Update:
Thank you for your prayers!! God answered! My dad's surgery went beyond well. It was completed in half the time it usually takes, he didn't need a valve replaced so he won't need to be on blood thinners as originally thought, and he is already in the recovery process. He will be in the hospital the rest of the week and then able to go home where he will be recovering the next couple of months.
We are so thankful for the many prayers that were prayed and words of encouragement and faith. May the glory of God continue to be shown through trials such as these...He is always faithful.