Editor's Choice - Outcome of Radical Surgical Treatment of Abdominal Aortic Graft and Endograft Infections Comparing Extra-anatomic Bypass with In Situ Reconstruction: A Nationwide Multicentre Study

Coaxial electrospun Ag-NPs-loaded endograft membrane with long-term antibacterial function treating mycotic aortic aneurysm

The use of endovascular stent-graft has become an important option in the treatment of aortic pathologies. However, the currently used endograft membranes have limited ability to prevent bacterial colonization. This makes them unsuitable for the treatment of mycotic aneurysms, as the infection is prone to progress after endograft implantation. Moreover, even in non-mycotic aortic pathologies, endograft infections can occur in the short or long term, especially for patients with diabetes mellitus or in immune insufficiency conditions. So, this study aimed to develop a kind of Ag-NPs-loaded endograft membrane by coaxial electrospinning technique, and a series of physical and chemical properties and biological properties of the Ag-NPs-loaded membrane were characterized. Animal experiments conducted in pigs confirmed that the Ag-NPs-loaded membrane was basically non-toxic, exhibited good biocompatibility, and effectively prevented bacterial growth in a mycotic aortic aneurysm model. In conclusion, the Ag-NPs-loaded membrane exhibited good biocompatibility, good anti-infection function and slow-release of Ag-NPs for long-term bacteriostasis. Thus, the Ag-NPs-loaded membrane might hold potential for preventing infection progression and treating mycotic aortic aneurysms in an endovascular way.

Editor's Choice -- European Society for Vascular Surgery (ESVS) 2024 Clinical Practice Guidelines on the Management of Abdominal Aorto-Iliac Artery Aneurysms

OBJECTIVE

The European Society for Vascular Surgery (ESVS) has developed clinical practice guidelines for the care of patients with aneurysms of the abdominal aorta and iliac arteries in succession to the 2011 and 2019 versions, with the aim of assisting physicians and patients in selecting the best management strategy.

METHODS

The guideline is based on scientific evidence completed with expert opinion on the matter. By summarising and evaluating the best available evidence, recommendations for the evaluation and treatment of patients have been formulated. The recommendations are graded according to a modified European Society of Cardiology grading system, where the strength (class) of each recommendation is graded from I to III and the letters A to C mark the level of evidence.

RESULTS

A total of 160 recommendations have been issued on the following topics: Service standards, including surgical volume and training; Epidemiology, diagnosis, and screening; Management of patients with small abdominal aortic aneurysm (AAA), including surveillance, cardiovascular risk reduction, and indication for repair; Elective AAA repair, including operative risk assessment, open and endovascular repair, and early complications; Ruptured and symptomatic AAA, including peri-operative management, such as permissive hypotension and use of aortic occlusion balloon, open and endovascular repair, and early complications, such as abdominal compartment syndrome and colonic ischaemia; Long term outcome and follow up after AAA repair, including graft infection, endoleaks and follow up routines; Management of complex AAA, including open and endovascular repair; Management of iliac artery aneurysm, including indication for repair and open and endovascular repair; and Miscellaneous aortic problems, including mycotic, inflammatory, and saccular aortic aneurysm. In addition, Shared decision making is being addressed, with supporting information for patients, and Unresolved issues are discussed.

CONCLUSION

The ESVS Clinical Practice Guidelines provide the most comprehensive, up to date, and unbiased advice to clinicians and patients on the management of abdominal aorto-iliac artery aneurysms.

Biofilm formation on endovascular aneurysm repair (EVAR) grafts-a proof of concept in vitro model

OBJECTIVES

An endovascular aneurysm repair (EVAR) graft is a catheter-implanted vascular prosthesis and is the preferred treatment for patients with aortic aneurysm. If an EVAR graft becomes the focus of infection, the treatment possibilities are limited because it is technically difficult to remove the graft to obtain source control. This study examines whether Pseudomonas aeruginosa and Staphylococcus aureus form biofilm on EVAR prostheses.

METHODS

EVAR graft sections were exposed to bacteria at 102 or 108 colony forming units (CFU)/mL in lysogeny broth and Krebs-Ringer at 37°C, bacterial biofilm formation was evaluated by scanning electron microscopy and counting CFU on the graft sections after antibiotic exposure at × 10 minimal inhibitory concentration. Bacteria were tested for tolerance to benzylpenicillin, tobramycin, and ciprofloxacin.

RESULTS

Bacterial exposure for 15 minutes established biofilms on all prosthesis fragments (6/6 replicates). After 4 hours, bacteria were firmly attached to the EVAR prostheses and resisted washing. After 18-24 hours, the median CFU/g of EVAR graft reached 5.2 × 108 (1.15 × 108-1.1 × 109) for S. aureus and 9.1 × 107 (3.5 × 107-6.25 × 108) for P. aeruginosa. Scanning electron microscopy showed bacterial attachment to the graft pieces. There was a time-dependent development of tolerance with approximately 20 (tobramycin), 560 (benzylpenicillin), and 600 (ciprofloxacin) times more S. aureus surviving antibiotic exposure in 24- compared with 0-hour-old biofilm. Five (tobramycin) and 170 times (ciprofloxacin) more P. aeruginosa survived antibiotic exposure in 24- compared with 0-hour-old biofilms.

DISCUSSION

Our results show that bacteria can rapidly adhere to and subsequently form antibiotic-tolerant biofilms on EVAR graft material in concentrations equivalent to levels seen in transient bacteraemia in vivo. Potentially, the system can be used for identifying optimal treatment combinations for infected EVAR prosthesis.

Aortic Endograft Infection: Diagnosis and Management

Aortic endograft infection (AEI) is a rare but life-threatening complication of endovascular aneurysm repair (EVAR). The clinical features of AEI range from generalized weakness and mild fever to fatal aortic rupture or sepsis. The diagnosis of AEI usually depends on clinical manifestations, laboratory tests, and imaging studies. Management of Aortic Graft Infection Collaboration (MAGIC) criteria are often used to diagnose AEI. Surgical removal of the infected endograft, restoration of aortic blood flow, and antimicrobial therapy are the main components of AEI treatment. After removing an infected endograft, in situ aortic reconstruction is often performed instead of an extra-anatomic bypass. Various biological and prosthetic aortic grafts have been used in aortic reconstruction to avoid reinfection, rupture, or occlusion. Each type of graft has its own merits and disadvantages. In patients with an unacceptably high surgical risk and no evidence of an aortic fistula, conservative treatment can be an alternative. Treatment results are determined by bacterial virulence, patient status, including the presence of an aortic fistula, and hospital factors. Considering the severity of this condition, the best strategy is prevention. When encountering a patient with AEI, current practice emphasizes a multidisciplinary team approach to achieve an optimal outcome.

Semi-Conservative Treatment Versus Radical Surgery in Abdominal Aortic Graft and Endograft Infections

OBJECTIVE

Abdominal aortic graft and endograft infections (AGIs) are rare complications following aortic surgery. Radical surgery (RS) with resection of the infected graft and reconstruction with extra-anatomical bypass or in situ reconstruction is the preferred therapy. For patients unfit for RS, a semi-conservative (SC), graft preserving strategy is possible. This paper aimed to compare survival and infection outcomes between RS and SC treatment for AGI in a nationwide cohort.

METHODS

Patients with abdominal AGI related surgery in Sweden between January 1995 and May 2017 were identified. The Management of Aortic Graft Infection Collaboration (MAGIC) criteria were used for the definition of AGI. Multivariable regression was performed to identify factors associated with mortality.

RESULTS

One hundred and sixty-nine patients with surgically treated abdominal AGI were identified, comprising 43 SC (14 endografts; 53% with a graft enteric fistula [GEF] in total) and 126 RS (26 endografts; 50% with a GEF in total). The SC cohort was older and had a higher frequency of cardiac comorbidities. There was a non-significant trend towards lower Kaplan-Meier estimated five year survival for SC vs. RS (30.2% vs. 48.4%; p = .066). A non-significant trend was identified towards worse Kaplan-Meier estimated five year survival for SC patients with a GEF vs. without a GEF (21.7% vs. 40.1%; p = .097). There were significantly more recurrent graft infections comparing SC with RS (45.4% vs. 19.3%; p < .001). In a Cox regression model adjusting for confounders, there was no difference in five year survival comparing SC vs. RS (HR 1.0, 95% CI 0.6 - 1.5).

CONCLUSION

In this national AGI cohort, there was no mortality difference comparing SC and RS for AGI when adjusting for comorbidities. Presence of GEF probably negatively impacts survival outcomes of SC patients. Rates of recurrent infection remain high for SC treated patients.

Surgical Repair of Abdominal Aorto-Iliac Prosthetic Graft Infections: A Nationwide Japanese Cohort Study

OBJECTIVE

Prosthetic graft infection (PGI) after open abdominal aortic and iliac artery reconstruction is life threatening. However, because it is rare and frequently difficult to diagnose, robust evidence on its treatment and optimal management strategies are lacking. This study aimed to clarify the clinical characteristics and surgical treatment outcomes of this condition and to identify pre-operative and operative factors affecting its prognosis.

METHODS

This was a nationwide cohort study. Using a nationwide clinical registry system, patients who were treated surgically for PGI after open abdominal aortic and iliac artery reconstruction between 2011 and 2017 were investigated, and their profiles and clinical courses were analysed. The relationships between the pre-operative and operative factors and the post-operative outcomes, including death and persistent or recurrent graft related infection, were evaluated.

RESULTS

The study included 213 patients. The median duration between the index arterial reconstruction and surgical treatment for PGI was 644 days. Fistula development to the gastrointestinal tract was confirmed during surgery in 53.1% of patients. The cumulative overall survival rates at 30 and 90 days, one, three, and five years were 87.3%, 74.8%, 62.2%, 54.5%, and 48.1%, respectively. Pre-operative shock was the only factor independently associated with 90 day and three year death. Short term and late mortality rates, as well as the rate of persistent or recurrent graft related infection, did not differ significantly between patients treated with total removal of the infected graft and those treated with partial removal of the graft.

CONCLUSION

Surgery for PGI after open reconstruction of the abdominal aorta and iliac arteries is complex, and the post-operative mortality rate remains high. Partial removal of the infected graft may be an alternative in selected patients with limited extent of infection.

A Systematic Review of In-situ Aortic Reconstructions for Abdominal Aortic Graft and Endograft Infections: Outcomes of Currently Available Options for Surgical Replacement

BACKGROUND

This review synthetizes recent literature about in-situ aortic reconstructions for abdominal aortic graft or endograft infections (AGEIs), aiming to report outcomes individually related to currently available vascular substitutes (VSs).

METHODS

We performed a systematic review of all published literature from January 2005 to December 2022. We included articles reporting on open surgical treatment of abdominal AGEIs, with removal of the infected graft and in-situ reconstruction with biological or prosthetic material. Articles not distinguishing between abdominal and thoracic aortic-related outcomes were excluded, as well as studies reporting on cumulative in-situ and extra-anatomic reconstruction results.

RESULTS

Of 500 records identified through database searching (Pubmed: 226; Embase: 274), 8 of them were included in the present review. Overall, 30-days mortality rate was 8.7% (25/285), while the most frequent early complications were respiratory adverse events (46/346, 13.3%) and renal function deterioration (26/85, 30%). In 250/350 cases (71.4%), a biological VS was utilized. In 4 articles, the outcomes of different types of VSs were presented jointly. Patients analyzed in the remaining 4 reports were sorted in a "biological" and a "prosthetic" group (BG and PG). The cumulative mortality rate of the BG and PG were 15.6% (33/212) and 27% (9/33), respectively, while graft reinfection was 6.3% (15/236) in the BG, and 9% (3/33) in the PG. The cumulative mortality rate reported in articles focused on autologous veins was 14.8% (30/202), while their 30-days reinfection rate was 5.7% (13/226).

CONCLUSIONS

Since abdominal AGEIs are uncommon conditions, literature focused on direct comparison between different types of VSs is scarce, particularly when related to materials other than autologous veins. Although we found a lower overall mortality rate in patients treated with biological material or with autologous veins only, in recent reports prosthesis provide promising results in terms of mortality and reinfection rate. However, none of the available studies distinguish and compares different types of prosthetic material. Large multicenter studies are advisable, especially focused on different types of VSs and their comparison.

Conservative Management First Strategy in Aortic Vascular Graft and Endograft Infections

OBJECTIVE

The aim of this study was to describe and present the outcomes of a specific treatment protocol for aortic vascular graft and endograft infections (VGEIs) without explantation of the infected graft.

METHODS

This was a retrospective, observational single centre cohort study carried out between 2012 and 2022 at a tertiary hospital. An aortic VGEI was defined according to the Management of Aortic Graft Infection Collaboration (MAGIC) criteria. Fitness for graft excision was assessed by a multidisciplinary team and included an evaluation of the patient's general condition, septic status, and anatomical complexity. Antimicrobial treatments were individualised. The primary outcome was survival at the last available follow up; secondary outcomes were antimicrobial treatment duration, infection eradication, treatment failure despite antimicrobial treatment, and the development of aortic fistulation.

RESULTS

Fifty patients were included in the study, of whom 42 (84%) had had previous endovascular repair. The median patient age was 72 years (range 51 - 82 years) and median duration of treatment with antimicrobials was 18 months (range 1 - 164 months). Kaplan-Meier analysis estimated the 30 day survival to be 98% (95% confidence interval [CI] 96 - 100), the one year survival rate to be 88% (95% CI 83.4 - 92.6), and the three year survival rate to be 79% (95% CI 72.7 - 84.7). Twenty-four (48%) patients were able to discontinue antibiotic treatment after a median of 16 months (range 4 - 81 months). When categorised according to infected graft location, deaths occurred in four (40%) patients with thoracic, two (40%) with paravisceral, seven (30%) with infrarenal VGEIs, and in one (25%) patient with an aorto-iliac VGEI; no (0%) patient with a thoraco-abdominal VGEI died.

CONCLUSION

Identifying the microbiological aetiology in patients with aortic VGEI enables individualised, specific antibiotic treatment, which may be useful in patients with a VGEI excluded from surgery. This single centre retrospective analysis of patients with VGEIs without fistula selected for conservative treatment suggests that conservative management of aortic VGEIs with targeted antibiotic therapy without graft excision is potentially effective, and that antimicrobial treatment will not necessarily be needed indefinitely.

Infection of Vascular Prostheses: A Comprehensive Review

Vascular graft or endograft infection (VGEI) is a complex disease that complicates vascular-surgery and endovascular-surgery procedures and determines high morbidity and mortality. This review article provides the most updated general evidence on the pathogenesis, prevention, diagnosis, and treatment of VGEI. Several microorganisms are involved in VGEI development, but the most frequent one, responsible for over 75% of infections, is Staphylococcus aureus. Specific clinical, surgical, radiologic, and laboratory criteria are pivotal for the diagnosis of VGEI. Surgery and antimicrobial therapy are cornerstones in treatment for most patients with VGEI. For patients unfit for surgery, alternative treatment is available to improve the clinical course of VGEI.

Outcomes of Candida and Non-Candida Aortic Graft Infection

OBJECTIVE

To evaluate and compare the outcomes of Candida- and non-Candida-associated aortic graft infections.

METHODS

We retrospectively analyzed the data from patients treated for aortic graft infection from 2015 to 2021 in our hospital.

RESULTS

A total of 66 patients (56 men; median age, 69 years; range, 50-87 years) were admitted with aortic graft infection, including 21 (32%) patients in the Candida group and 45 (68%) in the non-Candida group. The average time between initial operation and presentation of aortic graft infection was 50 months (range, 1-332 months). Graft-enteric fistulas (GEFs) were more often in the Candida group (57% vs 27%, P = .017). The most proven causative fungal specimen was C. albicans in 16 (76%) patients. Non-albicans Candida was found in 9% of all patients and 29% of the Candida patients. The median ICU length of stay was longer in the Candida group than non-Candida (10 vs 9 days, P = .012). Additionally, the median hospital length of stay was longer in the Candida group (33 vs 22 days, P = .048). There were no statistically significant differences between Candida and non-Candida groups according to the in-hospital mortality (24% vs 24%, P = .955), and 1-year mortality (38% vs 38%, P = .980).

CONCLUSIONS

Patients with bacterial and fungal aortic graft infections have high rates of morbidity and mortality. We found no significant differences in postoperative morbidity and mortality between Candida and non-Candida patients. However, the ICU and hospital length of stay were longer in the Candida group.

Diagnosis and treatment of vascular graft and endograft infections: a structured clinical approach

A vascular graft or endograft infection (VGEI) is a severe complication that can occur after vascular graft or endograft surgery and is associated with high morbidity and mortality rates. A multidisciplinary approach, consisting of a team of vascular surgeons, infectious diseases specialists, medical microbiologists, radiologists, nuclear medicine specialists, and hospital pharmacists, is needed to adequately diagnose and treat VGEI. A structured diagnostic, antibiotic, and surgical treatment algorithm helps clinical decision making and ultimately aims to improve the clinical outcome of patients with a VGEI.

In-situ Bypass Is Associated with Superior Infection-free Survival Compared to Extra-Anatomic Bypass for the Management of Secondary Aortic Graft Infections Without Enteric Involvement

OBJECTIVE

The optimal revascularization modality following complete resection of aortic graft infection (AGI) without enteric involvement remains unclear. The purpose of this investigation is to determine the revascularization approach associated with the lowest morbidity and mortality using real-world data in patients undergoing complete excision of AGI.

METHODS

A retrospective, multi-institutional study of AGI from 2002-2014 was performed using a standardized database. Baseline demographics, comorbidities, and perioperative variables were recorded. The primary outcome was infection-free survival. Descriptive statistics, Kaplan-Meier survival analysis, and univariate and multivariable analyses were performed.

RESULTS

241 patients at 34 institutions from 7 countries presented with AGI during the study period (median age 68 years; 75% male). The initial aortic procedures that resulted in AGI were 172 surgical grafts (71%) and 66 endografts (27%) and 3 unknown (2%). 172 (71%) of the patients underwent complete excision of infected aortic graft material followed by in situ (in-line) bypass (ISB), including antibiotic-treated prosthetic graft (35%), autogenous femoral vein (NAIS) (24%), and cryopreserved allograft (41%). 69 patients (29%) underwent extra-anatomic bypass (EAB). Overall median Kaplan-Meier (KM) estimated survival was 5.8 years. Perioperative mortality was 16%. When stratified by ISB versus EAB, there was a significant difference in KM estimated infection-free survival (2910 days, IQR 391, 3771 versus 180 days, IQR 27, 3750 days; p<0.001). There were otherwise no significant differences in presentation, comorbidities, nor perioperative variables. Multivariable Cox regression showed lower infection-free survival among patients with EAB (HR 2.4, 95% CI 1.6-3.6; p<0.001), polymicrobial infection (HR 2.2, 95% CI 1.4-3.5; p=0.001), MRSA infection (HR 1.7, 95% CI 1.1-2.7; p=0.02), as well as the protective effect of omental/muscle flap coverage (HR 0.59, 95% CI 0.37-0.92; p=0.02).

CONCLUSIONS

After complete resection of AGI, perioperative mortality is 16% and median overall survival is 5.8 years. EAB is associated with nearly a two-and-half fold higher re-infection/mortality compared to ISB. Omental and/or muscle flap coverage of the repair appear protective.