Aortic injury
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Contents |
Background
Blunt chest trauma accounts for approximately 100,000 hospital admissions per year in the United States [3]. Blunt traumatic aortic injury (BTAI) causes mortality in 15-20% of motor vehicular crash (MVC) fatalities [1]. Approximately 85% of patients with BTAI die at the scene of the accident. Historically, of those who survive the initial traumatic event, approximately one third die within 6 hours of the initial injury and 50% die within 24 hours [1, 3]. Therefore, prompt diagnosis and appropriate treatment are crucial to attaining favorable outcome.
Pathophysiology
Blunt thoracic aortic injuries are usually tears and not dissections. They are usually due to major deceleration forces, as in high-speed motor vehicular crashes, automobile vs pedestrian accidents, and falls from significant height. Approximately 85% of patients die at the scene of the accident -- these are usually aortic root tears. Approximately 15% to 20% of patients survive to the emergency department -- these are usually aortic isthmus tears.
The tear is through the intima and media, with the thin but very tough adventitia being able to contain the process in the form of a pseudoaneurysm. Failure of the adventitia usually results in immediate death due to exsanguination.
In thoracic aortic injuries, the mediastinum is usually of abnormal size or contour on radiograms. This abnormality may be due to hemorrhage into the mediastinum. This hemorrhaging is usually due to smaller vessels bleeding, and infrequently from the aorta itself.
Diagnosis
The initial diagnostic study in patients with traumatic injury is chest radiogram. It is important to note that approximately 90% of patients with abnormal-appearing mediastinum (i.e. widening) on the initial radiogram will not have traumatic aortic injury. At the same time, only 1% of patients with normal-appearing mediastinum do have traumatic aortic injury.
Patients may be noted to have one of the following signs on plain chest roentgenogram: (a) mediastinal widening >8cm; (b) loss of the aortic knob; (c) displacement of nasogastric tube to the right of the T4 spinous process; (d) apical pleural cap; (c) tracheal deviation to the right with abnormally low left main stem bronchus [3]. Helical computed tomography (CT) has been shown to be more sensitive (100%) than aortography (92%) but less specific (83%) than aortography (99%) in a study by Fabian et al [2].
Treatment
In blunt thoracic aortic injury, beta-blockers have been shown to reduce the incidence of rupture, and their use is rarely contraindicated [1]. In fact, Fabian et al noted that early diagnosis of BTAI in conjunction with an appropriate antihypertensive medical regimen eliminated in-hospital aortic rupture [2].
Notes & References
[1] Morgan PB, Buechter KJ. Blunt thoracic aortic injuries: initial evaluation and management. South Med J. 2000 Feb;93(2):173-175.
[2] Fabian TC, Davis KA, Gavant ML, Croce MA, Melton SM, Patton JH Jr, Haan CK, Weiman DS, Pate JW. Prospective study of blunt aortic injury: helical CT is diagnostic and antihypertensive therapy reduces rupture. Ann Surg. 1998 May;227(5):666-676; discussion 676-677.
[3] Kuhlman JE, Pozniak MA, Collins J, Kinsley BL. Radiographic and CT findings of blunt chest trauma: aortic injuries and looking beyond them. RadioGraphics. 1998;18:1085-1106.
Credits & Notices
Authors-contributors to this page (listed alphabetically, last name, first & middle initial only, no institutional affiliations, no scientific titles):
Stawicki SP
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