An aortic aneurysm is dilation, bulging, or ballooning of a weakened part of the aortic artery wall. It can grow large and burst (rupture) or cause a dissection. Both conditions are often fatal.
An aneurysm that occurs in the part of the aorta that’s located in the chest and above the diaphragm is called a thoracic aortic aneurysm.

Treatment for an aneurysm varies according to its severity and size. Thoracic aneurysms whose diameter is twice the size of the normal aorta – or about 5.5 cm – should be considered for surgical repair. In some cases, a minimally invasive procedure called endovascular stent graft aortic aneurysm repair may be performed.