Dissecting aneurysm. Gross specimen of a section through a dissecting aneurysm of the aorta (round, centre). This is where the layers of the wall of an artery split or dissect. Blood flows into the gap (dark blood clots) between the inner (bright red) and outer wall. The aorta is the major artery carrying blood from the heart to most parts of the body. If an aneurysm ruptures, massive internal bleeding may result in death. It can be surgically repaired by reinforcing the wall of the artery, but an aneurysm can develop with no or few symptoms.