The incidences of valve failure were 3.35%/patient-year for bovine valves, 1.52%/patient-year for porcine valves and 2.2%/patientyear for dura mater valves.

• 49例的51只生物瓣膜损破；损破率为2.；62%25病人-年；牛心包瓣的损破率为3