Injury of the thoracic aorta refers to any injury which affects the portion of the aorta which lies within the chest cavity. Injuries of the thoracic aorta are usually the result of physical trauma; however, they can also be the result of a pathological process. The main causes of this injury are deceleration (such as a car accident) and crush injuries. There are different grades to injuries to the aorta depending on the extent of injury, and the treatment whether surgical or medical depends on that grade. It is difficult to determine if a patient has a thoracic injury just by their symptoms, but through imaging and a physical exam the extent of injury can be determined. All patients with a thoracic aortic injury need to be treated either surgically with endovascular repair or open surgical repair or with medicine to keep their blood pressure and heart rate in the appropriate range. However, most patients that have a thoracic aortic injury do not live for 24 hours. Mechanism Injuries to the aorta are usually the result of trauma, such as deceleration and crush injuries. Deceleration injuries almost always occur during high speed impacts, such as those in motor vehicle crashes and falls from a substantial height. Several mechanical processes can occur and are reflected in the injury itself. A more recently proposed mechanism is that the aorta can be compressed between bony structures (such as the manubrium, clavicle, and first rib) and the spine. In the ascending aorta (the portion of the aorta which is almost vertical), one mechanism of injury is torsion (a two-way twisting). There are clinical predictors of an aortic injury. The predictors include if a patient is older than 50, was an unrestrained patient, has hypotension, has a thoracic injury requiring thoracotomy, has a spinal injury, or has a head injury. If four of these criteria are met their likelihood for an aortic injury is 30% The aortic wall is made up of three different components the inner layer (intima), the muscle layer (media), and the outer layer (adventitia). A traumatic injury to the thoracic aorta can cause disruption of any of these parts. Therefore, aortic injury is on a scale from injury to a part of the inner layer to a complete tear of all three layers. There are 4 grades of aortic injury. Type I: Intimal tear Type II: Intramural hematoma Type III: Pseudoaneurysm