-chromium-nickel alloy (ELGILOY). Gluteraldehyde, a chemical used for tanning of leather causes stability to valve leaflets due to cross linkage of collagen fibres and it reduces antigenicity. It has sewing ring with polytetra fluoro ethylene (PTFEGoretex), incorporating silicon rubber. Valves are available for aortic and mitral position in various sizes. Biological deterioration will occur after 7- 10 years but mechanical failure is uncommon. The rate of biological deterioration 'is faster in children.