It can be fixed surgically. I wouldn't go so far as to call it "a simple fix," however, because it's a very complex operation. Aortic arch surgery is highly specialized, and on a child, even more so. I looked at your profile, and you are lucky to live in an area of the US where you should be able to find an expert surgeon. I would look for a surgeon who has done this procedure many times -- not just a handful of times. I don't know a specific number to tell you to look for, because this is not an everyday operation for even a top pediatric heart surgeon, but the higher the number the surgeon has done, the better.
You will know more about what to expect, after you talk to the cardiologist. If he does want to refer you to a pediatric heart surgeon, as I expect he will, I would ask for a referral to a surgeon who does this type of operation on a frequent basis. Hopefully that's the kind of referral he would give you anyway, but I still would bring it up in the conversation.
There are some online support organizations for mothers of children with congenital heart defects. Sometimes they call themselves "heart moms." I don't have contact information for them, but I know they're out there. You should be able to find them by googling. In one of those organizations, you might be able to communicate with another mother whose child has the same condition. You will definitely be able to find mothers of children who have gone through open-heart surgery.
These days, all doctors know that their patients have hit the internet before seeing them. However, unless you are medically educated, it is important to believe that cardiac specialists have studied their subject for years and very likely know more than you do. No joke, and they have no interest in fooling your or harming your child.
So, before the appointment, write down your questions on something like a yellow pad, leaving a lot of space for the answers, and take that with you to the appointment. Keep an open mind, and listen. Really listen. The truth is that when most people ask a question, they scarcely hear the answer because they are so busy with their own thoughts.
And as skydnsr says, look for support groups, too. These people will be your real lifeline.
Thank you so much for taking the time to respond to my question!
Thank you so much for taking the time to respond to my question, I'm really nervous about Wednesday. Do you think that they will tell me that there is something wrong with his heart or is it just the double arched aorta?
I don't know. That's why your child needs to be examined by the cardiologist. I know it's easy for me to tell you not to be nervous, but please try.
Look at this visit as an opportunity for you to get an expert opinion. Achillea's comments on that point are well taken. I invite you to take her advice about writing down your questions in advance.
BTW, I googled "heart moms," and right up at the top of the list was a Moms with Heart group that is sponsored by the American Heart Association.