An aneurysm occurs when the wall of a blood vessel becomes weak and starts to bulge. This weakening creates an abnormal widening or “ballooning” more than 50 percent of the vessel’s normal diameter. Most Americans diagnosed with an aneurysm have an aortic aneurysm, an aneurysm in the aorta. This is the largest artery in the body, which extends from above the heart and down towards the hips.
Aortic aneurysms can occur in the wall of the aorta in the abdomen (abdominal aortic aneurysm) or in the chest (thoracic aortic aneurysm). Left untreated, aortic aneurysms can dissect or rupture, and can cause life-threatening complications.