@Peter69. Got it, makes sense.
Do you know why your wife is getting bent: FOP? Only skin bents if she continues diving, right. Good luck to both of you. My wife got skin bent 3 years ago. Since then, only 2 dives per day. She is fine.
Yes she has a tiny PFO and they cannot find it to seal it. Its not a direct through opening, but rather enters the heart wall, then runs parallel with the wall a small way and then opens into the other heart chamber. The only way to fix it possibly would be to punch a hole through the heart and he was (understandably) not willing to do this.
We found the solution for her is;
Where possible use 100% O2 at 6 m when doing deco dives
A less aggressive algorithm, regardless of recreational or tech diving. We were using a Oceanic Pro Plus 2 when she got bent, and it seems a very aggressive algorithm compared to the Petrel, so now we only use the Petrel with some conservatism set in. I did some comparisons when diving with both, and the Pro Plus 2 when set on air was showing no or little deco obligation when the Petrel (set on 32% Nx) was showing some obligation.
Also with diving, where in particular at the end of the dive you have to work hard, ie like diving the SS Coolidge, where you have to walk about 40m in water to the beach with twin tanks on. Or shifting tanks and washing gear at the end of the dive. This seems to promote skin bends due to stress of the heart with some nitrogen loading. Thus wherever we can now, my wife takes off her gear in the water and pass the gear up to the boat crew, or I carry the gear back if there is a walk of any length. Also I shift and wash all our gear. She gets to rest and take it easy.
The combination of these things seems to have solved her problems, as we did significant deco diving at Truk, and 4 weeks diving at both Truk and Palau with no incident.
We like to have a 2 hr surface interval or longer, however this is not always possible when doing recreational dives on a boat. With tech diving its more accepted to have at least 2 hours between dives.
When we are diving for long periods (weeks), we slip in some non dive days as well.