An aneurysm is an abnormal dilation of the wall of an artery that leads to weakening of the artery. As a result, the artery may rupture and cause serious internal bleeding and, possibly, death.
Aneurysms occur most often in the body's largest artery, the aorta, but can occur in smaller arteries such as the cerebral (brain), renal (kidney) and carotid (neck) arteries. Ruptures in the arteries of the brain cause brain hemorrhages, which will lead to stroke like symptoms. Aneurysms can occur in the arteries of the legs, but these arteries are less likely to cause serious problems.
Aortic aneurysms usually develop at a region on the artery weakened by atherosclerosis and long-standing high blood pressure. Blood vessel walls are comprised of multiple layers of muscle and connective tissue. When plaque deposits form on the inside of the artery, oxygen and other nutrients cannot penetrate to get to the middle layer of tissue. The lack of nourishment weakens this tissue. Eventually, the force of the pounding blood vessels stretches the damaged vessel wall. In addition to atherosclerosis, recent studies have indicated that there may be other factors causing aneurysm formation; these include hereditary factors, abnormalities in the blood vessel wall matrix, and other hemodynamic factors related to poor blood pressure control. Bacterial infection may also be a source of arterial wall compromise. In this case, the most common organism found is Salmonella. This type of aneurysm is usually found in the abdominal aorta and is also known as a Mycotic abdominal aortic aneurysm.
