It is difficult to know why his replacement valve is not working properly. I would guess that it is uncommon for an implanted valve to not work properly. Perhaps after they remove the valve they can determine why it has not been working properly. Replacement valves can and do work well and mechanical valves can last a long time. Good luck on the re-replacement.
Sorry to hear about the problems that your husband is having. It is possible that the valve was not the right size or the sutures were not done properly? But normally the mechanical valve is suppose to last a lifetime! I is no fun going for OHS and absolutely NO fun to do it twice in a liftetime!
All the best for the upcoming surgery. I am sure that the Surgeon will be able to report back to you why the 1st valve op was unsuccessful.
we have been told that the valve is not opening and closing properly