I'm sorry you have to go thru this, b/c I know EXACTLY how you feel~ I went thru it with my dad a few years ago, and he was in Hawaii and I'm a cardiac nurse
~ I was scared poopless!!! And I hope we don't have to go thru it again, however....at least surgery is in most cases, a permanent fix for his problem.
Just try to keep in mind that hundreds of thousands of heart surgeries are done every year (not on YOUR dad of course, which makes your situation unique) and it's become practically routine. I know that doesn't make you feel too much more secure, and once he's out of surgery you'll feel SO MUCH BETTER!!!
If you have any questions or just want to chat, PM me. I worked with heart surgery patients for almost 25 yrs, so I'm familiar with almost any situation that might arise.
Prayers for you, your dad and your mom that the surgery goes without a hitch and his recovery is smooth sailing!