Jamie, congrats on your up coming surgery, depending on your surgeon, they will have you stop all meds except if you take heart or diabetes meds about 2 weeks before surgery, Dr. Mcginn lets you stay on spiro till a couple days before surgery but estradiol was stopped 2 weeks before, the reason for watching your potassium is because of the spiro, a banana once in awhile should be ok, watch other foods too, you might want to Google foods with potassium to see what to stay away from or limit intake, make sure when you have blood work they the check the potassium level, too much could cause heart failure, after surgery you should be off spiro and back to eating what ever you enjoy.
Paula