1. The Emerging Use of Endovascular Stenting in Primary Aortoduodenal Fistula
Good afternoon, today I will talk about “The Emerging Use of Endvoascular Stenting in Primary Aortoduodenal Fistula”.
YU Hok Yee Harry
Pamela Youde Nethersole Eastern Hospital
Joint Hospital Surgical Grand Round
16th April 2011

2. Introduction First described by Sir Astley Cooper in 1822
About 300 reported in literature
Incidence
0.04 – 0.07% in large autopsy study
3% of massive GI bleed, 6% of fatal GI bleed
Mortality: 67%; inevitable fatal without operative intervention
Primary vs. secondary
Can occur anywhere between oesophagus,
commonest in duodenum (80%); can be multiple
Mostly associated with AAA (>80%), infection;
and other rarer causes
Edgard et al, 2001
Kane et al, 1955
Farber et al., 2001
Aortoenteric fistula was first described in the 19th century. It is rare but accounts for 3% of massive GI bleeding and 6% of fatal GI bleeding. The disease is inevitably fatal without operation.
Duodenum is the commonest site of aortoenteric fistula, as it is a fixed, retroperitoneal organ in close approximation to aorta. Together with expanding nature of AAA may result in eventual fistulation over time.
Infection also played important role in formation of primary aortoduodenal fistula.
Sevastos et al, 2002
Sintler et al, 2008

3. Clinical Presentation
Presentation of “Classical Triad” is minority (11%)
Gastrointestinal bleed (94%): “herald” bleeding  massive haemorrhage and exsanguination
Abdominal pain (48%)
Pulsating abdominal mass (17%)
Non-specific symptoms
Suspicious in patient
Known AAA
Unexplained GI bleeding, over 50-year-old
Upper endoscopy & CT scan as the mainstay of investigation modalities
Saers et al, 2005
Sintler et al, 2008
The diagnosis of primary aortoenteric fistula requires acute awareness. Only minority of patients will present with the classical triad of gastrointestinal bleeding, abdominal pain and pulsating abdominal mass. Often, an initial, sentinel bleed is reported by patients before exsanguination occur.
Patient may also present with non-specific complaints, including symptoms of inflammation or arterial bleed.
Low threshold of clinical suspicion is mandatory for prompt diagnosis. The possibility of a primary AEF should be considered in patient known to have AAA or any patient older than 50 years with unexplained GI bleeding.
The main value of upper endoscopy is to establish or rule out other diagnosis. CT scan has high sensitivities and specificities for the disease.
Mylona et al, 2007

4. Management
Prompt operation is only the only mean to save patient’s life
Treatment aim
To control bleeding
To eradicate infection
To maintain adequate distal perfusion
Surgical treatment is the only means to save patient’s life. The aim of treatment is haemostasis, eradicate infection and maintain distal circulation.
Montgomery et al, 1996

5. Management Classical methods: Debridement of infected tissues
together with
Primary repair of intestinal defect, with
Aneurysmorrphaphy; or,
Replacement of aneurysm with prosthetic graft
Aortic ligation with extra-anatomical bypass, e.g. axillary-bifemoral graft
For conventional therapy, to repair the defect, it is necessary to disconnect the vascular tree from the gastrointestinal tract.
The first choice is primary repair of intestinal defect and aortic reconstruction with an in-situ graft.
In case of severe peritonitis or extensive local sepsis, an alternative treatment is to disconnect the fistula followed by oversewing of the aorta and axillobifemoral bypass.

6. Management -Problems with Conventional Treatment
Overall mortality: 63%
Complications
Aortic stump rupture: 10 – 50%
Limb loss, resulting in amputation: 5 – 25%
Time consuming operation: extra strain to a stressful condition
Farber et al., 2001
Burks et al, 2001
The problem of conventional treatment is its high mortality rate, which maintains at a static figure over decades.
The average perioperative mortality rate for in-situ reconstruction is around 30%.
Extra-anatomical bypass grafting and aortic ligation carried even higher mortality rate, and high morbidity rate including stump rupture and limb loss.
Duration of convention operation is long, which gives extra strain to the cardiovascular system of an already stressed patient.

7. Prognosis of a disease depends on surgeons factor, disease factor and patient’s factor. In this emergency situation, patient’s factor are consistently to be poor, the disease is known to be highly fatal. Surgeons factor is the only one which is possible to amend in the emergency setting. With the emerging use of endovascular technique, there is a believe that the disease can also be tackled with the use of endovascular aortic repair.
Emergence of Endovascular Aortic Repair (EVAR) in Aortoduodenal Fistula

8. Emergence of EVAR First reported by Burks in 2001
2 of 7 patients with primary aortoenteric fistula
82-year-old, male, hypertension, coronary artery disease, 10cm AAA
Treated with Aortouniiliac stent graft
Immediate cessation of bleeding achieved
Died 13 months due to myocardial infarction
Several case reports with similar success
The use of EVAR in aortoduodenal fistula first reported in a case series published in A 82-year-old man with known coronary artery disease and hypertension is diagnosed with primary aortoduodenal fistula due to 10cm AAA. He was successfully treated with aortouniiliac stent graft. Patient was able to discharge and died 13 months later due to myocardial infarction.
Several case reports are being published later for successful haemostasis. Most of the patients were having multiple medical comorbidities and limited life expectancies that are regarded to have very high risk of open operation. They concluded endovascular aortic repair offers less invasive alternative to seal the fistula and control bleeding.

9. EVAR in Aortoduodenal Fistula - Advantages
Rapid control of bleeding
Minimal physiologic insult to patient
Avoidance of operating in hostile abdomen
Straightforward and speed of procedure
Eliminating complications associated with open surgical repair
Lower perioperative complication incidence
Shorter hospital stay and more likely to discharge home
Roche-Nagle et al, 2009
Here concludes the advantages of EVAR.
First of all, rapid haemostasis is possible, either by direct application of stent graft or deployment of aortic balloon.
As the operation requires only femoral dissection, it gives minimal physiological insult to patients, who usually are old, fragile patient with multiple underlying medical diseases.
EVAR approach prevents operation in hostile abdomen in patients with history of laparotomy. In experience hands, EVAR is a much straightforward procedure which can usually be finished in 2 hours. The time is shorter compared to conventional treatment.
Complications of open repair including depressed respiratory function, adhesions, aortic cross clamping, large incision, etc. are not associated with EVAR.
A comparative study showed a lower incidence of perioperative complications and shorter length of hospital stay in endovascular group. Furthermore, nearly all of the endovascular patients could be discharged home, whereas most patients who underwent open repair required placement in skilled nursing facilities.
Chan et al, 2005

10. EVAR in Aortoduodenal Fistula - Candidate Selection
Pre-operative CT scan: diagnosis and planning
Significant co-morbidities / High-risk for conventional operation
Medical: cardiopulmonary, renal, etc.
Surgical: hostile abdomen
Expertise for emergency EVAR
Stent graft in immediate availability
The most important selection criteria for EVAR is pre-operative CT scan. It helps to diagnose and also for planning.
Patients with relatively good pre-morbid status are usually selected to undergo conventional operation. Those being reported to have EVAR for aortoduodenal fistula are patients with significant comorbidities. Most of them have underlying medical conditions, including cardiopulmonary or renal diseases. Surgical constrains like hostile abdomen make open operation less feasible.
Of course, there must have expertise being able to perform the endovascular operation well, with range of selection of stent graft in immediate availability.

11. EVAR in Aortoduodenal Fistula - Complications
Persistent sepsis
Repeat intervention or image-guided drainage
Fungal infection, e.g. Aspergillus
Long-term (or life-long) antibiotics
Medical: underlying co-morbidities of patient
Persistent bleeding
No reported incidence
Case report: unsuccessful result not reported?
Secondary aortoenteric fistula
Specific complications related to EVAR in abdominal aortic aneurysm will also appear in EVAR for aortoduodenal fistula. There are several specific complications regarding the use of EVAR in aortoduodenal fistula.
The three aims in the treatment of aortoduodenal fistula are haemostasis, maintain distal circulation and eradicate source of sepsis. Clearly, EVAR is able to achieve the first two aims. However, as there is no removal of infectious nidi during the operation, persistent sepsis will cause harm to patient. In fact, in the reported cases, most of the perioperative mortalities are due to uncontrolled sepsis. Of particular interest is fungal infection, which had been reported in at least 2 mortalities.
Long-term or even life-long antibiotics is therefore recommended in most of the case reports. Ideally, the choice of antibiotic should be able to target against both Gram positive and negative strains and, of course, according to the culture result. It should be continued for at least 6 weeks and prolonged antibiotic treatment may also be sensible if patient’s condition indicate ongoing infection.
As it is known from the selection criteria that the patients are usually having multiple comorbidities, patient may die from their underlying diseases during or after the operative period. It is found that late mortalities are mostly due to underlying medical conditions.
There is no persistent bleeding identified from case reports. However, case reports tend to report successful management only and such a potential complication needs special attention.
Several reports had revealed that EVAR can still cause fistulation despite the theoretical lack of extraluminal disruption. If patient live long enough, secondary aortoenteric fistula may occur.

12. Stent Graft in Infected Region - A Contraindication?
Against general surgical principle: putting endovascular graft in infected environment
Lack of excision and debridement of infected nidi
Arguments
Low bacterial load over aortic side due to direction of blood flow: bacteria washed away to enteric side
Increased infection resistance by stent-grafts compared to standard polyester grafts
Endovascular stent graft: 0.43%
Conventional open repair: 0.5 – 3%
Adjunct techniques to suppress local infection: antibiotics; CT-guided drainage, injection of fibrin, cyanocylate sealants, local antibiotic cleansing
Ducasse et al 2004
The most frequent debate about EVAR in the treatment is the placement of graft in an infected environment. Putting graft into this infected site violates general surgical principle. Such measures creates concerns over its safety and efficacy. As most of the perioperative mortality are related to overwhelming sepsis, question of whether it is feasible generates major debate.
However, there are reasons for continuation of report of such success in the treatment of aortoduodenal fistula.
First of all, the blood flow direction is from the aorta to the intestine, bacterial colonies are often washed away and the bacterial population in aortic side is diminished.
In open repair, debridement of the site decreases local bacterial population, but on the other hand, there are indications that stent-grafts present increased infection resistance compared to standard polyester grafts. A retrospective review including 9000 stenting in 40 institutions showed infection rate of 0.43%. This is comparatively lower than the conventional open repair.
Additionally, after control of massive haemorrhage by endografting, further techniques can be used to suppress the local infection apart from systemic antibiotics.

13. Haemostasis is the Key
Basic principle of resuscitation: Airway, Breathing, Circulation
Basic principle to manage gastrointestinal bleed: Resuscitation, identify the bleeding, stop the bleeding
High mortality and morbidity with conventional treatment: to achieve haemostasis and eradicate infection in haemodynamically unstable patient
EVAR allows expeditious bleeding control with less physiological insult
Infection can be dealt in later stage of management
Traditional repair after EVAR remained an option
The most important advantage of EVAR in the setting of aortoduodenal fistula is its ability to control bleeding in a relatively short period of time with minimal physical insult. Back to the general principles of resuscitation, circulation is in the third sequence. Exsanguination would take the life of the patient in a short time, but not infection. Once haemostasis is achieved, patient can be managed in a relatively haemodynamically stable condition.
Conventional management to have extensive and long operation may contribute to the cause of high mortality.
On the other hand, EVAR is a comparatively shorter and relatively straightforward operation. Moreover, the initial phase of the operation can start with local anaesthesia to groin.
After stablised the initial emergency condition, patient can be managed in a less stressful environment. The decision for whether patient need a second-stage operation or a less invasive treatment, or even just to continue with antibiotics can be made with a longer period of observation, considering patient’s underlying co-morbidities, responsiveness to treatment and surgeon’s preference.
It is also important to know, in patients who have eventual failure of the endograft, traditional surgical repair remains an option.
Verhey et al, 2006

14. Mortality - Comparison between Types of Operation
Type of Operation
No. of Patients
Mortality Rate (%)
Standard in-situ graft 39 36
Antibody-impregnated in-situ graft 8
Closure of defect alone 75
Endovascular stent-graft 7 14
Extra-anatomic bypass 5 40
Embolic coiling 1
Total 68 34
There is no comparative study between conventional open repair and endovascular repair due to the small sample size. A retrospective study including 68 patients with aortoenteric fistula were examined.
Most patients underwent conventional in-situ graft repair in the study, which carried 36% mortality rate. Mortality rate of extra-anatomic bypass is 40%. Antibody-impregnated in-situ graft carried no mortality, but it is still an open operation. 7 patients underwent endovascular stent graft, result in 14% mortality rate.
From this study, it showed EVAR potentially carries lower mortality and is a feasible method for aortoduodenal fistula.
Saers et al. 2005

15. EVAR in Aortoduodenal Fistula - Definitive vs. “Bridging”
Debatable
Particular on “infection” issue
Endovascular stent does not include intestinal repair
Life-long antibiotics
Long-term suppression of sepsis
Death mainly due to coexistent cardiopulmonary disease
Adjunctive treatment may contain sepsis
Percutaneous drainage
Bowel diversion
At last, there are debates as if EVAR is a definitive or “bridging” operation. Most importantly is the infection issue. The other issue is that EVAR does not include intestinal repair.
Most of the current literature agreed, without debridement of all contaminated retroperitoneal tissue, EVAR is not a definitive therapy. The newly placed prosthetic endograft is contaminated by gut flora. Complete eradication of infection is probably impossible. However, with prolonged antibiotic treatment, long-term suppression of sepsis may be feasible. As seen in most of the studies, once bleeding is controlled, many patients die of coexistent cardiopulmonary diseases before infection or aortic degeneration becomes a significant problem. Adjunctive treatments may be helpful to contain sepsis in the setting of gross aortic graft infection.
Burks et al. 2001

16. Summary EVAR in Primary Aortoduodenal Fistula
Rare disease carries high mortality
Conventional therapy
Aim to control bleeding, maintain distal circulation and eradicate infection
Very high mortality
EVAR can have rapid control of bleeding
Multiple adjunct techniques available to control infection
Definitive or “bridging” therapy depends on scenario
In summary, primary aortoduodenal fistula is a rare disease carrying high mortality.
Conventional therapy aim for haemostasis, maintain distal circulation and eradicate infection in one-go carried very high mortality rate.
EVAR is able to achieve rapid haemostasis and multiple adjunctive techniques are available to deal with sepsis.
Whether EVAR is a definitive or “bridging” therapy depends on scenario.
This concludes my presentation.