aneurysm, aortic

aneurysm, aortic An aneurysm of the largest artery in the body, the aorta, involving that vessel in its course above the diaphragm (thoracic aortic aneurysm) or, more commonly, below the diaphragm (abdominal aortic aneurysm). Because of the volume of blood flowing under relatively high pressure within the aorta, a ruptured aneurysm of the aorta is a catastrophe. See also aneurysm, abdominal aortic; aneurysm, thoracic.