IS Case 607: Traumatic aortic injury - aortic transection
Imaging Sciences URMC 2010
Publication Date: 2011-11-17
History
The patient is a 59-year-old male restrained driver involved in a head on motor vehicle collision. The airbag was deployed and a steering wheel deformity was noted. The patient was found seizing at the scene and transported to the hospital with stable vital signs on arrival.
Findings
Initial chest and pelvis radiographs demonstrated significant widening of the mediastinum most likely consistent with traumatic aortic injury, a left clavicular fracture with distraction. Chest CT with contrast revealed an aortic tear just distal to the left subclavian artery. Aortic angiography reveals contrast extravasation at the aortic tear just distal to the left subclavian artery.
Discussion
“Transection of the aorta is one of the most urgent diagnoses to be considered following major trauma. Signs of mediastinal hemorrhage radiographically include mediastinal widening greater than 8.5 cm, a mediastinal width to chest width ratio greater than 25%, a left apical cap, a wide right paratracheal stripe greater than 5 mm, and a pleural effusion” [1]. Any suspicion for a traumatic aortic injury should be investigated further with CT angiography or conventional aortography.
Blunt trauma, often obtained during a motor vehicle accident, is the most common cause of injury to the thoracic aorta. “The mechanism of blunt trauma is traditionally described as a result of sudden deceleration, with tearing of the aorta at the junction of its fixed and mobile portions: proximal ascending aorta, just beyond the left subclavian (aortic isthmus), and just above the level of the diaphragm. Angiographically 85-95% of aortic injuries involve the isthmus” [2]. The CT angiogram should be analyzed specifically for evidence of mediastinal hemorrhage (poorly defined fat planes, perivascular hematoma, periaortic hematoma, and contrast extravasation) or direct signs of aortic injury (abnormal contour, change in caliber, intraluminal irregularity).
Fifty to 85% of patients with aortic injury die before reaching the hospital. Multiple concomitant injuries are sustained which complicates the treatment and recovery periods. Treatment involves placing a surgical graft over the injured segment with complications ranging from appropriate graft size, accurate placement, and possible occlusion of the left subclavian artery.
References
- Reed JC. Chest Radiology: Plain Film Patterns and Differential Diagnoses. Fifth edition. Mosby, 2007:100.
- Brant WE, Helms CA. Fundamentals of Diagnostic Radiology. Third Edition. Lippincott Williams & Wilkins, 2006:675-678.
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