Compare and contrast the advantages and disadvantages of Transoesophageal Echocardiography,   Angiography,  and  CT  Angiography  for  the  diagnosis  of  aortic injuries.

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College Answer

The major aortic injury is traumatic aortic rupture. This usually occurs at the aortic isthmus, between the left subclavian and the first intercostals arteries, where a few cm only of subadventitial rupture may be seen, with an associated intraluminal flap.   Other potential injuries include intimal tears, mural thrombi and aortic dissection.

All of the techniques have potential practical limitations, as they all require expert practitioners to perform, and a degree of sedation/anaesthesia. No comparative studies have evaluated management based on a particular technique. Choice will usually depend on local expertise!

The definitive test (gold standard) is still direct angiography (aortography). It requires catheter placement into the proximal aorta, and has problems associated with arterial access (eg. femoral) and arterial dye injection, but it provides better anatomical details for some areas (eg. aortic arch, brachiocephalic arteries and distal arteries).

CT angiography (usually high resolution, contrast enhanced spiral CT) has the advantages of providing other anatomical information, is more widely available, can be performed at short notice with rapid results (in trauma centres) and can be performed as part of workup for other injuries (eg. patient has other indications for chest CT).  It still requires IV contrast injection, transport to CT scan, immobilisation and expert interpretation.

Trans-Oesophageal Echocardiography is becoming more accessible at short notice as more practitioners are trained in its use.   Limitations include availability of expert practitioner (and equipment), requirement for sedation (+/- airway protection) and need for oesophageal placement of scope (in patient with unknown cervical spine status).   Artefacts may limit diagnostic accuracy (including atherosclerotic change).  Advantages include portability of procedure, rapid results with good sensitivity and specificity (comparable to spiral CT), and the ability to assess other cardiac and aortic structures (eg. in the presence of aortic dissection).

Discussion

This question closely resembles Question 13 from the second paper of 2010.

Though the question does not specify dissection, the same principles apply.

Assuming it is blunt aortic injury we are talking about, nice guidelines are available from a 2000 article in Trauma. To briefly visit this paper, aortography by direct angiography is still the gold standard, and TOE is still only supported by level 3 evidence.

References

References

Nagy, Kimberly, et al. "Guidelines for the diagnosis and management of blunt aortic injury: an EAST Practice Management Guidelines Work Group." Journal of Trauma-Injury, Infection, and Critical Care 48.6 (2000): 1128-1143.

 

The canonical source for this information would have to be the most recent iteration of the ACCF/AHA Guidelines for Diagnosis and Management of Patients With Thoracic Aortic Disease.