(See also Overview of Thoracic Trauma Overview of Thoracic Trauma Thoracic trauma causes about 25% of traumatic deaths in the US. Many chest injuries cause death during the first minutes or hours after trauma; they can frequently be treated at the bedside... read more .)
Etiology of Traumatic Aortic Disruption
With blunt trauma, the usual mechanism is a severe deceleration injury; patients often have multiple rib fractures, 1st and/or 2nd rib fractures, or other manifestations of severe chest trauma.
With penetrating trauma, the usual wound traverses the mediastinum (eg, entering between the nipples or the scapulae).
Pathophysiology of Traumatic Aortic Disruption
Complete rupture causes rapid death by exsanguination. Partial disruption with contained rupture tends to occur near the ligamentum arteriosum (see figure Most partial ruptures of the aorta occur near the ligamentum arteriosum Most partial ruptures of the aorta occur near the ligamentum arteriosum ) and to have blood flow maintained, usually by an intact adventitial layer. However, partial ruptures may also cause limited mediastinal hematomas.
Most partial ruptures of the aorta occur near the ligamentum arteriosum
Symptoms and Signs of Traumatic Aortic Disruption
Patients with traumatic aortic disruption typically have chest pain.
Signs can include upper extremity pulse deficits, a harsh systolic murmur over the precordium or posterior interscapular space, hoarseness, and evidence of impaired blood flow to the lower extremities, including decreased pulse strength or blood pressure in the lower extremities compared to the upper extremities.
Diagnosis of Traumatic Aortic Disruption
Traumatic aortic disruption should be suspected in patients with a suggestive mechanism or suggestive findings. Chest x-ray is done.
Suggestive chest x-ray findings include the following:
Widened mediastinum (high sensitivity except among older patients)
1st or 2nd rib fracture
Obliteration of the aortic knob
Deviation of the trachea or esophagus (and thus also any nasogastric tube) to the right
Depression of the left mainstem bronchus
Pleural or apical cap
Hemothorax, pneumothorax, or pulmonary contusion
However, some of these suggestive chest x-ray findings may not be present immediately. Also, no finding or combination of findings is sufficiently sensitive or specific; thus, many authorities recommend aortic imaging for all patients who have had a severe deceleration injury, even in the absence of suggestive findings on examination or chest x-ray.
The aortic imaging study of choice varies by institution. Studies that are reasonably accurate include the following:
CT angiography CT angiography In CT, an x-ray source and x-ray detector housed in a doughnut-shaped assembly move circularly around a patient who lies on a motorized table that is moved through the machine. Usually, multidetector... read more : Immediately available (in most trauma centers) and rapid.
Aortography Uses of Angiography Angiography is sometimes called conventional angiography to distinguish it from CT angiography (CTA) and magnetic resonance angiography (MRA). Angiography provides detailed images of blood vessels... read more : Considered the most accurate but is invasive (resulting in a higher complication rate) and takes longer to complete (usually 1 to 2 hours).
Transesophageal echocardiography Techniques : Rapid (usually < 30 minutes), has low complication rate, can detect certain associated injuries (eg, to the innominate vessels) that can be missed on CT, and, because it is a bedside test, can be used in unstable patients. However, accuracy is operator-dependent, and it is not always available.
If patients are not stable enough to undergo any of the available imaging studies and the cause of shock is suspected to be traumatic aortic disruption, immediate surgery is indicated.
Treatment of Traumatic Aortic Disruption
Blood pressure control
Surgical repair or stent placement
In patients with traumatic aortic disruption, fluid resuscitation is indicated, but impulse control therapy (decreasing heart rate and blood pressure, usually with a beta-blocker) should be started once other sources of hemorrhage have been excluded. Targets are heart rate ≤ 90 beats/minute and systolic blood pressure ≤ 120 mm Hg; and patients should not perform a Valsalva maneuver. Measures should be taken to avoid coughing and gagging if patients require endotracheal intubation (eg, pretreatment with 1 mg/kg lidocaine IV) or nasogastric intubation (eg, avoiding any resistance to tube passage).
Previously, definitive treatment was immediate operative repair, but endovascular stent placement is now the treatment of choice. Surgical repair can be delayed while evaluating and treating other potentially life-threatening injuries.
Partial disruption of the aorta should be considered in patients with a chest injury caused by severe deceleration.
Chest x-ray abnormalities are common but may be absent and are often nonspecific; better aortic imaging studies include CT angiography, aortography, and transesophageal echocardiography.
Control heart rate and blood pressure (usually with a beta-blocker) and place an endovascular stent or do operative repair.
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