Abdominal Vascular Graft Complications

Author: Richard Slama, MD (EM Resident Physician, Naval Medical Center Portsmouth) // Edited by: Alex Koyfman, MD (@EMHighAK – EM Attending Physician, UTSW / Parkland Memorial Hospital) and Manpreet Singh, MD (@MPrizzleER – Clinical Instructor & Ultrasound/Med-Ed Fellow / Harbor-UCLA Medical Center)

Cases

In my very brief medical career I can think of two times that seriously made me reassess my approach to patients with intra-abdominal vascular grafts…

1. The 55-year-old male with flank pain and hematochezia 6 months after receiving an endograft for a AAA.

2. The 62-year-old female pancreatic cancer/cirrhosis patient s/p endovascular graft to the aorta and palliative esophageal stents for dysphagia now presenting with massive hemoptysis.

Introduction

As trainees I think it is beaten into our heads that all males over the age of 50 with new onset hematuria and flank pain should also be screened for AAA. One thing that is not so much beaten into our heads is how we still have to take hematuria and or hematochezia seriously in these same patients even after they receive endovascular repair. There are many complications that can occur from having an aortic graft placed, but for the purpose of this article let’s focus on Aortoenteric fistula and Endoleaks.

Aortoenteric fistula

This is a relatively rare complication of aortic graft placement at 0.4-1.6%, however it is arguably the deadliest with a mortality rate as high as 50% even with operative intervention.¹ As emergency medicine physicians this is not something that we can afford to miss. Even more concerning is that these fistulas can occur anywhere along the GI tract. In my second case above this demonstrates an unfortunate cancer patient whose esophageal stent eroded into her aorta causing symptoms mimicking a massive variceal bleed.

Presentation

A vast majority of patients will present with nausea, vomiting, back pain, hematochezia, and other non-specific abdominal pain. However there is a smaller subset of patients who are suffering from an underlying graft infection with secondary fistulization. These patients present with less obvious symptoms such as fever, weight loss, sepsis, and lack of obvious GI hemorrhage. Therefore it is very important for emergency clinicians to keep a high index of suspicion in these patients.

Diagnosis

CT angiography is going to be the most sensitive, fastest, and least invasive diagnostic modality for this condition. Unfortunately its sensitivity for diagnosing aortoenteric fistula is only between 30-80%.² There are other diagnostic modalities such as EGD and aortography, but these are more invasive and have not proven to have better sensitivity than CT. With new generation scanners this sensitivity has moved closer to 94%, but this is still not a perfect test.³

Treatment

As many of these are associated with infection and or graft failure/migration there will be a need for urgent vascular surgery. In the meantime the most that you can do for these patients is to support their hemodynamics and get antibiotics on board early if you are suspecting infection.

Endoleaks

Very simply put an endoleak is flow outside of the endograft, but still contained in the aortic aneurysm sac.⁴ There are 5 different types of endoleaks, which can be summarized as follows…

• Type 1: at the attachment site/seal failure; 10%
• Type 2: through a collateral vessel; 40%
• Type 3: graft failure/tear; 4%
• Type 4: porosity of the graft
• Type 5: Endotension/unidentifiable source

For the purpose of our discussion we are going to focus on types 1-3 which are the most common types of endoleaks that we will likely diagnose in the ED.

Presentation

Unfortunately the presentation for an endoleak is usually completely asymptomatic.⁵ However, remember that any patient undergoing endovascular repair can have as high as a 25% postoperative complication rate. Therefore even these non-specific presentations (abdominal pain, hematuria, flank pain, syncope, etc) should trigger you to search for a graft complication.

Diagnosis

Thankfully most patients with endografts undergo routine imaging at 30 days, 6 months, and then annually after placement of the graft. The type of imaging varies between institutions but is almost always going to be a CT scan with IV contrast. But now that they are in your ED how do you go about diagnosing them? This is not just a regular CT scan with IV contrast. The gold standard for diagnosis is a triple phase CT scan (non-con, arterial, delayed phase), which you will very likely need to tell your radiologist so he/she knows what to look for.⁴

Treatment

Above all else, when you diagnose or even think this may be what is going on, then you want to have your vascular surgeon there as soon as possible. Aside from supportive care (transfusion, O2, etc) there really is not much that you can do in the ED as most of these patients will require endovascular repair of the defect.

Rare but possible complications of EVAR⁶

• Limb Ischemia: up to 40% of cases
  • Early Limb Ischemia: occurs within 2 months of graft placement
  • Late Limb Ischemia: can occur as far out as 4-5 years after the procedure
• Renal Artery Occlusion: < 5 % of cases
• Colonic Ischemia: up to 3%
• Graft Infection: approx. 1%
• Spinal Cord Ischemia: 0.21 %

Conclusions

1. Endovascular grafts are often life-saving, but can have disastrous complications
2. Complications of endovascular grafts can present atypically or silently. Always maintain a high index of suspicion and have a low threshold to perform imaging.
3. Endoleaks are the most common complication of Endovascular Aortic grafts.
4. Don’t be hesitant to get a vascular surgeon involved even if your workup is normal.

References / Further Reading

1. Chenu C, Marcheix B, Barcelo C, Rousseau H. Aorto-enteric fistula after endovascular abdominal aortic aneurysm repair: case report and review. Eur J Vasc Endovasc Surg. 2009;37(4):401-406. doi:10.1016/j.ejvs.2008.11.037.
2. Ruby BJ, Cogbill TH. Aortoduodenal fistula 5 years after endovascular abdominal aortic aneurysm repair with the Ancure stent graft. J Vasc Surg. 2007;45(4):834-836. doi:10.1016/j.jvs.2006.11.039.
3. Hughes FM, Kavanagh D, Barry M, Owens A, MacErlaine DP, Malone DE. Aortoenteric fistula: a diagnostic dilemma. Abdom Imaging. 32(3):398-402. doi:10.1007/s00261-006-9062-7.
4. Rand T, Uberoi R, Cil B, Munneke G, Tsetis D. Quality improvement guidelines for imaging detection and treatment of endoleaks following endovascular aneurysm repair (EVAR). Cardiovasc Intervent Radiol. 2013;36(1):35-45. doi:10.1007/s00270-012-0439-4.
5. Endoleak | Radiology Reference Article | Radiopaedia.org. http://radiopaedia.org/articles/endoleak. Accessed March 28, 2016.
6. Maleux G, Ph D, Koolen M, Heye S. Complications after Endovascular Aneurysm Repair. Semin Intervent Radiol. 2009;26(1):3-9. doi:10.1055/s-0029-1208377.