Aorto-esophageal fistula secondary to penetrating atherosclerotic ulcer.

Aorto-esophageal fistula (AEF) is a rare and life threatening condition, which can be rapidly fatal. More than half of such cases are secondary to aortic aneurysm rupture. There are only two previous reports describing AEF caused by penetrating atherosclerotic ulcer. We present multidetector computed tomography findings in a case of AEF secondary to penetrating atherosclerotic ulcer.

INTRODUCTION

Aorto-esophageal fistula (AEF) is a rare cause of upper gastrointestinal bleed which can be rapidly fatal. Most cases are diagnosed post-mortem.[1] More than half of the cases are secondary to aortic aneurysm, other relatively common causes being foreign bodies and esophageal carcinoma. AEF secondary to penetrating atherosclerotic ulcer is extremely rare, and to our knowledge, there are only two case reports in the literature.[23] We describe multidetector computed tomography (MDCT) findings in one such patient who also had associated anterior mediastinal mass which was proved on fine needle aspiration cytology (FNAC) to be thymoma.

CASE REPORT

A 65-year-old male patient presented with history of four episodes of hematemesis for one day. There was history of dysphagia (to solids more than liquids) from last one week. Patient also had history of fever and backache from last one and a half months. He had a long history of diabetes, hypertension, and was a chronic smoker and alcoholic for 25 years. Upper gastrointestinal endoscopy revealed long segment of clotted blood extending from the upper esophagus till pylorus of stomach. Near the proximal part of clot, there was deep erosion in the posterior wall of esophagus. MDCT with CT angiography was done which revealed diffuse atheromatous disease with multifocal intimo-medial thickening and calcifications with ulcerated plaques [Figure 1]. A focal outpouching producing contour deformity was seen arising from medial aspect of proximal part of descending aorta suggestive of penetrating atherosclerotic ulcer with pseudoaneurysm formation. There was associated hematoma on its medial aspect which was surrounding the esophagus and bulging into the azygo-esophageal recess [Figure 2]. Hematoma with air-fluid level was seen in the esophagus just proximal to this level. Based on the typical history and MDCT findings, diagnosis of penetrating atherosclerotic ulcer with AEF was made. Patient remained hemodynamically stable for one day, likely because of restraining clot, which temporarily plugged the fistula. Patient then developed sudden massive, forceful, and continuous hematemesis likely due to dehiscence of clot and patient expired soon afterwards.

Figure 1

Coronal multiplanar reconstruction image shows diffuse atherosclerotic changes in the thoracic aorta

Figure 2

Maximum intensity projection axial (a) and coronal (b) images show penetrating atheroscreotic ulcer with pseudoaneurysm (black arrow) with associated hematoma bulging into the azygoesophageal recess (solid white arrow). Also noted is anterior mediastinal mass (dotted white arrow). Sagittal MIP image (c) shows tapering of esophagus with surrounding hematoma (arrow)

DISCUSSION

AEF is a rare cause of upper gastrointestinal bleeding. AEF is divided into primary and secondary causes. Primary causes include thoracic aortic aneurysm, foreign bodies, esophageal carcinoma, corrosive ingestion, Barrett's ulcer, tuberculosis, trauma, prolonged intubation, and congenital arch anomalies. Secondary AEF is a sequelae of aortic or esophageal surgery and graft placement.[1] Penetrating atherosclerotic ulcer is a very rare primary cause of AEF.

Primary AEF is a rare and dreaded cause of upper gastro intestinal bleeding and often presents with fatal hemorrhage with no opportunity for diagnostic or therapeutic manoeuvres. It has been suggested that about 80% patients present with a prodromal bleed before final massive bleeding.[14] The window period may range from few hours to many days.[3] In our case, it was one day. This is important to recognise as it allows time for diagnostic and therapeutic manoeuvres.[35] The triad of mid thoracic pain, sentinel arterial haemorrhage and final massive haemorrhage after a symptom free interval is known as Chiari's triad.[3]

Computed tomography (CT) is an excellent modality for evaluating the cause of AEF. With emergence of MDCT, high quality multiplanar reconstructions can be obtained routinely. Penetrating atherosclerotic ulcer refers to the ulcerated plaque which extend beyond the intima with varying degree of hematoma in the wall.[6] Penetrating atherosclerotic ulcer can be difficult to differentiate from ulcerated atheromatous plaques, however, presence of contour abnormality is highly suggestive of penetrating atherosclerotic ulcer. Further extension of ulceration can lead to focal saccular aneurysm, mediastinal hematoma, or aortic dissection.[7] AEF is extremely rare complication with only two cases reported in the literature prior to our case. Endoscopy can reveal esophageal ulceration and intraluminal clot, however, some have advocated against its use because of fatal haemorrhage induced by flexible endoscopy in such cases.[8]

In conclusion, AEF is a rare and dreaded cause of upper gastrointestinal hemorrhage. Many patients present with herald bleeding before the final exsanguination, which is critical to recognise as it allows window period for diagnostic and therapeutic manoeuvres. Presentation with upper gastrointensitinal hemorrhage and CT findings associated penetrating atherosclerotic ulcer with associated hematoma surrounding the esophagus and extending into azygo-esophageal recess is highly suspicious for AEF even if no air bubble are seen in the hematoma or actual fistulous tract is not visualised. This should lead to aggressive surgical management as risk of massive exsanguination is high, which is invariably fatal.