Antibiotic-impregnated grafts for aortic reconstruction

Reinterventions after TEVAR

Thoracic cardiovascular aortic repair is an alternative procedure to open surgery for degenerative thoracic aortic aneurysm and thoracic aortic dissection. The advancements in graft design and imaging techniques have expanded its utility. However, the long-term patency of thoracic endovascular aortic repair (TEVAR) graft is still a concern. This review delves into the literature on re-intervention following TEVAR, highlighting factors that influence the re-intervention rate.

Ten-year experience with cryopreserved vascular allografts in the Croatian Cardiovascular Tissue Bank

The Croatian Cardiovascular Tissue Bank (CTB) was established in June 2011. Activities managed by CTB are processing of heart valves and blood vessels, as well as quality control, storage, medical release and distribution of allografts. The aim of this report is to present CTB's vascular tissue activities and retrospectively evaluate the outcomes of their use in the University Hospital Centre Zagreb. Between June 2011 and July 2021, 90 vascular allografts (VAs) from 55 donors after brain death were referred to CTB. Only 54% of VAs met the tissue quality requirements while 46% of tissues were discarded. The most frequent reasons for discard were unacceptable morphology and initial microbiological contamination. Altogether 42 VAs were released for transplantation and 37 of them were used in 27 surgical procedures. The most common indication for surgery was prosthetic graft or stent infection. According to the anatomic position of vascular reconstruction, patients were divided in the aortic and peripheral reconstruction group. A total of 23 patients were treated. In the aortic reconstruction group 58% of patients did not experience any graft-related complications. In the group of patients who underwent peripheral reconstruction significant incidence of reinfection was observed highlighting it as a major graft-related complication. Despite the small patient groups and limited duration of follow-up, presented clinical outcomes provide valuable information on the efficacy of vascular allografts. Additional clinical results collected on a larger patient groups and comparison to other reconstructive treatment options are necessary.

Novel dalbavancin-PLLA implant coating prevents hematogenous Staphylococcus aureus infection in a minimally invasive mouse tail vein model

Infective/bacterial endocarditis is a rare but life-threatening disease with a hospital mortality rate of 22.7% and a 1-year mortality rate of 40%. Therefore, continued research efforts to develop efficient anti-infective implant materials are of the utmost importance. Equally important is the development of test systems that allow the performance of new materials to be comprehensively evaluated. In this study, a novel antibacterial coating based on dalbavancin was tested in comparison to rifampicin/minocycline, and the suitability of a recently developed mouse tail vein model for testing the implant coatings was validated. Small polymeric stent grafts coated with a poly-L-lactic acid (PLLA) layer and incorporated antibiotics were colonized with Staphylococcus (S.) aureus before implantation into the tail vein of mice. The main assessment criteria were the hematogenous spread of the bacteria and the local tissue reaction to the contaminated implant. For this purpose, colony-forming units (CFU) in the blood, spleen and kidneys were determined. Tail cross sections were prepared for histological analysis, and plasma cytokine levels and expression values of inflammation-associated genes were examined. Both antibiotic coatings performed excellently, preventing the onset of infection. The present study expands the range of available methods for testing the anti-infectivity of cardiovascular implants, and the spectrum of agents for effective surface coating.

Lyophilized Human Bone Allograft as an Antibiotic Carrier: An In Vitro and In Vivo Study

Background: Antibiotics delivered from implanted bone substitute materials (BSM) can potentially be used to prevent acute infections and biofilm formation, providing high concentrations of antibiotics at the surgical site without systemic toxicity. In addition, BSM should allow osteoconductivity supporting bone healing without further surgery. Promising results have been achieved using lyophilized bone allografts mixed with antibiotics. Methods: In this study specially prepared human bone allografts were evaluated as an antibiotic carrier in vitro and in vivo. The efficacy of different antibiotic-impregnated bone allografts was measured by drug release tests in vitro and in vivo and bacterial susceptibility tests using four bacterial species usually responsible for implant-associated infections. Results: The loading procedures of allograft bone substitutes with antibiotics were successful. Some of the antibiotic concentrations exceeded the MIC90 for up to 7 days in vitro and for up to 72 h in vivo. The susceptibility tests showed that S. epidermidis ATCC 12228 was the most susceptible bacterial species in comparison to the other strains tested for all antibiotic substances. Vancomycin and rifampicin showed the best results against standard and patient-isolated strains in vitro. In vivo, new bone formation was comparable in all study groups including the control group without antibiotic loading. Conclusions: Human bone allografts showed the capacity to act as customized loaded antibiotic carriers to prevent acute infections and should be considered in the management of bone infections in combination with systemic antimicrobial therapy.

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.

Polycatecholamine and gentamicin as modifiers for antibacterial and blood-biocompatible polyester vascular prostheses

Polyester (PET) prostheses are commonly used in reconstructive vascular surgery. The most serious complication after implantation is early or late infection of the graft. Therefore, there is high demand to protect prosthesis against bacterial adhesion and biofilm development. For this reason, in this work PET prostheses were first coated by highly adhesive polycatecholamine layer. The grafts were then coupled with gentamicin and studied in relation to morphological and structural properties, biological safety (contact with blood, reaction of vascular endothelial cells (HUVEC), Danio rerio fish), drug release and antibacterial activity. Among two tested catecholamine monomers, L-DOPA was found to be more effective precursor in this process than dopamine. For L-DOPA, assistance of Cu²⁺, Mg²⁺ and Na⁺ ions seems to increase the amount of further immobilized drug. Coated prostheses exhibited greater human endothelial cell proliferation increase and lower cytotoxic effect than uncoated. The modification reduced the hemolysis observed for pristine commercial graft and limited the rate of abnormalities in D. rerio larvae, confirming the safety of the proposed modification. The coating allowed to double the amount of immobilized antibiotic in comparison with uncoated graft which resulted in increased antibacterial activity and reduced bacterial adhesion against 4 bacterial strains prevalent in biomaterials infections. Overall, poly(L-DOPA)-coatings deposited on PET vascular grafts can effectively functionalize these prostheses for higher safety in biomedical applications.

Pre-clinical in vivo Models of Vascular Graft Coating in the Prevention of Vascular Graft Infection: A Systematic Review

OBJECTIVE

Vascular graft infection (VGI) remains an important complication with a high mortality and morbidity rate. Currently, studies focusing on the role of vascular graft coatings in the prevention of VGI are scarce. Therefore, the aims of this study were to survey and summarise key features of pre-clinical in vivo models that have been used to investigate coating strategies to prevent VGI and to set up an ideal model that can be used in future preclinical research.

DATA SOURCES

A systematic review was conducted in accordance with the Preferred reporting items for Systematic Reviews and Meta-Analysis guidelines. A comprehensive search was performed in MEDLINE (PubMed), Embase, and Web of Science.

REVIEW METHODS

For each database, a specific search strategy was developed. Quality was assessed with the Toxicological data Reliability Assessment Tool (ToxRTool). The type of animal model, graft, coating, and pathogen were summarised. The outcome assessment in each study was evaluated.

RESULTS

In total, 4 667 studies were identified, of which 94 papers focusing on in vivo testing were included. Staphylococcus aureus was the organism most used (n = 65; 67.7%). Most of the graft types were polyester grafts. Rifampicin was the most frequently used antibiotic coating (n = 43, 48.3%). In the outcome assessment, most studies mentioned colony forming unit count (n = 88; 91.7%) and clinical outcome (n = 72; 75%). According to the ToxRTool, 21 (22.3%, n = 21/94) studies were considered to be not reliable.

CONCLUSION

Currently published in vivo models are very miscellaneous. More attention should be paid to the methodology of these pre-clinical reports when transferring novel graft coatings into clinical practice. Variables used in pre-clinical reports (bacterial strain, duration of activity coating) do not correspond well to current clinical studies. Based on the results of this review, a proposal for a complete and comprehensive set up for pre-clinical invivo testing of anti-infectious properties of vascular graft coatings was defined.

[Quo vadimus? Fundamental problems of developing hybrid prostheses of thoracic aorta]

This article is a review briefly characterizing the state of the art of hybrid surgery of the thoracic aorta using the frozen elephant trunk technique worldwide and in Russia, also discussing unsolved problems of fundamental science, being key issues in creation of new models of hybrid prostheses of the thoracic aorta. The main attention is paid to the problem of radial stiffness of the stent-graft portion of the prosthesis. Performed is a detailed analysis of the factors influencing this characteristic of the sent graft: shape, size and number of cells of the stent element, thickness of the nitinol wire it is made of, method of edge connection, nitinol properties depending on the alloy grade and methods of thermoforming. It is shown that excessive stiffness leads to the development of d-SINE syndrome. This is followed by discussing the problem of optimal stiffness of stent grafts, based on the design of stent graft elements and elastic properties of the wall of the true channel of a dissecting aortic aneurysm. Also proposed is an approach to solving the problem of d-SINE, consisting in creation of conical stent grafts and/or a gradual decrease of radial stiffness of stent elements in the direction of the distal portion. Comprehensively addressed are disadvantages of the graft portion of the prosthesis, in 95% of items made of polyethylene terephthalate fiber: susceptibility to degradation associated with manufacturing defects and intraoperative microdamages, abrasive effect in the zone of contact with stent elements, partial postoperative hydrolysis and an inflammatory reaction to a foreign body, often being clinically pronounced. Also touched upon are certain aspects of creating hermetic coatings of the graft portion, with the use of vancomycin possessing low cytotoxicity as part of an antibacterial component being promising. As a whole, it is demonstrated that advances in creating a novel generation of hybrid prostheses should be associated with new approaches and materials, to be obtained at the junction of medicine and fundamental sciences.

Contemporary Review to Reduce Groin Surgical Site Infections in Vascular Surgery

Surgical site infection (SSIs) in lower extremity vascular procedures is a major contributor to patient morbidity and mortality. Despite previous advancements in preoperative and postoperative care, the surgical infection rate in vascular surgery remains high, particularly when groin incisions are involved. However, successfully targeting modifiable risk factors reduces the surgical site infection incidence in vascular surgery patients. We conducted an extensive literature review to evaluate the efficacy of various preventive strategies for groin surgical site infections. We discuss the role of preoperative showers, preoperative and postoperative antibiotics, collagen gentamicin implants, iodine impregnated drapes, types of skin incisions, negative pressure wound therapy, and prophylactic muscle flap transposition in preventing surgical site infection in the groin after vascular surgical procedures.

[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.

Efficacy of antiseptic impregnation of aortic endografts with rifampicin compared to silver against in vitro contamination with four bacteria that frequently cause vascular graft infections

OBJECTIVE

This in vitro study investigates the antimicrobial efficacy of impregnation of commercially available aortic endografts (EG) with rifampicin (RIF) and nanocolloidal silver.

METHODS

Endografts were flushed with 50 mL of RIF 600 mg, 70 mL of a silver-based aqueous solution (AG), or 50 mL of phosphate-buffered saline (PBS) over 15 minutes. Endografts were then retrieved from the sheath and cut in 1 × 1 cm sized graft units (n = 80 of each impregnation), which were then incubated for 1 hour separately with inoculates containing 10⁶ or 10³ bacteria per milliliter (bact/mL) of each of the following bacteria: Staphylococcus epidermidis, Escherichia coli, multisensitive Staphylococcus aureus, and Pseudomonas aeruginosa. After sonication of the graft units, bacterial counts were measured by plating out twice the sonication solution on Mueller-Hinton plates.

RESULTS

RIF showed a statistically significant decrease of colony forming units per milliliter for all four bacterial strains in both concentrations compared with PBS and AG, except for 10³ bact/mL of E coli. AG showed a significant decrease of colony forming units per milliliter compared with PBS only for 10⁶ bact/mL of E coli and was statistically significantly inferior to RIF for all four bacterial strains in both concentrations with the exception of E coli at a concentration of 10³ bact/mL.

CONCLUSIONS

This in vitro study demonstrated infectivity resistance of aortic EG after flushing with RIF. Moreover, the feasibility of flushing aortic EG with a new silver-based agent could be demonstrated, but without statistically significant antimicrobial efficacy compared with native EG.

Aortic reconstruction in infected aortic pathology by femoral vein "neo-aorta"

The use of autologous femoral veins for in situ reconstruction of the aortoiliac segment is an effective technique to treat native aorta or prosthetic graft infections. The indications, technical details, and outcomes of this procedure are detailed. Graft infection involving the aortic segment, while rare, remains one of the most challenging vascular surgery conditions to treat. The original technique of "neo-aortoiliac surgery" with in situ autologous vein grafts has evolved over the past 25 years and remains a worthwhile alternative for the treatment of aortic graft infections, with lower mortality rates compared with other extra-anatomic or in situ surgical options. Acceptance of this surgical option is due to low graft re-infection rates, rare graft disruption, and low long-term aneurysmal degeneration. Excision of the femoral veins is associated with acceptable rates of lower limb edema. The use of an autologous femoral vein graft can be considered the standard of care in selected patients for the management of aortic graft infections. Optimal management of patients with aortic graft infections requires consideration of all potential therapeutic options because no single modality can be used, and individualizing treatment according to the clinical condition will yield the best patient outcomes.

Comparing Venous Reconstructions and Antimicrobial Graft Reconstructions in Mycotic Abdominal Aortic Aneurysms and Aortic Graft Infections

BACKGROUND

The perioperative mortality and morbidity rates of surgical repair of mycotic abdominal aortic aneurysms and aortic graft infections are high, and the appropriate treatment is debated. This retrospective study compared venous and antimicrobial prosthetic aortic graft reconstructions.

METHODS

All patients of the Northwest Clinics and St. Antonius Hospital who were treated for mycotic abdominal aortic aneurysms or aortic graft infections between January 1, 2008, and January 1, 2018, were analyzed. Exclusion criterion was treatment other than venous or antimicrobial reconstructions. Primary end points were 30-day complications and mortality rates and 3-year overall survival. Secondary end points were reintervention-free survival, persistent infection and reinfection rates, and hospital length of stay.

RESULTS

Fifty-one patients met the inclusion criteria, of whom 32 underwent venous reconstructions and 19 antimicrobial prosthetic aortic graft reconstructions. Baseline characteristics did not differ significantly between these groups, except for duration of surgical repair, which was longer in the venous group. The 30-day and 1-year mortality rates, reinfection rates, complication rates, and hospital length of stay did not significantly differ between the groups. The 3-year overall survival was 77% for venous reconstruction compared with 66% for antimicrobial reconstruction (P = 0.781). The 30-day reintervention rate was 19% for the venous group compared with 42% for the prosthetic group (P = 0.071). Reintervention-free survival at 3 years was 46% for the venous group compared with 52% for the prosthetic group (P = 0.615).

CONCLUSIONS

Venous reconstruction tends to have better 3-year overall survival and lower 30-day reintervention rates compared with antimicrobial prosthetic graft reconstruction in patients with mycotic abdominal aortic aneurysms or abdominal aortic graft infections. In the acute setting, antimicrobial prosthetic graft reconstruction is a valuable solution due to the shorter operation time and similar 30-day mortality and complication rates.

An iliac-appendiceal fistula causing gastrointestinal bleeding

Aortoenteric fistulas are an uncommon cause of gastrointestinal bleeding, and iliac-appendiceal fistulas are an even rarer cause. We describe a case of an iliac-appendiceal fistula in a patient who presented several months after aortic reconstruction with gastrointestinal bleeding. An extensive workup revealed that the source of bleeding was localized to the appendiceal orifice. The patient underwent an appendectomy with a two-stage procedure involving the iliac graft for definitive repair and ultimately recovered well. Despite the rarity of aortoenteric and iliac-appendiceal fistulas causing gastrointestinal bleeding, keeping a high index of suspicion in patients with a prior vascular repair can prevent death.

Histoplasmosis Infection of Aortobifemoral Graft Treated with a Neoaortoiliac System

Aortic graft infections are a feared complication of aortic bypass operations and impart significant morbidity and mortality when they occur. The most common etiology is bacterial, with a presentation ranging from subclinical to acutely symptomatic depending on the organism. Fungal infections of prosthetic grafts are rare, especially in immunocompetent patients. Graft infections remain a clinical diagnosis. We report a rare case of an aortobifemoral graft infection with Histoplasma capsulatum that was diagnosed on surgical pathology, as the preoperative infectious evaluation was negative. The neoaortoiliac system operation was successfully used to solve this patient's highly morbid condition.

In vitro Evidence of Improved Antimicrobial Efficacy of Silver and Triclosan Containing Vascular Grafts Compared with Rifampicin Soaked Grafts

OBJECTIVES

The aim was to compare the antimicrobial efficacy of four different grafts: a standard graft (Intergard, IG), an IG graft soaked in rifampicin (IGrif), a silver impregnated graft (Intergard Silver, IGS), and a silver + triclosan impregnated graft (Intergard Synergy, IGSy).

METHODS

This was a seven day in vitro study. The IG, IGrif, IGS, and IGSy grafts were each contaminated separately with the following microorganisms: Staphylococcus epidermidis, Methicillin resistant Staphylococcus aureus (MRSA), Escherichia coli, and Candida albicans from both clinical and American Type Culture Collection (ATCC) origins. The in vitro antimicrobial efficacy was evaluated by time to kill assays at T0, T24h, T48h, T72h, and T168h. Bactericidal activity was defined as >3 log₁₀ reduction factor (logRF). Additionally, Rifampicin, triclosan and silver resistance development were screened.

RESULTS

As anticipated for the non-antimicrobial IG, all microorganism strains proliferated. The IGSy and the IGS showed a seven day bactericidal efficacy (>3 logRF) for all tested microorganisms. This efficacy was confirmed at all time points for IGSy only, demonstrating faster bactericidal efficacy than IGS. The IGrif demonstrated a seven day bactericidal efficacy against the ATCC MRSA only, while showing no activity against C. albicans and ATCC E. coli. Regarding ATCC S. epidermidis, clinical MRSA and clinical E. coli, IGrif, although bactericidal at earlier time points, lost its antimicrobial efficacy at seven days leading to the emergence of rifampicin resistant mutants in four of six, two of six, and two of six assays, respectively. Mutant strains were also detected in ATCC MRSA in one of six assays. No triclosan or silver resistance has emerged at T7days.

CONCLUSION

For all microorganisms tested, the Synergy graft combining silver with triclosan demonstrated a more sustainable and efficient seven day antimicrobial activity than the rifampicin soaked graft. The emergence of rifampicin resistant mutants suggests preference for a Synergy graft over a graft soaked in rifampicin, to prevent or treat an infection when a biological solution is not feasible.

A rare case of Clostridium septicum aortitis with colon adenocarcinoma

Clostridium septicum aortitis is a rare, highly morbid condition typically accompanied by malignant disease, such as hematologic cancer or colon adenocarcinoma. Presenting symptoms commonly described include acute onset of abdominal pain, nausea, and fevers. Prompt diagnosis of infectious aortitis is critical to prevent deadly complications, such as sepsis and vascular catastrophe. The described management largely involves surgical resection of the infected aorta, débridement, and arterial revascularization through extra-anatomic bypass or aortic graft placement.

The Usefulness of Biosynthetic Vascular Graft Omniflow II and Autologous Veins for the Treatment of Massive Infection of Dacron Vascular Graft with Enterococcus faecalis HLAR

Infections of vascular grafts are the most severe complications in vascular surgery. We present the case of a 73-year-old male with infection of a dacron prosthesis with a strain of Enterococcus faecalis. The patient was treated with replacement of a full prosthesis with a combined graft constructed from Biosynthetic Vascular graft Omniflow and autologous veins. This graft is recommended for implantation in patients with a higher risk of infection. Our case is one of the first reported usage of this kind of graft in the aortic region and in a 2 years observation period no recurrence of infection was observed.

Cryopreserved Cadaveric Arterial Allograft for Arterial Reconstruction in Patients with Prosthetic Infection

OBJECTIVE

The aim of this study was to report outcomes of cryopreserved arterial allografts used as a vascular substitute in the setting of prosthetic material infection.

METHODS

A retrospective analysis of prospectively collected data was conducted including all consecutive interventions performed with cryopreserved arterial allografts used for vascular reconstruction in the setting of prosthetic material infection between January 2005 and December 2014. Five year outcomes included allograft related re-interventions, survival, primary patency, and limb salvage rates.

RESULTS

Fifty-three procedures were performed using cryopreserved allografts for vascular prosthetic infection: 25 procedures (47%) were performed at aorto-iliac level (Group 1) and 28 procedures (53%) at peripheral level (Group 2). The mean follow-up was 52 months. Five year allograft related re-intervention was 55% in Group 1 (6 allograft ruptures and 5 allograft aneurysm degenerations) and 33% in Group 2 (2 allograft ruptures and 7 allograft aneurysm degenerations). Five year survival was 40% and 68%, primary patency was 89% and 59% and limb salvage was 100% and 89% for Group 1 and 2 respectively.

CONCLUSION

Use of cryopreserved arterial allografts provides acceptable results but is tempered by suboptimal 5 year outcomes with high re-intervention rates.

Endograft Infection After Endovascular Abdominal Aortic Aneurysm Repair: A Systematic Review and Meta-analysis

Purpose: To report a meta-analysis of the published evidence on the outcomes of aortic endograft infection after endovascular aneurysm repair (EVAR). Methods: A search of electronic information sources (PubMed/MEDLINE, SCOPUS, CENTRAL) and bibliographic reference lists identified 12 studies reporting on 362 patients (mean age 72 years; 279 men). The methodological quality of the selected studies was assessed using the Newcastle-Ottawa scale. Endpoints were 30-day/in-hospital mortality and follow-up mortality. Pooled estimates are reported with the 95% confidence interval (CI). The review was registered at the International Prospective Register of Systematic Reviews in Health and Social Care (CRD42016034166). Results: The incidence of graft infection after EVAR was 0.6% (95% CI 0.4% to 0.8%). The time from implantation to diagnosis ranged from 1 to 128 months (mean 25). The majority of patients (293, 81%) underwent surgical treatment (95% CI 77% to 83%); 9 (2.5%) patients (95% CI 21% to 43%) received conservative treatment. Aortic replacement with a prosthetic graft was performed in 58% (95% CI 52% to 62%), whereas cryopreserved allografts and autologous grafts were used in 31% (95% CI 28% to 33%) and 11% (95% CI% 8 to 14%), respectively. Less than half of the patients (40%) had emergency surgery. The pooled estimate of 30-day/in-hospital mortality was 26.6% (95% CI 16.9% to 39.2%). The pooled 30-day/in-hospital mortality for 9 patients treated conservatively was 63.3% (95% CI 30.7% to 87.0%). The pooled overall follow-up mortality was 45.7% (95% CI 36.4% to 55.4%) vs 58.6% (95% CI 28.8% to 83.3%) for the 9 patients receiving conservative treatment. Conclusion: Aortic endograft infection is a rare complication after EVAR. Surgical treatment with complete explantation of the infected endograft seems to be the optimal management in selected patients. Supportive medical treatment without surgical intervention has a significant associated mortality.

Vascular Graft Impregnation with Antibiotics: The Influence of High Concentrations of Rifampin, Vancomycin, Daptomycin, and Bacteriophage Endolysin HY-133 on Viability of Vascular Cells

Background

Rifampin-soaked synthetic prosthetic grafts have been widely used for prevention or treatment of vascular graft infections (VGIs).

This in vitro study investigated the effect of the antibiotics daptomycin and vancomycin and the new recombinant bacteriophage endolysin HY-133 on vascular cells, as potential alternatives compared to rifampin.

Material/Methods

Primary human ECs, vascular smooth muscle cells (vSMC), and fibroblasts were cultivated in 96-well plates and incubated with rifampin, daptomycin, vancomycin, and endolysin HY-133 for 24 h. Subsequently, after washing, cell viability was determined by measuring mitochondrial ATP concentration. Antibiotics were used in their corresponding minimum and maximum serum concentrations, in decimal multiples and in maximum soaking concentration. The experiments were performed in triplicate.

Results

The 10-fold max serum concentrations of rifampin, daptomycin, and vancomycin did not influence viability of EC and vSMC (100 μg/ml, p>0.170). Higher concentrations of rifampin (>1 mg/ml) significantly (p<0.001) reduced cell viability of all cell types. For the other antibiotics, high concentrations (close to maximum soaking concentration) were most cytotoxic for EC and vSMC and fibroblasts (p<0.001). Endolysin did not display any cytotoxicity towards vascular cells.

Conclusions

Results of this in vitro study show the high cytotoxicity of rifampin against vascular cells, and may re-initiate the discussion about the benefit of prophylactic pre-soaking in high concentrations of rifampin. Further studies are necessary to determine the influence of rifampin on the restoration of vessel functionality versus its prophylactic effect against VGIs. Future use of recombinant phage endolysins for alternative prophylactic strategies needs further investigations.

Open Surgical Treatment of Secondary Aortoesophageal and Aortobronchial Fistula after Thoracic Endovascular Aortic Repair and Esophagocoloplasty in a Second Procedure

Aortoesophageal (AEF) and aortobronchial fistula (ABF) after thoracic endovascular aortic repair (TEVAR) are rare complications with catastrophic consequences without treatment. In this case report, we presented a patient with AEF and ABF after TEVAR successfully treated with endograft explantation and replaced by Dacron graft followed by esophagectomy and left principal bronchus repairing. We report a patient with AEF and ABF after TEVAR who was evaluated due to dysphagia and chest pain followed by hematemesis and hemoptysis. Endoscopic examination revealed lesion of the esophageal wall with chronic abscess formation and stent-graft protrusion into the cavity. Patient was operated on with extracorporeal circulation. AEF and ABF were confirmed intraoperatively. Endograft was explanted and in situ reconstruction of thoracic aorta was carried out with tubular Dacron 22-mm prosthesis wrapped with omental flap. After aortic reconstruction, esophageal mucosal stripping was performed with cervical esophagostomy, pyloromyotomy, and Stamm-Kader gastrostomy for nutrition. In addition, omentoplasty of the defect in the left principal bronchus was performed. To re-establish peroral food intake esophagocoloplasty was carried out 8 months after previous surgery utilizing transversosplenic segment of the colon and retrosternal route. In very selective cases, stent-graft explantation and in situ reconstruction with Dacron graft covered by omental flap followed by esophagectomy and bronchus repairing permit adequate debridement reducing the risk of mediastinitis and graft infection and allow a safe esophageal reconstruction in a second procedure.

Aortic Graft Infection: Graphene Shows the Way to an Infection-Resistant Vascular Graft

Aortic graft infection is a potentially lethal complication of open and endovascular repair of aortic aneurysms. Graphene is the only existing two-dimensional material, and its unique structure gives graphene and its derivatives a plethora of original characteristics. Among other characteristics, graphene demonstrates bacteriostatic and bactericidal effects that could potentially resolve the problem of graft infection in the future. Data already exist in literature supporting this antibacterial effect of graphene oxide and reduced graphene oxide. Combining these materials with other substances enhances the antibacterial effect. Additionally, it looks feasible to expect antibiotic-delivering graphene-based graft materials in the future. Based on already published data, we could conclude that regarding graphene and its derivatives, the blessing of bactericidal effect comes with the curse of human cells toxicity. Therefore, it is important to find a fine balance between the desired antibacterial and the adverse cytotoxic effect before graphene is used in graft materials for humans.

Late Fate of Cryopreserved Arterial Allografts

OBJECTIVE

Initial enthusiasm for use of cryopreserved arterial allografts was subsequently tempered by suboptimal long-term outcome. Thrombosis, anastomotic pseudo-aneurysm, allograft disruption, aneurysmal degeneration, recurrent intestinal fistulization, and persistent infection are commonly reported in series with long-term follow-up. The authors reviewed their experience over the past 15 years with the use of cryopreserved arterial allografts as a vascular substitute for vascular prosthetic infection or for primary arterial infection, to investigate allograft-related complications.

MATERIAL AND METHODS

A retrospective analysis of prospectively collected data was conducted for 103 cryopreserved arterial allografts inserted in 96 patients between July 2000 and July 2015. There were 78 patients with infected vascular prosthesis (IVP), nine patients with an aorto-enteric fistula (AEF), and nine patients with primary arterial infection (PAI).

RESULTS

The in-hospital mortality was eight out of 78 (9%) IVP patients, three out of nine AEF patients, and zero out of nine PAI patients. Median follow-up was 49 months. Allograft-related re-interventions were necessary in 29% of the patients with IVP and four of the patients with AEF, but none of the patients with PAI. Five-year survival for the IVP, AEF, and PAI patients was 53%, 44%, and 90%, respectively.

CONCLUSION

This series highlights some shortcomings of cryopreserved arterial allografts in the long term, including suboptimal outcome-results and shortage of material. The authors discuss the allograft-related complications and suggest some tricks to minimize their risk.

Treatment of aortic graft infection by in situ reconstruction with Omniflow II biosynthetic prosthesis

Currently available conduits for in situ reconstruction after excision of infected aortic grafts have significant limitations. The Omniflow II vascular prosthesis is a biosynthetic graft associated with a low incidence of infection that has succesfully been used in the treatment of infected infrainguinal bypass. We report on the first use of the Omniflow II prosthesis for in situ reconstruction after aortic graft infection.

A bifurcated biosynthetic bypass was created by spatulating and anastomosing two 8-mm tubular Omniflow II grafts. This bypass was used for in situ reconstruction after excision of infected aortic grafts in three cases. After a mean follow-up of 2.2 years, no occlusion, degeneration, or rupture of the Omniflow II grafts was observed. Although one patient suffered from graft reinfection, the bypass retained structural integrity and no anastomotic dehiscence was observed.

Treatment of aortic graft infection by in situ reconstruction with the Omniflow II vascular prosthesis is feasible. Its resistance to infection and off-the-shelf availability make this graft a promising conduit for aortoiliac reconstruction.

Explantation of infected aortic aneurysm and endograft with ascending aorta to mesenteric bypass for mesenteric ischemia

A 65-year-old man presented with an infected perivisceral aortic aneurysm after previous treatment of an abdominal aortic aneurysm with an endograft. On presentation, he was septic and had occlusion of the celiac, superior mesenteric, inferior mesenteric, and bilateral renal arteries. He underwent a three-stage procedure: first, axillobifemoral bypass; then resection of the thoracoabdominal aorta; and finally bypass from the ascending aorta to the celiac and superior mesenteric arteries with a rifampin-soaked Gelsoft graft (Vascutek, Renfrewshire, Scotland). The abdominal pain resolved, and the patient remains symptom free 10 months postoperatively. This rare surgical revascularization technique offered a nontraditional solution to a difficult surgical issue.

Surgical and Antimicrobial Management of a Thoracic Aortic Aneurysm Due to Q Fever: A Case Report and Brief Review

Coxiella burnetii, the etiologic agent of Q fever, has been associated with vascular infection and aneurysm formation. We report the case of a 36-year-old woman from Iraq who presented with long-standing malaise as well as vague chest and shoulder discomfort and was found to have a saccular aneurysm of the descending thoracic aorta. Serology assays were positive for chronic C burnetii infection. She was treated with successful aneurysm resection and aortic replacement with a rifampin-impregnated Maquet Hemashield (TM) Dacron interposition graft interposition graft in addition to 18 months of doxycycline and hydroxychloroquine. The patient is without evidence of recurrent infection on follow-up at 3 years. To our knowledge, this is the first case of aortic aneurysm secondary to Q fever reported in the United States. We review the diagnosis, surgical management, antibiotic therapy, and surveillance of a thoracic aortic aneurysm secondary to Q fever.

Acute acalculous cholecystitis as a rare manifestation of chronic mesenteric ischemia. A case report

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Acute acalculous cholecystitis can present de novo in an outpatient setting without any major illness or associated trauma and aortic occlusive disease may represent the most relevant etiological factor in these patients.

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In the settings of chronic mesenteric ischemia, acute acalculous cholecystitis may be interpreted as a herald sign of critical ischemia and mesenteric infarction as a consequence of an acute-on-chronic mesenteric ischemia.

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In our patient, the decision was taken to proceed with immediate mesenteric revascularization simultaneously with the cholecystectomy in order to minimize the risk and extension of a possible bowel infarct.

Introduction

Symptomatic chronic mesenteric ischemia (CMI) is an uncommon condition that usually presents with intestinal angina, sitophobia and unintentional weight loss. Acute acalculous cholecystitis (AAC) has very rarely been described in the settings of CMI.

Presentation of case

We describe a case of a 73 year old man that developed an AAC as a complication of CMI. The patient underwent a simultaneous cholecystectomy and open aortic revascularization which was successful. At 24 months of follow-up the patient is clinically well and regained weight.

Discussion

Ischemia has been considered an important etiology for the development of AAC. In the settings of CMI, an AAC might develop has a herald sign of progression to acute mesenteric ischemia and infarction, as the cystic artery is a terminal artery with no collateral network. Performing the aortic revascularization simultaneously with the cholecystectomy might prevent this possible fatal outcome.

Conclusion

This case reinforces aortic and visceral occlusive disease as a possible risk factor for the development of AAC, and discusses the treatment controversies when managing both conditions simultaneously.

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.

Use of Aortic Occluders and Endovascular Plugs in a 2-step Hybrid Treatment of Secondary Aortoenteric Fistulas

Aortoenteric fistula (AEF) is a dreadful complication of abdominal aortic surgery. Surgical treatment is associated to high mortality and requires urgent graft removal with extra-anatomic or in situ reconstruction. Other authors suggest the use of stent grafts, both as a stand-alone procedure or as a bridge solution before open repair. We reviewed the results of a cohort of patients that presented at our institution with an AEF and were treated with a novel 2-step endovascular-open surgical procedure. The first step consisted in immediate endovascular occlusion of the infrarenal graft with deployment, below the renal arteries, of an aortic occluder and/or endovascular plugs. After occlusion of the infrarenal graft, extra-anatomic reconstruction (axillofemoral bypass) was performed. The second step consisted in the removal of the infrarenal graft with aortic stump ligation and took place after a few days recovery to allow improvement of patients' condition. A total of 5 selected patients were treated. Endovascular aortic occlusion was achieved in all cases with the deployment of 1 (3 patients) or 2 (2 patients) devices. The mean interval between the first and the second step was 7 days (min 4-max 13). Complete removal of the aortic graft was possible in all patients. One patient died on the first postoperative day due to multiorgan failure (1 of 5, 20%). Mean survival after discharge was 24 months (min 6-max 36). One patient died at 6 months because of aortic stump blowout. In our initial experience, endovascular aortic occlusion seems an effective option to prevent fatal enteric bleeding and a valuable first-step treatment for selected cases of AEF.

Mechanical and biocompatibility performance of bicomponent polyester/silk fibroin small-diameter arterial prostheses

BACKGROUND

In this study, we fabricated prototype bicomponent polyester/silk fibroin small-diameter arterial prostheses using a specially designed narrow ribbon shuttle loom.

METHODS

The 2-layered flat fabrics were then heatset on a mandrel to form tubes with a round cross section.

RESULTS

The woven samples had a wall thickness between 0.23 mm and 0.29 mm and an inner diameter between 3.53 mm and 3.95 mm, depending on the yarn type and the weave structure.

CONCLUSIONS

The bicomponent polyester/silk fibroin samples had superior bursting strength, circumferential strength and suture retention strength compared with a commercial small-diameter arterial prosthesis made from ePTFE. In addition, these prototype samples had greater suture retention strengths than a dog femoral artery, which indicates that they have adequate biostability for clinical use. While their amount of radial compliance was superior to that of the ePTFE commercial graft control, it did not match that of a natural artery. So there is still a need for future improvement in compliance. All of the woven prototypes had water permeability values between 26 and 180 ml/(cm(2)*min), which confirms that none of these arterial prostheses needs to be preclotted at the time of implantation. The biocompatibility of the woven prototypes was evaluated using porcine endothelial cells and an MTT assay. Their cytocompatibility was found to be superior to the ePTFE commercial control, and the level of cell attachment was observed to increase on these prototypes woven with a higher silk fibroin content.

Mycotic Aneurysm of the Common Carotid Artery as a Presenting Symptom for Early Colorectal Malignancy

Mycotic carotid aneurysms are rare vascular conditions that are associated with high mortality if left untreated. We present a gentleman who had a progressively enlarging tender pulsatile swelling on the right side of neck. Emergency computed tomography scan showed a large mycotic aneurysm arising from the right common carotid artery, and he underwent emergency open exploration with interposition bypass graft. Bacteroides fragilis species, which signified gastrointestinal-related sepsis, was isolated from the thrombus culture. Subsequently search of systemic septic source showed an early rectal adenocarcinoma. This is the first case in the world's literature of a patient who had B. fragilis mycotic carotid aneurysm as a presenting complaint of his occult rectal malignancy.

Biofilm-related infections: bridging the gap between clinical management and fundamental aspects of recalcitrance toward antibiotics

Surface-associated microbial communities, called biofilms, are present in all environments. Although biofilms play an important positive role in a variety of ecosystems, they also have many negative effects, including biofilm-related infections in medical settings. The ability of pathogenic biofilms to survive in the presence of high concentrations of antibiotics is called "recalcitrance" and is a characteristic property of the biofilm lifestyle, leading to treatment failure and infection recurrence. This review presents our current understanding of the molecular mechanisms of biofilm recalcitrance toward antibiotics and describes how recent progress has improved our capacity to design original and efficient strategies to prevent or eradicate biofilm-related infections.

Inadvertent vascular injury of the aorta or vena cava caused by acupuncture

Major visceral vascular injury after acupuncture is a rare but serious complication. We recently treated two patients with an inferior vena cava or an abdominal aorta injury caused by acupuncture. Although both patients underwent successful surgical repair, the highly invasive nature of the operations led to complications, including infection and chyle leakage. Vascular surgeons should be aware that acupuncture can cause serious damage to the vena cava or aorta due to direct injury or subsequent infection.

Infective Etiology Affects Outcomes of Late Open Conversion After Failed Endovascular Aneurysm Repair

Purpose: To retrospectively review all patients undergoing late open conversion (LOC) after endovascular aneurysm repair (EVAR) in order to identify any clinical or technical predictors of poor outcome. Methods: Twenty-six consecutive patients (24 men; mean age 74.7±8.3 years) underwent LOC between June 2006 and April 2013 at our institution. The mean interval from index EVAR to LOC was 40.4±29.2 months (range 5–93 months). The indication for LOC was endoleak in 14 (54%) patients and infection in 12 (46%): 2 (8%) patients with endoleak had a ruptured aneurysm and 6 (23%) patients with infection had a recurrent secondary aortoesophageal fistula (sAEF). Results: In all 12 cases of infection and in 12 of 14 endoleaks, the entire endograft was explanted. A rifampin-soaked Dacron silver graft was implanted in all patients with infection. Patients with any infection and with recurrent AEF required more blood units than patients with endoleak (6.40 vs. 1.86, p=0.045; 6.76 vs. 1.86, p=0.0036, respectively). Compared with endoleak, the duration of conversions in the setting of infection (274 vs. 316 minutes, p=0.42) and recurrent sAEF (274 vs. 396 minutes, p=0.021) was longer. All patients with recurrent sAEF died at a mean 3.0±2.5 days after LOC from proximal anastomosis disruption and hemorrhagic shock (n=2), myocardial infarction (n=2), acute stroke (n=1), or persistent sepsis (n=1). Perioperative mortality was significantly higher in patients with endograft infection (6/12, p=0.002) and in cases of supraceliac cross-clamping (4/6, p=0.003). The association of infection with supraceliac cross-clamping was a strong predictor for perioperative mortality (p<0.001). Conclusion: In our experience, endograft infection led to greater perioperative mortality after LOC. Recurrent aortoenteric fistula in association with supraceliac cross-clamping is a strong predictor of poor outcome. Patients surviving the perioperative period may have good chances of long-term survival.

How To Diagnose and Manage Infected Endografts after Endovascular Aneurysm Repair

The prevalence of endograft infections (EI) after endovascular abdominal aortic aneurysm repair is below 1%. With the growing number of patients with aortic endografts and the aging population, the number of patients with EI might also increase. The diagnosis is based on an association of clinical symptoms, imaging, and microbial cultures. Angio-computed tomography is currently the gold-standard technique for diagnosis. Low-grade infection sometimes requires nuclear medicine imaging to make a correct diagnosis. There is no good evidence to guide management so far. In the case of active gastrointestinal bleeding, pseudoaneurysm, or extensive perigraft purulence involving adjacent organs, an invasive treatment should always be attempted. In the other cases (the majority), when there is not an immediate danger to the patient's life, a conservative management is started with a proper antimicrobial therapy. Any infectious cavity can be percutaneously drained. Management depends on the patient's condition and a tailored approach should always be offered. In the case of a patient who is young, has a good life expectancy, or in whom there is absence of significant comorbidities, a surgical attempt can be proposed. Surgical techniques favor, in terms of mortality, patency, and reinfection rate, the in situ reconstruction. Choice of technique relies on the center and the operator's experience. Long-term antibiotic therapy is always required in all cases, with close monitoring of the C-reactive protein.

Complexes of silver(I) ions and silver phosphate nanoparticles with hyaluronic acid and/or chitosan as promising antimicrobial agents for vascular grafts

Polymers are currently widely used to replace a variety of natural materials with respect to their favourable physical and chemical properties, and due to their economic advantage. One of the most important branches of application of polymers is the production of different products for medical use. In this case, it is necessary to face a significant disadvantage of polymer products due to possible and very common colonization of the surface by various microorganisms that can pose a potential danger to the patient. One of the possible solutions is to prepare polymer with antibacterial/antimicrobial properties that is resistant to bacterial colonization. The aim of this study was to contribute to the development of antimicrobial polymeric material ideal for covering vascular implants with subsequent use in transplant surgery. Therefore, the complexes of polymeric substances (hyaluronic acid and chitosan) with silver nitrate or silver phosphate nanoparticles were created, and their effects on gram-positive bacterial culture of Staphylococcus aureus were monitored. Stages of formation of complexes of silver nitrate and silver phosphate nanoparticles with polymeric compounds were characterized using electrochemical and spectrophotometric methods. Furthermore, the antimicrobial activity of complexes was determined using the methods of determination of growth curves and zones of inhibition. The results of this study revealed that the complex of chitosan, with silver phosphate nanoparticles, was the most suitable in order to have an antibacterial effect on bacterial culture of Staphylococcus aureus. Formation of this complex was under way at low concentrations of chitosan. The results of electrochemical determination corresponded with the results of spectrophotometric methods and verified good interaction and formation of the complex. The complex has an outstanding antibacterial effect and this effect was of several orders higher compared to other investigated complexes.