A doctor can determine the size of a thoracic aortic aneurysm by ordering a magnetic resonance imaging or computed tomography scan of a patient's chest and measuring it, states the Society for Vascular Surgery. If the aneurysm is less than 2 inches long and the patient has no symptoms, the physician may wait and take repeat scans every six months. Aneurysms that are larger than 2 inches or cause symptoms may require treatment.
A thoracic aortic aneurysm occurs when a weakened part of the aorta bulges, explains the Society for Vascular Surgery. The aorta is the largest blood vessel in the body, running from the heart through the chest and into the abdomen. Chest, or thoracic, aneurysms account for 25 percent of all aortic aneurysms. If the aneurysm ruptures, the internal bleeding can quickly lead to shock or death. Though many people don't have symptoms, those that do may cough, have difficulty breathing, or pain in the neck, chest, jaw or back. Risk factors include heredity, smoking and high blood pressure. Some patients develop aneurysms when the walls of their aortas weaken due to Marfan's syndrome, syphilis or tuberculosis.
High blood pressure increases the risk of an rupture, so a doctor may prescribe medication to reduce blood pressure, according to the Society for Vascular Surgery. If a patient requires surgery, a surgeon can insert a stent graft into the artery. The graft allows blood to pass through the vessel without further weakening the wall.