Surgery Tomorrow
Luisa, it's natural to be nervous. Breathe... in and out. In and out. Remember that you are not the first patient your doctor and surgical team have operated on. It might be your first time, but it isn't theirs. 
There's a breathing technique that I use when I'm super stressed. It's the 4-7-8 technique. If you google it, you'll find writeups and also some demo videos. I think there's even one by Dr. Andrew Weil.
Try to get some sleep. Don't worry so much about a high heart rate. They're going to give you medication before you get to the operating room that will take the edge off. In my case, "taking the edge off" meant I was asleep before I got to the actual operating room. I was bummed out because my doctor did the procedure robotically and I had really wanted to see the machine before they put me under all of the way!
I'll be thinking of you and sending lots of good thoughts and positive energy up your way!
Mary
Once you make a decision, the universe conspires to make it happen
- Ralph Waldo Emerson 
