Vascular prosthetic graft infection: epidemiology, bacteriology, pathogenesis and treatment

Highly compliant biomimetic scaffolds for small diameter tissue-engineered vascular grafts (TEVGs) produced via melt electrowriting (MEW)

Biofabrication approaches toward the development of tissue-engineered vascular grafts (TEVGs) have been widely investigated. However, successful translation has been limited to large diameter applications, with small diameter grafts frequently failing due to poor mechanical performance, in particular mismatched radial compliance. Herein, melt electrowriting (MEW) of poly(ϵ-caprolactone) has enabled the manufacture of highly porous, biocompatible microfibre scaffolds with physiological anisotropic mechanical properties, as substrates for the biofabrication of small diameter TEVGs. Highly reproducible scaffolds with internal diameter of 4.0 mm were designed with 500 and 250µm pore sizes, demonstrating minimal deviation of less than 4% from the intended architecture, with consistent fibre diameter of 15 ± 2µm across groups. Scaffolds were designed with straight or sinusoidal circumferential microfibre architecture respectively, to investigate the influence of biomimetic fibre straightening on radial compliance. The results demonstrate that scaffolds with wave-like circumferential microfibre laydown patterns mimicking the architectural arrangement of collagen fibres in arteries, exhibit physiological compliance (12.9 ± 0.6% per 100 mmHg), while equivalent control geometries with straight fibres exhibit significantly reduced compliance (5.5 ± 0.1% per 100 mmHg). Further mechanical characterisation revealed the sinusoidal scaffolds designed with 250µm pores exhibited physiologically relevant burst pressures of 1078 ± 236 mmHg, compared to 631 ± 105 mmHg for corresponding 500µm controls. Similar trends were observed for strength and failure, indicating enhanced mechanical performance of scaffolds with reduced pore spacing. Preliminaryin vitroculture of human mesenchymal stem cells validated the MEW scaffolds as suitable substrates for cellular growth and proliferation, with high cell viability (>90%) and coverage (>85%), with subsequent seeding of vascular endothelial cells indicating successful attachment and preliminary endothelialisation of tissue-cultured constructs. These findings support further investigation into long-term tissue culture methodologies for enhanced production of vascular extracellular matrix components, toward the development of the next generation of small diameter TEVGs.

2022 ACC/AHA guideline for the diagnosis and management of aortic disease: A report of the American Heart Association/American College of Cardiology Joint Committee on Clinical Practice Guidelines

AIM

The "2022 ACC/AHA Guideline for the Diagnosis and Management of Aortic Disease" provides recommendations to guide clinicians in the diagnosis, genetic evaluation and family screening, medical therapy, endovascular and surgical treatment, and long-term surveillance of patients with aortic disease across its multiple clinical presentation subsets (ie, asymptomatic, stable symptomatic, and acute aortic syndromes).

METHODS

A comprehensive literature search was conducted from January 2021 to April 2021, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, the Cochrane Library, CINHL Complete, and other selected databases relevant to this guideline. Additional relevant studies, published through June 2022 during the guideline writing process, were also considered by the writing committee, where appropriate.

STRUCTURE

Recommendations from previously published AHA/ACC guidelines on thoracic aortic disease, peripheral artery disease, and bicuspid aortic valve disease have been updated with new evidence to guide clinicians. In addition, new recommendations addressing comprehensive care for patients with aortic disease have been developed. There is added emphasis on the role of shared decision making, especially in the management of patients with aortic disease both before and during pregnancy. The is also an increased emphasis on the importance of institutional interventional volume and multidisciplinary aortic team expertise in the care of patients with aortic disease.

Methicillin-Susceptible Staphylococcus aureus Biofilm Formation on Vascular Grafts: an In Vitro Study

The aim of this study was to quantify in vitro biofilm formation by methicillin-susceptible Staphylococcus aureus (MSSA) on the surfaces of different types of commonly used vascular grafts. We performed an in vitro study with two clinical strains of MSSA (MSSA2 and MSSA6) and nine vascular grafts: Dacron (Hemagard), Dacron-heparin (Intergard heparin), Dacron-silver (Intergard Silver), Dacron-silver-triclosan (Intergard Synergy), Dacron-gelatin (Gelsoft Plus), Dacron plus polytetrafluoroethylene (Fusion), polytetrafluoroethylene (Propaten; Gore), Omniflow II, and bovine pericardium (XenoSure). Biofilm formation was induced in two phases: an initial 90-minute adherence phase and a 24-hour growth phase. Quantitative cultures were performed, and the results were expressed as log10 CFU per milliliter. The Dacron-silver-triclosan graft and Omniflow II were associated with the least biofilm formation by both MSSA2 and MSSA6. MSSA2 did not form a biofilm on the Dacron-silver-triclosan graft (0 CFU/mL), and the mean count on the Omniflow II graft was 3.89 CFU/mL (standard deviation [SD] 2.10). The mean count for the other grafts was 7.01 CFU/mL (SD 0.82). MSSA6 formed a biofilm on both grafts, with 2.42 CFU/mL (SD 2.44) on the Dacron-silver-triclosan graft and 3.62 CFU/mL (SD 2.21) on the Omniflow II. The mean biofilm growth on the remaining grafts was 7.33 CFU/mL (SD 0.28). The differences in biofilm formation on the Dacron-silver-triclosan and Omniflow II grafts compared to the other tested grafts were statistically significant. Our findings suggest that of the vascular grafts we studied, the Dacron-silver-triclosan and Omniflow II grafts might prevent biofilm formation by MSSA. Although further studies are needed, these grafts seem to be good candidates for clinical use in vascular surgeries at high risk of infections due to this microorganism. IMPORTANCE The Dacron silver-triclosan and Omniflow II vascular grafts showed the greatest resistance to in vitro methicillin-susceptible Staphylococcus aureus biofilm formation compared to other vascular grafts. These findings could allow us to choose the most resistant to infection prosthetic graft.

2022 ACC/AHA Guideline for the Diagnosis and Management of Aortic Disease: A Report of the American Heart Association/American College of Cardiology Joint Committee on Clinical Practice Guidelines

AIM

The "2022 ACC/AHA Guideline for the Diagnosis and Management of Aortic Disease" provides recommendations to guide clinicians in the diagnosis, genetic evaluation and family screening, medical therapy, endovascular and surgical treatment, and long-term surveillance of patients with aortic disease across its multiple clinical presentation subsets (ie, asymptomatic, stable symptomatic, and acute aortic syndromes).

METHODS

A comprehensive literature search was conducted from January 2021 to April 2021, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, the Cochrane Library, CINHL Complete, and other selected databases relevant to this guideline. Additional relevant studies, published through June 2022 during the guideline writing process, were also considered by the writing committee, where appropriate. Structure: Recommendations from previously published AHA/ACC guidelines on thoracic aortic disease, peripheral artery disease, and bicuspid aortic valve disease have been updated with new evidence to guide clinicians. In addition, new recommendations addressing comprehensive care for patients with aortic disease have been developed. There is added emphasis on the role of shared decision making, especially in the management of patients with aortic disease both before and during pregnancy. The is also an increased emphasis on the importance of institutional interventional volume and multidisciplinary aortic team expertise in the care of patients with aortic disease.

2022 ACC/AHA Guideline for the Diagnosis and Management of Aortic Disease: A Report of the American Heart Association/American College of Cardiology Joint Committee on Clinical Practice Guidelines

AIM

The "2022 ACC/AHA Guideline for the Diagnosis and Management of Aortic Disease" provides recommendations to guide clinicians in the diagnosis, genetic evaluation and family screening, medical therapy, endovascular and surgical treatment, and long-term surveillance of patients with aortic disease across its multiple clinical presentation subsets (ie, asymptomatic, stable symptomatic, and acute aortic syndromes).

METHODS

A comprehensive literature search was conducted from January 2021 to April 2021, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, the Cochrane Library, CINHL Complete, and other selected databases relevant to this guideline. Additional relevant studies, published through June 2022 during the guideline writing process, were also considered by the writing committee, where appropriate.

STRUCTURE

Recommendations from previously published AHA/ACC guidelines on thoracic aortic disease, peripheral artery disease, and bicuspid aortic valve disease have been updated with new evidence to guide clinicians. In addition, new recommendations addressing comprehensive care for patients with aortic disease have been developed. There is added emphasis on the role of shared decision making, especially in the management of patients with aortic disease both before and during pregnancy. The is also an increased emphasis on the importance of institutional interventional volume and multidisciplinary aortic team expertise in the care of patients with aortic disease.

FDG PET/CT in abdominal aortic graft infection: A case report and literature review

This case report follows a 47-year-old man who had multiple grafts undergoing FDG PET/CT (positron emission tomography/computed tomography) scan to evaluate for graft infection. Initial CT showed enhancing soft tissue and fluid collection around the graft, and the subsequent FDG PET/CT showed findings concerning for graft infection. This case exemplifies that FDG PET/CT is a synergistic tool in diagnosing aortic graft infections, a rare and often fatal complication of aortic grafts.

Predictive Factors for Aortic Graft Infection: A Case-Control Study

BACKGROUND

Graft infections are one of the most serious complications in vascular surgery, with high mortality rates. Few studies addressed risk factors associated with a higher susceptibility to infection. The aim of this study is to identify perioperative factors associated with aortic graft infections (AGI).

METHODS

We designed a retrospective, case-control study from patients subjected to open aortic repair between 2013 and 2019. Cases of AGI were defined according to the management of aortic graft infection collaboration (MAGIC) criteria and matched to controls without proven infection. Demographics, hospital complications, and laboratory workups were assessed. Predictors of AGI were identified through univariate and multivariate analysis.

RESULTS

Most graft infections occurred in a late period (n = 17; 85%), after a median interval of 13.5 months interquartile range (IQR 1.5-36). Gram-negative bacteria were most frequently isolated in infected grafts, namely Enterobacteriaceae (n = 12). Cases had significantly lower postoperative serum albumin levels (1.9 g/dL vs. 2.4 g/dL; P = 0.002). Alcohol abuse, malignancy, prolonged lengths of stay, wound infection and dehiscence, in-hospital infection, postoperative heart failure or bowel ischemia were significantly correlated to the onset of AGI. In the multivariate analysis, prolonged hospital stays odds ratio (OR 1.05; P = 0.03), malignancy (OR 5.82; P = 0.03) and alcohol abuse (OR 42.41; P = 0.002) maintained a significant association.

CONCLUSIONS

The risk of AGI seems to be higher in patients with concurrent malignancy, alcohol abuse or prolonged hospital stays. Strategies to mitigate this complication in these patients are of utmost importance.

Treatment of vascular graft infections: gentamicin-coated ePTFE grafts reveals strong antibacterial properties in vitro

Vascular graft infections (VGI) are severe complications in prosthetic vascular surgery with an incidence ranging from 1 to 6%. In these cases, synthetic grafts are commonly used in combination with antimicrobial agents. Expanded polytetrafluoroethylene (ePTFE) is in clinical use as a synthetic graft material and shows promising results by influencing bacterial adhesion. However, the literature on antibiotic-bound ePTFE grafts is scarce. Gentamicin is a frequently used antibiotic for local treatment of surgical site infections, but has not been evaluated as antimicrobial agent on ePTFE grafts. In this study, we examine the antimicrobial efficacy and biocompatibility of novel types of gentamicin-coated ePTFE grafts in vitro. ePTFE grafts coated with gentamicin salt formulations with covalently-bound palmitate were evaluated in two drug concentrations (GP1.75% and GP3.5%). To investigate effects from types of formulations, also suspensions of gentamicin in palmitate as well as polylactide were used at comparable levels (GS + PA and GS + R203). Antibacterial efficacies were estimated by employing a zone of inhibition, growth inhibition and bacterial adhesion assay against Staphylococcus aureus (SA). Cytotoxicity was determined with murine fibroblasts according to the ISO standard 10993-5. Gentamicin-coated ePTFE grafts show low bacterial adherence and strong antibacterial properties in vitro against SA. Bactericidal inhibition lasted until day 11. Highest biocompatibility was achieved using gentamicin palmitate GP1.75% coated ePTFE grafts. ePTFE grafts with gentamicin-coating are effective in vitro against SA growth and adherence. Most promising results regarding antimicrobial properties and biocompatibility were shown with chemically bounded gentamicin palmitate GP1.75% coatings. Graphical abstract.

Vascular Graft Infections: An Overview of Novel Treatments Using Nanoparticles and Nanofibers

Vascular disease in elderly patients is a growing health concern, with an estimated prevalence of 15–20% in patients above 70 years old. Current treatment for vascular diseases requires the use of a vascular graft (VG) to revascularize lower or upper extremities, create dialysis access, treat aortic aneurysms, and repair dissection. However, postoperative infection is a major complication associated with the use of these VG, often necessitating several operations to achieve complete or partial graft excision, vascular coverage, and extra-anatomical revascularization. There is also a high risk of morbidity, mortality, and limb loss. Therefore, it is important to develop a method to prevent or reduce the incidence of these infections. Numerous studies have investigated the efficacy of antibiotic- and antiseptic-impregnated grafts. In comparison to these traditional methods of creating antimicrobial grafts, nanotechnology enables researchers to design more efficient VG. Nanofibers and nanoparticles have a greater surface area compared to bulk materials, allowing for more efficient encapsulation of antibiotics and better control over their temporo-spatial release. The disruptive potential of nanofibers and nanoparticles is exceptional, and they could pave the way for a new generation of prosthetic VG. This review aims to discuss how nanotechnology is shaping the future of cardiovascular-related infection management.

Biofabrication of small diameter tissue-engineered vascular grafts

Current clinical treatment strategies for the bypassing of small diameter (<6 mm) blood vessels in the management of cardiovascular disease frequently fail due to a lack of suitable autologous grafts, as well as infection, thrombosis, and intimal hyperplasia associated with synthetic grafts. The rapid advancement of 3D printing and regenerative medicine technologies enabling the manufacture of biological, tissue-engineered vascular grafts (TEVGs) with the ability to integrate, remodel, and repair in vivo, promises a paradigm shift in cardiovascular disease management. This review comprehensively covers current state-of-the-art biofabrication technologies for the development of biomimetic TEVGs. Various scaffold based additive manufacturing methods used in vascular tissue engineering, including 3D printing, bioprinting, electrospinning and melt electrowriting, are discussed and assessed against the biomechanical and functional requirements of human vasculature, while the efficacy of decellularization protocols currently applied to engineered and native vessels are evaluated. Further, we provide interdisciplinary insight into the outlook of regenerative medicine for the development of vascular grafts, exploring key considerations and perspectives for the successful clinical integration of evolving technologies. It is expected that continued advancements in microscale additive manufacturing, biofabrication, tissue engineering and decellularization will culminate in the development of clinically viable, off-the-shelf TEVGs for small diameter applications in the near future. STATEMENT OF SIGNIFICANCE: Current clinical strategies for the management of cardiovascular disease using small diameter vessel bypassing procedures are inadequate, with up to 75% of synthetic grafts failing within 3 years of implantation. It is this critically important clinical problem that researchers in the field of vascular tissue engineering and regenerative medicine aim to alleviate using biofabrication methods combining additive manufacturing, biomaterials science and advanced cellular biology. While many approaches facilitate the development of bioengineered constructs which mimic the structure and function of native blood vessels, several challenges must still be overcome for clinical translation of the next generation of tissue-engineered vascular grafts.

Vascular grafts collagen coating resorption and healing process in humans

Background

The objective of the present study was to evaluate the bioresorption rate of collagen coating (CC) sealed on textile vascular grafts (VGs) and their healing in humans using histologic analysis of explanted VGs.

Methods

A total of 27 polyester textile VGs had been removed during surgery from 2012 to 2020. The segments underwent histologic assessment. The CC bioresorption rate was assessed using morphometric analysis to determine the internal and external capsule thickness, inflammatory reaction degree, presence of neovessels, and endothelial cell layer.

Results

A total of 27 VGs were explanted from 25 patients because of infection (n = 5; 18.5%), thrombosis (n = 7; 25.9%), stenosis (n = 2; 7.4%), rupture (n = 4; 14.8%), aneurysmal degeneration (n = 3; 11.1%), revascularization (n = 4; 14.8%), or another cause (n = 2; 7.4%), with a median implantation duration of 291 days (interquartile range [IQR], 48-911 days). VGs with remaining CC (n = 7; 26%) had been explanted earlier than had those without (n = 20; 74%; 1 day [IQR, 1-45 days] vs 516 days [IQR, 79-2018 days]; P = .001). After 1 year, no remaining CC was detected on the analyzed VG sections. VGs implanted for <90 days had had a greater CC maximal thickness (63.90 μm [IQR, 0-83.25 μm] vs 0 μm [IQR, 0-0 μm]; P = .006) and a greater CC surface coverage (180° [IQR, 0°-360°] vs 0° [IQR, 0°-0°]; P = .002) than those implanted for >90 days. VGs implanted for >90 days had a greater external capsule thickness (889.2 μm [IQR, 39.6-1317 μm] vs 0 μm [IQR, 0-0 μm]; P = .002), a higher number of inflammatory mononuclear cells and giant cells (168 cells [IQR, 110-310 cells] vs 0 cells [IQR, 0-94 cells]; P < .0001) and a higher number of neovessels (4 [IQR, 0-5] vs 0 [IQR, 0-0]; P = .001) than those implanted for <90 days.

Conclusions

CC had a slow bioresorption rate in humans. Complete healing was never achieved, with no endothelial coverage observed. This finding implies that CC might not help graft healing.

The objective of the present study was to evaluate the bioresorption rate of collagen coating (CC) sealed on explanted textile vascular grafts (VGs) and their healing in humans using histologic analyses. We found that CC had a slow bioresorption rate in humans. Complete healing was never achieved, and no endothelial coverage was observed. Therefore, we question their use in daily practice because the faster healing potential of CC VGs has been an argument advanced by manufacturers for their use. Knowledge of the mechanisms of graft healing is necessary to understand the success and failure of the current bypass grafts.

A Radiation-Crosslinked Gelatin Hydrogel That Promotes Tissue Incorporation of an Expanded Polytetrafluoroethylene Vascular Graft in Rats

A prosthetic vascular graft that induces perigraft tissue incorporation may effectively prevent serious sequelae such as seroma formation and infection. Radiation-crosslinked gelatin hydrogel (RXgel) mimics the chemical and physical properties of the in vivo extracellular matrix and may facilitate wound healing by promoting tissue organization. Fibroblasts cultured on RXgel actively migrated into the gel for up to 7 days. RXgels of three different degrees of hardness (Rx[10], soft; Rx[15], middle; Rx[20], hard) were prepared, and small disc-like samples of RXgels were implanted into rats. In vitro and in vivo results indicated that Rx[10] was too soft to coat vascular grafts. Thus, expanded polytetrafluoroethylene (ePTFE) vascular grafts coated with RXgel were developed using Rx[15] and Rx[20] gels, and ring-shaped slices of the graft were implanted into rats. Alpha-smooth muscle actin (αSMA) and type III collagen (Col-III) levels were detected by immunohistochemistry. Immunohistochemical staining for αSMA and Col-III demonstrated that RXgel-coated vascular grafts induced more granulation tissue than non-coated grafts on days 14 and 28 after implantation. RXgel-coated ePTFE vascular grafts may provide a solution for patients by reducing poor perigraft tissue incorporation.

Systematic Review of the Management of Ureteroarterial Fistulas After Ileal Conduit Urinary Diversion

OBJECTIVE. No studies or guidelines exist to direct management of ureteroarterial fistula (UAF) after ileal conduit urinary diversion in which the possible risks and complications associated with stent-graft infection from the conduit flora must be reconciled with those of open surgical repair. This study seeks to characterize the clinical presentation, pathogenesis, and optimal diagnostic and therapeutic management of this entity through a systematic review of the literature. MATERIALS AND METHODS. A systematic search of the English-language literature using the PubMed, Scopus, and ScienceDirect databases was performed: 264 abstracts were identified. From those abstracts, 32 studies comprising 40 patients with 43 UAFs were selected for analysis. Data points including demographics, clinical presentation, UAF specifications, procedural details, postprocedural complications, and clinical outcomes were reviewed. RESULTS. Predisposing factors included female sex, chronic ureteral stent placement, and past surgical intervention and irradiation for pelvic malignancy. Fistulization was overwhelmingly unilateral (95.0% of patients) and included the common iliac artery (90.7% of UAFs). Combined endovascular and endoureteral modalities presented similar outcomes compared with surgical approaches in terms of UAF-related mortality (7.1% vs 13.3%, respectively) and complication rates (28.6% vs 26.7%) during a similar median follow-up period (9.5 vs 14.0 months). Endovascular stent-graft infections were present in 14.3% of cases and represented a leading indication for reintervention after endovascular management (50.0%). CONCLUSION. Short- and intermediate-term outcomes of combined endovascular and endoureteral techniques compare favorably with those of surgical approaches in the treatment of UAF after ileal conduit urinary diversion. Although there is a relatively low stent-graft infection rate, close follow-up within the first year after the procedure is required given the propensity of complications to develop during this window. The use of postprocedural antibiotics is uncertain but is likely prudent.

Use of rifampicin and graft removal are associated with better outcomes in prosthetic vascular graft infection

OBJECTIVES

Prosthetic vascular graft infection (PVGI) is a very severe disease. We aimed to determine the factors associated with treatment failure.

METHODS

Patients admitted to two University Hospitals with PVGI were included in this retrospective study. PVGI was classified as possible, probable or proven according to an original set of diagnostic criteria. We defined treatment failure if one of the following events occurred within the first year after PVGI diagnosis: death and infection recurrence due to the same or another pathogen.

RESULTS

One hundred and twelve patients were diagnosed with possible (n = 26), probable (n = 22) and proven (n = 64) PVGI. Bacterial documentation was obtained for 81% of patients. The most frequently identified pathogen was Staphylococcus aureus (n = 39). Surgery was performed in 96 patients (86%). Antibiotics were administered for more than 6 weeks in 41% of patients. Treatment failure occurred in 30 patients (27.5%). The factors associated with a lower probability of treatment failure were total removal of the infected graft (OR = 0.2, 95% CI [0.1-0.6]), rifampicin administration (OR = 0.3 [0.1-0.9]) and possible PVGI according to the GRIP criteria (OR = 0.3 [0.1-0.9]).

CONCLUSIONS

Treatment failure occurred in 27.5% of patients with PVGI. Total removal of the infected graft and rifampicin administration were associated with better outcomes.

Microbial evolution of vascular graft infections in a tertiary hospital based on positive graft cultures

BACKGROUND

Vascular graft infections are a serious complication in vascular surgery. Correct antibiotic therapy targeted to the most likely infecting species is essential to treat these patients, although the bacterial epidemiology and pathogenesis are still not completely understood. We analyzed the behavior of vascular graft infections and the microbiologic patterns of resistance.

METHODS

A 10-year (2008-2018), single-center, retrospective cohort study was performed of all patients admitted with vascular graft infection identified by positive direct graft cultures. An extensive microbiologic study was performed to analyze the bacterial strains, antibiotic resistance and sensitivity, and prevalence stratified by the year.

RESULTS

A total of 72 vascular graft infections with positive graft cultures occurring in 65 patients were found. Their mean age was 67 ± 9.6 years, and 85% were men. Infection-related mortality was 11%. Of the 65 patients, 14 had undergone aortobifemoral bypass, 13 axillofemoral bypass, 5 femorofemoral bypass, 27 femoropopliteal bypass, and 4 femoral endarterectomy with synthetic patch angioplasty. The median interval from the index procedure to infection was longer for intracavitary than for extracavitary grafts (P = .011). Of the 72 infections, 48 were monomicrobial and 24 were polymicrobial. Gram-negative bacteria were predominantly identified in intracavitary graft infections (54%). In contrast, gram-positive bacteria were most frequent in the extracavitary graft group (58%). Multidrug-resistant bacterial species occurred more frequently in early graft infections (P = .002). Throughout the study duration, an overall decrease in gram-positive infections and an increase in gram-negative infections was observed, especially in extensively drug-resistant strains. A similar progression was found in all nosocomial infections.

CONCLUSIONS

The present study has shown that vascular graft infection microbiology changed in accordance with graft location and interval to infection from revascularization surgery and had also evolved over the study period with patterns similar to those for all nosocomial infections. This highlights the importance of studying the specific microbiology of each healthcare center and its relationship to vascular graft infections to achieve the best treatment possible.

[Bypass grafting in patients with infected vascular grafts]

Analysed herein are the results of treating a total of 17 patients presenting with pathology of the aorta and lower-limb arteries, who from 2010 to 2018 required redo interventions due to infection of a previously implanted synthetic vascular graft. At admission, 3 patients were diagnosed as having an open infected wound, 11 were found to have a fistula, 2 had a false aneurysm in the area of the distal anastomosis of the branch of the bifurcation aortofemoral prosthesis, and 1 had thrombosis of the branch of the prosthesis with evidence of infection. As redo surgery, 4 patients underwent subclavian-femoral bypass grafting, 2 were subjected to crossover iliac-femoral bypass grafting, 8 to unilateral iliac-femoral bypass grafting, 3 to loop endarterectomy. In the majority of cases (14 of the 17) we used bypass grafting with creation of the tunnel through the muscular lacuna. Lethal outcomes were registered in 35% (n=6) of cases in the early postoperative period. Death was caused by acute renal failure in 6% (n=1), by acute mesenteric thrombosis in 12% (n=2), by gastrointestinal haemorrhage in 6% (n=1), and by multiple organ failure in 12% (n=2). Long-term mortality amounted to 33% (n=3) within 12 months. The main causes of death were increasing renal failure in 10% (n=1) and cardiovascular insufficiency on the background of heart diseases in 10% (n=1), as well as respiratory insufficiency in 10% (n=1). Reinfection in the remote period was diagnosed in 1 patient. A conclusion was drawn that bypass grafting is traumatic, however, it may be the only way to save the limb or patient's life in a complicated clinical situation. Using the superficial femoral vein as a shunt demonstrated good long-term results as to patency and resistance to surgical infection. Using a flap of the greater omentum, retroperitoneal fat, as well as wrapping of the prosthesis with a muscular flap ensured good tolerance of the zone of bypass grafting to reinfection.

Limb salvage after aneurysmal degeneration of a cryopreserved vein allograft: Searching the autologous veins of the arm is worth the effort

CLINICAL DATA

We hereby report a case of limb salvage involving a 64-year-old man who was hospitalized with ischemic foot ulcers for two months. Endarterectomy with patching and stenting of the left iliofemoral artery failed. A composite bypass of two segments of the endarterectomized superficial femoral artery and a cryopreserved saphenous vein graft was implanted one week later. On day 4 postoperatively, an infection (Staphylococcus epidermidis and Pseudomonas aeruginosa) was treated empirically with antibiotics. Four months later, the femoro-tibial bypass thrombosed and the patency was restored by thrombolysis. The aneurysmal cryopreserved vein was excised. Iterative complications followed and final success was attained after implantation of autologous cephalic and basilic veins. Four years later, this femoro-tibial is still patent.

PATHOLOGICAL ANALYSES

After a gross observation, the explant was dissected and the most significant sections were processed for histology, followed by analyses in scanning electron microscopy, light microscopy and transmission electron microscopy.

RESULTS

The explanted specimen showed a smooth flow surface proximally but a severe distortion distally, with an accumulation of poorly organized mural thrombi. The wall of the arterialized vein was accompanied with an important inflammatory reaction. The degradation of the collagen structure was evidenced in TEM. The fibrils of collagen were still individualized but were fragmented and did not display parallelly. The regular banding was preserved. The presence of Pseudomonas aeruginosa was shown inside the wall of the homologous vein.

COMMENTS

In case of sepsis, the most aggressive antibiotic treatments cannot fully eliminate the bacteremic colonizations within the wall of an alternative conduit. The cephalic and basilic autologous veins are proved to be preferable in absence of the autologous saphenous vein. The amputation was prevented and four years later the bypass is still patent. This is an outstanding result based upon the comorbidities of the patient. The most aggressive harvesting shall be recommended. This patient represented a considerable challenge and the clinical result is highly gratifying: the search for the autologous cephalic and basilic veins proved to be worth the effort.

Management of Vascular Infections in Low- and Middle-Income Countries

Background: Vascular infections are rare and challenging conditions with significant deaths and morbidity. Their management necessitates a multi-disciplinary approach and substantial human and financial resources. The management selected may be influenced by the available resources in low- and middle-income countries (LMICs), where such resources may be variable. Methods: We reviewed the published literature and reviewed the management options for various vascular infections with a focus on carotid, aortic, infrainguinal, and dialysis access infections. Results: Recommendations related to prevention and treatment will be offered from the perspective of LMICs. The general principles for prevention are in compliance with established surgical site infection guidelines and minimize the use of prosthetic material. Early detection and intervention by removing all infected prosthetic material, debridement, drainage, and coverage of the infected field with vascularized tissue are essential steps in the management of the infection. Revascularization using an extra-anatomic or in situ approach is individualized based on the resources and expertise available. Conclusions: The prevention and management of vascular infections in LMICs are effective by adhering to time-proven principles even with limited resources.

Diagnostic yield of 18F-FDG PET/CT in suspected diagnosis of vascular graft infection: A prospective cohort study

BACKGROUND

Prosthetic vascular graft infection (PVGI) is a severe complication associated with high morbidity and mortality. Clinical diagnosis is complex, requiring image testing such as CT angiography or leukocyte scintigraphy, which has considerable limitations. The aim of this study was to know the diagnostic yield of PET/CT with 18F-Fluorodeoxyglucose (18F-FDG) in patients with suspected PVGI.

METHODS

We performed a prospective cohort study including 49 patients with suspected PVGI, median age of 62 ± 14 years. Three uptake patterns were defined following published recommendations: (i) focal, (ii) patched (PVGI criteria), and (iii) diffuse (no PVGI criterion).

RESULTS

Sensitivity, specificity, and positive and negative predictive values for 18F-FDG-PET/CT were 88%, 79%, 67%, and 93%, respectively. 18F-FDG-PET/CT identified 14/16 cases of PVGI showing a focal (n = 10) or patched pattern (n = 4), being true negative in 26/33 cases with either a diffuse pattern (n = 16) or without uptake (n = 10). Five of the seven false-positive cases (71%) showed a patched pattern and all coincided with the application of adhesives for PVG placement.

CONCLUSIONS

18F-FDG-PET/CT is a useful technique for the diagnosis of PVGI. A patched pattern on PET/CT in patients in whom adhesives were applied for prosthetic vascular graft placement does not indicate infection.

Direct site endovascular repair as salvage procedure after anastomotic breakdown of primary repair following trauma

A 16-year-old boy presented to a level I trauma center after multiple gun shot wounds and a motorcycle crash. He was in profound hemorrhagic shock and had multiple traumatic injuries, including a right common iliac arterial injury. The vessel was shunted for damage control and subsequently repaired primarily. On hospital day 18, he experienced dehiscence of the anastomosis requiring urgent surgery. The artery was ultimately repaired with an expandable polytetrafluoroethylene stent graft deployed in an open fashion through the site of injury. We discuss the use of stent grafts as an interesting alternative to suture repair after anastomotic disruption.

PET/CT Imaging in Soft Tissue Infection and Inflammation-An Update

Nuclear medicine procedures, including Ga-67 and labeled leucocyte SPECT/CT as well as PET/CT using 18F-FDG and recently Ga-68 tracers, have found extensive applications in the assessment of infectious and inflammatory processes in general and in soft tissues in particular. Recent published data focus on summarizing the available imaging information with the purpose of providing the referring clinicians with optimized evidence based results. Guidelines and/or recommendations of clinical societies have incorporated nuclear medicine tests (using both labeled leucocytes and FDG) in their suggested work-up for evaluation of infective endocarditis and in certain patients with suspected vascular graft infections. Joint guidelines of the European and American nuclear medicine societies include fever of unknown origin, sarcoidosis, and vasculitis among the major clinical indications that will benefit from nuclear medicine procedures, specifically from FDG PET/CT. Limitations and pitfalls for the use of radiotracers in assessment of infection and inflammation can be related to patient conditions (eg, diabetes mellitus), or to the biodistribution of a specific radiopharmaceutical. Limited presently available data on the use of functional and/or metabolic monitoring of response to infectious and inflammatory processes to treatment and with respect to the effect of drugs such as antibiotics and glucocorticoids on the imaging patterns of these patients need further confirmation.

Study protocol for the groin wound infection after vascular exposure (GIVE) audit and multicentre cohort study

INTRODUCTION

Surgical site infections (SSIs) following groin incision for arterial exposure are commonplace and a significant cause of morbidity and mortality following major arterial surgery. Published incidence varies considerably. The primary aim of GIVE will be to compare individual units' practice with established guidelines from The National Institute for Health and Care Excellence (NICE). Secondary aims will be to describe the contemporary rate of SSI in patients undergoing groin incision for arterial exposure, to identify risk factors for groin wound infection, to examine the value of published tools in the prediction of SSI, to identify areas of equipoise which could be examined in future efficacy/effectiveness trials and to compare UK SSI rates with international centres.

METHODS AND ANALYSIS

This international, multicentre, prospective observational study will be delivered via the Vascular and Endovascular Research Network (VERN). Participating centres will identify all patients undergoing clean emergency or elective groin incision(s) for arterial intervention during a consecutive 3-month period. Follow up data will be captured at 90 days after surgery. SSIs will be defined according to the Centres for Disease Control and Prevention (CDC) criteria. Data will be gathered centrally using an anonymised electronic data collection tool or secure email transfer.

ETHICS AND DISSEMINATION

This study will be registered as a clinical audit at all participating UK centres; research ethics approval is not required. National leads will oversee the appropriate registration and approvals in countries outside the UK as required. Site specific reports of SSI rates will be provided to each participating centre. Study results will be disseminated locally at each site, publicised on social media and submitted for peer-reviewed publication.

Systematic Review and Meta-Analysis on the Management of Open Abdominal Aortic Graft Infections

OBJECTIVE

Aortic graft infection (AGI) is a disastrous complication with an incidence of 0.2-6% in operated patients. With little or no high quality evidence, the best treatment option remains unclear. Therefore, the literature on the management of open abdominal AGI was systematically reviewed to determine optimal treatment.

METHODS

In accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, a systematic review and meta-analysis was conducted for AGI. MEDLINE, Embase, and the Cochrane Database of Systematic Reviews were searched. Methodological quality was assessed using the Methodological Index for Non-randomised Studies (MINORS) score. Primary outcomes were 30 day mortality and one year survival. Secondary outcomes were survival, infection recurrence, limb salvage, and graft patency.

RESULTS

Of 1574 studies identified, 32 papers were included in the study. The overall quality of the studies was moderate, with an average MINORS score of 11.9. Pooled overall 30 day mortality and one year survival were 13.5% (95% CI 10.5-16.4) and 73.6% (95% CI 68.8-78.4), respectively. The lowest 30 day mortality and highest one year survival were found for in situ repair compared with extra-anatomic repair and for prosthetic grafts compared with venous grafts or arterial allografts. The infection recurrence rate was highest for prosthetic grafts.

CONCLUSIONS

There is a lack of well designed, qualitative comparative studies making conclusive recommendations impossible. The current best available data suggests that partial graft removal should be avoided and the lowest 30 day mortality and best one year survival are achieved with in situ repair using prosthetic grafts. Initiatives such as the MAGIC database to collaboratively collect prospective data are an important step forward in obtaining more solid answers on this topic.

Peripheral artery reconstructions using cryopreserved arterial allografts in infected fields

OBJECTIVE

Cryopreserved human arterial allografts are a recognized acceptable alternative for vascular reconstruction when other traditional conduits are either unavailable or contraindicated. We reviewed our experience using cryopreserved arterial allografts for peripheral artery reconstructions in contaminated and infected surgical fields.

METHODS

A single-center, retrospective review was conducted of 57 patients who underwent a peripheral vascular reconstruction using a cryopreserved arterial allograft from January 2002 through July 2017. Indications for repair included removal of infected prosthetic bypass (n = 29), revascularizations in contaminated fields (n = 11), primary arterial repair in the setting of infection (n = 10), and infected vascular closure devices (n = 7). Aorta-based repairs were excluded. Demographics, index procedural details, postoperative complications, and conduit patency were analyzed. Primary end points included conduit-related mortality and graft failure as measured by reinfection, hemorrhage, or aneurysmal degeneration. Mean follow-up for the study is 27.8 months (range, 2-125 months).

RESULTS

A total of 57 peripheral vascular reconstructions using cryopreserved arterial allografts were performed during the 15-year period. Among the 22 women and 35 men treated, the mean age was 61 years. The vascular beds involved included iliofemoral (n = 39), femoropopliteal or femoral-distal (n = 10), axillosubclavian or brachial (n = 2), mesenteric (n = 3), and carotid (n = 3) arteries. Adjunctive muscle flap coverage of the allograft conduit was performed in the majority of cases (61%; n = 35). The 30-day mortality was 9%; one death was directly related to conduit insertion. The 30-day conduit-related complication rate was 14% and included hemorrhage from the graft requiring return to the operating room (n = 4) and graft infection (n = 4). The late conduit-related complication rate was 15.8% and included graft infection (n = 1), graft thrombosis (n = 3), major amputation resulting from conduit failure (n = 1), pseudoaneurysm degeneration requiring repair (n = 2), graft hemorrhage (n = 1), and symptomatic graft stenosis (n = 1).

CONCLUSIONS

A cryopreserved arterial allograft is a useful alternative conduit for peripheral vascular reconstruction in infected or contaminated surgical fields when other autologous or prosthetic conduits are either unavailable or contraindicated. In the immediate postoperative period, these repairs demonstrate acceptable resistance to graft failure and reinfection, particularly in conjunction with adjunctive rotational muscle flap coverage. Late conduit-related complications appear to be infrequent.

A meta-analysis of outcomes of in-situ reconstruction after total or partial removal of infected abdominal aortic graft

INTRODUCTION

There is currently a lack of evidence for the relative effectiveness of partial resection (PR) and total resection (TR) before managing abdominal aortic graft infection (AGI). Most authorities agree that TR is mandatory for intracavitary AGI in patients with favorable conditions but there is an increasing number of patients with severe comorbidities for whom this approach is not suitable, resulting in a prohibitive mortality rate. The purpose of this study was to determine the most appropriate indication for TR or PR.

EVIDENCE ACQUISITION

A meta-analysis was conducted on the rates of early/late mortality, amputations and reinfection. A meta-regression was performed with eight variables: patient age, male prevalence, presence of virulent or nonvirulent organisms, urgency, omentoplasty and follow-up.

EVIDENCE SYNTHESIS

Twenty-one studies and 1052 patients were included. For TR and PR, the rates of early mortality and reinfection were 16.8% and 10.5%, 11% and 27%, respectively. For TR urgency and male gender were associated with increased rate of early mortality and male gender, PDF and virulent organisms were associated with increased risk of reinfection. For PR no statistical correlation was analyzable except for PDF with increased risk of reinfection.

CONCLUSIONS

Early mortality rates are higher for TR and reinfection rates are higher for PR. For TR early mortality increases in urgent cases and it is suggested that alternative option must be discussed, reinfection decreases in the presence of nonvirulent organisms and TR seems optimal. For TR and PR reinfection increases in presence of PDF and alternative technique may be more appropriate.

Vascular Graft Infections: An update

Vascular graft infection is a devastating complication of vascular reconstructive surgery. The infection can occur early in the postoperative period and is largely due to intraoperative contamination or by contiguous extension from a nearby infection. It can also occur years after implantation. Staphylococci remain the most common organisms and biofilm production makes eradication difficult. Factors commonly reported to predispose to vascular graft infection are periodontal disease, nasal colonization with Staphylococcus aureus, bacteremia, certain graft characteristics, diabetes mellitus, postoperative hyperglycemia, location of the incision, wound infection, and emergency procedure. Management consists of antibiotic and surgical therapy. Preventive methods are described.

Efficacy of Preoperative Antibiotic Therapy for the Treatment of Vascular Graft Infection

Objective: We aimed to assess the efficacy of preoperative antibiotic therapy for the treatment of prosthetic graft infection.

Materials and Methods: We retrospectively analyzed the treatment strategies used for managing patients with prosthetic vascular graft infections between 2000 and 2016. The patients were divided into two groups: early antibiotic (EA) group, those who were administered with antibiotics ≥2 weeks preoperatively and late antibiotic (LA) group, those who were administered with antibiotics <2 weeks preoperatively. We evaluated the outcomes including surgical procedures, length of hospital stay, and surgical revision.

Results: All the surgical procedures performed in the EA group were elective surgeries. Three of the 11 surgeries performed in the LA group were emergency surgeries (P=0.16). No significant differences were observed in the operative procedure (P=0.64), operation time (P=0.37), and blood loss (P=0.63) of the two groups. Although the length of postoperative hospital stay did not significantly differ (P=0.61), the total length of hospital stay was longer in the EA group (P=0.02). Surgical revisions were performed for five patients in the LA group and for none in the EA group (P=0.04).

Conclusion: Preoperative antibiotic therapy provided excellent outcomes in terms of avoiding surgical revisions in the treatment of vascular graft infection.

Initial Inoculation Concentration Does Not Affect Final Bacterial Colonization of In vitro Vascular Conduits

BACKGROUND

Despite improved peri-operative care, prosthetic graft infections continue to cause substantial morbidity and mortality. Contemporary graft infection models have tested a conduit's infectability using varying concentrations without standardization. Using a static assay in vitro model, we sought to evaluate the impact of inoculation concentration on vascular conduit attachment.

METHODS

The 2-hour and 24-hour attachment of Staphylococcus aureus TCH1516 and Pseudomonas aeruginosa PA01-UW were determined on polytetrafluoroethylene (PTFE), Dacron^®, nitinol, cobalt chromium, and Viabahn^® (W.L. Gore and Associates, Newark, DE) endoprotheses. Individually and in combination, concentrations at 10⁴, 10⁵, 10⁶, 10⁷, and 10⁸ were tested on 2-mm sections of each graft. After each time interval, the prosthetics were rinsed to remove non-attached bacteria, sonicated to release the attached bacteria, spiral plated, and then analyzed for the attached concentration.

RESULTS

After two hours, the higher initial inoculation concentration translated into a higher attachment percentage, but the mean attachment percentage was only 14.8% in the 10⁸ group. Pseudomonas aeruginosa had the greatest mean attachment across all material and concentration groups. The sequence of attachment on the conduits followed a constant order: Dacron, PTFE, cobalt, nitinol, and Viabahn with no difference between Dacron and PTFE. Although there were still differences at the 24-hour mark, the median attachment at each concentration was greater than the highest initial concentration (10⁸).

CONCLUSIONS

Initial attachment percentage is poor consistently regardless of inoculation concentration, however, Staphylococcus aureus and Pseudomonas aeruginosa are still able to achieve full attachment after 24 hours. A concentration of less than 10⁷ should be used in vascular graft infection models to ensure adequate bacterial attachment.

A Meta-Analysis of Outcomes After In Situ Reconstructions for Aortic Graft Infection

OBJECTIVE

To confirm the advantage of in situ reconstruction (ISR) over extra-anatomic reconstruction (EAR) for aortic graft infection and determine the most appropriate conduit including autogenous veins, cryopreserved allografts, and synthetic prosthesis (standard, rifampicin of silver polyesters).

METHODS

A meta-analysis was conducted with rate of mortality, graft occlusion, amputation, and reinfection. A meta-regression was performed with 4 factors: patients' age, presence of prosthetic-duodenal fistula (PDF), virulent organisms, or nonvirulent organisms.

RESULTS

In situ reconstruction over EAR seems to favor all events. For the 5 conduits used for ISR, according to operative mortality, age of the patients looks to have a positive correlation only for silver polyester and no conduit present any advantage in the presence of PDF. Reinfection seems to be not significantly different for the 5 conduits, and only autogenous veins appear to have a positive correlation with infecting organisms.

CONCLUSION

In situ reconstruction may be considered as first-line treatment. Our results suggest that silver polyesters appear to be most appropriate for older patients, and in order to limit reinfection, autogenous veins are probably the most suitable conduit.

Antiviral Resistance of Splenocytes in Aged Mice

We compared the susceptibility to viral infection of splenocytes, isolated from young versus old CBA mice, and evaluated the antiviral actions of lactoferrin in splenocytes infected with Encephalomyocarditis virus (EMCV). Recombinant mouse lactoferrin (rmLF) and bovine lactoferrin (bLF) were used. There were no differences in the susceptibility to EMCV infection in the studied age categories. Both types of lactoferrins were protective in young and old mice. The study confirmed the undisturbed viral resistance in old mice and the protective actions of lactoferrin in viral infection. The antiviral action of the homologous mouse lactoferrin was demonstrated for the first time.

Beyond conventional antibiotics - New directions for combination products to combat biofilm

Medical device related infections are a significant and growing source of morbidity and mortality. Biofilm formation is a common feature of medical device infections that is not effectively prevented or treated by systemic antibiotics. Antimicrobial medical device combination products provide a pathway for local delivery of antimicrobial therapeutics with the ability to achieve high local concentrations while minimizing systemic side effects. In this review, we present considerations for the design of local antimicrobial delivery systems, which can be facilitated by modeling local pharmacokinetics in the context of the target device application. In addition to the need for local delivery, a critical barrier to progress in the field is the need to incorporate agents effective against biofilm. This article aims to review key properties of antimicrobial peptides that make them well suited to meet the demands of the next generation of antimicrobial medical devices, including broad spectrum activity, rapid and biocidal mechanisms of action, and efficacy against biofilm.

Bovine Pericardium as New Technical Option for In Situ Reconstruction of Aortic Graft Infection

BACKGROUND

Alloplastic aortic graft infection is a devastating complication following aortic surgery. It is associated with excessively high mortality and morbidity caused by anastomotic rupture or septicemia. Many authors consider in situ replacement after complete surgical graft removal as the method of choice. However, there is an ongoing debate about the most suitable material for reconstruction. We present our first experiences with replacing the descending and infrarenal aorta using custom-made bovine pericardium grafts.

MATERIAL AND METHODS

From January 2013 to 2015, 13 patients (10 male, median age 70 years, range 53-84) were treated for 5 early-graft infections after open reconstructions and 7 late graft infections (1 TEVAR, 2 EVAR, and 4 open reconstructions), and 1 patient was treated for mycotic aneurysm. Septicemia was evident in 8 patients, whereas 5 patients were presented with low-grade infection. In all cases, graft infection was proven by a synopsis of clinical findings, laboratory tests, imaging, and microbiologic tests (positive pathogen detection in 11 patients). Cutaneous and aortoenteric fistulae were present in 3 and 4 patients, respectively. All patients received an in situ replacement using a hand-sewn xenoprosthesis or patch made from a bovine pericardium sheet. Follow-up was routinely performed 3, 12, and 24 months after discharge.

RESULTS

For reconstruction, 4 pericardium tubes, 7 bifurcated grafts, and 2 large patches were implanted in situ. Technical success was 100%. Median length of hospital stay was 44 days (range, 20-136 days), with an in-hospital mortality rate of 7.7% (n = 1). Major procedure- and disease-related complications were temporary (n = 2) and permanent dialysis (n = 1), limb loss (n = 1), and long-term ventilation (n = 5). Complete infection control and initial healing could be achieved in 75% (n = 10). During the follow-up (median 9 months, range: 1-27 months), primary graft patency was 100%, and mortality was 41.7%. We observed 2 secondary ruptures due to reinfection at 4 and 7 months.

CONCLUSIONS

Custom-made bovine pericardium grafts provide a good option for in situ replacement following early or late aortic graft infection. Despite of its high biocompatibility, pericardium provides not an absolute protection against ongoing retroperitoneal infection. For the treatment, the principles of septic surgery need to be applied and close follow-up is mandatory.

Editor's Choice - Management of Secondary Aorto-enteric and Other Abdominal Arterio-enteric Fistulas: A Review and Pooled Data Analysis

OBJECTIVES

To compare management strategies for secondary abdominal arterio-enteric fistulas (AEFs).

METHODS

This study is a review and pooled data analysis. Medline and Scopus databases were searched for studies published between 1999 and 2015. Particular emphasis was given to short- and long-term outcomes in relation to AEF repair type.

RESULTS

Two hundred and sixteen publications were retrieved, reporting on 823 patients. In-hospital mortality was 30.7%. Open surgery had higher in-hospital mortality (246/725, 33.9%), than endovascular methods (7/98, 7.1%, p < .001, OR 6.7, 95% CI 3-14.7, including staged endovascular to open surgery, 0/13, 0%). In-hospital mortality after graft removal/extra-anatomical bypass grafting was 31.2% (66/226), graft removal/in situ repair 34% (137/403), primary closure of the arterial defect 62.5% (10/16), and for miscellaneous open procedures 41.3% (33/80), p = .019. Among the subgroups of in situ repair, homografts were associated with a higher mortality than impregnated prosthetic grafts (p = .047). There was no difference in recurrent AEF-free rates between open and endovascular procedures. Extra-anatomical bypass/graft removal and in situ repair had a lower AEF recurrence rate than primary closure and homografts. Late sepsis occurred more often after endovascular surgery (2-year rates 42% vs. 19% for open, p = .001). The early survival benefit of endovascular surgery was blunted during follow-up, although it remained significant (p < .001). Within the in situ repair group, impregnated prosthetic grafts were associated with the worst overall and AEF related mortality free rates and vein grafts with the best. No recurrence, sepsis, or mortality was reported following staged endograft placement to open repair after a mean follow-up of 16.8 months (p = .18, p = .22, and p = .006, respectively, compared with patients in other groups).

CONCLUSIONS

Endovascular surgery, where appropriate, is associated with better early survival than open surgery for secondary AEFs. Most of this benefit is lost during long-term follow-up, implying that a staged approach with early conversion to in situ vein grafting may achieve the best results in selected patients.

Aortic Graft Infection: Update on Management and Treatment Options

Replacement of the abdominal aorta, whether by autogenous or prosthetic conduit, has been an a priori requisite in the vascular surgeon's armamentarium since its technical feasibility was described in the early 1950s. The Achilles' heel of this operation, in spite of the progress made over the last half century, is still, however, aortic graft infection. Though survival and limb salvage rates have improved over time—commensurate with advances in surgical technique, critical care, and antimicrobial agents—the prevention and treatment of aortic graft infection remains a formidable challenge to the vascular surgeon. The authors herein review the current literature on this topic with an emphasis on the surgical management options available and suggest an individualized operative strategy based on patient as well as microbial factors to attain the best possible outcome.

Prevention of perioperative vascular prosthetic infection with a novel triple antimicrobial-bonded arterial graft

OBJECTIVE

Previously, we investigated a locally developed technique of bonding arterial grafts with three antimicrobials to protect against early (within 2 weeks) perioperative bacterial contamination encountered occasionally during aortic graft prosthetic reconstruction. Vascular graft infections are classified by their appearance time (early [<4 months] vs late [>4 months] after graft implantation), degree of incorporation into the surrounding vessel wall, connectivity to the postoperative wound, and extent of graft involvement. In the current phase of testing, we evaluated the ability of our novel triple antimicrobial-bonded graft to prevent infection in the first 8 weeks after implantation.

METHODS

In nine Sinclair miniature pigs, we surgically implanted a 6-mm vascular Dacron patch graft in the infrarenal abdominal aorta. Five pigs received grafts chemically bonded with a 60-mg/mL solution of rifampin, minocycline, and chlorhexidine, and four pigs received unbonded grafts. Before implantation, the five bonded grafts and three of the unbonded grafts were immersed for 15 minutes in a 2-mL solution containing 1-2 × 10⁷ colony-forming units (CFUs)/mL of Staphylococcus aureus (ATCC 29213); the fourth unbonded graft served as a control.

RESULTS

At week 9, all of the grafts were explanted. All S aureus-inoculated bonded grafts (n = 5) showed no bacterial growth. The unbonded, uninoculated graft (n = 1) showed low-level bacterial growth (<1.2 × 10³ CFUs); S cohnii spp urealyticus, but not S aureus, was isolated, which suggested accidental direct perioperative contamination. Two pigs that received S aureus-inoculated, unbonded grafts were euthanized because of severe S aureus infection (<6.56 × 10⁸ CFUs per graft). Results of histopathologic analysis were concordant with the microbiologic findings. Most intergroup differences were observed in the inflammatory infiltrate in the aortic wall at the site of graft implantation. In all pigs that received bonded grafts, Gram staining showed no bacteria.

CONCLUSIONS

Our triple-bonded aortic graft prevented perioperative aortic graft infection for at least 8 weeks in a porcine model. The synergistic antimicrobial activity of this graft was sufficient to prevent and/or eradicate infection during that period. Further studies are needed to assess the graft's ability to combat early-onset vascular graft infection for up to 4 months.

The Tissue-Engineered Vascular Graft-Past, Present, and Future

Cardiovascular disease is the leading cause of death worldwide, with this trend predicted to continue for the foreseeable future. Common disorders are associated with the stenosis or occlusion of blood vessels. The preferred treatment for the long-term revascularization of occluded vessels is surgery utilizing vascular grafts, such as coronary artery bypass grafting and peripheral artery bypass grafting. Currently, autologous vessels such as the saphenous vein and internal thoracic artery represent the gold standard grafts for small-diameter vessels (<6 mm), outperforming synthetic alternatives. However, these vessels are of limited availability, require invasive harvest, and are often unsuitable for use. To address this, the development of a tissue-engineered vascular graft (TEVG) has been rigorously pursued. This article reviews the current state of the art of TEVGs. The various approaches being explored to generate TEVGs are described, including scaffold-based methods (using synthetic and natural polymers), the use of decellularized natural matrices, and tissue self-assembly processes, with the results of various in vivo studies, including clinical trials, highlighted. A discussion of the key areas for further investigation, including graft cell source, mechanical properties, hemodynamics, integration, and assessment in animal models, is then presented.

Aortic graft in hollow viscus

Secondary aortoenteric fistulas (AEFs) and aortic graft infection are relatively rare but fatal complications of aortic surgery. A 77-year-old man had a 1-week history of fever and abdominal pain with right inguinal area swelling. The patient's medical history included hypertension, aortobifemoral bypass grafting due to right iliac artery, and superficial femoral artery occlusion. Abdominopelvic computed tomography revealed the presence of an aortic graft in the hollow viscus. Although there have been several reports of secondary AEF, there have been few reports of an aortic graft in a hollow viscus. Diagnosis of AEF can be delayed in patients with atypical symptoms. Without a high index of suspicion, this condition has fatal consequences.

Conservative Treatment of an Infected Aortic Graft with Antibiotic Irrigation

Conservative management of an aortic graft infection is defined as "the nonresectional treatment of an aortic graft that has an established infection." Incidence of aortic graft infections is 0.5 to 5% and the estimated mortality rate from aortic graft infections ranges from 8 to 27%. We present the case of a 73-year-old male patient with an infected abdominal aortic graft following an emergency ruptured abdominal aortic aneurysm repair. Postemergency repair, he developed ischemic colitis with sigmoid colon perforation leading to fecal peritonitis and secondary sepsis. He developed a large infective collection within the aortic sac growing vancomycin-resistant enterococcus sensitive to linezolid. A percutaneous drain was placed in the aortic sac and this was irrigated with linezolid for a total of 28 days. The patient clinically improved. Overall, 7 months later, follow-up scan shows complete resolution of infection and the patient remains clinically stable. Conventional treatment of aortic graft infections involves an extra-anatomical bypass. Percutaneous drainage and antibiotic use may be used as bridging therapy for surgery or as definitive therapy when surgical treatment is impractical. Most aortic graft infections grow gram-positive cocci, the organisms form a biofilm which is protected from the external environment. Percutaneous drainage and antibiotic irrigation could possibly penetrate the biofilm and eradicate infection. Morris et al conducted a study on 10 patients having irrigation therapy and systemic antibiotic treatment and found a 1-year survival rate of 80%. In conclusion, conservative aortic graft treatment may be an effective alternative where surgical intervention is not suitable.