I am not sure if it's you that think there is something wrong with the arch or it is the Dr that has told you that. In my experience nothing beats a good and experienced cardiovascular/thoracic surgeon and a Cardiologist that focuses on aneurysms, they would tell you exactly the extent of the issue and the repair process with all the risks involved. If you are not being supported by an experienced team, find yourself one, I know we all have to advocate for ourselves but there are limits (big limits at least in my case maybe you do have a medical background) to what we can infer from tests and imaging, it is already stressing to know that you have an aneurysm. I have posetd my story several times but just in case, I had my surgery about 4 1/2 years ago, I was very stressed since when they found my aneurysm it was 5.2 cm but I couldn't have surgery immediately since I had to recover from leg fracture surgery (how they found it). My surgeon and my cardiologist were (are) incredible, experienced, knowledgeable, caring, they answered all my questions, gave me all the details I needed, they showed me samples of the graft that needed to be placed and how it would work, just amazing. I hope everything goes well!!!!!