Blunt thoracic trauma with the formation of pseudoaneurysm with the junction of the right subclavian artery

KEYWORDS:
Thoracic injuries; Subclavian artery, non-penetrating wounds

PALAVRAS-CHAVE:
Traumatismos torácicos; Artéria subclávia; Ferimentos não penetrantes

INTRODUCTION

A male, 27-year-old ambulating patient, assisted in the Emergency Medical Unit, complaining about pains in the anterior region of the cervicothoracic transition a few minutes ago. He reported that crashed into a car door when it was opened while riding a bicycle, causing an impact on right hemothorax, and falling to the ground. He denied prior comorbidities. At physical examination, it was noted a heart rate of 135 beats per minute, arterial pressure of 92/56 mmHg and respiratory frequency of 22 per minute; no hematoma, abrasions or puncturing and cutting wounds.

The Computed Tomography (CT) of the thorax was carried out, showing in the precontrast phase: mediastinal formation with soft tissue density and central region discreetly hyperdense with the junction of the right subclavian artery, discrete areas of ground-glass attenuations in both lungs, massive right hemothorax with passive pulmonary atelectasis partially ipsilateral (figures 1A and 1B). When administering the intravenous contrast media, the formation showed a filling-up, confirming a pseudoaneurysm of the right subclavian artery (figures 2A, 2B and 3A). No injuries were found.

FIGURE 1
(A)High resolution axial tomographic section of the chest, pulmonary window showing discrete areas of ground- glass attenuation in both lungs (black arrows), massive right pleural effusion (*) with ipsilateral partial passive pulmonary atelectasis. (B) Axial tomographic section without venous contrast showing evidence of mediastinal formation with soft tissue density and central region discretely hyperdense (white arrowhead), measuring approximately 7.7 × 6.9 × 4.1 cm, determining contralateral mediastinal deviation and massive right pleural effusion (*).

FIGURE 2
(C, D, E) Computed tomography imaging, axial (A) and sagittal (B) plans, demonstrating the filling of the formation by contrast after its intravenous administration (thin white arrow).

FIGURE 3
(A) Coronal tomographic reconstruction discretely oblique demonstrating the pseudoaneurysm filled by contrast after its intravenous administration (thin white arrow) and its intimate contact with the right subclavian artery (double black arrowhead).

During the assessments, the patients presented dyspnea and signs of hemodynamic instability. It was chosen the emergency surgical approach, evolving to a recent postoperative death.

Diagnosis: Blunt thoracic trauma with a mediastinal injury of great artery.

DISCUSSION

In traumas, the thorax is the third topography frequently affected (fatal at 20%), and it is secondary especially to automobile accidents (66%-85%), in which young men 1^–4 are the victims

Classified in “penetrating” or “blunt”, with a slight predominance of this second type. Some frequent changes: hemothorax, pneumothorax, pulmonary laceration-contusions injuries, herniations, tracheobronchial and diaphragmatic ruptures, esophageal and cardiac injuries, hematomas, pseudoaneurysms, ruptures and vascular dissections, fractures mainly of costal arches (if present in two or more sites of at least three ribs, it may be considered an “unstable thorax”)1^,5^,6.

In general, traumas involving aorta and great mediastinal vessels add approximately 5% of incidents; however, there is a high rate of mortality representing up to 15% of deaths in the automobile collisions. About 4/5 of patients with aortic injuries die before intra-hospital care with a rate of up to 90% of death after 14 days of those who survive1^–3.

The mechanisms of aortic injury and the junction of supra-aortic vessels involve pinchcock between the anterior thoracic wall and column; extension of neck and shoulder traction, respectively, with the action of sudden deceleration, traction, torsion, and hydrostatic forces1^,7.

The ascending aorta is rarely affected (5%) due to its anchorage, where the arterial ligament1^,2.

Pseudoaneurysms are very common in vascular wounds in this scope, characterized by hematic overflow by rupture of the layers in the arterial walls, organizing a hematoma in contact with the lumen, contained by adjacent and scar tissues7^,8.

The radiography has a sensitivity of 90% and specificity of 10% for vascular injuries in this context, highlighting the signs: enlargement of mediastinum, blurring of aortic contours, paratracheal thickening1^,4^–6.

The angiography and CT are the best methods of assessment. CT has a predictive negative value of 100%, with the advantage of not being so invasive, direct view of injuries and other non-vascular injuries; however, the use of intravenous contrast injection is very important in detecting vessels injuries1^–5.

REFERENCES

• 1. Kaewlai R, Avery LL, Asrani AV, Novelline RA. Multidetector CT of blunt thoracic trauma. Radiographics. 2008;28(6):1555-70.
• 2. Melo ASA, Moreira LBM, Marchiori E. Lesões traumáticas do mediastino: aspectos na tomografia computadorizada. Radiol Bras. 2003;36(5):283-6.
• 3. O'Connor JV, Byrne C, Scalea TM, Griffith BP, Neschis DG. Vascular injuries after blunt chest trauma: diagnosis and management. Scand J Trauma Resusc Emerg Med. 2009;17:42.
• 4. Mioto Neto B, Aun R, Estenssoro AEV, Puech-Leão P. Tratamento das lesões de aorta nos traumatismos torácicos fechados. J Vasc Bras. 2005;4(3):217-26.
• 5. Palas J, Matos AP, Mascarenhas V, Herédia V, Ramalho M. Multidetector computer tomography: evaluation of blunt chest trauma in adults. Radiol Res Pract. 2014;2014:864369.
• 6. Escuissato DL, Warszawiak D. Trauma torácico. In: Santos Silva CI, Muller NL, eds. Tórax - Série CBR. São Paulo: Elsevier; 2010. p.567-79.
• 7. Enamorado-Enamorado J, Egea-Guerrero JJ, Revuelto-Rey J, Gordillo-Escobar E, Herrera-Melero C. Left subclavian artery pseudoaneurysm after a traffic accident: a case report. Case Rep Crit Care. 2011;2011:451819.
• 8. Romanus AB, Mazer S, Carvalho Neto A, Liu CB, De Toni FS, Jacob GVV, et al. Pseudo-aneurismas: relato de dois casos e revisão da literatura. Radiol Bras. 2002;35(5):303-6.

Publication Dates

• Publication in this collection
  Nov 2018

History

• Received
  18 Jan 2018
• Accepted
  24 Feb 2018