Concerned about anesthesia with bradycardia

They can give you a sedative and to the procedure while you are essentially awake. However, unless you know for a fact otherwise, the procedure is done with propofol, and quick-acting and quickly metabolized anesthetic drug. In some instances, propofol is also mixed with a smidge of fentanyl (don't freak out!. I had it, properly administered, during at least two electric cardioversions to restore sinus rhythm while I had been fibrillating).

Your surgeon runs the show, largely based on experience and skill. I would raise the topic with him/her and ask if you can be minimally sedated. You may not know this, maybe you do, but the procedure isn't for the squeamish, and it is often quite painful. That is why most surgeons insist on putting their patients out because our brains are wired for classical conditioning, and when we associate discomfort or horror with an event, we avoid it like the plague. But, you may need more colonscopies in the years ahead.