Aortic aneurysm. Gross specimen of a longitudinal section (along its length) through an aorta that has an aneurysm (swelling). The aorta is the main body artery that supplies blood from the heart to most parts of the body. This is the thoracic (chest) part of the aorta. The swelling (largest at lower left) is due to weakening of the wall of the artery, which then swells under the pressure of arterial blood. If an aneurysm ruptures, death often results from massive internal bleeding. The aneurysm can be surgically repaired by grafting a reinforcing implant to replace the weakened part of the artery.