Fabrice Schneider

Efficacy of Collagen Silver-Coated Polyester and Rifampin-Soaked Vascular Grafts to Resist Infection from MRSA and Escherichia coli in a Dog Model

The primary objective of this study was to compare the efficacy of a collagen silver-coated polyester graft, InterGard, with a gelatin-sealed graft, Gelsoft, both soaked in rifampin, for resistance to direct bacterial contamination in an animal model. The second objective was to confirm the lack of inflammation from silver acetate. Vascular grafts, 6 mm in diameter, were implanted in the infrarenal aorta of 28 dogs. Intravenous cefamandole (20 mg/kg) was injected intraoperatively in all dogs. The dogs were divided into three groups. Group I included 12 dogs. Six dogs received silver grafts and six dogs received gelatin-sealed grafts, all soaked with rifampin. Grafts implanted in group I were directly infected with methicillin-resistant Staphylococcus aureus (MRSA). Group II included also six silver grafts and six gelatin-sealed grafts, all soaked with rifampin. Dogs of group II were directly infected with Escherichia coli. Group III comprised four dogs, which received gelatin unsealed grafts, directly infected with MRSA, the control group. All dogs were followed by regular clinical examination, including blood cultures. Grafts in groups I and III and in group II were harvested at 30 days and 10 days, respectively. Bacterial analyses were performed on the explanted grafts. Histology was performed on both the tissue samples and the anastomotic sites of the harvested grafts. In group I, no grafts were infected with MRSA, irrespective of graft type. In group II, no silver grafts were infected with E. coli, whereas one (16.6%) of six gelatin-sealed grafts was infected (p = 0.317). In group III, three (75%) of the four grafts were infected with MRSA. The infection rate in the silver grafts and the gelatin-sealed grafts soaked in rifampin in group I compared with the unsealed gelatin grafts in group III was statistically significantly different (p < 0.05). There was no statistically significant difference in the inflammation score, obtained by histological analysis, between rifampin-soaked silver and Gelsoft grafts in either group I or group II. There were signs of necrosis at the anastomoses in three (25%) gelsoft grafts of 12 in groups I and II. There were no clinical or biological signs of inflammation from use of silver-coated grafts. These results indicate that collagen silver-coated grafts and gelatin-sealed grafts, both soaked in rifampin, provide resistance against MRSA and E. coli. There was a trend toward better resistance but without statistical significance against E. coli from the rifampin silver graft compared with the rifampin-soaked Gelsoft graft, without signs of inflammation from InterGard silver grafts.

In vitro evaluation of the antimicrobial efficacy of a new silver-triclosan vs a silver collagen-coated polyester vascular graft against methicillin-resistant Staphylococcus aureus

OBJECTIVES Vascular graft infection is a rare but serious complication of vascular reconstructive surgery. This in vitro study investigated the antimicrobial efficacy of a new, silver-triclosan collagen-coated polyester vascular graft compared with a silver collagen-coated polyester vascular graft alone during the first 24 hours. METHODS The antimicrobial efficacy of the investigated vascular grafts was assessed by performing a time-kill kinetic assay following Clinical and Laboratory Institute Standards-approved guidelines M26-A. For the purpose of the experimental study, the ATCC 33591 strain of methicillin-resistant Staphylococcus aureus (American Type Culture Collection, Manassas, Va) was used. All assays were repeated sixfold. Bacterial survival numbers were obtained at 1, 4, 8, 12, and 24 hours using a standard plate count procedure. Bactericidal activity was defined as a 3 log(10) reduction factor (logRF), according to the approved guideline M26-A. RESULTS Both antimicrobial vascular grafts achieved >3 logRF and fulfilled the efficacy criterion for bactericidal activity but performed differently in their speed of antimicrobial action. The silver-triclosan vascular graft achieved 3.37 logRF after 8 hours, and the silver vascular graft showed a 4.19 logRF after 24 hours. The silver-triclosan graft yielded significantly lower colony-forming units/mL counts after 4 hours compared with the silver graft (4.29 × 10(4) vs 1.03 × 10(6); P = .031). CONCLUSIONS Both antimicrobial collagen-coated polymer vascular grafts showed bactericidal activity against methicillin-resistant Staphylococcus aureus in vitro. Although the silver-triclosan vascular graft showed a faster antimicrobial efficacy, the silver graft exhibited its antimicrobial properties after 24 hours. Which concept will protect an implanted vascular prosthetic graft better from bacterial contamination and subsequent infection needs to be investigated further in in vivo animal and clinical studies.

Prosthetic bypass for restenosis after endarterectomy or stenting of the carotid artery

Objective: The objective of this study was to evaluate the results of prosthetic carotid bypass (PCB) with polytetrafluoroethylene (PTFE) grafts as an alternative to carotid endarterectomy (CEA) in treatment of restenosis after CEA or carotid artery stenting (CAS). Methods: From January 2000 to December 2014, 66 patients (57 men and 9 women; mean age, 71 years) presenting with recurrent carotid artery stenosis ≥70% (North American Symptomatic Carotid Endarterectomy Trial [NASCET] criteria) were enrolled in a prospective study in three centers. The study was approved by an Institutional Review Board. Informed consent was obtained from all patients. During the same period, a total of 4321 CEAs were completed in the three centers. In these 66 patients, the primary treatment of the initial carotid artery stenosis was CEA in 57 patients (86%) and CAS in nine patients (14%). The median delay between primary and redo revascularization was 32 months. Carotid restenosis was symptomatic in 38 patients (58%) with transient ischemic attack (n = 20) or stroke (n = 18). In this series, all patients received statins; 28 patients (42%) received dual antiplatelet therapy, and 38 patients (58%) received single antiplatelet therapy. All PCBs were performed under general anesthesia. No shunt was used in this series. Nasal intubation to improve distal control of the internal carotid artery was performed in 33 patients (50%), including those with intrastent restenosis. A PTFE graft of 6 or 7 mm in diameter was used in 6 and 60 patients, respectively. Distal anastomosis was end to end in 22 patients and end to side with a clip distal to the atherosclerotic lesions in 44 patients. Completion angiography was performed in all cases. The patients were discharged under statin and antiplatelet treatment. After discharge, all of the patients underwent clinical and Doppler ultrasound follow‐up every 6 months. Median length of follow‐up was 5 years. Results: No patient died, sustained a stroke, or presented with a cervical hematoma during the postoperative period. One transient facial nerve palsy and two transient recurrent nerve palsies occurred. Two late strokes in relation to two PCB occlusions occurred at 2 years and 4 years; no other graft stenosis or infection was observed. At 5 years, overall actuarial survival was 81% ± 7%, and the actuarial stroke‐free rate was 93% ± 2%. There were no fatal strokes. Conclusions: PCB with PTFE grafts is a safe and durable alternative to CEA in patients with carotid restenosis after CEA or CAS in situations in which CEA is deemed either hazardous or inadvisable.

Impact of angiosome- and nonangiosome-targeted peroneal bypass on limb salvage and healing in patients with chronic limb-threatening ischemia

Background Direct (DIR) or indirect (IND) revascularization of pedal angiosomes in patients with chronic limb‐threatening ischemia (CLTI) has an unclear impact on limb salvage and healing. The aim of this study was to evaluate the outcomes of DIR and IND revascularization in patients with a peroneal bypass and tissue loss. Methods We conducted a retrospective study of a prospectively maintained database in two European university centers from 2004 to 2015. We extracted from this database all patients with CLTI and tissue loss who had received a bypass to the peroneal artery. All patients underwent angiography before bypass. Revascularization was considered DIR if the wound was in a peroneal angiosome. Wounds, ischemia, and infection were categorized according to the Wound, Ischemia, and foot Infection (WIfI) classification. Limb salvage and amputation‐free survival were calculated using the Kaplan‐Meier method. Cox regression was used to compare the role of patient characteristics, including diabetes, peroneal runoff, pedal arch angiosome, WIfI grade, chronic kidney disease, and diabetes, in amputation‐free‐survival. Results From January 2004 through October 2015, there were 120 peroneal bypasses performed in 120 patients with CLTI and foot tissue loss. Only 55 wounds (46%) could be ascribed to a peroneal angiosome. At 3 years, amputation‐free survival in patients with DIR revascularization was 54.9% ± 7.3% compared with 56.5% ± 6.3% in patients with IND revascularization (P = .44), with no significant difference in wound healing. Amputation‐free survival at 3 years in patients with two patent peroneal branches was 74.8% ± 6.9% compared with 45.0% ± 6.0% in patients with one patent peroneal branch (P = .003). Amputation‐free survival at 3 years in patients with a patent pedal arch (Rutherford 0‐1) was 73.0% ± 7.0% vs 45.7% ± 6.0% in patients with incomplete pedal arch (Rutherford 2‐3; P = .0002). Amputation‐free survival at 3 years in patients with grade 1 or grade 2 WIfI was 87.4% ± 8.3% compared with 48.4% ± 5.3% in patients with grade 3 or grade 4 WIfI (P = .001). Amputation‐free survival at 3 years in patients with diabetes was 43.7% ± 6.2% compared with 73.1% ± 6.7% in patients without diabetes (P = .002). Wound healing at 6 months was not significantly improved by its location within or outside a peroneal angiosome. Cox regression analysis demonstrated that diabetes, patency of both peroneal branches, patency of pedal arch, and WIfI stage but not DIR angiosome revascularization were significant predictors of amputation‐free survival. Conclusions Our results suggest that in patients with CLTI and tissue loss receiving a peroneal bypass, patency of both peroneal branches and pedal arch was associated with a better healing rate and a better amputation‐free survival rate irrespective of wound angiosome location.

The role of completion imaging following carotid artery endarterectomy.

A variety of completion imaging methods can be used during carotid endarterectomy to recognize technical errors or intrinsic abnormalities such as mural thrombus or platelet aggregation, but none of these methods has achieved wide acceptance, and their ability to improve the outcome of the operation remains a matter of controversy. It is unclear if completion imaging is routinely necessary and which abnormalities require re-exploration. Proponents of routine completion imaging argue that identification of these abnormalities will allow their immediate correction and avoid a perioperative stroke. However, much of the evidence in favor of this argument is incidental, and many experienced vascular surgeons who perform carotid endarterectomy do not use any completion imaging technique and report equally good outcomes using a careful surgical protocol. Furthermore, certain postoperative strokes, including intracerebral hemorrhage and hyperperfusion syndrome, are unrelated to the surgical technique and cannot be prevented by completion imaging. This controversial subject is now open to discussion, and our debaters have been given the task to clarify the evidence to justify their preferred option for completion imaging during carotid endarterectomy.

Part Two: Against the Motion. Young Patients with Good Risk Factors Should not be Treated with EVAR

Surgical repair is indicated for large asymptomatic abdominal aortic aneurysms (AAA) in patients with an acceptable operative risk. Following Parodi’s landmark paper, early results of randomized controlled trials (RCTs) have demonstrated lower peri-operative mortality after endovascular aortic aneurysm repair (EVAR) compared with open surgical repair (OSR). Next to these results, the number of patients receiving EVAR exceeded those treated by OR. However, some years later, the mid-term results of these RCTs have shown equivalent mortality after either EVAR or OSR, with a significantly higher re-intervention rate after EVAR, failing to support evidence favoring its use as firstline therapy, especially in young and/or fit patients. The goal of this debate is to compare early and late outcomes in patients younger than 65 years receiving OSR or EVAR.

Role of interventions for atherosclerotic renal artery stenoses

The role of and indications for interventions for renal artery stenosis have long been a hot topic of debate. Despite numerous reports and studies over the years, there remain many unanswered questions. Among them are: Who should be intervened upon? What should be the objectives of intervention? What is the optimal mode of intervention? More recently, several randomized studies have attempted to answer some of these basic questions, but unfortunately have left many unanswered questions. In the following debate, the authors consider the existing literature and attempt to convince us that the majority, or the minority, of patients with renal artery stenoses should be intervened upon.

Prognostic Values of Inflammatory and Redox Status Biomarkers on the Risk of Major Lower-Extremity Artery Disease in Individuals With Type 2 Diabetes

OBJECTIVE Inflammation and oxidative stress play an important role in the pathogenesis of lower-extremity artery disease (LEAD). We assessed the prognostic values of inflammatory and redox status biomarkers on the risk of LEAD in individuals with type 2 diabetes. RESEARCH DESIGN AND METHODS Plasma concentrations of tumor necrosis factor-α receptor 1 (TNFR1), angiopoietin-like 2, ischemia-modified albumin (IMA), fluorescent advanced glycation end products, protein carbonyls, and total reductive capacity of plasma were measured at baseline in the SURDIAGENE (Survie, Diabete de type 2 et Genetique) cohort. Major LEAD was defined as the occurrence during follow-up of peripheral revascularization or lower-limb amputation. RESULTS Among 1,412 participants at baseline (men 58.2%, mean [SD] age 64.7 [10.6] years), 112 (7.9%) developed major LEAD during 5.6 years of follow-up. High plasma concentrations of TNFR1 (hazard ratio [95% CI] for second vs. first tertile 1.12 [0.62–2.03; P = 0.71] and third vs. first tertile 2.16 [1.19–3.92; P = 0.01]) and of IMA (2.42 [1.38–4.23; P = 0.002] and 2.04 [1.17–3.57; P = 0.01], respectively) were independently associated with an increased risk of major LEAD. Plasma concentrations of TNFR1 but not IMA yielded incremental information, over traditional risk factors, for the risk of major LEAD as follows: C-statistic change (0.036 [95% CI 0.013–0.059]; P = 0.002), integrated discrimination improvement (0.012 [0.005–0.022]; P < 0.001), continuous net reclassification improvement (NRI) (0.583 [0.294–0.847]; P < 0.001), and categorical NRI (0.171 [0.027–0.317]; P = 0.02). CONCLUSIONS Independent associations exist between high plasma TNFR1 or IMA concentrations and increased 5.6-year risk of major LEAD in people with type 2 diabetes. TNFR1 allows incremental prognostic information, suggesting its use as a biomarker for LEAD.

Commentary on 'Thirty Day Outcomes and Costs of Fenestrated and Branched Stent Grafts Versus Open Repair for Complex Aortic Aneurysms' An Innovative but Expensive Tool Requiring Further Evaluation

The benefits of standard endovascular grafts (EVAR) for abdominal aortic aneurysm (AAA) have been well documented in terms of 30 day mortality, length of stay, and early cost-effectiveness compared with open surgical repair (OSR). However, these standard stent grafts are not well adapted to complex aortic aneurysms with a short neck or involving the visceral arteries. In this issue of the European Journal of Vascular and Endovascular Surgery, Michel et al. present an interesting study comparing outcomes and costs of f/b EVAR and OSR for complex AAA. The study design is that of the WINDOW registry, which has previously been published. In this registry the control group of patients (OSR) was extracted from the French National Hospital Discharge Database (PMSI). Therefore, the study compares a group of patients at high risk for OSR receiving f/b EVAR in selected centres (the cases, n 1⁄4 268) with a large group of patients at acceptable risk for OSR (controls, n 1⁄4 1,678). Although risk adjustments using the Charlson index improved the comparison between these two groups, most of the comorbidities could not be adjusted, resulting in an analysis comparing two different techniques in two different populations. Furthermore, clinical outcomes and costs were not evaluated in the same way in the two groups. The data for f/b EVAR cases were extracted from a complete case report file (CRF), compared with the cases where data were issued from the coding of the national discharge administrative database. As an example, matches corresponding to thoracoabdominal aneurysms versus juxtarenal aortic aneurysms in the infra-diaphragmatic area were identified in “cases” by reviewing pre-operative CT scans, whereas for “controls,” the matches relied on the coding system alone with no access to the patients’ charts. As suggested by the authors, the data available from the control group are subject to coding incentives and more likely to contain comorbidities that impact the level of reimbursement.

Cholesterol Crystal Embolism and Delayed-onset Paraplegia after Thoracoabdominal Aneurysm Repair

Postoperative paraplegia caused by ischemic injury of the spinal cord is the most disabling complication of thoracoabdominal surgery. We described the case of a 75-year-old patient who underwent a thoracoabdominal aneurysm repair (type IV aneurysm according to Crawford classification). The aorta clamping was done at the T11 level without specific medullary protection. The first postoperative week was uneventful. On the postoperative day 8, renal failure and livedo of the left lower limb occurred together with complete hypotonic paraplegia and severe sepsis. Exploratory laparotomy revealed a gangrenous cholecystitis, and skin biopsies showed cholesterol crystals embolisms in the hypodermis small arteries. The patient died on the postoperative day 28 from a multiorgan failure. In this case, paraplegia was due to cholesterol crystal embolism, which migrated secondarily after aortic clamping.