IMAGE OF THE WEEK

WEEK 25

  

 

Figure 1a

Figure 1b

 

 

 

AORTIC TRANSECTION

 

Aortic transection (Figure 1a) remains the second leading causes of death following road traffic accident (RTA), claiming 15% of RTA death, with 75-90% of cases died at the scene of the accident.  

 

The mechanics behind aortic transection is the result of a sudden forward acceleration followed by sudden deceleration force associated with a head-on motor vehicle accident or a stationary pedestrian hit by a fast oncoming car, resulting in differential sliding displacement of two segments of the aorta, of which one of the segment is anchored or fixed by either branches or surrounding tissues or organs. Any segments of the aorta can be transected but the commonest site is the aortic isthmus (36-54%) [See figure 2]. The transection usually occurs in a transverse fashion involving all 3 layers.

 

Figure 2

 

For the few that survive to reach a hospital with Trauma care, rapid confirmation of a diagnosis of aortic transection makes a significant difference between survival and death of the patient. A contrasted thoracic and abdominal CT should be performed urgently upon arrival if an initial chest radiograph shows mediastinum widening. Other radiographic features that may suggest aortic transection is shown in table 1. The CT appearance of aortic transection or aortic dissection can be difficult to differentiate but the clue to the former lies in the history of significant acceleration and deceleration injury and a large amount of mediastinal haematoma with a left haemothorax (Figure 1b). Other CT features of aortic transection is shown in table 1.

 

Table 1: Radiological features of aortic transection.

 

Chest Radiograph

CT Scan

Widened mediastinum (>8.0cm)

Wall thickening

Mediastinum-to-chest width ratio >0.25

Extravasation of contrast (Figure 1)

Tracheal shift to the patientís right

Filling Defects (Figure 1: Arrow)

Blurred aortic contour

Para-aortic Haematoma (figure 1: arrow head)

Irregularity or loss of the aortic knob

Intimal flaps/irregular intimal outline (Figure 1b)

Left apical cap

Mural thrombi

Depression of the left main bronchus

Pseudoaneurysms

Opacification of the aortopulmonary window

Pseudocoarctation

Right deviation of the nasogastric tube

Left haemathorax (Figure 1: star)

Wide paraspinal lines

Pocket of contrast outside of aortic lumen

First rib fracture

 

Any other rib fracture

 

Clavicle fracture

 

Pulmonary contusion

 

Thoracic spine fracture

 

 

 

Patients diagnosed with aortic transection requires to be referred urgently to a cardiothoracic unit for emergency repair of the transected aorta either with an open thoracotomy and replacement of the transected segment using a
Gortex or Dacron graft, or Thoracic Endovascular aortic repair (TEVAR) with covered stented graft.

 

Images prepared by Mr Chong Chee Fui, Consultant Cardiovascular & Thoracic Surgeon, Thoracic Unit, Department of General Surgery, RIPAS Hospital, Brunei Darussalam.

All images are copyrighted and property of RIPAS Hospital.

 

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