Traumatic rupture of aortic isthmus

Clinical History

A 27-year-old man was admitted in our institution after a car accident. He was suffering from dorsal pain.

Imaging Findings

A contrast-enhanced thoraco-abdominal computed tomography (CT) was performed. Thoracic CT with mediastinal window revealed haemomediastinum (Fig. 1). Aortic analysis showed a hypodense endoluminal flap (Fig. 2), associated with a deformity of the contour consistent with a pseudoaneurysm (Fig. 3). Tridimensional reconstruction with volume rendering techniques (VRT) showed the saccular outpouching of the aortic isthmus (Fig. 4).

Discussion

Traumatic aortic injury (TAI) is a rare, but life-threating complication of chest trauma. It is usually encountered following severe deceleration in high-speed motor vehicle collisions [1, 2]. The most common site for aortic tears is the aortic isthmus, just distal to the origin of the left subclavian artery [1]. Early diagnosis is crucial, because undiagnosed and untreated TAI carry a poor prognosis, with immediate death in 80-90% of the people involved in these accidents, and 90% mortality at 4 months [1, 3]. Clinical diagnosis is difficult because patients with TAI usually have a wide range of unspecific signs. Therefore, imaging is critical in the diagnosis and evaluation of this injury [3]. The portable chest radiography, usually the first diagnostic method performed in patients with TAI, may show radiographic signs of haemomediastinum, including mediastinal widening, obscuration of the aortic knob, widened paraspinal line, widened right paratracheal stripe (>5mm) [4]. Although aortic angiography remains the gold standard in evaluation of TAI, it is an invasive procedure with possible complications [4]. Therefore, contrast-enhanced helical CT have been proposed to screen aortic rupture, with high sensitivity and specificity [4, 5]. CT finding related to TAI include haemomediastinum, intimal flap, intraluminal thrombi, calibre change in the aorta, pseudoaneurysms or any irregularity of the aortic contour, and contrast material extravasation [4, 5]. It is also important to note that the absence of haemomediastinum, and a regular aorta surrounded by normal fat has a 100% negative predictive value for TAI [6]. The initial management of patients with suspected TAI involves blood pressure control. The treatment of choice of acute TAI is operative repair. Open surgery and endovascular stent grafting show similar results [7].

Differential Diagnosis List

Final Diagnosis

Traumatic rupture of aortic isthmus.

URL:	https://www.eurorad.org/case/13728
DOI:	10.1594/EURORAD/CASE.13728
ISSN:	1563-4086