CASE 18526 Published on 16.04.2024

Aortoenteric fistula following Onyx embolisation of a type 2 endoleak

Section

Interventional radiology

Case Type

Clinical Case

Authors

Yunus Hussain, Ali Zaman, Imran Syed, Noreen Rasheed, Rumman Ahmed

Basildon & Thurrock University Hospital, Mid and South Essex NHS Foundation Trust, Basildon, United Kingdom

Patient

81 years, male

Categories

Area of Interest Interventional vascular, Vascular ; Imaging Technique CT-Angiography

Procedure Embolisation ; Special Focus Aneurysms ;

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Clinical History

An 81-year-old male presented with abdominal pain, malaise, and weight loss one month after undergoing a transarterial embolisation of a type two endoleak (T2E) for an expanding abdominal aortic aneurysm sac post-endovascular aortic repair (EVAR). His blood infection markers were markedly raised, and his blood culture was Clostridium perfringens positive.

Imaging Findings

Computer Tomography (CT) imaging from two months earlier (Figures 1a, 1b and 1c) showed a persistent T2E from the lumbar L4 arteries with a rapid 2cm increase in aneurysm sac diameter over 3 months. Additionally, there was adjacent retroperitoneal fat stranding which was concerning for an unstable aortic sac.

After a multidisciplinary team discussion, a transarterial approach via the left iliolumbar artery was selected for T2E embolisation using Onyx in order to fill the nidus and ostia of contributing lumbar arteries (Figure 2). Whilst variations in techniques and agents exist [19], it was felt that Onyx alone would be sufficient and perhaps allow more comprehensive filling of any unidentified contributing arteries.

One month post-embolization, a CT-angiography (Figures 3a, 3b and 3c) showed ongoing T2E and extensive intra-aneurysmal gas, indicating potential gas gangrene. Although there was no contrast extravasation into the bowel, an adjacent distal ileal bowel wall appeared inflamed and adherent to the aneurysm sac; this was interpreted as an aortoenteric fistula (AEF). Blood cultures grew Clostridium perfringens, suggestive of aortic gas gangrene.

Discussion

EVAR has become a mainstay in treating abdominal aortic aneurysm (AAA). Recognised complications include endoleaks and infection. T2Es are caused by retrograde blood flow into the aneurysm sac from arterial branches arising from the stented aortic segment, most commonly from the inferior mesenteric or lumbar arteries. T2Es occur in up to 20% of cases and can cause sac expansion and rupture. Treatment involves embolisation with coils, liquid embolics or a combination of the two [20]. Onyx, an ethylene vinyl alcohol copolymer, is one such liquid embolic with a reported 80% sac stabilisation rate. Approaches in accessing the nidus of T2Es include the transarterial, direct sac puncture and transcaval routes [1–3].

Endograft infections (EI) occur in <1% of cases and typically >2 years post-EVAR. They carry a mortality rate of up to 59% [4]. Patients may present with pain, fever, rigors, lethargy and gastrointestinal (GI) haemorrhage [5].

Secondary AEFs occur in 0.46% of cases and present similarly to EIs but with a greater predisposition for GI haemorrhage [6].

Rare cases of AEFs developing post-coil embolisation of endoleaks have been documented but none following Onyx embolisation [7,8].

CT-angiography is the chosen imaging modality for EIs and AEFs due to its high sensitivity. Oesophagogastroduodenoscopy, positron emission tomography-CT or magnetic resonance imaging may also be considered [6,9,10].

Despite the absence of contrast extravasation into the bowel in this case, other indirect AEF features were present, including peri-graft gas and effacement of the peri-aneurysmal soft tissue and adjacent apposing bowel wall [6,11].

AEF management includes graft explantation, extra-anatomical revascularisation, and fistula exclusion [5,10,12,13]. Although perioperative mortality is high, conservative management is associated with 100% mortality after 1 year [13,14].

Clostridium perfringens is an anaerobic gram-positive bacillus found in intestinal flora, soil, and raw meat. It is commonly associated with GI infections and can cause myonecrosis [15].

Rare cases of EIs with Clostridium perfringens have been documented occurring in the context of AEFs [16–18]. However, there are no documented cases of EIs with enteric organisms following transarterial T2E embolisation with Onyx.

We postulate that our patient developed sepsis following Clostridium perfringens translocation from the small bowel into the aortic aneurysm via an AEF, which developed spontaneously following T2E Onyx embolisation. Sadly, the patient died shortly after admission.

Teaching points

AEF is a rare but severe complication of EVAR.
Endoleak embolisation with Onyx could be associated with AEF development.
Optimal management for AEFs involves surgical intervention despite high perioperative mortality rates.

Differential Diagnosis List

Clostridium perfringens infection post-endoleak embolisation secondary to an aortoenteric fistula

Peri-graft infection without an aortoenteric fistula

Mycotic aortic aneurysm infection with another organism

Inflammatory aortitis

Final Diagnosis

Clostridium perfringens infection post-endoleak embolisation secondary to an aortoenteric fistula

References

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[2] Zhou W (2023) Endoleaks (Type I-V). Society of Vascular Surgery. [Online]. Available at: https://vascular.org/patients-and-referring-physicians/conditions/endoleaks-type-i-v#resource-115. Accessed 23rd July 2023

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[5] Smeds MR, Duncan AA, Harlander-Locke MP, Lawrence PF, Lyden S, Fatima J, Eskandari MK; Vascular Low-Frequency Disease Consortium (2016) Treatment and outcomes of aortic endograft infection. J Vasc Surg 63(2):332-40. doi: 10.1016/j.jvs.2015.08.113. (PMID: 26804214)

[6] Kahlberg A, Rinaldi E, Piffaretti G, Speziale F, Trimarchi S, Bonardelli S, Melissano G, Chiesa R; MAEFISTO collaborators (2016) Results from the Multicenter Study on Aortoenteric Fistulization After Stent Grafting of the Abdominal Aorta (MAEFISTO). J Vasc Surg 64(2):313-320.e1. doi: 10.1016/j.jvs.2016.04.008. (PMID: 27289529)

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[8] Elkouri S, Blair JF, Thérasse E, Oliva VL, Bruneau L, Soulez G (2003) Aortoduodenal fistula occurring after type II endoleak treatment with coil embolization of the aortic sac. J Vasc Surg 37(2):461-4. doi: 10.1067/mva.2003.146. (PMID: 12563223)

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Case information

URL:	https://eurorad.org/case/18526
DOI:	10.35100/eurorad/case.18526
ISSN:	1563-4086

License

This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

Figure 1

CT abdomen and pelvis demonstrating a lumbar type 2 endoleak with an aneurysm sac diameter of 8.2cm and fat stranding surrounding the aneurysm sac anteriorly without extravasation of contrast. (a) Axial view, (b) Sagittal view, (c) Coronal view. Green arrows point to an intact interface between the distal ileal loop and the aneurysm sac. The yellow arrow points to a previously Onyx-embolised inferior mesenteric artery type 2 endoleak nidus. There is satisfactory filling of this nidus with backfilling cranially into a potentially secondary nidus towards the bifurcation of the graft (red arrow).

Figure 2

Sagittal fluoroscopic acquisition. Fluoroscopic guided embolisation done via left common femoral artery access with a 6-French sheath. The left iliolumbar artery was successfully cannulated, and the micro-catheter advanced into the aneurysm sac via a left lumbar artery. 9.5ml of 34L Onyx liquid embolic was injected with a satisfactory filling of the nidus and several lumbar arteries. There were no immediate complications.

Figure 3

CT angiogram showing extensive gas within the aortic aneurysm sac, with gas extending up to the level of the renal arteries within the sac 1 month after embolisation with Onyx. (a) Axial view, (b) Sagittal view, (c) Coronal view. There is no visible luminal arterial gas. This appearance indicates infection of the aneurysm sac post-embolisation with a gas-forming organism. The distal ileal loop is matted with the inferior aspect of the aneurysmal sac with a defect demonstrated in the superior wall of the ileal loop, possibly representing an aortoenteric fistula (green arrows). There is no extraluminal contrast noted. The EVAR stent itself is intact.