Reviewed by Brian R. Robinson, MD
An aneurysm occurs when the normally straight tube that is an artery widens out, expanding its diameter to form a balloon-like area in the artery. This widening of the artery causes the walls to weaken and, in some cases, to burst, causing serious internal bleeding that may lead to death.
Aneurysms occur most often in the body’s largest artery, the aorta. The smaller arteries in the vein are the next most common area for aneurysms. Aneurysms can occur in the arteries of the legs, but these arteries are less likely to cause serious problems. Aortic aneurysms usually form at a spot on the artery weakened by atherosclerosis and long-standing high blood pressure. This is because blood vessel walls comprise multiple layers of muscle and connective tissue, and when plaque deposits that characterize atherosclerosis 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, and eventually, when compounded by high blood pressure, the force of the pounding blood vessels stretches the damaged vessel wall, and enables the aneurysm’s formation.