What is an aneurysm and how do they form?
When the wall of an artery becomes weakened, the pressure within the vessel can cause the wall to bulge out forming a localized dilation, or aneurysm. Although a small percentage of such cases are due to inherited factors, the vast majority appear to represent a variant of atherosclerosis and like atherosclerosis, they tend to occur in a limited number of locations. Most aneurysm seem to occur in the abdominal aorta, the main artery lying in the center of the abdomen. Other common sites include the groin and the vessels behind the knee.
