Unless Dick has had some valve dysfunction, this would appear wrong (Dick is well past that) and is typical of the shoddy research I currently see.
I'm surprised they didn't at least have the humility to use probably or call the maker and ask. However then they wouldn't click over their publication counter ....
The only "oops" I've had was a stroke that was due to my mismanagement of warfarin (before the INR system was introduced).
Doesn't surprise me that long-term valve success is not followed closely by the Cardiovascular industry. 10-15 years ago I tried to get an ID card to carry in my wallet in case of emergency. Even Edwards Lifesciences (manufacturer of the valve) had no record of me. I finally tracked down my surgeon in Texas......sent him the only remaining operating room document (signed by him) and he intervened for me with Edwards and got me an ID card.
My ID card reads:
Implant date 16-Aug-1967
sIze 23MM, position Aortic
I think the UNK stands for UNKNOWN. Either they didn't put serial numbers on the valves in 1967.......or I got some kind of experimental valve. I've donated my body to the University of Louisville so I guess they will finally find out what I have when they open me up