Aortoenteric fistulae temporization and treatment: lessons learned from a multidisciplinary approach to 3 patients.

Aortoenteric fistulae are life-threatening conditions characterized by abnormal communications between the aorta and gastrointestinal tract. Aortoenteric fistulae may be characterized by the triad of bleeding, abdominal pain, or a pulsatile abdominal mass. Although hemorrhage is the most common presentation, it does not always occur; thus, patients may present with nonspecific symptoms. Computed tomography angiography findings suggestive of aortoenteric fistulae include ectopic gas within or adjacent to the aorta, discontinuity of the aortic wall, bowel wall thickening, and extravasation of contrast into the bowel. Endovascular treatments include retrograde balloon occlusion of the aorta and stent-graft deployment as well as coil, fibrin, and glue embolization of the fistulous tract. This report describes 3 cases of aortoenteric fistulae temporized and treated by interventional radiology and vascular and cardiac surgery at a single institution in an effort to increase awareness of this important clinical condition.

Introduction

Aortoenteric fistulae are rare life-threatening conditions characterized by abnormal communications between the aorta and gastrointestinal tract. The incidence of primary aortoenteric fistulae, those occurring without history of prior aortic intervention, is less than 1%, whereas the incidence of secondary aortoenteric fistulae, from erosion of an aortic prosthesis into the surrounding gastrointestinal structures, is 0.36%-1.6% [1], [2]. Although the pathogenesis of aortoenteric fistulae remains unknown, it is theorized to be the result of aortic or graft pulsation against the wall of the gastrointestinal tract. Aortoenteric fistulae may be characterized by the clinical triad of bleeding, abdominal pain, and pulsatile abdominal mass. Hematemesis and melena, secondary to rupture of the closely adherent aorta into the gastrointestinal tract, occurs in 32%-78% of patients with primary aortoenteric fistulae [3]. Although hemorrhage is the most common presentation, it does not always occur and patients may present with nonspecific symptoms including generalized malaise, weight loss, sepsis, and graft thrombosis. Computed tomography (CT) angiography findings suggestive of aortoenteric fistulae include ectopic gas within or adjacent to the aorta, discontinuity of the aortic wall, bowel wall thickening, and extravasation of contrast into the bowel lumen [4]. Endovascular treatments, although not definitive therapies (because the deployed materials by definition become contaminated), include retrograde balloon occlusion of the aorta and stent graft deployment, as well as coil, fibrin, and glue embolization of the fistulous tract. Despite potential treatment options, due primarily to its uncommon and variable clinical presentation, surgical mortality and overall mortality are high at 36% and 86%, respectively [5]. This report describes 3 cases of aortoenteric fistulae temporized and treated by interventional radiology and vascular and cardiac surgery at a single institution in an effort to increase awareness of this important clinical condition.

Case report

Institutional review board approval was not required for preparation of this report. All 3 patients presented in August and September 2016. The first patient was a 76-year-old man who presented with anemia, hypotension, fever, and chills after 5 episodes of large volume, dark red, malodorous stools. CT angiogram revealed a 2.9-cm saccular aneurysm arising from the anterolateral surface of the infrarenal aorta, intimately associated with the crossing duodenum, and with surrounding inflammatory changes and a focus of gas in the aneurysm sac (Fig. 1). Aortography revealed brisk contrast extravasation into the small bowel, consistent with the suspected aortoenteric fistula. As the patient remained unstable, the decision was made to place a temporizing stent graft. A 23 × 120 mm Gore Excluder C3 main body device (Gore Medical, Flagstaff, AZ) and a Gore Excluder 12 mm × 100 mm left iliac limb (Gore Medical) were placed. Postdeployment aortogram demonstrated continued flow into the bowel which resolved after seal and overlap zone molding with a Coda balloon (Cook Medical, Bloomington, IN). The patient was stabilized, placed on long-term antibiotics, and discharged 10 days later.

Fig. 1

(A) Axial image from CT angiogram revealing focal aortic disruption (black arrow), duodenum draping over the aorta (white arrowhead), and focus of gas within the aortic aneurysm sac (white arrow). (B) Coronal reconstructed image demonstrating disruption of aortic wall (black arrow) with adjacent focus of gas within the aneurysm sac (white arrow). (C) Aortogram before endovascular repair highlighting site of aortic disruption (black arrow). (D) Aortogram after endovascular aortic repair (before balloon molding) confirming contrast within the bowel (black arrowheads). (E) Digital subtraction angiogram image from completion aortography showing resolution of aortoenteric fistula with widely patent endograft. CT, computed tomography.

The second patient was a 57-year-old man with metastatic gastric cancer and an esophageal stent who presented with acute hematemesis. Emergent esophagogastroduodenoscopy demonstrated clotted blood in the stomach and brisk bleeding at the proximal end of the esophageal stent on withdrawal of the endoscope, requiring emergent intubation and transfusion. CT angiography showed close contact of the descending thoracic aorta and the midesophageal stent, suggesting an aortoesophageal fistula (Fig. 2). Aortography confirmed irregularity along the anterior margin of the descending thoracic aorta immediately adjacent to the posterior margin of the esophageal stent at the level of the diaphragmatic hiatus. Based on the results, a 28 × 28 × 117 mm Medtronic Valiant Captivia endoprosthesis (Medtronic, Minneapolis, MN) was deployed in the descending thoracic aorta, centered on the aortic irregularity. Postdeployment aortography confirmed exclusion of the aortic irregularity without endoleak. The patient recovered without further episodes of gastrointestinal bleeding, was placed on long-term antibiotics, and was discharged 6 days later. He was seen in the medical oncology clinic 4 weeks later and had restarted chemotherapy.

Fig. 2

(A) Axial image from CT angiogram showing relationship of esophageal stent (black arrowhead) and aortic injury (white arrowhead). (B) Sagittal reconstructed image demonstrating esophageal stent (black arrowhead) and aortic disruption with contrast material within the esophageal stent (white arrow). (C) Digital subtraction angiography image from lateral aortography confirming irregularity along the anterior aorta (white arrow) near the rostral aspect of the esophageal stent (black arrowhead). (D) Digital subtraction angiography image from completion aortogram with a widely patent aortic endograft and resolution of anterior aortic irregularity. No endoleak was seen. CT, computed tomography.

The third patient, a 75-year-old man with an aortobifemoral bypass graft and prior episodes of gastrointestinal bleeding (secondary to cecal and duodenal arteriovenous malformations) presented emergently with upper gastrointestinal bleeding. CT angiography showed the third portion of the duodenum draped over the aortobifemoral graft anastomosis; however, there was no contrast extravasation into the bowel or ectopic gas (Fig. 3). Aortography demonstrated brisk extravasation from the cranial aspect of the aortobifemoral graft anastomosis. Because of massive hemorrhage, hypotension, and instability, a Coda balloon was inflated at the fistulous site with intermittent deflation to allow perfusion of the lower extremities at 10-minute intervals. A 22-mm Zenith Flex endovascular graft main body extension cuff (Cook Medical) was placed across the aortoenteric fistula; however, repeat aortography demonstrated persistent extravasation into the fistula, suggestive of a type-1a endoleak, at the cranial aspect of the newly deployed graft. To resolve this, a 24-mm Zenith Flex graft main body extension cuff (Cook Medical) was deployed to provide overlap and cranial extension. Repeat aortography confirmed resolution of the type-1a endoleak; however, contrast extravasation was then identified at the caudal aspect of the aortobifemoral graft, suggestive of a type-1b endoleak, which continued to supply the aortoenteric fistula. A 26-mm Zenith Flex graft main body extension cuff (Cook Medical) was deployed to provide overlap and caudal extension. Repeat aortography demonstrated persistent extravasation into the bowel at the caudal aspect of the recently deployed cuffs and the aortobifemoral bypass graft anastomosis. Kissing 10 × 100 mm Viabahn endoprostheses (Gore Medical) were then deployed simultaneously in each iliac limb to completely exclude the persistent aortoenteric fistula. Repeat aortography showed complete exclusion of the aortoenteric fistula. Unfortunately, the patient subsequently underwent decompression of abdominal compartment syndrome. The patient experienced a large cerebrovascular accident and myocardial infarction, and expired 7 days later.

Fig. 3

(A) Axial image from CT angiogram showing relationship of aorta with anterior disruption (black arrow), inflammatory aneurysm sac (white arrow) and anteriorly located small bowel (white arrowhead). (B) Sagittal reconstructed image showing the irregular aortic contour (white arrow) and anteriorly located small bowel (white arrowhead). (C) Digital subtraction angiography image from oblique aortography confirming aortoenteric fistula with contrast noted in the bowel (black arrowheads). Also noted is the native left iliac artery (black arrow) as the aortobifemoral bypass graft was created with an end-to-side proximal anastomosis. (D) Fluoroscopic image demonstrating position of inflated Coda balloon (black arrow) occluding the infrarenal aorta. (E) Fluoroscopic image illustrating coverage of main body with extension endoprotheses (between white arrowheads) and iliac artery Viabahn stent grafts (white arrows). Also noted is contrast within the small bowel (black arrowhead). (F) Digital subtraction angiography image from completion aortography showing resolution of aortoenteric fistula with widely patent endograft. Again noted is the native left iliac artery (black arrow). CT, computed tomography.

Discussion

All 3 cases demonstrate that early diagnosis and prompt, aggressive treatment may be used to successfully manage aortoenteric fistulae in a minimally invasive fashion. Multidisciplinary discussion and treatment is paramount. CT angiography is the first-line imaging modality for the detection of aortoenteric fistulae and has a reported sensitivity of 94% and specificity of 85% [4]. Contrast extravasation into the bowel lumen is rarely seen on CT angiography and was only seen in 1 patient in this experience. Because of massive hemorrhage and hemodynamic instability, temporizing measures such as emergent balloon tamponade may be necessary. Moreover, treatments are typically temporizing or palliative as the deployed materials are by definition contaminated. Patients likely require lifelong antibiotics and remain at risk for secondary infection and refistulation. Although aortoenteric fistulae are rare diagnoses, both interventional radiologists and vascular and cardiac surgeons need to be aware of their varied clinical presentation and imaging findings, work closely and cooperatively, and treat these life-threatening conditions.