I'm sorry for your loss. The aorta
is the main artery
out of the heart. If there are signals coming from ie the kidneys since you mention them and they do ask for more blood if they don't think they are receiving what they want, then the heart as "the pump" will keep putting out more and more blood. This can cause wear on the aorta especially right beside of the valve/heart. If the wall gets to thin USUALLY the aorta will stretch and aneurysms form and then hopefully the doctors will happen to find them. However there are those who are more prone to having weakened walls such as people with connective tissue
disorders. The most known, but not well enough known, is Marfan syndrome
. You can find information about aortic aneurysms on many marfan websites. There are other reasons also that aneurysms can form in the "plumbing" system of our bodies but looking that up might help put some peices together in your mind or give your friend some questions she can ask the doctor to get a better understanding.
Usually if the wall does rupture out there is not much time and CPR really isn't the best thing since you would be pumping on the heart speeding up the leakage of blood. With the right hospital and doctors it sometimes can be survived today, I'm a survivor.