A family member got a "tissue engineered" valve a few years ago, so the cells (from a human valve, salvaged from the recipient of a heart transplant) were removed, and can be colonized by body cells, very mild to non-existent rejection. This seems to be a permanent solution.

Mechanical prosthetic heart values are generally favoured only in older patients where re-operation is not likely to be required. The reason being that bioprosthetic valves have a more limited long-term durability. So why not always use mechanical valves? Their clotting risk is considerably higher and so they require higher intensity anticoagulant therapy - along with all of the attendant complications of that...