Are artificial valves better than animal valves for replacement operations?

Depends: Each have their own pros and cons. The best thing to do is discuss these with your surgeon.

Depends: Not a straightforward answer since it would depend on the valve needing replacement, the degree of injury, and type of valve to be used. Often mechanical valves need longer and more intense anti-coagulation to keep them going. Best to discuss options with the cardiac surgery team contemplating the procedure.