Aortic Ligation and Extraanatomic Bypass for AEFs

In stable patients with a small herald bleed caused by an AEF, Reilly et al. at the University of

California-San Francisco advocated staging of the two component operations at an interval of several

days to minimize the physiologic impact on the patient.75 The first stage of this approach consists of

performing an axillobifemoral bypass or bilateral axillary–popliteal bypasses, followed several days

later by resection of the infected graft with aortic stump closure. In the patient with ongoing bleeding

or hemodynamic instability, a staged approach is not feasible. Reilly reported a 26% mortality rate with

the staged approach, compared to 43% for the traditional, nonstaged.75 A subsequent study by Seeger

reported a 19% treatment-related mortality rate.76 In addition to a high mortality rate, this approach is

plagued by a significant risk of aortic stump blowout (9%), reinfection of the extraanatomic bypass

graft (16%), and major amputation (16%).75

In Situ Aortic Reconstruction for AEFs

In response to the sobering results associated with the traditional approach, in situ aortic reconstruction

has been touted as a relatively simple and effective alternative.80–84 Oderich et al. from the Mayo Clinic

reported their results using in situ rifampin-soaked grafts in 54 patients with aortic graft-enteric

erosions or fistulae.80 In their series, operative mortality was 9%, and graft reinfection occurred in 4%.

A subsequent multicenter study of 37 patients with AEFs treated with either in situ prosthetic grafts (n

= 9), extraanatomic bypass (n = 25), or endografting (n = 3), reported a 30-day mortality rate of 43%

for in situ reconstructions.82 In that series, 3 of 11 (27%) long-term survivors with in situ grafts

developed reinfection of the in situ graft, which was universally fatal.

Alternative conduits for in situ reconstruction for AEFs include cryopreserved aortoiliac allograft and

femoral vein. Harlander-Locke et al. published a multicenter experience with 220 patients with aortic

graft infections treated with in situ cryopreserved aortoiliac allograft, which included 33 patients with

AEFs.83 The reinfection rate in patients presenting with AEFs was 12%. In situ repair with autogenous

femoral vein is not appropriate in the unstable patient due to the time required for femoral vein

harvest, but may be reasonable in the stable patient with a herald bleed due to an AEF. Valentine

reported a 42% mortality rate in 24 patients treated with in situ femoral vein for AEFs and graft-enteric

erosions, so femoral vein may not offer any advantage over the alternative conduits for AEFs.84

Aortic Infection with Sepsis

Sepsis caused by an aortic infection poses a challenge because temporizing with an endograft is not an

option since the septic focus is not eliminated. In unstable patients, CT-guided percutaneous drainage

may be a reasonable option for source control if there is a large perigraft fluid collection. In a series of

23 patients with graft infections, Belair et al. found that percutaneous drainage was associated with

improved perioperative mortality, compared to surgery alone.85 In the absence of a large perigraft fluid

collection for percutaneous drainage, graft excision with extraanatomic bypass is the most reasonable

approach.

Aortic Infections in the Stable Patient

Preoperative Evaluation

The incidence of coronary artery disease is high in surgical series of arterial infections, especially in

subjects with infected endografts.2,6,14 Thus, a thorough cardiovascular history, physical examination,

12-lead electrocardiogram, and echocardiogram should be obtained to evaluate for heart failure,

valvular dysfunction, and pulmonary hypertension. These investigations may reveal a history of active

cardiac conditions that may modify the type of operation selected or preclude surgery. Only rarely is

stress testing or coronary arteriography indicated since coronary revascularization is usually

contraindicated in the context of an active infection. However, this information may alter the surgical

plan, provide valuable information for the anesthesiologists, and guide discussions with the patient or

family regarding the expected outcomes. Pulmonary evaluations are rarely undertaken, as this

information seldom alters the management of the patient. Only those patients with the most severe

pulmonary insufficiency may benefit from formal testing to guide perioperative management.86

Operative planning is greatly facilitated by a preoperative CTA to define the arterial anatomy.

Angiography of the lower extremities is reserved for cases when a concurrent infrainguinal bypass is

considered likely. Noninvasive measurements of distal perfusion and lower extremity vein mapping

should be performed. Ankle-brachial indices (ABIs) may forewarn the surgeon of the potential for

infrainguinal revascularization after graft excision and aortoiliac reconstruction. Mapping of the

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bilateral greater saphenous veins and femoral–popliteal veins is essential if an autogenous conduit is

contemplated. Femoral–popliteal veins with a diameter of less than 6 mm or evidence of vein wall

sclerosis are inadequate for aortoiliac reconstruction.2

Anesthetic Considerations

Operations to excise infected aortic grafts are technically challenging, lengthy, and prone to a large

volume of blood loss. The importance of a quality anesthesia team in managing these challenges cannot

be over-stated. Hypothermia, hypovolemia, and intraoperative anemia must be assiduously avoided

with the use of warming blankets, warmed resuscitative fluids, warm ambient operating room

temperature, and a low threshold for blood and crystalloid replacement. The blood bank should be

prepared to provide fresh-frozen plasma, cryoprecipitate, or platelets on short notice if coagulopathy

develops. Culture data are often not available at the time of operation, so broad-spectrum antibiotic

coverage for gram-positive, gram-negative, and anaerobic organisms should be redosed throughout the

operation.

Aortic Ligation and Extraanatomic Bypass Versus In Situ Reconstruction

A major advantage of graft excision with extraanatomic bypass is the removal of all prosthetic graft

material from the infected operative field. This approach also obviates the need to procure an aortoiliac

allograft. Finally, use of an extraanatomic bypass circumvents any reticence a surgeon may have with

harvesting femoral veins since some surgeons are not familiar with the technique. The obvious pitfalls

of this approach are the risk of aortic stump blowout, reinfection of the extraanatomic bypass graft, and

poor long-term patency of the extraanatomic reconstruction. In situ reconstruction is appealing because

it avoids the risk of aortic stump blowout and the poor long-term patency of extraanatomic bypasses.

For patients with insufficient infrarenal aorta for a secure three-layer closure, in situ may be the only

reasonable option. Reinfection of new graft is the obvious risk of this approach. In the following

sections, we will offer technical suggestions for performing these complex operations and summarize

the published results for each approach.

Aortic Graft Excision

Common to each of the described surgical approaches to aortic graft infection is the need for complete

graft excision. For graft excision, aortic exposure can be performed via a transperitoneal or

retroperitoneal approach. Proximal control of the infrarenal aorta can be challenging in a redo operative

field, so the surgeon should be prepared to obtain proximal control of the aorta at the suprarenal or

supraceliac level. When treating an AEF, we always obtain either suprarenal or supraceliac aortic

control prior to mobilizing the duodenum since there may be uncontrolled hemorrhage in the absence of

proximal aortic control. Balloon control is another useful adjunct in cases of severe inflammation or

scarring.50 The left renal vein may be densely adherent to the graft or the native aorta, which may

necessitate its division to gain access to the aorta near the renal arteries. Once proximal control is

obtained, distal control of the bilateral common iliac arteries should ensue, unless these arteries are

occluded. When excising an aortofemoral graft, the femoral limbs should be controlled in the abdomen

to facilitate their removal. Removal of aortofemoral grafts requires considerable dissection in the groins

for control of the prosthetic graft limbs and native common femoral, superficial femoral, and profunda

femoris arteries. Femoral exposure may be performed through an incision directly over the femoral

limb or incisions lateral to the sartorius muscle. The lateral incision avoids some of the prior scarring

and may preserve soft tissue for arterial coverage. Systemic heparin is administered prior to crossclamping, and the graft is removed in its entirety. Any arterial tissue that appears to be abnormally

friable is probably infected and should be debrided. Remnants of graft and arterial tissue should be sent

for Gram stain, culture, and sensitivity testing. A critical adjunct is wide debridement of the

retroperitoneum, which is believed to decrease the residual bacterial bioburden that will predispose to

recurrent infection. After completing graft excision and debridement, closure of the aortic stump or in

situ aortoiliac reconstruction may ensue.

Extraanatomic Bypass

For stable patients, staging of the extraanatomic bypass and graft excision should be considered, as

proposed by Reilly.75 The first stage of this approach consists of performing an axillobifemoral bypass

or bilateral axillary–popliteal bypasses, meticulously avoiding any infected or contaminated planes

when tunneling the new grafts. The second stage consists of aortic graft excision, retroperitoneal

debridement, and aortic stump closure. Aortic stump closure requires a meticulous three-layer closure of

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the aorta. The first two layers consist of two layers of nonabsorbable polypropylene suture; a vertical

mattress suture, followed by running “baseball” suture. The final layer is an omental wrap secured with

sutures.75 When staging the extraanatomic bypass and graft excision, the optimal time interval between

the two operations has not been defined. It has been our experience, however, that the presence of both

an aortobifemoral bypass and an extraanatomic bypass creates competitive flow between the grafts that

often results in thrombosis of the extraanatomic bypass graft. To minimize the risk of interval graft

thrombosis, patients are anticoagulated with intravenous unfractionated heparin between operations,

and a short (1 to 3 days) time interval (usually 1 to 2 days) between the two operations is planned. If

the two operations are performed at the same operative setting, the clean portion of the procedure (the

extraanatomic bypass) is performed prior to the infected portion of the case (graft excision) whenever

feasible to minimize the risk of bacterial inoculation of the new graft.

The outcomes for graft excision with extraanatomic bypass have been sobering. In their landmark

review, Yeager and Porter reported an average mortality rate of 21% with an average amputation rate

of 11% and recurrent infection rate of 18%.77 In a series of 36 patients with aortic graft infections,

Seeger et al. subsequently reported a similar mortality rate (overall treatment-related mortality rate of

19%), but a lower rate of reinfection and aortic stump blowout (2.8% incidence of each complication).76

Seeger noted that the patency of the extraanatomic bypasses was directly related to the type of graft

configuration. Axillobifemoral bypasses had a primary patency of 75% at 41 months, whereas the

primary patency for axillopopliteal bypasses was 0%. Similar results have been observed using this

approach in treating infected abdominal aortic aneurysms. Lee reported a series of 28 patients with

infected abdominal aortic aneurysms treated with aortic resection plus either in situ repair (n = 13) or

extraanatomic bypass (n = 15).87 Lee observed a 27% mortality rate for the cohort receiving

extraanatomic bypass in this nonrandomized study.

In Situ Reconstruction with Cryopreserved Arterial Allografts

Experience with allograft replacement of primary or secondary arterial infections began with Alexis

Carrel more than a century ago.88 Difficulties with procurement and preservation resulted in poor

quality control. Allografts were largely abandoned until their resurrection for the treatment of

infectious pathologies of the ascending aorta in the 1980s.89 Initial positive experience resulted in more

widespread use, including the treatment of infected infrarenal aortic graft infections.90 Initially, local

tissue banks were responsible for procuring, preserving, and allocating allografts for clinical use. This

resulted in considerable variability in the processes of preparing and storing the product, which may

have impacted the quality of the product. Currently these processes have been centralized in both North

America and Europe with primary suppliers of the cryopreserved allografts.

The primary advantage of cryopreserved allografts is its resistance to infection, which is substantiated

by recurrent infection rates ranging between 0% and 3.6%.83,90–94 Primary patency was 97% at 5 years

in a multi-institutional registry, which is comparable to other conduits for in situ reconstruction.83 The

primary disadvantages of cryopreserved allograft in the early experience with this conduit were graft

rupture and pseudoaneurysm formation. Newer cryopreservation techniques have improved the

preservation of the arterial collagen matrix, decreasing the incidence of graft rupture and

pseudoaneurysmal dilation. However, it is not clear that these issues have been fully resolved. Vogt et

al. reported an allograft complication rate of 16% in a cohort of 43 implants, including one

intraoperative rupture and three late ruptures (>30 days after implantation).92 In a multicenter registry

of cryografts, 24% of patients experienced major complications, including eight ruptures and six

pseudoaneurysms.83 The most frequent complication, however, was persistent sepsis, occurring in 17

subjects. Other disadvantages of cryopreserved allograft include the cost of the grafts (approximately

$18,000 per aortoiliac segment).80 Moreover, these grafts are not readily available in most centers,

making it less practical for infected pathologies complicated by hemorrhagic or septic shock.

In response to the early complications, Vogt recommended several techniques to prevent early

adverse outcomes.92 These included proper timing of the allograft thawing and ligature of the allograft

side branches with polypropylene suture that incorporates a portion of the allograft wall. Tension on the

anastomoses must be avoided, and reinforcement of the anastomosis with circumferential allograft

strips and gentamycin-impregnated fibrin glue is also recommended.

In Situ Reconstruction with Rifampin-Soaked and Silver-Impregnated Grafts

Rifampin shows unique activity against S. epidermidis biofilms, making it an excellent choice for

prosthetic graft infections.95 Rifampin-soaked Dacron grafts (600 mg rifampin in 250 mL of normal

saline, soaked for 30 minutes) with omental wrapping has been shown to have variable resistance to

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recurrent infection, ranging between 4% and 11.5%.80,81 Recurrent infections have been fewer when

treating AEFs, compared to prosthetic graft infections. Primary patency is also excellent, ranging

between 89% and 92%, with limb salvage rates of 100%.80,81,96 Circumferential omental wrapping of

the grafts is a critical technical adjunct to decrease the risk of reinfection.80

Silver-impregnation relies upon the ability of silver to adsorb gram-positive and gram-negative

bacterial membranes, resulting in disruption of the membrane and cell lysis. There has been no reported

bacterial resistance to silver.97 It is theorized that silver-impregnated grafts would have activity against

E. coli and methicillin-resistant S. aureus, which would be an improvement over rifampin-soaked

grafts.98 The limited clinical data suggest that silver-impregnated grafts are not equivalent to rifampinsoaked grafts since the reinfection rate was 15.7% in a single-center series in France.99,100

In Situ Reconstruction with Autogenous Femoral Vein

Autogenous femoral vein was proposed as an alternative conduit for in situ reconstruction for infected

aortic grafts in the early 1990s.101 Clagett described creating a “neoaortoiliac system” using femoral

veins harvested from both legs. The proposed advantages of femoral vein include an innate resistance to

infection and excellent long-term patency, which is borne out by the two largest series to date using

femoral vein. Ali reported 187 neoaortoiliac reconstructions using femoral vein.2 The 30-day mortality

for this approach (10%) was not significantly different from other in situ reconstructions for graft

infection. Predictors of mortality included preoperative sepsis and infection with Candida glabrata,

Klebsiella pneumonia, or Bacillus fragilis. Reinfection occurred in 5%. Primary patency was 81% at 72

months. Daenens reported similar outcomes using femoral vein, including an 8% inhospital mortality

rate.102 Daenens group observed no reinfections and no cases with aneurysmal degeneration of the

femoral vein graft. The 5-year primary patency was 91% with a limb salvage rate of 98%.

The major pitfall of using femoral vein for in situ reconstruction is the time required to harvest the

veins. Although many surgeons have not had formal training in the technique for harvesting femoral

veins, it is well within the capability of any vascular surgeon. The technique is described in detail

elsewhere.103 Briefly, femoral veins are harvested using an incision extending along the lateral edge of

the sartorius muscle from the anterior superior iliac spine to the medial condyle of the femur. The

sartorius muscle is reflected medially to preserve the segmental blood supply of the sartorius. Collateral

vessels from the superficial femoral and popliteal arteries should be preserved during vein harvest,

especially in the setting of known superficial femoral artery occlusive disease.103 The saphenous nerve

should be avoided to prevent postoperative neuralgia. The femoral vein is harvested from its confluence

with the profunda vein to the knee joint to provide a length of vein required to replace an

aortobifemoral bypass graft. All side branches greater than 3 mm in diameter are doubly ligated, rather

than suture-ligated, since the latter may tear the wall of the vein graft. The femoral vein is divided flush

with the profunda vein to avoid creating a blind stump that could serve as a nidus for thrombus

formation and subsequent pulmonary embolism. The vein is then everted in its entirety, with the

intimal layer on the outside, to allow excision of the venous valves. After reversion, the graft is

distended and any defects are repaired with 6-0 or 7-0 polypropylene suture. The graft is used in

nonreversed orientation to improve the size match at the aortic and femoral anastomoses.

Among clinicians who are not familiar with using femoral vein for aortoiliac reconstruction, there

appears to be reluctance based on concerns with any venous morbidity associated with harvesting the

femoral vein. Our group has extensively studied this issue.104,105 In the early postoperative period, there

is a risk of venous congestion that may produce lower leg compartment syndrome requiring fasciotomy.

Early in our experience with deep vein harvest, fasciotomy was required in 17% of limbs, although

many of those fasciotomies were “prophylactic.”104 With additional experience, our tolerance for acute

leg swelling has increased, so fasciotomy is now rarely performed. Two preoperative predictors of a

higher probability of fasciotomy were identified: concurrent harvesting of the greater saphenous vein in

the same limb and a low ankle–brachial index (<0.55) in the harvested limb. Prior harvest of the

ipsilateral greater saphenous vein was not a risk factor for requiring a fasciotomy. Venous collaterals

develop over time to normalize venous physiology in most patients, so long-term venous morbidity is

minimal. One-third of patients experience mild chronic leg swelling, and the remainder are

asymptomatic.105 To our knowledge, no limbs have developed venous ulceration as a consequence of

femoral vein harvest.

Comparisons of Arterial Reconstruction Methods for Aortic Arterial Infections

There is a dearth of direct comparisons of the various surgical options for managing graft infections in

the literature. Over the past decade, there has been a trend toward various types of in situ

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