Search

International audience

International audience; The main reason for the early failure of radio-cephalic arteriovenous fistula (RCAVF) is non-maturity, which means that the blood flow rate in the fistula cannot increase to the expected value for dialysis. From a mechanical perspective, the vascular resistance at the artificially designed anastomosis causes an energy loss that affects blood flow rate growth and leads to early failure. This research studied how to maximize the RCA VF maturity and primary patency by controlling the energy loss rate. We theoretically analyzed and derived a model that evaluates the energy loss rate Eavf in RCAVF as a function of its blood vessel geometric parameters (GPs) for given flow rates. There was an aggregate of five controllable GPs in RCAVF: radial artery diameter (Dra), cephalic vein diameter (Dcv), blood vessel distance between artery and vein (h), anastomotic diameter (Da), and anastomotic angle (). Through this analysis, it was found that Eavf was inversely proportional to Dra, Dcv, Da, and , whereas proportional to h. Therefore, we recommended surgeons choose the vessels with large diameters , close distance, and increase the diameter and angle of the anastomosis to decrease the early failure of RCAVF. Simultaneously, we could explain the results of many clinical empiricisms with our formula. We found that increasing Dcv and  were more significant in reducing Eavf than increasing Dra and Da. Based on our model, we could define two critical energy loss rates (CELa, CELb) to help surgeons evaluate the blood vessels and choose the ideal range of . Help them design the preoperative RCAVF plan for each patient to increase the maturity and the primary patency of RCAVF.

International audience; The severe acute respiratory syndrome novel coronavirus-2 pandemic is affecting almost every country in the world. Even if the major symptoms of coronavirus disease-2019 are respiratory, different symptoms at presentation are now recognized. Venous thromboembolism has been reported in infected patients and few but increasing cases of arterial thrombosis have been described. We report a case of acute aortoiliac and lower limb artery occlusions in a patient presenting with severe coronavirus disease-2019 infection. The mechanism of the occlusion seemed to be distal embolization from a floating thrombus in the aortic arch caused by a major inflammatory state and virus infection. The patient underwent aortoiliac and lower limb artery mechanical thrombectomy, but required unilateral major amputation.

Objective The chimney technique (ChEVAR) allows for proximal landing zone extension for endovascular repair of complex aortic aneurysms. The aim of the present study was to assess ChEVAR national outcomes in French university hospital centres. Methods All centres were contacted and entered data into a computerised online database on a voluntary basis. Clinical and radiological data were collected on all consecutive ChEVAR patients operated on in 14 centres between 2008 and 2016. Patients were deemed unfit for open repair. Factors associated with early (30 day or in hospital) mortality and type 1 endoleak (Type I EL) were calculated using multivariable analysis. Results In total, 201 patients with 343 target vessels were treated. There were 94 juxtarenal (46.8%), 67 pararenal (33.3%), 10 Crawford type IV thoraco-abdominal (5%) aneurysms, and 30 (15.1%) proximal failures of prior repairs. The pre-operative diameter was 66.8 ± 16.7 mm and 28 (13.9%) ChEVAR were performed as an emergency, including six (2.9%) ruptures. There were 23 (11.7%) unplanned intra-operative procedures, mainly related to access issues. The rate of early deaths was 11.4% (n = 23). The elective mortality rate was 9.8% (n = 17). Nine patients (4.5%) presented with a stroke. The rate of early proximal Type I EL was 11.9%. Survival was 84.6%, 79.4%, 73.9%, 71.1% at 6, 12, 18, and 24 months, respectively. The primary patency of chimney stents was 97.4%, 96.7%, 95.2%, and 93.3% at 6, 12, 18, and 24 months, respectively. Performing unplanned intra-operative procedures (OR 3.7, 95% CI 1.3–10.9) was identified as the only independent predictor of post-operative death. A ChEVAR for juxtarenal aneurysm was independently associated with fewer post-operative Type I ELs (OR 0.17, 95% CI 0.05–0.58). Conclusion In this large national ChEVAR series, early results were concerning. The reasons may lie in heterogeneous practices between centres and ChEVAR use outside of current recommendations regarding oversizing rates, endograft types, and sealing zones. Future research should focus on improvements in pre-operative planning and intra-operative technical aspects.

International audience; BACKGROUND: A distal approach in endovascular procedures for revascularization of lowers limbs can be considered in case of no re-entry in subintimal recanalization. The aim of this study is to evaluate the feasibility of a medial approach to the infrageniculate popliteal artery (IPA) using existing computed tomography (CT) scan simulation and punctures performed on cadavers. METHODS AND RESULTS: CT angiographies of lower extremities were used to simulate IPA puncture and puncture trajectory. Tissues damaged during the trajectory between the puncture site and the access-related injuries were analyzed. Anatomical punctures on cadaverous model were also performed. Corpses were placed in supine position, the hip in slight flexion (40°) and abduction (external rotation of 60°). A 16 G needle was used for the IPA puncture. Twelve CT angiography simulations were made. Of these 12 simulations, 9 revealed an isolated lesion of the popliteal vein and 2 isolated lesions of the tibial nerve. A lesion of the tibial nerve and the popliteal vein on the same simulation was once observed. Damage to the medial gastrocnemius muscle could not be avoided in each case. Ten punctures were performed on cadavers with technical success. There were 6 popliteal vein lesions, 3 tibial nerve lesions, and 1 case without lesion. In all cases, damage to the medial gastrocnemius muscle was seen. CONCLUSIONS: This medial approach was feasible and is accompanied by trauma of elements of the popliteal pedicle. Preoperative CT angiography could anticipate best site of puncture and potential access-related injury.

International audience; Vulnerable carotid atherosclerotic plaques are characterised by several risk factors, such as inflammation, neovascularization and intraplaque haemorrhage (IPH). Vulnerable plaques can lead to ischemic events such as stroke. Many studies reported a relationship between IPH, plaque rupture, and ischemic stroke. Histology is the gold standard to evaluate IPH, but it required carotid endarterectomy (CEA) surgery to collect the tissue sample. In this context, several imaging methods can be used as a non-invasive way to evaluate plaque vulnerability and detect IPH. Most imaging studies showed that IPH is associated with plaque vulnerability and stroke, with magnetic resonance imaging (MRI) being the most sensitive and specific to detect IPH as a predictor of ischemic events. These conclusions are however still debated because of the limited number of patients included in these studies; further studies are required to better assess risks associated with different IPH stages. Moreover, IPH is implicated in plaque vulnerability with other risk factors which need to be considered to predict ischemic risk. In addition, MRI sequences standardization is required to compare results from different studies and agree on biomarkers that need to be considered to predict plaque rupture. In these circumstances, IPH detection by MRI could be an efficient clinical method to predict stroke. The goal of this review article is to first describe the pathophysiological process responsible for IPH, its histological detection in carotid plaques and its correlation with plaque rupture. The second part will discuss the benefits and limitations of imaging the carotid plaque, and finally the clinical interest of imaging IPH to predict plaque rupture, focusing on MRI-IPH.

In case of acute thrombosis, lower limb bypasses can, in certain cases, be cleared by local intra-arterial fibrinolysis (LIF). The aim of this study is to evaluate the secondary patency of thrombosed bypasses after fibrinolysis.This retrospective study includes all patients hospitalized for thrombosed bypasses of the lower limbs that were treated with in situ fibrinolysis using urokinase, between 2004 and 2013, in 2 French university hospital centers. Fibrinolysis was indicated in case of recent thrombosis (3 weeks) provoking acute limb ischemia without sensory-motor deficit and in the absence of general contraindications. The secondary patency of the grafts was defined as the time after fibrinolysis without a new thrombotic event.There were 207 patients, hospitalized for recent thrombosis of 244 bypasses. The LIF was efficient in 74% of the cases (n = 180). Secondary patency of these bypasses was 54.2% and 32.4% overall, 68.3% and 50.3% for the suprainguinal bypasses, and 48.3% and 21.5% for the infrainguinal bypasses at 1 and 5 years, respectively. There is a significant difference (P = 0.002) regarding the permeability of the suprainguinal and infrainguinal bypasses. The survival rate was 75% (±6.4%) at 5 years and the limb salvage rate was 89% (±3.3%), 78.2% (±5.1%), and 75% (±5.8%) at 1, 3, and 5 years, respectively. The only independent factor influencing the secondary patency of infrainguinal bypasses that was significant in a multivariate analysis was the infragenicular localization of the distal anastomosis (P = 0.023).LIF is an effective approach that often allows the identification of the underlying cause, permitting elective adjunctive treatment of the underlying cause. Although LIF is at least as effective as its therapeutic alternatives described in the literature, the secondary patency of the bypasses remains modest and encourages close monitoring, particularly in patients with an infragenicular bypass.

International audience; BACKGROUND: In atherosclerotic renal artery disease, the benefit of revascularization is controversial. A clinical decision-making process based on a multidisciplinary meeting was formalized in the Lyon university hospital. OBJECTIVES: To investigate whether this decisional process ensured a clinical benefit to patients assigned to renal revascularization. METHODS: Single-centre retrospective cohort study, including patients diagnosed from April 2013 to February 2015 with an atherosclerotic renal artery disease with a peak systolic velocity \textgreater180cm/s. For each patient, the decision taken in multidisciplinary meeting (medical treatment or revacularization) was compared to the one guided by international guidelines. Blood pressure values, number of antihypertensive medications, presence of an uncontrolled or resistant hypertension, and glomerular filtration rate at one-year follow-up were compared to baseline values. Safety data were collected. RESULTS: Forty-nine patients were included: 26 (53%) were assigned to a medical treatment and 23 (47%) to a renal revascularization. Therapeutic decision was in accordance with the 2013 American Health Association guidelines and with the 2017 European Society of Cardiology guidelines for 78% and 22% of patients who underwent revascularization, respectively. Patients assigned to revascularization presented a significant decrease in systolic blood pressure (-23+/-34mmHg, p = 0.007), diastolic blood pressure (-12+/-18mmHg, p = 0.007), number of antihypertensive medications (-1.00+/-1.03, p = 0.001), and number of uncontrolled or resistant hypertension (p = 0.022 and 0.031) at one-year follow-up. Those parameters were not modified among patients assigned to medical treatment alone. There was no grade 3 adverse event. CONCLUSION: Based on a multidisciplinary selection of revascularization indications, patients on whom a renal revascularization was performed exhibited a significant improvement of blood pressure control parameters with no severe adverse events.

International audience; Blood is a complex fluid in which the presence of the various constituents leads to significant changes in its rheological properties. Thus, an appropriate non-Newtonian model is advisable; and we choose a Modified version of the rheological model of Phan-Thien and Tanner (MPTT). The different parameters of this model, derived from the rheology of polymers, allow characterization of the non-Newtonian nature of blood, taking into account the behavior of red blood cells in plasma. Using the MPTT model that we implemented in the open access software OpenFOAM, numerical simulations have been performed on blood flow in the thoracic aorta for a healthy patient. We started from a patient-specific model which was constructed from medical images. Exiting flow boundary conditions have been developped, based on a 3-element Windkessel model to approximate physiological conditions. The parameters of the Windkessel model were calibrated with in vivo measurements of flow rate and pressure. The influence of the selected viscosity of red blood cells on the flow and wall shear stress (WSS) was investigated. Results obtained from this model were compared to those of the Newtonian model, and to those of a generalized Newtonian model, as well as to in vivo dynamic data from 4D MRI during a cardiac cycle. Upon evaluating the results, the MPTT model shows better agreement with the MRI data during the systolic and diastolic phases than the Newtonian or generalized Newtonian model, which confirms our interest in using a complex viscoelastic model.

cited By 1; International audience; This work aims at providing a complete analysis of the effect of plasticizers on the electrostrictive terpolymer performance. To achieve this, several plasticizing agents such as 2-ethylhexyl phtalate (DEHP), diisononyl phtalate (DINP), and palamoll 652 have been incorporated in the polymer matrix. Experimental results demonstrate that the proposed novel materials exhibited excellent electromechanical enhancement in terms of transverse strain and mechanical energy density under a moderate electric field, which is definitively critical in recent microscale actuation. Another objective of this article was to explore material characteristics as a function of the DINP content, and it was found that the plasticizer weigh fraction was the key parameter determining performance of the modified fluorinate terpolymer blends. Accordingly, it was revealed that high performance flexible actuators can be achieved merely by employing a simple and cheap plasticizer, thus making it possible to overcome the current technological barrier of conventional electroactive polymers that suffer from the high applied electric field usually required to reach sufficient strain. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017, 55, 355–369. © 2017 Wiley Periodicals, Inc.

International audience; BACKGROUND:The aim of this study is to assess the safety and the short-term results of endovascular treatment of common iliac artery (CIA) aneurysms using the new GORE EXCLUDER iliac branch endoprosthesis (IBE) device.METHODS:The study is a retrospective with prospective follow-up nonrandomized, single-arm evaluation. Patients with a CIA aneurysm (diameter >30 mm) extending to the iliac bifurcation underwent endovascular treatment with the Gore IBE. Anatomic and procedural data were collected. Computed tomography angiography (CTA) was performed within the 30 days after the procedure and every 6 month. Thirty-day and at least 6-months outcomes were investigated.RESULTS:From February 2014 to December 2014, 10 male patients with aneurysmal CIA (mean age 75 years old) underwent consecutive endovascular treatment with the Gore IBE. The CIA aneurysm (mean diameter 43.2 mm, range 32-49) treated with the Gore IBE was associated with an abdominal aortic aneurysm (AAA) in 5 patients. One patient had a previous AAA open repair. CIA aneurysm was bilateral in 5 patients. Preliminary procedure of internal iliac artery embolization was performed in 3 patients. Technical success rate of the Gore IBE implantation was 100% with a median fluoroscopy time of 35 min (range 12-64, ±16) and median contrast load of 150 mL (range 100-250, ±45). No perioperative complications were observed. Median length of stay was 4 days (range 3-7, ±2). One aortic type Ia endoleak was observed on the postoperative CT scan requiring an aortic extension at day 3. Branch patency was observed in all 10 patients at 1 month and 9 patients at 6 month. All CIA aneurysms were excluded without type Ib or type III endoleak.CONCLUSIONS:The technical success and short-term results demonstrate encouraging results and clinical benefits of the new GORE EXCLUDER IBE. A longer follow-up is needed to assess midterm and long-term results.

International audience; BACKGROUND: Technical success rates of endovascular recanalizations for Trans-Atlantic Inter-Society Consensus (TASC) C-D chronic occlusions are highly variable and depend on the characteristics and sites of the lesions as well as on the operator experience. We hypothesized that an antegrade approach via transbrachial access could improve the technical success rate of endovascular treatment of TASC C-D occlusions in case of failed femoral access. METHODS: From January 2010 to December 2012, all patients with symptomatic chronic TASC C-D aortoiliac occlusion were treated with an endovascular-first approach. Recanalization was first attempted using a femoral access. In case of failure, an antegrade approach using a transbrachial access was performed. Patient characteristics, anatomic details, procedural data, and immediate outcomes were prospectively recorded. RESULTS: During the study period, 73 patients (99 arteries) were included. Twenty-seven (37%) patients had TASC C occlusions including 11 bilateral common iliac artery occlusions and 16 external iliac artery (EIA) occlusions involving the common femoral or the internal iliac arteries. Forty-six (63%) patients had TASC D occlusions including 10 aortoiliac occlusions, 31 unilateral occlusions of both common and EIAs, and 5 bilateral EIA occlusions. Technical success with femoral access has been obtained in 53 arteries. An antegrade approach via transbrachial access allowed technical success in the other arteries, except in 7 arteries. Overall technical success rate was 93%, and 2 complications were related to the brachial accesses including 1 thrombosis and 1 pseudoaneurysm both requiring a reintervention. CONCLUSIONS: Brachial access for TASC C-D aortoiliac chronic occlusion improves the technical success rate without the need for reentry devices.

International audience; BACKGROUND: To evaluate the efficacy of percutaneous transluminal angioplasty (PTA) of atherosclerotic lesions of the common femoral artery (CFA) and its bifurcation. METHODS: From 2009 to 2013, 53 patients (43 men, average age, 68 years) were included in a single-center, nonrandomized, prospective study. Indication was disabling intermittent claudication (n = 36) or chronic critical limb ischemia (n = 17). Thirty-four procedures (64%) were isolated CFA PTA, whereas 7 of 53 (13%) involved inflow (including 4 iliac occlusions) and 12 of 53 (23%) involved outflow vessels. Primary stenting was performed in 50 cases (95%). CFA occlusions were recanalized in 4 of 53. Lesions involved the bifurcation in 22 cases (40%). Follow-up consisted of clinical examination and duplex scanning with ankle-brachial index measurement at 1, 6, and 12 months. A biplane X-ray was performed at 1 year. The primary end point was the absence of binary restenosis (\textgreater50% reobstruction of the CFA). Secondary end points were freedom from target lesion revascularization (TLR) and stent fracture rate. RESULTS: Procedural success was achieved in 96% of cases. At a mean follow-up of 24 months (with 1 patient lost of follow-up), the absence of binary restenosis was 92.5%. At the end of follow-up, 82% of patients continued to show clinical improvement. Freedom from TLR was 97%. Stent fracture rate at 1 year was 9%. CONCLUSIONS: PTA of the CFA and its bifurcation is a reliable technique with good midterm functional results. These results justify performing a randomized study comparing surgery and endovascular treatment.