I had open heart surgery (plus 4 bypasses) You go into the hospital, they get you ready, give you a needle, and at point I went to sleep. (I remember getting ether as a kid and didn't like the smell so I tried to go to sleep (ether is no longer used)) When you wake up, your chest will hurt and you will have to do breathing exercises. (They will want you to cough and you will hate them for it but what can you do) Intensive care for a day or two, and then a couple of days to make sure you are ok and off home. Because you are asleep, you feel nothing during the operation.
Couple of weeks and you will start feeling better than before surgery, if you are on medication after, do not stop the meds unless your doctor tell you. You may feel 100% but that does not mean you can stop taking your meds.