Traumatic aortic isthmus pseudoaneurysms are formed when the entire structure of the arterial wall in the aortic isthmus is destroyed due to traumatic injury or when the intima-media is destroyed and only the outer aortic membrane remains. Etiology and pathogenesis Acute deceleration injury to the chest, such as when riding on a high-speed vehicle and hitting a fixed object, because the arteriovenous ligament and intercostal artery anchor the proximal segment of the thoracic descending aorta to the thorax and the cephalic brachial artery to the thoracic outlet, the proximal segment of the thoracic descending aorta and the cephalic brachial artery decelerate with the thorax, while the distal segment of the aortic arch and the blood in its lumen continue to move forward due to inertia, this huge shear force can cause the isthmus to rupture of the nearby aorta. Foreign studies have found that. Aortic trauma rupture is mostly seen in the proximal end of the ductus arteriosus ligament, within 1 cm of the opening of the left subclavian artery, and also in the opening of the left subclavian artery. In rare cases, the rupture may extend to the aortic arch proximal to the left subclavian artery; traumatic aortic rupture can be complete, including rupture of both the epicardium and mediastinal pleura of the aorta. If the shear force is less, the aortic dissection can be incomplete and the mediastinal pleura or even the epiaortic membrane can remain intact. In surviving patients, without surgical intervention, the periaortic hematoma begins to liquefy after 2 weeks, and the liquefied hematoma resorbs or communicates with the aorta, gradually forming a pseudoaneurysm. Clinical Presentation There is a clear history of previous trauma, which may be accompanied by injury to other organs of the body. Some patients may have no specific symptoms, but mediastinal widening is detected on chest X-ray and further CT or MRI examinations are performed to confirm the diagnosis. Some patients have pain in the interscapular region or left chest pain, mostly dull, sometimes persistent pain. Pseudoaneurysm may compress the laryngeal nerve and cause hoarseness and choking; compression of the cervical sympathetic ganglion may cause unilateral pupil narrowing, eyelid ptosis, inversion of the eyeballs and sweatless face and other manifestations of Horner syndrome; compression of the esophagus may cause difficulty in swallowing, and in the late stage, it may break into the esophagus, trachea or bronchus and cause massive vomiting of blood, clicking blood, resulting in hemorrhagic shock or death by asphyxia. Diagnosis After trauma, pain in the interscapular region or left chest gradually appears, and some patients show signs such as Horner’s syndrome and laryngeal nerve compression, etc. X-ray plain film can reveal widening of mediastinum and displacement of trachea and esophagus by pushing. Aortic CTA and MRI can accurately evaluate the size, location, extent and growth rate of aortic pseudoaneurysm, and are also valuable for the evaluation of the timing of surgery, selection of surgical method and postoperative treatment effect, which cannot be replaced by other examinations.