The role of imaging techniques in evaluating possible graft infections

Imaging plays a central role in the management of graft infections. Most graft infections are clinically apparent, and imaging techniques are used primarily for diagnostic confirmation and operative planning. The accurate diagnosis of less overt graft infections requires a thorough understanding of the available imaging options. Late aortic graft infections (more than 3 months postoperative) are best evaluated initially by computed tomography (CT) or magnetic resonance (MR) scanning. CT findings consistent with a graft infection include ectopic gas, perigraft fluid, perigraft inflammatory changes, anastomotic pseudoaneurysm, and thickening of adjacent bowel. MRI offers the additional advantage of T2-weighted images to identify perigraft inflammation and minute quantities of perigraft fluid. Radionuclide scanning techniques such as 111indium-labeled WBC scans are highly sensitive but suffer from a relative lack of specificity. Duplex ultrasonography is best applied to the diagnosis of late infections of superficial grafts. Sonographic findings of a graft infection include perigraft fluid and pseudoaneurysms. The imaging of early postoperative grafts (less than 3 months) for infection is problematic because perigraft fluid and inflammatory changes persist for up to 3 months postoperatively. Suspected early graft infections often require operative exploration for diagnosis. A thorough understanding of the utility and limitations of imaging techniques will enable the clinician to develop a reasonable diagnostic algorithm that is appropriate for each case.     

Conservative treatment of major aortic graft infection

Major infections of Dacron aortic grafts involving the proximal anastomosis or the whole graft are rare but lethal. Traditional surgical treatment involves radical excision of the graft and extra-anatomic revascularisation of the lower limbs, and carries a forbidding mortality and complication rate. This paper describes an alternative conservative approach used on four patients, three of whom appear to have been successfully treated by continuous antibiotic irrigation of the prosthesis without removal of the graft, whilst the fourth died 42 months later of recurrent graft infection. This is the first time that prolonged survival has been reported following conservative treatment of major graft infection. The authors believe this method may offer substantial advantages over the traditional surgical treatment for this dreaded complication of aortic surgery.     

Experience with femoro-popliteal vein as a conduit for vascular reconstruction in infected fields.

OBJECTIVE: to review the outcome of femoro-popliteal vein grafts for arterial reconstruction in the presence of sepsis. PATIENTS AND METHODS: twenty-six patients underwent 27 arterial reconstructions with femoro-popliteal vein in the presence of infection. Five had mycotic aneurysms (3 aortic, 1 iliac and 1 femoral), 21 had prosthetic graft infections (9 aortic, 8 femoro-femoral, 2 axillo-femoral, 1 ilio-femoral and 1 femoral dacron patch) and one underwent superior mesenteric artery reconstruction following ischaemic small bowel perforation.Arterial reconstruction followed debridement of infected tissue, removing any infected graft, povidone iodine washout and appropriate antibiotic cover. Where possible, new grafts were placed in a clean field or wrapped in omentum. Four femoral anastomoses were covered by rectus femoris flaps. RESULTS: there was one early postoperative death (4%) and no limb loss. All others remained free from infection with patent grafts at 1 month to 5 years (median 22 months). Three major wound infections healed without exposing the graft. One infarcted rectus femoris flap required removal. Donor limb swelling was transient. Five required percutaneous angioplasty and one underwent open profundaplasty within 3 months. CONCLUSION: femoro-popliteal vein reconstruction with debridement and appropriate antibiotic therapy is recommended for the treatment of arterial or graft infections.     

In-situ replacement and extra-anatomic bypass for the treatment of infected abdominal aortic grafts

We reviewed the surgical results of 21 patients who had infected abdominal aortic grafts to determine the efficacy of in-situ graft replacement and extra-anatomic bypass in the management of these patients. Twelve patients had a primary perigraft infection, and nine had an infection secondary to an aortoenteric fistula (AEF). Whereas the infected graft was replaced with a new aortic prosthesis in 18 patients, an axillobifemoral bypass operation followed graft excision in three patients. Twelve of the graft replacement patients (two AEF patients) had a low-grade infection, with negative perigraft and blood cultures. All 12 patients were alive at a mean follow-up of 8 years. Two had required above-knee amputation because of severe occlusive disease, and one had required an axillobifemoral bypass because of reinfection. The remaining six graft replacement patients (five AEF patients) had severe graft infections, with positive perigraft fluid and blood cultures in which one or more bacteria were present. Five died of sepsis within 1 month of operation. The remaining patient, who later required an axillobifemoral bypass because of reinfection, was alive at follow-up 4.3 years after operation. The three patients (two AEF patients) who had axillobifemoral bypasses had severe graft infections, with positive perigraft fluid and blood cultures. They survived the extra-anatomic bypass operation and were alive at a mean follow-up of 4.5 years. We conclude that patients who have a low-grade graft infection and negative blood and perigraft cultures can be treated safely by graft excision and in-situ replacement with a new prosthesis.(ABSTRACT TRUNCATED AT 250 WORDS)     

In situ replacement of vascular prostheses infected by bacterial biofilms

Late prosthetic graft infections are commonly the result of coagulase-negative staphylococci that survive within a biofilm on prosthetic surfaces and provoke perigraft inflammation. The indolent nature and microbiologic characteristics of bacterial biofilm infections coupled with the morbidity of graft excision and extraanatomic bypass grafting prompted us to use in situ graft replacement in 15 patients admitted to the hospital with 17 infected graft segments at a mean (+/- SEM) time interval of 70 +/- 16 months after graft implantation (n = 6) or revision (n = 9). Since 1986, 17 grafts (14 aortofemoral, 2 axillofemoral, and 1 femoropopliteal) infected by bacterial biofilms have been treated. Signs on admission included femoral pseudoaneurysm (n = 7), perigraft abscess (n = 6), or graft-cutaneous sinus tract (n = 4). No patient exhibited septicemia. At operation graft incorporation was absent and Gram's stain of perigraft exudate showed polymorphonuclear leukocytes but no bacteria. Culture of explanted graft material isolated coagulase-negative staphylococci (n = 12), Staphylococcus aureus (n = 1), and no growth (n = 2). All patients were successfully treated by a regimen that included parenteral antibiotics, removal of involved graft material, excision of inflamed perigraft tissue, and in situ replacement with an expanded polytetrafluoroethylene prosthesis. No deaths, graft thromboses, or deep wound infections occurred after operation. Recurrent graft infection did not develop during a follow-up interval that ranged from 5 to 50 months (mean, 21 months). Diagnosis of vascular prosthesis infection caused by bacterial biofilms can be based on signs at admission and operative findings. Complications of this perigraft infection can be eradicated by antibiotic administration, local debridement, and in situ graft replacement.     

Infection of vascular prostheses caused by bacterial biofilms

A canine model was developed to study the efficacy of graft replacement as treatment for vascular prosthesis infections from Staphylococcus epidermidis. Infrarenal aortic graft infections were established in 18 dogs by implantation of Dacron prostheses colonized in vitro with a slime-producing strain of S. epidermidis to form an adherent bacteria-laden biofilm (5 X 10(6) colony-forming units/cm2 graft). Study animals developed a graft infection with anatomic and microbiologic characteristics typical of late prosthetic graft infections in humans (sterile perigraft exudate, absent graft incorporation, and normal serum leukocyte count and sedimentation rate). The S. epidermidis study strain was isolated from 14 of 18 explanted grafts (78%) by mechanical disruption of the graft surface biofilm and culture in broth media. Four dogs with sterile graft cultures had histologic evidence of bacterial infection. The established prosthetic surface biofilm infection was treated by graft excision, parenteral cefazolin, and graft replacement with a Dacron or polytetrafluoroethylene (PTFE) vascular prosthesis. One month after graft replacement, no PTFE graft had signs of infection, but perigraft exudate and inflammation involved three of nine Dacron grafts (33%). The study strain was recovered from four of nine PTFE grafts (44%) and two of nine Dacron (22%) replacement grafts (p greater than 0.05). Prosthetic replacement of Dacron prostheses infected by S. epidermidis as a bacteria-laden surface biofilm can result in early graft healing, but persistent colonization of one third of replacement grafts signify that recurrent clinical infection remains a risk.     

Mediastinitis following graft replacement of the ascending aorta: conservative approach by omental transposition.

A 57-year-old patient underwent prosthetic replacement of a previously implanted ascending aorta graft and developed a periprosthetic purulent collection 1 month later. He was successfully treated by debridement of infected tissues, antiseptic irrigation and transposition of an omental flap. The postoperative course was uneventful. A chest computed tomography scan performed 15 months later showed no signs of perigraft infection. Prompt conservative surgical treatment including omental transposition can be effective in the treatment of mediastinitis following graft replacement of the ascending aorta.     

Intra-abdominal aortic graft infection: complete or partial graft preservation in patients at very high risk

BACKGROUND: Total graft excision with in situ or extra-anatomic revascularization is considered mandatory to treat infection involving the body of aortic grafts. We present a series of nine patients with this complication and such severe comorbid medical illnesses or markedly hostile abdomens that traditional treatments were precluded. In these patients selective complete or partial graft preservation was used. METHODS: Over the past 20 years we have treated nine infected infrarenal aortic prosthetic grafts with complete or partial graft preservation, because excision of the graft body was not feasible. In all nine patients infection of the main body of the aortic graft was documented at computed tomography or surgery. Essential adjuncts included percutaneous or operative drain placement into retroperitoneal abscess cavities and along the graft, with instillation of antibiotics three times daily, repeated debridement of infected groin wounds, and intravenous antibiotic therapy for at least 6 weeks. RESULTS: One patient with purulent groin drainage treated with complete graft preservation died of sepsis. One patient with groin infection treated with complete graft preservation initially did well, but ultimately required total graft excision 5 months later, after clinical improvement. In four patients complete graft preservation was successful; two patients required excision of an occluded infected limb of the graft; and one patient underwent subtotal graft excision, leaving a graft remnant on the aorta, and axillopopliteal bypass. In summary, seven of nine patients survived hospitalization after complete or partial graft preservation; amputation was avoided in all but one patient; and no recurrent infection developed over mean follow-up of 7.6 years (range, 2-15 years). CONCLUSIONS: Although contrary to conventional concepts, partial or complete graft preservation combined with aggressive drainage and groin wound debridement is an acceptable option for treatment of infection involving an entire aortic graft in selected patients with prohibitive risks for total graft excision. This treatment may be compatible with long-term survival and protracted absence of signs or symptoms of infection.     

Management of infections of polytetrafluoroethylene-based mesh

BACKGROUND: Mandatory removal of infected expanded polytetrafluoroethylene (ePTFE) mesh has been advocated, leading to a high rate of hernia recurrence. Although salvage of infected mesh has been reported, the feasibility, efficacy, and long-term outcomes of this practice remain unclear. The purpose of this study was to delineate a protocol for salvaging infected ePTFE mesh. METHODS: We reviewed retrospectively the records of patients with infections of ePTFE-based mesh placed for complex abdominal hernias at a tertiary referral center from October 1997 to September 2005. RESULTS: Twenty-two patients were treated for ePTFE-based mesh infections. Fifteen patients had undergone laparoscopic repair, and seven patients had undergone open repair. The median time of presentation after repair was 70 days (range 10-480 days). Fourteen patients had an extensive mesh infection and underwent mesh excision, with twelve patients having attempted fascial closure; hernias recurred in all twelve patients. Two patients underwent mesh excision and repair with a biologic mesh. Eight patients had a limited area of mesh involvement; six of these patients underwent surgical debridement, partial excision of the mesh, re-approximation of the remaining mesh with non-absorbable suture and drains, and application of a vacuum-assisted closure system to the open portion of the wound. These patients received four weeks of antibiotics with delayed wound closure. Two patients underwent percutaneous drainage of a perigraft abscess. There was no hernia recurrence in seven patients with a mean follow-up of approximately three years. CONCLUSIONS: Infections of ePTFE-based mesh can present in early or delayed fashion. Although mesh with extensive infection could not be salvaged, limited mesh infections could be managed successfully with percutaneous or open drainage and prolonged antibiotic courses.     

OBTURATOR FORAMEN BYPASS IN THE MANAGEMENT OF INFECTED PROSTHETIC VASCULAR GRAFTS

The obturator foramen bypass graft remains an excellent option for revascularking the lower extremity when dealing with an infected prosthetic vascular graft in the groin. In this series, six obturator foramen bypass grafts were performed in five patients for infectious groin complications following vascular surgery. Conservative measures such as local antibiotic irrigation and abscess drainage designed to preserve the graft in situ had failed to eradicate the infection in all instances and was complicated by suture-line haemorrhage in three instances. An aggressive approach should be adopted, aimed at excision of the infected graft. The obturator foramen bypass graft remains a durable graft for limb salvage. Five out of six obturator foramen bypass grafts were patent after 11–26 months follow up.     

TEVAR后移植物感染合并主动脉食管瘘的外科治疗

背景与目的 主动脉食管瘘（AEF）是一种相对罕见的疾病,通常危及生命。尽管胸主动脉腔内修复术（TEVAR）已成为治疗胸主动脉瘤、胸主动脉夹层的一种成熟手术策略,但TEVAR后继发性AEF更为棘手。笔者报告7例该疾病的治疗方式和结果。方法 回顾性分析2018—2021年间收治的7例TEVAR后继发性AEF合并移植物感染患者的临床资料。所有7例患者均接受了介入或手术治疗,其中4例患者施行了开放手术治疗,即：非体外循环下升主动脉－腹主动脉解剖外人工血管旁路术、感染移植物及感染灶切除术、食管瘘口旷置引流术;2例患者施行了TEVAR;1例患者分期施行了TEVAR和开放手术。结果 一期和分期施行开放手术治疗的5例患者,2例痊愈出院,3例死亡。单纯施行TEVAR的2例患者,计划待抗感染、营养支持后限期施行开放手术,治疗期间死亡。结论 因感染移植物及感染灶的存在,保守治疗或单纯行TEVAR往往无法使患者获得救治。虽然开放手术病死率较高,但在条件允许时,清除感染灶及移植物,并进行解剖外主动脉重建及食管瘘旷置引流,是治疗TEVAR术后移植物感染合并主动脉食管瘘的合理策略。     

Repair of a saccular aortic aneurysm with superficial femoral-popliteal vein in the presence of a pancreatic abscess

When one is faced with impending rupture, repair of an aortic aneurysm cannot be delayed. In the presence of coexisting intra-abdominal sepsis, traditional therapy would call for aneurysm exclusion and axillofemoral bypass grafting. Consequences of this choice of treatment include limited long-term graft patency and recurrent prosthetic infection. Autogenous deep veins from the lower extremities have demonstrated exceptional patency and resilience to infection when used to replace infected aortic grafts. We now report a case of concomitant open drainage of a pancreatic abscess and repair of a saccular abdominal aortic aneurysm using the superficial femoral-popliteal vein as a conduit.     

Management of infected aortic prosthetic grafts

The management of infected prosthetic grafts is one of the most challenging problems facing vascular surgeons. High mortality and morbidity rates with traditional treatment have led many surgeons to consider different and novel strategies. Diagnosis is usually straightforward, but occasionally is unclear even after extensive clinical and radiologic investigations. Although routine total graft excision for all infected aortic grafts is still favored by some vascular surgeons, most favor only partial graft excision if only the distal limb of the graft is involved. Placement of in situ autologous vein or cryopreserved grafts have gained popularity, and investigations are continuing regarding the use of in situ antibiotic and silver-coated prosthetic grafts. In this article the authors review the incidence and etiology of aortic graft infections, methods to prevent these complications, the diagnosis of infected aortic grafts, and lastly the management of these complicated cases, including total graft excision and partial and complete graft preservation.     

Successful treatment of infected thoracoabdominal aortic graft by percutaneous catheter drainage

A large perigraft abscess infected with Klebsiella sp. developed around a woven Dacron prosthesis inserted into a patient at high-risk with a leaking thoracoabdominal aortic aneurysm. Percutaneous insertion of a sump drainage catheter under ultrasound guidance accompanied by local and systemic antibiotic therapy was the only reasonable management option. Two years later the patient remains well with no evidence of sepsis on clinical examination, hematologic studies, computerized tomography or indium 111 labeled autologous leucocyte imaging. This technique may be successful in selected high-risk situations.     

Surgical management of ascending aortic graft infection. No-sedation-technique for open mediastinal irrigation.

Two patients with ascending aortic graft infection were successfully treated. The first patient underwent ascending aortic replacement using a Dacron graft for aortic dissection, and developed graft infection. After 25 days' open mediastinal irrigation, allograft replacement and rectus muscle flap transfer were performed. The second patient underwent translocation of the aortic valve with a composite graft for calcific aortic stenosis, and developed graft infection. After 29 days' open irrigation, omental and rectus muscle flap transfer were performed. We were able to perform long-term open mediastinal irrigation using our original no-sedation-technique without any severe complication such as bleeding or secondary infection. We believe this technique is helpful in the management of severe ascending aortic graft infection.     

Constructing muscle flap coverage for vascular grafts in the groin

Groin wound infections can jeopardize patency and function of vascular bypass grafts anastomosed to the femoral artery. Attempts to salvage vascular reconstructions threatened by perigraft infection often fail because of inadequate debridement of surrounding infected soft tissue or because of an inability to cover an exposed graft with sufficient healthy tissue. In selected circumstances, use of rotational myocutaneous flaps makes it possible to salvage vascular grafts threatened by localized wound infection.     

Improved management of aortic graft infection: the influence of operation sequence and staging

To investigate the influence of operation sequence and staging on the outcome of aortic graft infection, we studied the mortality and amputation rates and incidence of new graft infection involving the extra-anatomic bypass (EAB) among 101 patients treated for secondary aortoenteric fistula (N = 43) or primary perigraft infection (N = 58). Patients were retrospectively grouped according to the operative treatment technique. Seven patients underwent infected graft removal (IGR) followed immediately by EAB (traditional). Fifty-seven patients were revascularized first, followed by immediate IGR in 38 patients (sequential) or by delayed IGR in 19 patients (staged). The median interoperative interval for the staged group was 5 days (range 2 to 31 days). Twenty patients underwent simultaneous IGR and in-line autogenous reconstruction (synchronous) and finally in 15 patients treatment consisted of IGR only with no extremity revascularization (none). The mean follow-up interval for all patients was 36.8 months. There was no statistically significant difference in mortality rate (traditional, 43%; sequential, 24%; and staged, 26%) or incidence of new graft infection (traditional, 43%; sequential, 18%; or staged, 16%) among those patients treated with EAB, although there was a trend toward an improved outcome with either sequential or staged treatment. There was a significantly lower amputation rate among sequential patients (11%) (p = 0.038) but not staged patients (16%) (p = 0.171) when compared with traditional treatment (43%). Staged operative treatment was associated with significantly less physiologic stress than sequential treatment as reflected by multiple perioperative metabolic variables (95% confidence limits). The treatment groups were comparable in the incidence of aortoenteric fistulas, culture-negative infections, emergent procedures, and appropriate antibiotic use. We conclude that reversed sequence or staged operative treatment of infected aortic grafts can be performed with no increased patient risk. Although traditional or sequential treatment may be required in the setting of acute hemorrhage, the staged operative approach is recommended for the treatment of chronic aortic graft infections.     

Antibiotic-impregnated grafts for aortic reconstruction

An infected aorta, or aortic graft, is a challenge to manage. Extra-anatomical bypass followed by resection of the infected aorta has been considered standard practice. Outcomes are far from ideal and anatomical constraints make this impossible at the visceral and thoracic aorta. In situ aortic repair is an alternative and can be accomplished in most cases. Use of this technique has been tempered by concerns of graft durability and reinfection. In vitro and in vivo laboratory experiments have demonstrated antibiotics can be bound to polytetrafluoroethylene and Dacron aortic grafts. In animal models, antibiotic-soaked grafts were resistant to infection when seeded with an intravenous bacteria challenge. Purulent, infected aortic grafts created in animal models by direct bacteria inoculation could be successfully replaced in situ with infection-resistant antibiotic-soaked Dacron grafts. The antibiotic of choice is rifampin, which readily binds to commercially available, off-the-shelf gelatin- or collagen-impregnated Dacron. In humans, rifampin-soaked Dacron has not only been used to reconstruct the aorta in the face of infection, but also in elective aortic reconstruction as a prophylaxis against future infection. Outcomes from case series are difficult to interpret because of the heterogeneous nature of patients presenting with aortic infections. Thirty-day mortality ranges from 7% to 21% and morbidity from 2% to 60%. Amputations are rarely seen in these cases, but are common in extra-anatomical bypass from graft occlusion. Reinfection of the rifampin grafts are seen in 4% to 22% of patients, and 5-year survival is near 50%. In the future, the utility of rifampin-soaked Dacron will have to be tested against the emergence of antibiotic-resistant bacteria. Improvements in alternative conduits, such as cryopreserved aortic grafts, may diminish the use of antibiotic-soaked grafts, but it will remain a useful tool in the vascular surgeon's armamentarium.     

Prosthetic graft infection, five years after ascending aortic replacement

Fifty-year-old male developed an infected perigraft collection five years following wrapping of a Dacron tube with residual aneurysmal ascending aortic tissue. Treatment consisted of excision of the graft, debridement of the infected surrounding tissues, and replacement using a rifampin-soaked Hemashield tube graft. This case demonstrates the potential risk of wrapping prosthetic grafts with native aneurysmal aortic tissue.     

Treatment strategies for aortic and peripheral prosthetic graft infection

Purpose

The aim of this study was to investigate the outcomes correlated with our treatment strategy for prosthetic graft infection.

Methods

Seventeen patients were treated for prosthetic graft infections between 1997 and 2009. Initially, total graft excision was applied in five cases, partial graft excision was applied in six cases and graft preservation with drainage and irrigation was applied in six cases. Among the graft-preserved cases, four patients were infected with methicillin-resistant Staphylococcus aureus (MRSA) and treated with gentian violet (GV).

Results

The overall survival rate was 88 % at 30 days and 82 % at 1 year in this series. Of the excised cases, nine patients survived; however, two patients died. Among the cases in which MRSA-infected grafts were preserved, three patients survived; however, one patient died under a septicemic state. Infected graft preservation was applied at a high rate of 36 %, and the mortality rate remained at 16 %, without any signs of graft reinfection.

Conclusions

In the treatment of infected grafts, the patient’s condition should be considered in order to select the appropriate treatment in each case. Graft preservation should be considered as an alternative treatment option, especially in high-risk patients, and GV can be effective for conservative treatment of prosthetic graft infections, including MRSA infections.