Computed tomography (CT) angiogram of a 55 year old patient with an ascending thoracic aortic aneurysm. An aortic aneurysm is a swelling of the aorta, usually due to an underlying weakness in the wall of the artery. This may lead to rupture, causing severe pain, massive internal haemorrhage (bleeding), and, if left untreated, death. The patient was treated for aortic valvular stenosis, 17 years earlier.