Thoracic aortic pseudoaneurysm as a consequence of a road accident

A 20-year-old man suffered a high-impact road accident and was admitted to the emergency room with haemodynamic instability. A whole-body CT scan was performed following the polytrauma protocol.

Non-contrast cranial and neck CT do not display acute pathology.

A Contrast-enhanced thoraco-abdominal CT demonstrates an undefined outpouching of the proximal descending aorta, just distal to the origin of the left subclavian artery, surrounded by some anterior and posterior mediastinal acute haematoma. These findings were compatible with aortic pseudoaneurysm at the aortic isthmus. Supra-aortic arteries were permeable.

Other findings were left haemo-pneumothorax, little nodular consolidations attributable to pulmonary contusions, and fractures of three left lateral costal arches (from 8th to 10th).

In the abdomen, there was a complete infarction of the left kidney and a shattered spleen.

Traumatic aortic injury (TAI) is the second most frequent cause of trauma-related death after traumatic brain injury, with a high mortality rate if not treated (90%) [1].

The most common causes of TAI are high-velocity road traffic accidents and falls from height [2].  There are four combined types of insults producing TAI: stretch, shear, pinch (osseous compression of the aorta between thoracic cage and vertebrae), and thump effect [3].

The wide majority of lesions occur at the aortic isthmus because it is attached to the ligamentum arteriosum, which gives the isthmus relative immobility [2,3].

The Society for Vascular Surgery (SVS) classifies aortic injuries into four grades [2-4]:

-Grade I: intimal tear (intraluminal filling defect measuring 10 mm or less),

-Grade II: intramural haematoma (focal hyperdense thickening of the aortic wall on non-contrast CT),

-Grade III: pseudoaneurysm (contained rupture),

-Grade IV: aortic rupture.

Grade I and II lesions are considered minimal aortic injuries (MAI) as they do not alter the aortic contour, while grades III and IV are called significant aortic injuries (SAI) [3].

Intimal tears (grade I) can be asymptomatic. The clinical features of intramural haematoma and pseudoaneurysms are irradiating and acute chest pain since they are acute aortic syndromes. Grade IV lesions manifest with haemodynamic instability and cause the patient's death before arriving at the emergency room. For all that, it is important to inform interventional radiologists and vascular surgeons as soon as these findings are seen in CT to increase the patient’s chance of survival.

The SVS proposes medical and expectant management with serial imaging control for grade I lesions. The medical treatment consists of heart rate and blood pressure control. 

Emergent or urgent endovascular aortic repair (EVAR) is indicated for grades II to IV. Nevertheless, recent studies have pointed out the possibility to include intramural haematoma (grade II) in the non-operative management strategy. Surgical repair is used when EVAR is unavailable or the patient's anatomy makes EVAR not feasible [3,4].