Case 83

Aneurysm Of Aberrant Right Subclavian Artery Presenting As Dysphagia
 


 

INTRODUCTION:

 An aberrant right subclavian artery in the presence of an otherwise normal aorta is the most common developmental anomaly of arch of aorta, occurring in 0.5% of normal population. Here a case is presented coming with complaint of dysphagia.
 

CASE HISTORY:
91 year old male patient, presented to a private institute with history of dysphagia. His frontal chest radiograph taken there, shows superior mediastinal widening with a soft tissue density mass having smooth and well-defined lateral margins, on right side- in right paratracheal region and on the left side- in the region of aortic knuckle. Its medial margins are merging with mediastinum.

Patient came to our institute for CT Thorax-plain and contrast. CT was done (Philips CT Secura) with slice thickness of 7mm and reconstruction at 5mm. CT shows hypodense mass with well defined margins in posterior superior mediastinum displacing trachea and oesophagus anteriorly. On intravenous contrast administration, mass seems to be arising as posterior and the last branch of arch of aorta i.e. “Aberrant Right Subclavian Artery” with it’s aneurysm with peripheral mural thrombus and calcified atheromatous plaques.

Dilatation of aberrant right subclavian artery with thrombus, is seen extending in posterior and superior mediastinum behind trachea and oesophagus, then to the right of trachea to reach behind medial end of clavicle to attain its normal position.

The diagnosis of “ Aneurysm of Aberrant Right Subclavian Artery” with peripheral thrombus and calcified atheromatous plaques causing compression and anterior displacement of trachea and oesophagus was given.


 

Figure. 1 Xray chest

Figure.2 C.T.

Figure.3 C.T.

Figure.4 C. T.

Figure.5:  C. T. Films

DISCUSSION:

 An aberrant right subclavian artery in the presence of an otherwise normal aorta is the most common developmental anomaly of arch of aorta, occurring in 0.5% of normal population. It may arise directly from the arch of aorta or from an aortic diverticulum of Kommerell. It may be the first, second, third or fourth branch of aorta. When it arises as the last and most posterior branch of aortic arch, it crosses the mediastinum behind trachea and oesophagus and continues in right axilla along the right margin of trachea.

By definition, a true aneurysm involves all the components of vessel wall. The morphological subtypes of aneurysm are saccular, fusiform dissecting and false. In addition, acquired aneurysms can be atherosclerotic, mycotic, post-traumatic and secondary to cystic median necrosis.

Aneurysm that arise within aberrant right subclavian artery occur most often in elderly patients and appear to be atherosclerotic in origin as in our case, but can also be affected by arteritis.

Aberrant right subclavian artery and its aneurysm can cause compression of oesophagus and hence dysphagia which is termed as “Dysphagia Lusoria”. Dyshphagia lusoria has been described in the literature as difficulty in swallowing because of “jest of nature”.Dysphagia due to lusorian artery appears after the age of 40 years and one of the hypothesis of dysphagia lusoria is that it is caused by oesophageal motility disorder and not by vascular compression which is supported by oesophageal manometric studies.

Contrast CT is virtually diagnostic for detection of aberrant right subclavian artery and its aneurysm showing following features of aneurysmal-dilatation of vessel, calcification, intraluminal thormbi, displacement or erosion of adjacent structures, perianeurysmal thickening.
It can also display complications of the aneurysms like leaking or rupture
in the form of increased tissue density of the mediastinum, mediastinal haemotoma, pleural effusion etc..

MR imaging and MR Angiography is equally diagnostic as CECT in these cases, however Digital Subtraction Angiography is necessary
to plan the surgical management.

 

REFERENCES:
  1. John R. Haaga, Charles F. Lanzieri, Robert C. Gilkeson. CT and MR Imaging of the Whole Body.Fourth edition, 2003,volume 1

2. Patrick C. Freeny, Giles W. Stevenson-Margulis and Burhevne’s Alimentary Tract Radiology, volume 1,fifth edition

3.Predy T. A. , Mc Donald V. , Demos T.C. , Moncada R. CT of congenital anomalies of the aortic arch. Semin. Roentgenol 24, 1989

4. Proto A.V. , Cuthbert N.W., Raider L. Aberrant Right Subclavian Artery ;
Further Observations. A.J.R. Am. J. Roentgenol 148,1987.

5. Ronald G. Grainger, David Allison, Albert Baert, E. James Potchen. Grainger and Allison’s Daignostic Radiology; A Text book of Medical Imaging, volume 1,Third edition.

6. S.Cakirer, K. Devir, M. Beser, G. M. Gallp. Aneurysm of Aberrant Right Suclavian Artery Arising from Diverticulum of Kommerell- Eurorad clinic






 
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