Sorry to hear that HM... my brother was born with a bad valve on his heart. Doctors told him when he turned 25 he'd have to have either an artificial valve or a donor valve installed. When he turned 25 he opted to have the artificial valve and has to take Coumadin the rest of his life. He's now 39 y/o and doing fine. Funny thing was, after he fully recovered from his surgery, we went on vacation and while we'd be laying in bed and it was dead quiet, you could here this metal valve open and close if you listened closely.
Still praying for you and your bro-in-law... trust in the Lord!