CASE 9196 Published on 04.04.2011

Post-traumatic aortic pseudoaneurysm: not an uncommon incidental finding?

Section

Cardiovascular

Case Type

Clinical Cases

Authors

Simon-Yarza I, Ferreira M, Sanchez-Carpintero M, Viteri-Ramirez G, K Grochowicz L, Bastarrika G

Patient

25 years, male

Categories
Area of Interest Arteries / Aorta ; Imaging Technique CT-Angiography, CT
Clinical History
A 25-year-old male smoker, previously asymptomatic, referred to the Emergency Department with non-irradiating chest pain, not associated to strain. Nine years ago he suffered a traffic accident. Cardiac enzymes were normal. He underwent through a ECG (sinusal rhythm, 72 bpm), a chest radiography and a CT angiography.
Imaging Findings
Chest radiography revealed a left superior mediastinal widening and multiple rib fractures in the right side. With the suspicion of a mediastinal mass, a CT was performed. The CT-angiography of the aorta showed a saccular pseudoaneurysm of the thoracic descending aorta, with a maximal diameter of 55x53 mm, partially calcified, especially in the posterior wall. The pseudoaneurysm extended from the isthmus to the descending aorta over 89 mm in caudo-cranial direction. Given the background of the patient, we suggested a post-traumatic pseudoaneurysm (Fig. 1). As in the chest radiography, multiple rib fractures were also observed.
The pseudoaneurysm was treated, under general anesthesia, with an aortic stent (Valiant Medtronic 28x157 mm). Eleven days after the procedure a control CT angiography demonstrated the proper placement of the stent, which excluded aneurysm completely (Fig. 2). No leakage or complication of the procedure was found and the patient was discharged.
Discussion
After a traffic accident, aortic rupture is a major cause of mortality, only preceded by craneoencephalic trauma. Although less than 1% of the patients with an accident have an aortic rupture, the mortality is high: only 80% arrive at the hospital alive, and most of them die during the surgery [1]. According to different series, 2-15% of polytraumatised patients leave the hospital with a non-diagnosed aortic rupture and may develop a pseudoaneurysm [2, 3]. 90%-95% of the aortic lesions occur at the isthmus, between the left subclavian artery and the arteriousus ligament, which is the place were the thoracic aorta gets anchored to adjacent structures [3]. Multiple physiopathological mechanisms have been proposed (shear, torsion, stretching), and probably a combination of them is implicated in most of the lesions [1]. Sudden deceleration results in a shear at the junction between the fixed and mobile portion of the aorta [1, 4]. There is also an increase of intra-abdominal pressure, which is transmitted to the chest, where the aorta is entrapped [1, 5]. Depending on the intensity of the trauma, the extension of the aortic injury may vary from subintimal hemorrhage to a complete rupture of the vessel. Terms employed to classify aortic injuries are tear, laceration or disruption, transection and pseudoaneurysm [6]. Aneurysm is a dilatation of the vessel affecting all the wall layers (intima, media and adventitia). Unlike a true aneurysm, pseudoaneurysms have fewer than three layers and the blood is contained by the adventitia [4]. Diagnosis can be made by CT, angiography, transesophageal ultrasounds or magnetic resonance imaging [7]. Among these techniques, CT is the first option because of its availability, speed, high sensibility and specificity. CT allows observing not only the vessel, but also perilesional complications [4] as haematomas, bone fractures, lung contusions and lacerations, or diaphragmatic and esophageal lesions [3]. Traumatic aetiology of an aneurysm may be suspected when its origin is in the arteriousus ligament. Other signs that support the diagnosis are: saccular morphology, narrow neck, wall calcification [4] and presence of other non-vascular lesions as rib fractures or splenectomy. Treatment of post-traumatic pseudoaneurysms is the same as non-traumatic aneurysms. Those with low risk (calcified wall [8, 9] and more than two years of evolution), may be treated with beta-blockers and follow up every 6-12 months. Clinical symptoms or increase of the aneurysm size associate high risk of rupture, and they are indications of surgery or endovascular treatment [10].
Differential Diagnosis List
Post-traumatic pseudoaneurysm of the descending aorta.
Mediastinal mass on chest radiography
Non-traumatic aortic aneurysm
Final Diagnosis
Post-traumatic pseudoaneurysm of the descending aorta.
Case information
URL: https://www.eurorad.org/case/9196
DOI: 10.1594/EURORAD/CASE.9196
ISSN: 1563-4086