Aortic Disruption (Traumatic)
The aorta can rupture completely or incompletely after blunt or penetrating chest trauma. Signs may include asymmetric pulses or BP, decreased blood flow to the lower extremities, and precordial systolic murmur. Diagnosis is often suspected because of the mechanism of injury and/or chest x-ray findings and confirmed by CT, ultrasonography, or aortography. Treatment is open repair or stent placement.
(See also Overview of Thoracic Trauma.)
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).
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.) and to have blood flow maintained, usually by an intact adventitial layer. However, partial ruptures may also cause limited mediastinal hematomas.
Patients 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 BP in the lower extremities compared to the upper extremities.
The diagnosis 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 elderly 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: Immediately available (in most trauma centers) and rapid.
Aortography: Considered the most accurate but is invasive (resulting in a higher complication rate) and takes longer to complete (usually 1 to 2 h).
Transesophageal echocardiography: Rapid (usually < 30 min), 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.
Fluid resuscitation is indicated, but impulse control therapy (decreasing heart rate and BP, usually with a beta-blocker) should be started once other sources of hemorrhage have been excluded. Targets are heart rate ≤ 90 beats/min and systolic BP ≤ 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).
Definitive treatment has traditionally been immediate operative repair, but recent experience suggests that 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 BP (usually with a beta-blocker) and place an endovascular stent or do operative repair.