Doctors are not sure what causes most abdominal aortic aneurysms
to form. Weakened Aortic Wall Stretches Over Time A leading
theory is that there is degradation of certain structural
elements of the aortic wall that cause it to weaken. The
pressure of blood pumping through the aorta causes the weakened
wall to stretch out and enlarge over time. Process Linked to
Atherosclerosis Some researchers believe this process is linked
to atherosclerosis -- hardening of the arteries -- or the risk
factors that lead to atherosclerosis, including high blood
pressure and smoking.