Everyone here knows I spent a month trying to outsmart my surgeon and his STRONG recommendation of a mechanical valve for me. I'm 61 with no co-morbidity; that is, no CAD, HTN, renal disease, diabetes, lung disease. The more co-morbidity the shorter your life-expectancy. More than one of these and it may be likely you would not outlive a tissue valve, regardless of your age. It took me the whole month to understand that since I have no co morbidity, the mech valve was the right choice. Be aware that trying to second-guess your surgeon on tissue versus mech or even the brand and model of valve may set you up for a difficult post-op period. TRUST is absolutely key to a comfortable post-op. All my knowledgeable second-guessing did nothing but create severe anxiety and sleeplessness during my hospital stay. I suggest you find a surgeon and hospital you think you can trust and do what they say.