Nellix Device Failure Mechanisms Analysis on Explanted Grafts.

OBJECTIVE: To understand possible reasons for poor durability of the Nellix (Endologix Inc., Irvine, USA) endovascular aneurysm sealing (EVAS) device. MATERIALS AND METHODS: 21 Nellix endoprostheses explanted for endoleaks and migration underwent visual examinations of stent structures and instrumental examinations of the polymer endobags on 4 devices. We harvested 2.0-gram polymer slices out of each of them and tested the samples in an in vitro implantation replication that included wet and dry exposures. During the wet phase, we placed samples in a beaker with saline, mimicking the filling of the endobags during implantation. An exposure to a 37°C environment with 60% humidity during the dry phase replicated the postimplantation conditions inside the aneurysmal sac. RESULTS: Iatrogenic defects affected 16 (76%) metal stents and 20 (95%) endobags. The polymer was disintegrated owing to degradation in 15 (71%) cases. The polymer could lose more than 70% of its initial weight when partially dehydrated and regain 80% when placed in saline. We observed volume decrease and polymer fragmentation during these study phases. CONCLUSIONS: The polymer can lose weight and volume while it dehydrates. This structural degradation of the polymer could lead to the development of endoleaks and/or migration of the device. CLINICAL IMPACT: Based on the results of previous investigations, due to possible endovascular device degradation, patients with endografts should be offered life-long surveillance, and the Nellix device is no exception. Herein we suggest polymer degradation as one of the possible reasons for the device failure. Although Nellix has been withdrawn from the market, there are numerous patients with this type of endograft. Due to its unpredictable performance in the medium and long term, these patients should be recommended enhanced life-long surveillance every 6 months. Any suspicious conditions during the follow-up must be taken seriously and explantation should be considered.

Editor's Choice -- Type IIIb Endoleaks: Fabric Perforations of Explanted New Generation Endoprostheses.

OBJECTIVE: To analyse explanted endografts (EGs) and describe fabric degradation responsible for type IIIb endoleaks. METHODS: As part of the European collaborative retrieval programme, 32 EGs with fabric defects on macroscopic evaluation were selected. The explanted EGs were processed and studied based on the ISO 9001 certified standard protocol. It includes instructions on the collection, transportation, cleaning, and examination of explanted material. The precise analysis was performed with a digital microscope of 20 - 200 times magnification. Possible perforation mechanisms were assessed in stress tests. RESULTS: The median time to explantation of the 32 EGs was 54 months. The explants included 65 separate EG modules, with 46 (70.8%) having a combined 388 fabric perforations. Each EG had a median of 4.79 mm2 (interquartile range [IQR] 9.86 mm2) of cumulated hole area (an average of 0.13% of an EG's area). There were 239 (61.6%) expanded polytetrafluoroethylene (ePTFE; 11 EGs) and 149 (38.4%) polyethylene terephthalate (PET; 21 EGs) fabric ruptures, with no difference in hole distribution between these types of material. Overall, 126 (32.5%) stent related and 262 (67.5%) non-stent related fabric perforations were identified. Perforations caused by fabric fatigue in ePTFE (151, 63.2%) and material kinking in PET (41, 27.5%) were the most common. The stent related perforations were larger in size (0.80 mm2) than non-stent related perforations (0.19 mm2); p < .001. Wider interstent spaces and prolonged implantation duration were associated with an increased risk of stent related perforation development; p < .001 and p = .004, respectively. Large stent related perforations were also detected in the short term, suggesting mechanical issues as underlying causes. CONCLUSION: The fabric of EGs may degrade and lead to the development of perforations. The largest perforations are stent related. Their occurrence and size depend on the implantation time and the EG shape affected by arterial tortuosity. The conclusions are limited to the samples from a select explant group.

Aortobifemoral Bypass in Kidney Transplant Candidates: A Ten-Year Experience.

In patients with severe aorto-iliac calcifications, vascular reconstructions can be performed in order to allow kidney transplantation. The aim of this study was to analyze the outcomes of kidney transplant candidates who underwent an aortobifemoral bypass (ABFB) for aorto-iliac calcifications. A retrospective study including all kidney transplant candidates who underwent an ABFB between 2012 and 2022 was performed. Primary outcome was 30-day morbidity-mortality after ABFB. Secondary outcome was accessibility to kidney transplant waiting list. Twenty-two ABFBs were performed: 10 ABFBs in asymptomatic patients presenting severe aorto-iliac circumferential calcifications without hemodynamic consequences, and 12 ABFBs in symptomatic patients in whom aorto-iliac calcifications were responsible for claudication or critical limb threatening ischemia. Overall 30-day mortality was 0%. Overall 30-day morbidity was 22.7%: 1 femoral hematoma and 1 retroperitoneal hematoma requiring surgical drainage in the asymptomatic group, and 2 digestive ischemia requiring bowel resection and 1 femoral hematoma requiring surgical drainage in the symptomatic group. Among the 22 patients, 20 patients could access to kidney waiting list and 8 patients underwent a kidney transplantation, including 3 living-donor transplantations. Aorto-iliac revascularization can be an option to overcome severe calcifications contraindicating kidney transplantation.

Intraoperative Staff Radiation Exposure During Aortic Endovascular Procedures.

BACKGROUND: The risk of radiation exposure in the surgical operating room (OR) and/or catheterization laboratory is now well established. Complex endovascular procedures often require multiple approaches and different positioning of the staff members around the patient, potentially increasing the levels of radiations exposure. Our goal was to evaluate the levels of radiation exposure of the members of the staff during endovascular aortic procedures in order to propose radioprotection optimization. METHODS: We included 41 aortic endovascular procedures out of 114 procedures performed between January 12, 2014, and August 31, 2015, including 24 standard endovascular aortic aneurysm repair (EVAR), 7 EVAR with iliac branch (EVARib), 8 complex fenestrated/branched EVAR (F/B EVAR), and 2 thoracic EVAR (TEVAR). Procedures were performed in an OR equipped with a carbon fiber table and a mobile fluoroscopy C-arm. We collected the usual dosimetry data given by the C-arm as well as the patient's peak skin dose (PSD). In all staff members, radiation exposure was measured with thermoluminescent chip dosimeters placed on both temples, on posterior sides of both hands, and on both lower legs. RESULTS: PSD levels were low for EVAR because 24 patients had values below the reading threshold. PSD significantly increased with more complex procedures. Main operator (MO) received the higher level of irradiation on whole body, hands, and ankles. Eye lenses irradiation was higher on both assistant operators (AOs). Other members received low levels of irradiation. We found a high ranges of radiation exposure with a high risk of exposure for the AO, mainly for F/B EVAR and EVARib. CONCLUSIONS: Even if all personal protections are used, staff positioning is a major point that must be considered. If MO is supposed to be the most exposed to X-rays, specific conditions of positioning of the AO may be at risk of exposure.

Fundamental Technical Skills of Endovascular Surgery: A Preliminary Study on Its Impact on Skills and Stress during Procedures.

BACKGROUND: Our objective is twofold: determining if simulation allows residents to reach proficient surgeons' performance concerning fundamental technical skills of endovascular surgery (FEVS) while investigating effects of the program on surgeons' stress. METHODS: Using a FEVS training simulator, 8 endovascular FEVS were performed by vascular surgery residents (simulator-naive or simulator-experienced residents [SER]) and seniors. Total time needed to complete the 8 tasks, called total completion time (TCT), was the main evaluation criterion. Analgesia Nociception Index (ANI) was monitored during simulation. Likert scale questionnaire was filled out after each simulation. RESULTS: For each task, TCT was significantly lower for SER and seniors than simulator-naive residents (P = 0.0163). After only 5 simulations, SER were able to reach and even exceed the seniors' level in terms of TCT, with a median time of 10.8 min for SER and 11.9 min for seniors, and wire's movements with a median distance during cannulation of 4.44 m for SER and 4.17 m for seniors. Seniors remained better than SER in terms of precise wire manipulation (wire movement after cannulation), 4.17 m against 4.44 m (3.72-5.96), respectively. Based on the Likert scale stress analysis, seniors felt less stressed than both residents' groups (P = 0.0618). Seniors' initial ANI and mean ANI over the session were significantly lower than those of the residents, P = 0.0358 and P = 0.0250, respectively. CONCLUSIONS: We showed that 5 simulation sessions allowed residents to reach experienced surgeons' capacities on FEVS concerning TCT. Subjectively, seniors felt less stressed than residents, contrary to the results of our objective measures of stress.

Endothelial Recovery in Bare Metal Stents and Drug-Eluting Stents on a Single-Cell Level.

OBJECTIVE: Healing processes, particularly reendothelialization, are essential for vascular homeostasis after plain old balloon angioplasty and stent implantation. Drug-eluting stents (DES) are commonly used for percutaneous coronary intervention because restenosis rates are reduced as compared with bare metal stents (BMS). However, in addition to understanding the nature of regenerated endothelial cells, concerns over incomplete stent healing persist, and the molecular effects of antiproliferative drug coatings on endothelium remain poorly understood. APPROACH AND RESULTS: We used the rabbit iliac artery model to analyze differences in stent endothelialization in BMS and DES. Histology and immunohistochemistry confirmed that stent coverage was significantly greater in BMS than in DES at 30 days after stent implantation. Single-cell RNA sequencing revealed a more immature transcriptomic signature of neointimal endothelial cell harvested from stented arteries in comparison with native and plain old balloon angioplasty­ treated arteries. Whereas the genetic signature of BMS was overall proangiogenic with enrichment of genes involved in endothelial proliferation, sprouting, and migration, as well as extracellular matrix assembly, DES-derived endothelial cell showed upregulation of genes associated with angiogenesis inhibition and endothelial activation. CONCLUSIONS: Single-cell RNA sequencing analysis identified unique transcriptional changes within regenerated endothelium after plain old balloon angioplasty and stent implantation. These data suggest unique endothelial transcriptional differences, which characterize the different response of the endothelium to vascular injury and may help explain why long-term responses in DES remain suboptimal.

Computed-tomography-based predictive scores of surgical complications to help decision-making in enrolling obese patients in kidney transplantation list.

This study aimed at developing scores predicting surgical complications in obese transplant recipients, based on preoperative computed tomography (CT) parameters. All consecutive patients with a body mass index (BMI) ≥ 30 kg/m2 who underwent kidney transplantation between 2012 and 2019 were included. The preoperative CT parameters were assessed: total fatty surface (TFS), subcutaneous fatty surface (SFS), iliac vessel to skin distance (VSD), and abdominal perimeter (AP). Per- and postoperative complications (vascular, urinary, parietal, and digestive complications) within 30 days were listed. Predictive models of surgical complications were generated based on the results of the logistic regression. Among the 163 patients included, 53 (32.5%) experienced surgical complications. The AP was a risk factor for complications in multivariate analysis (OR: 1.050; 95% CI: 1.016-1.087; p = 0.03). Two predictive models of complications were created based on the statistical analysis: a one-variable model based on AP (sensitivity 86.8%, specificity 41.8%, area under the curve (AUC) 65.3, with a cutoff value of 107 cm) and a five-variable model based on BMI, TFS, SFS, VSD, and AP (sensitivity 73.6%, specificity 57.3%, AUC 66.2). These models, based on patient morphometric measurements, could allow predicting the occurrence of surgical complications in obese candidates for kidney transplantation.

Vascular Response of a Polymer-Free Paclitaxel-Coated Stent (Zilver PTX) versus a Polymer-Coated Paclitaxel-Eluting Stent (Eluvia) in Healthy Swine Femoropopliteal Arteries.

PURPOSE: To compare the long-term vascular healing responses of healthy swine iliofemoral arteries treated with a polymer-free paclitaxel-eluting stent (Z-PES, Zilver PTX) or a fluoropolymer-based paclitaxel-eluting stent (FP-PES, Eluvia). MATERIALS AND METHODS: Bilateral iliofemoral arteries in 20 swine were treated with a Z-PES (n = 16) or a FP-PES (n = 24) and were examined histologically at 1, 3, 6, and 12 months. RESULTS: Morphometric analysis revealed larger external and internal elastic lamina, stent expansion, and lumen area in the FP-PES than in the Z-PES at all timepoints. Luminal narrowing was similar in the 2 groups at 1 month; however, greater stenosis was observed in the Z-PES group at 3 months, with significant regression thereafter, resulting in equivalent stenosis at 6 and 12 months. Greater drug effect and less complete vessel healing were found in the FP-PES group at all timepoints, including greater numbers of malapposed struts with excessive fibrin deposition at 1 and 3 months, than in the Z-PES group. Three of 12 FP-PESs from the 6- and 12-month cohorts also showed circumferential medial disruption with peri-strut inflammation, whereas no abnormal findings were observed in contralateral Z-PESs. CONCLUSIONS: Prolonged paclitaxel release with the presence of a permanent polymer may contribute to the differential vascular responses seen for the Z-PES and FP-PES groups, including medial layer disruption and aneurysmal vessel degeneration that was sometimes observed in the FP-PES group. These distinct features should be confirmed by pathology and in vivo imaging of human superficial femoral arteries to determine their clinical significance.

Co-Registration of Peripheral Atherosclerotic Plaques Assessed by Conventional CT Angiography, MicroCT and Histology in Patients with Chronic Limb Threatening Ischaemia.

OBJECTIVE: To co-register conventional computed tomography angiography (CTA), with ex vivo micro-computed tomography (microCT) and histology of popliteal atherosclerotic plaques. Improving the non-invasive imaging capabilities may be valuable to advance patient care with peripheral arterial obstructive disease towards lesion and individual based treatment. METHODS: In this prospective observational study, 12 popliteal arteries from 11 symptomatic patients who had undergone transfemoral amputations for chronic limb threatening ischaemia and who had pre-operative CTA, were analysed ex vivo by microCT and histology. A total of 353 histological cross sections were co-registered with microCT and CTA, and classified as: lipid rich (LP, n = 26), fibrous (FP, n = 80), or calcific (CP, n = 247) plaques. CTA and microCT plaque density was calculated in 791 regions of interest as Hounsfield units (HU). RESULTS: CTA and microCT could identify plaque components that were confirmed by histology such as fibrous tissue (FP), lipid pool/core (LP), and calcification (CP). MicroCT densities were 77.8 HU for FP (IQR 52.8, 129.5 HU), -28.4 HU for LP (IQR -87.1, 13.2 HU), and 3826.0 HU for CP (IQR 2989.0, 4501.0 HU). CTA densities of the three components of the plaque were: 78.0 HU for FP (IQR 59.5, 119.8 HU), 32.5 HU for LP (IQR 15.0, 42 HU), and 641.5 HU for CP (IQR 425.8, 1135 HU). The differences were statistically significant between the HU densitometric characteristics among the three groups (p < .0001) for both imaging modalities. Overall, microCT performed better diagnostically than conventional CTA for the three types of plaques: areas under the receiving operator characteristics curve were greater for microCT than CTA for FP (0.97 vs. 0.90), for LP (0.88 vs. 0.67), and for CP (0.97 vs. 0.90). CONCLUSION: CTA and microCT can be used to identify histological atherosclerotic plaque components, with better diagnostic performance for microCT. This study demonstrates the feasibility of using microCT to assess plaque morphology lesions in a manner that approaches histology thus becoming a useful tool for ex vivo assessment of atherosclerosis and towards lesion based treatment.

Diversity of macrophage phenotypes and responses in atherosclerosis.

The presence of macrophages within the plaque is a defining hallmark of atherosclerosis. Macrophages are exposed to various microenvironments such as oxidized lipids and cytokines which effect their phenotypic differentiation and activation. Classically, macrophages have been divided into two groups: M1 and M2 macrophages induced by T-helper 1 and T-helper 2 cytokines, respectively. However, for a decade, greater phenotypic heterogeneity and plasticity of these cells have since been reported in various models. In addition to M1 and M2 macrophage phenotypes, the concept of additional macrophage phenotypes such as M (Hb), Mox, and M4 has emerged. Understanding the mechanisms and functions of distinct phenotype of macrophages can lead to determination of their potential role in atherosclerotic plaque pathogenesis. However, there are still many unresolved controversies regarding their phenotype and function with respect to atherosclerosis. Here, we summarize and focus on the differential subtypes of macrophages in atherosclerotic plaques and their differing functional roles based upon microenvironments such as lipid, intraplaque hemorrhage, and plaque regression.

Vascular responses to coronary calcification following implantation of newer-generation drug-eluting stents in humans: impact on healing.

AIMS: Vascular calcification is routinely encountered in percutaneous coronary intervention (PCI) and severe coronary calcification is a known predictor of in-stent restenosis and stent thrombosis. However, the histopathologic mechanisms behind such events have not been systematically described. METHODS AND RESULTS: From our registry of 1211 stents, a total of 134 newer-generation drug-eluting stents (DES) (Xience, Resolute-Integrity, PROMUS-Element, and Synergy) with duration of implant ≥30 days were histologically analysed. The extent of calcification of the stented lesions was evaluated radiographically and divided into severe (SC, n = 46) and non-severely calcified lesions (NC, n = 88). The percent-uncovered struts per section {SC vs. NC; median 2.4 [interquartile range (IQR) 0.0-19.0] % vs. 0.0 (IQR 0.0-4.6) %, P = 0.02} and the presence of severe medial tears (MTs) (59% vs. 44%, respectively, P = 0.03) were greater in SC than NC. In addition, SC had a higher prevalence of ≥3 consecutive struts lying directly in contact with surface calcified area (3SC) (52% vs. 8%, respectively, P < 0.0001). Multivariate analysis demonstrated that sections with duration of implantation ≤6 months [odds ratio (OR): 7.7, P < 0.0001], 3SC (OR: 6.5, P < 0.0001), strut malapposition (OR: 5.0, P < 0.0001), and lack of MTs (OR: 2.5, P = 0.0005) were independent predictors of uncovered struts. Prevalence of neoatherosclerosis was significantly lower in SC than that of NC (24% vs. 44%, P = 0.02). CONCLUSION: Severe calcification, especially surface calcified area is an independent predictor of uncovered struts and delayed healing after newer-generation DES implantation. These data expand of knowledge of the vascular responses of stenting of calcified arteries and suggests further understand of how best to deal with calcification in patients undergoing PCI.

Volume Change after Endovascular Treatment of Common Iliac Arteries ≥ 17 mm Diameter: Assessment of Type 1b Endoleak Risk Factors.

OBJECTIVE: The aim of this study was to assess the post-operative volumetric evolution of common iliac arteries (CIA) ≥ 17 mm diameter with respect to the type of endovascular technique performed and to assess type 1b endoleak risk factors. METHODS: All consecutive patients presenting with aneurysmal disease with CIA ≥17 mm treated endovascularly from 2008 to 2016 were included. Patients were divided into two groups dependent upon the type of endovascular technique performed: bell bottom technique (BBT group), vs. other techniques (non-BBT group). Volumetric evolution of the CIA was assessed for each patient by computed tomography angiographic reconstructions performed pre-operatively, at six months, one year, and two years. Multivariable analysis was performed to identify risk factors for type 1b endoleak. RESULTS: From 2008 to 2016, 74 patients with 110 CIA ≥17 mm were treated (BBT group: n = 58; non-BBT group: n = 52). Mean follow up was 48.1 months (median 39.0, IQR 38.1). Mean volumetric evolution significantly differed in the BBT group +14.2% (median 19.9%, IQR 24.6) compared with the non-BBT group: -20.9% (median -20.1%, IQR -26.0), p < .001. The five year type 1b endoleak related re-intervention rate was 16.1% and 7.7% in the BBT and non-BBT groups, respectively (p = .04), mean time to type 1b endoleak was 24.8 months and 54.3 months, respectively. The BBT appeared as a risk factor for type 1b endoleak (OR: 7.13; 95% CI: 1.58-3.04; p < .001). CONCLUSION: The BBT is associated with an increase in CIA volume post-operatively and consequently can be considered a risk factor for type 1b endoleak. It might be avoided if an iliac branched endograft is possible.

A Popliteal Cyst Responsible for Acute Lower Limb Ischemia.

We report the case of a 68-year-old man complaining of sudden intermittent claudication of the left limb. The patient was rapidly diagnosed with duplex ultrasound (DUS), computed tomography angiography, and magnetic resonance angiography as having a popliteal cyst (PC) compressing the popliteal artery, responsible for intermittent claudication. The patient underwent DUS-guided PC aspiration allowing symptoms resolution. However, he presented 3 recurrent ischemic syndromes from brutal claudication to more severe ischemia in a 3-month period, with increasing severity of the symptoms, treated with 3 DUS-guided PC aspirations. An extensive work-up excluded an atherosclerotic etiology. Consequently, due to increasing severity and quick recurrence of the symptoms and given the underlying knee osteoarthritis, the patient underwent radical treatment and got a total knee prosthetic replacement. One year later, follow-up was uneventful.

Late Peroneal Neuropathy after Open Surgical Treatment of Popliteal Artery Aneurysm.

We report the case of a 71-year-old man complaining of swollen left limb and progressively worsening pain. He underwent surgery 12 years ago for popliteal artery aneurysm with proximal and distal ligation and venous bypass grafting. The patient was diagnosed as having left peroneal neuropathy caused by a 10.5 cm expanded aneurysmal sac compressing the peroneal nerve in the popliteal fossa. The patient underwent open repair with opening of the aneurysmal sac, removal of the thrombus, and sewing of the left genicular artery responsible for back-bleeding. Postoperative range of motion exercises and physical therapy allowed resolving foot drop 1 year after surgery.