Is it the time to reconsider the choice of valves for cardiac surgery： mechanical or bioprosthetic

Valvular heart disease is a pathologic processinvolving one or more of the four valves （aortic,pulmonary, mitral and tricuspid） of the heart typified bystenosis or regurgitation and leading to patient symp-toms. The most common causes are tissue degeneration,rheumatic fever and congenital heart diseases. Aorticvalve replacement （AVR） using either mechanical orbioprosthetic （tissue） valves via open-heart surgicalAVR （SAVR） is the most widely accepted standardtreatment.