Electrospun Chitosan-Based Nanofibrous Coating for the Local and Sustained Release of Vancomycin

As the population ages, the number of vascular surgery procedures performed increases. Older adults often have multiple comorbidities, such as diabetes and hypertension, that increase the risk of complications from vascular surgery including vascular graft infection (VGI). VGI is a serious complication with significant morbidity, mortality, and healthcare costs. Here, we aimed to develop a nanofibrous chitosan-based coating for vascular grafts loaded with different concentrations of the vancomycin antibiotic vancomycin (VAN). Blending chitosan with poly(vinyl alcohol) or poly(ethylene oxide) copolymers improved solubility and ease of spinning. Thermal gravimetric analysis and Fourier transform infrared spectroscopy confirmed the presence of VAN in the nanofibrous membranes. Kinetics of VAN release from the nanofibrous mats were evaluated using high-performance liquid chromatography, showing a burst followed by sustained release over 24 h. To achieve longer sustained release, a poly(lactic-co-glycolic acid) coating was applied, resulting in extended release of up to 7 days. Biocompatibility assessment using human umbilical vein endothelial cells demonstrated successful attachment and viability of the nanofiber patches. Our study provides insights into the development of a drug delivery system for vascular grafts aimed at preventing infection during implantation, highlighting the potential of electrospinning as a promising technique in the field of vascular surgery.

Referral Centre Experience with Infected Abdominal Aortic Endograft Explantation

OBJECTIVE

The increasing use of endovascular aneurysm repair (EVAR) appears to be associated with the burden of vascular endograft infections. Complete stent graft explantation is recommended but leads to significant mortality. This study aimed to assess the technical challenges, complications, and mortality rate following infected endograft explantation.

METHODS

Patients who underwent abdominal aortic endograft explantation for infection at the Bordeaux University Hospital from July 2008 to December 2020 were included retrospectively in this single centre observational study. The diagnosis was established based on the MAGIC criteria. The primary endpoint was 30 day mortality. Secondary endpoints were 90 day and in hospital mortality, survival, and re-infection.

RESULTS

Thirty-four patients were included, median age 69 years (interquartile range [IQR] 65, 76), with four (12%) treated as an emergency. The median time from EVAR to explantation was 17.5 months (4.5 - 36.3). In situ reconstruction was carried out with prosthetic grafts in 24 patients (71%, including 23 antimicrobial grafts combining silver and triclosan), and biological grafts in 10 (five femoral veins, four arterial allografts, three bovine patches, one biosynthetic graft). Seventeen aorto-enteric fistulae (AEnF) were addressed with direct repair of the intestinal tract (n = 10/17; 59%) or resection and anastomosis (n = 7/17; 41%). The culture was polymicrobial in 12 patients (35%) and remained sterile in four (12%). The 30 day and in hospital mortality rates were 21% (n = 7) and 27% (n = 9). Twenty-five patients (73%) presented with early post-operative complications, requiring 16 revision procedures (47%). Over a median follow up of 16.2 months (IQR 8.3, 33.6), the mortality rate was 35% (n = 12; 11 aortic related; 32%), with two re-infections (6%), both after biological reconstruction (one for an AEnF).

CONCLUSION

Early morbidity and mortality remain high after complete infected endograft explantation, even in a high volume centre. Comparison with other treatment modalities in large multicentre cohorts might be of interest.

Collagen-Sealed Polyester Vascular Prostheses Functionalized by Polycatecholamine Coatings

Collagen-sealed polyester (PET) prostheses are commonly used in reconstructive vascular surgery due to their self-sealing properties. To prevent post-surgical infection, different modification methods have been tested but so far none have showed long-term satisfactory efficiency. For this reason, in the present study, a commercial collagen-sealed PET prosthesis was coated by a highly adhesive poly (L-DOPA) layer maintaining the sealing protein without losing the original properties and functionality. This modified (as proven by SEM, FTIR, XPS and contact angle) graft exhibited comparable wettability and elasticity as pristine commercial graft, as well as reduced hemolysis-inducing effect, lowered toxicity against human endothelial cells and reduced toxicity in Danio rerio model. Poly (L-DOPA)-coated grafts were shown to bind six times more aminoglycoside antibiotic (gentamicin) than pristine graft. Poly (L-DOPA)-coated antibiotic-bound prostheses exhibited an improved antibacterial activity (bacterial growth inhibition and anti-adhesive capacity) in comparison with pristine antibiotic-bound graft. Overall, poly (L-DOPA)-coatings deposited on PET vascular grafts can effectively functionalize collagen-sealed prostheses without the loss of protein sealing layer and allow for antibiotics incorporation to provide higher safety in biomedical applications.

Contemporary results with the biosynthetic glutaraldehyde denatured ovine collagen graft (Omniflow II) in lower extremity arterial revascularization in a septic context

OBJECTIVE

Prosthetic peripheral vascular graft infections are poorly evaluated, despite a grim prognosis with high mortality and major amputation rates. The vascular substitute of choice remains controversial when autologous veins are unavailable. The main objective of this study was to evaluate the mid-term results of a new alternative biosynthetic collagen graft (Omniflow II®) in an infected field in patients with unavailable or unsuitable autologous saphenous vein.

METHODS

This retrospective, observational, multicentric study included all consecutive patients in whom an Omniflow II® graft was used for infra-inguinal revascularization in the context of sepsis from January 2015 to January 2020. The primary endpoint was freedom from major amputation; secondary endpoints were 30-day mortality, perioperative morbidity, and estimated survival, patency, and freedom from reinfection estimated using the Kaplan-Meier method.

RESULTS

Twenty-nine patients (27 men, median age 69 years (IQR:60;76) were included. Fever was present in 58.6% of cases, a septic rupture in 17.9%, and a pseudo-aneurysm in 25.0%. The 30-day mortality rate was 3.4% (septic shock). The median follow-up reached 49 months. At 1 and 3 years, the estimated freedom from major amputation was 88.4% and 83.9%, survival was 96%, primary patency was 74.6% and 65.8%, secondary patency was 82.1% and 77.7% and reinfection free-survival was 85.6%. There were 7 occlusions (1 iliofemoral, 1 below-knee, and 5 above-knee bypasses), 3 explantations for persistent sepsis, 4 reinfections (all within the first 6 months which led to 1 death and 3 major amputations), and a total of 4 major amputations. The risk of major amputation increased with bypass reinfection (p=.004), occlusion (p=.005), and polymicrobial infection (p=.05).

CONCLUSION

In a septic context, the Omniflow II® bioprosthetic graft represents an acceptable vascular substitute in the absence of an autologous vein. It provides acceptable freedom from major amputation and reinfection considering the seriousness of this pathology. This usage remains outside the instructions for use, it is, therefore, essential to pursue longer-term studies in larger cohorts.

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.

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.

Surgical treatment of carotid artery stent infection: a case report

The most effective treatment for graft infection is still debated, and the success rate of current treatments is low. We herein report the results of surgical treatment and follow-up of a case of infection acquired during carotid stenting with the aim of exploring the most effective treatments for graft infection. We retrospectively analyzed a patient who was admitted in September 2019. This patient underwent debridement, autologous saphenous vein replacement of the common carotid to internal carotid artery, external carotid artery suturing, and continuous negative-pressure wound therapy for carotid stent infection. Ten days after carotid artery revascularization, the growth of granulation tissue in the incision was good, and we decided to suture the neck incision. Five days after removing the stitches, grade A healing was noted. Furthermore, the carotid artery and autologous vein grafts were unobstructed as shown by carotid artery computed tomography angiography reexamination. The patient was monitored for 8 months with no new neurological symptoms and good healing of the incision. Effective treatment of vascular graft infection includes debridement and removal of the infected graft, autologous vein graft revascularization, and negative-pressure wound therapy combined with antibiotic therapy.

Results of the Proliferative Activity’s Analysis of Bifidobacterium Exometabolites in Regard to Hospital Isolates from Patients after Vascular Synthetic Prosthetics Implantation

Problems ofdevelopment of purulent septic complications in vascular surgery during the usage of synthetic prosthetics for shunting and arterial prosthetics are described in this work.Leading factors of development of prosthetic infection are described. Specialties of diagnostics and bacteriological researches wound discharge of wound’s discharge are shown. Tactics of complex treatment of patients with prosthetic infection are presented. This work is dedicated to the experimental researchof proliferative activityof the most encountered opportunistic microorganisms found from the patients of vascular surgery profile with purulent septical complications under the influence of bifidobacteriumbifidium’sexometabolites. Presented results proof the submission of proliferative activity of the most widespread antibiotic-resistant hospital’s isolates under the influence of bifidobacteriumbifidium’sexometabolites.Evaluation during the experiment in vitro of the influence of bifidobacteriumbifidium’sexometabolites on proliferative activityof opportunistic microorganisms.

Medical treatment of prosthetic vascular graft infections: Review of the literature and proposals of a Working Group

More than 400000 vascular grafts are inserted annually in the USA. Graft insertion is complicated by infection in 0.5-4% of cases. Vascular graft infections (VGIs) are becoming one of the most frequent prosthesis-related infections and are associated with considerable mortality, ranging from 10 to 25% within 30 days following the diagnosis. Treatment of VGI is based on urgent surgical removal of the infected graft followed by prolonged antibiotherapy. Data regarding the best antibiotherapy to use are lacking since no well designed trial to study antimicrobial treatment of VGI exists. Moreover, since VGIs demonstrate very specific pathophysiology, guidelines on other material-related infections or infective endocarditis treatment cannot be entirely applied to VGI. A French multidisciplinary group gathering infectious diseases specialists, anaesthesiologists, intensivists, microbiologists, radiologists and vascular surgeons was created to review the literature dealing with VGI and to make some proposals regarding empirical and documented antibiotic therapy for these infections. This article reveals these proposals.

Extra-anatomic autologous reconstruction with hepatic-iliac artery bypass graft for aortic endograft infection

We present a new intra-abdominal extra-anatomic bypass graft for a 64-year-old man treated with an abdominal aortic endograft and with signs of endograft infection. We performed surgical removal of the endograft and intra-abdominal extra-anatomic reconstruction of a hepatic-to-right external iliac artery bypass with autologous superficial femoral vein and a crossover graft between the right and left external iliac artery with the great saphenous vein. The later occlusion of the saphenous vein graft led us to perform a femoral-femoral prosthetic crossover. At 42 months from the intervention, the patient was in good health, and duplex scanning confirmed the patency of all grafts.

A silver nanocomposite biomaterial for blood-contacting implants

Cardiovascular implants must resist infection and thrombosis. A nanocomposite polymeric material [polyhedral-oligomeric-silsesquioxane-poly(carbonate-urea)urethane; POSS-PCU] demonstrates ideal properties for cardiovascular applications. Silver nanoparticles or nanosilver (NS) are recognized for efficient antibacterial properties. This study aims to determine the influence of NS integrated POSS-PCU on thrombogenicity. Silver nitrate was reduced with dimethylformamide and stabilized by the inclusion of fumed silica nanoparticles to prevent aggregation of NS and were incorporated into POSS-PCU to form a range of POSS-PCU-NS concentrations (by weight); 0.20% (NS16), 0.40% (NS32), 0.75% (NS64), and 1.50% (NS128). Surface wettability was determined with sessile-drop water contact angles. Platelets were introduced onto test samples and Alamar Blue (AB), mitochondrial-activity assay, quantified the degree of platelet adhesion whilst platelet-factor-4 (PF4) ELISA quantified the degree of platelet activation. Thromboelastography (TEG) determined the profiles of whole blood kinetics while hemolysis assay demonstrated the degree of blood compatibility. Increasing levels of NS induced greater hydrophilicity. A concentration dependant decrease in platelet adhesion and activation was observed with AB and PF4 readings, respectively. TEG demonstrated that the antithrombogenic properties of POSS-PCU were retained with POSS-PCU-NS16, and enhanced with POSS-PCU-NS32, but was reduced with POSS-PCU-NS64 and POSS-PCU-NS128. POSS-PCU-NS64 and POSS-PCU-NS128 demonstrated a hemolytic tendency, but no hemolysis was observed with POSS-PCU-NS16 and POSS-PCU-NS32. Overall, POSS-PCU-NS32 rendered potent antithrombogenic properties.