Degeneration of me
Degeneration of mechanical and tissue valves bioprostheses
Deterioration of gluteal dehyde-treated porcine aortic valve
bioprostheses by calcification which cause stenosis or regurgitation or both now commonly necessitates reparation following several years of function .The failure rate in a dults is approximately 25% or higher, ten years after implantation and recent evidence suggests that failure occurs inover 50% of cases at 15 years, thus , deterioration of bioprosthetic valves is frequent and strongly time dependent . The low rate of valve failure earlier than five years following surgery (1%per year) accelerate to approximately 5% per year , thereafter bioprostheses fabricated from bovine pericardium may have a greater propensity to late primary tissue failure than porcine aortic valves.