Hello @shaheenn and welcome to Connect. It is so good to hear that you are helping your brother with his medical problems. Being a health care advocate is an important role these days. It really is important for all of us to have advocates who are watching out for us and seeking the best treatment possible.

You pose a good question about which route to go. I can certainly understand your concerns no matter which decision you make. On Mayo Connect, we are not medical professionals and therefore cannot suggest the best solution for your brother. However, there may be others in the Connect community who will offer comments. As we wait for others to comment I've posted some discussions we have on aortic aneurysms on Connect. Perhaps these discussions might provide some perspective.
https://connect.mayoclinic.org/discussion/aortic-aneurism-and-hip-replacement/
https://connect.mayoclinic.org/discussion/ascending-aortic-aneurysm-and-exercise/
https://connect.mayoclinic.org/discussion/pending-surgery-for-ascending-aortic-aneurysm-5-2-prior-open-heart-at/
I would also like to invite Ginger, @gingerw, to this discussion. While she does not have an aneurysm, she does have kidney problems and has had to adjust to concerns about using contrast.

While you have had two opinions from good vascular surgeons, I'm wondering if a third opinion from a teaching hospital (like a university medical school) or a facility like Mayo, might provide you with a bit more confidence in which path to follow.

Have you considered getting one more opinion?