An aneurysm is an excessive localized enlargement of an artery caused by weakness in the arterial wall. Aneurysms may remain silent or rupture, causing serious problems and even death.

An aneurysm can occur in important arteries such as those supplying blood to the brain, and the aorta; the large artery that originates at the left ventricle of the heart and passes down through the chest and abdominal cavities.