Ann:
Losing 6 pounds in 36 hours is a helluvalot to lose. Are you sure the scales are accurate (i.e., are they new)?
How old is your fiance? Did he have symptoms pre-op? Was he in good physical shape/condition before surgery?
I was not -- my heart was enlarged, I had congestive heart failure, extreme fatigue, etc., and I felt crummy all the time. Post-op, I still had shortness of breath, fatigue, etc. I also lost 24 pounds in 1 month.
It took me much longer to recover than it should have.
Three years ago, another member here had problems post-op. She had AVR at same hospital, same surgeon as me. I had visited her in the hospital. Two to three weeks later, her sister called me to say XM had no appetite, was fatigued, short of breath. I said I had the same post-op, but suggested she call XM's cardio or the surgeon.
Within 30 minutes, she called back and said they were told to go to the hospital. She spent 3 days in the hospital because of fluid around the lungs. They drained off 1,000ml off fluid -- the contents of one of those bags you see hanging in hospital rooms.
When in doubt, call the doctors.
If they don't seem overly concerned and yet your fiance still feels crummy and has problems breathing -- go to the ER! Better to "waste" an ER co-pay than to ignore the beginnings of a serious situation.