Ce travail de thèse porte sur la simulation du déploiement des prothèses vasculaires de type stent-graft (SG) lors de la réparation endovasculaire (EVAR) des anévrismes de l’aorte abdominale (AAA). Cette étude se présente en trois parties: (i) tests mécaniques en flexion et compression de SG couramment utilisés (corps et jambage de marque Cook) ainsi que la simulation numérique desdits tests, (ii) développement d’un modèle numérique d’anévrisme, (iii) stratégie de simulation du déploiement des SG. La méthode numérique employée est celle des éléments finis. Dans un premier temps, une vérification du modèle éléments finis (MEF) des SG est realisée par comparaison des différents cas de charge avec leur pendant expérimental. Ensuite, le MEF vasculaire (AAA) est lui aussi vérifié lors d’une comparaison des niveaux de contraintes maximales principales dans la paroi avec des valeurs de la littérature. Enfin, le déploiement est abordé tout en intégrant les cathéters. Les tests mécaniques menés sur les SG ont été simulés avec une différence maximale de 5,93%, tout en tenant compte de la pré-charge des stents. Le MEF de la structure vasculaire a montré des contraintes maximales principales éloignées de 4,41% par rapport à un modèle similaire précédemment publié. Quant à la simulation du déploiement, un jeu complet de SG a pu être déployé avec un bon contrôle de la position relative et globale, dans un AAA spécifique pré-déformé, sans toutefois inclure de thrombus intra-luminal (TIL). La paroi du AAA a été modélisée avec une loi de comportement isotropique hyperélastique. Étant donné que la différence maximale tolérée en milieu clinique entre réalité et simulation est de 5%, notre approche semble acceptable et pourrait donner suite à de futurs développements. Cela dit, le petit nombre de SG testés justifie pleinement une vaste campagne de tests mécaniques et simulations supplémentaires à des fins de validation. / This thesis work is concerned with the simulation of the deployment of stent-graft (SG) vascular prostheses in abdominal aortic aneurysms (AAA) during endovascular repair (EVAR). This study is composed of three main parts: (i) mechanical tests in bending and compression of frequently used SG (body and leg from Cook) as well as the numerical simulation of these tests, (ii) development of a numerical AAA model, (iii) strategy of simulation of SG deployment. The finite element method is used. In a first step, a verification of the finite element model (FEM) of SG is performed by comparison of the different load cases with their experimental counterparts. Subsequently, the vascular FEM is also verified in terms of maximal principal constraints in the wall against values available in the literature. Finally, the deployment is investigated while taking the catheters into account. The mechanical tests performed on the SG were simulated with a maximal difference of 5.93%, while accounting for the pre-load in stents. The FEM of the vascular structure showed maximal principal stresses that were 4.41% far from the ones found in the literature for a similar model. Regarding the simulation of SG deployment, a complete set of SG could be deployed with a good control of the relative and global position into a specific and pre-deformed AAA, however, no intra-luminal thrombus (ILT) was included. The AAA wall was modeled with an isotropic hyperelastic constitutive law. In the clinical setting, the maximum tolerated difference between reality and simulation is 5%, therefore, our approach seems acceptable, and could give rise to further developments. However, the small amount of tested SG justifies a wide campaign of additional mechanical tests and simulations for the sake of validation.

La bifurcation coronaire est un site privilégié d’athérosclérose. Jusqu’alors aucune des techniques de stenting provisionnel percutanées avec juxtaposition de ballons n’a démontré de bénéfice clinique. Ces échecs peuvent être expliqués par le non-respect de la géométrie fractale des bifurcations qui pourtant doit toujours guider la revascularisation (correction de la malapposition et optimisation de l’ostium de la branche collatérale). Fort de ce constat, nous avons imaginé une nouvelle technique séquentielle et simple, en 3 temps, le rePOT, associant Proximal Optimizing Technique (POT) initial, ouverture de la branche collatérale et POT final. Son évaluations s’est voulue progressive en 4 étapes : 1) concept, 2) preuve expérimentale de concept, 3) confirmation des bénéfices mécaniques in vivo, et 4) validation clinique. Dans ce travail nous avons donc d’abord expérimentalement démontré la supériorité du résultat mécanique final du rePOT par rapport aux techniques non séquentielles de provisional stenting (manuscrit # 1). Ainsi, le rePOT effondre la malapposition globale du stent, conserve la circularité proximale physiologique et optimise l’obstruction ostiale résiduelle de la branche accessoire. Ces excellents résultats sont confirmés indépendamment du design ou de la composition des stents (manuscrits # 2, 4). Nous avons par ailleurs démontré l’importance de chacune des 3 étapes du rePOT: POT initial (manuscrit # 1), ouverture de SB et POT final (manuscrit # 3). Enfin, fort de ces démonstrations expérimentales, nous avons confirmé in vivo avec mesures OCT itératives à la fois les excellents résultats expérimentaux et la bonne évolution clinique à moyen terme (manuscrit # 5). Ce travail démontre donc étape par étape, de l’expérimentale à la clinique, l’ensemble des bénéfices de cette nouvelle technique séquentielle de stenting provisionnel "rePOT", devenue une référence en Europe dans la revascularisation percutanée des bifurcations coronaires / Coronary bifurcations are a preferential location for atherosclerosis development. Until now, no technic with balloons juxtaposition demonstrated a clinical benefit in percutaneous coronary bifurcation revascularization by provisional stenting (with 1 stent). Successive failures could be explained by the absence of respect of the bifurcations fractal geometry, which need to be systematically followed during all revascularization (correction of the malapposition and optimization of the side branch ostium). Thus, we imagined a new technique, simple and sequential, in 3 steps, named rePOT. It is combining initial Proximal Optimizing Technique (POT), side-branch opening and final POT. We proposed a demonstration in 4 steps : 1) concept, 2) experimental proofs of concept, 3) confirmation of the clinical benefits in vivo, and 4) clinical validation. In this work, we experimentally demonstrated the superiority of the final mechanical results of the rePOT compared to all non-sequential provisional stenting (manuscript # 1). Thus, rePOT decreased stent global malapposition, maintained the initial proximal circularity and optimized the final ostial side branch obstruction. These excellent results were confirmed independently of stent design or material (manuscripts # 2, 4). Moreover, we demonstrated the specific benefits of each steps of the rePOT : initial POT (manuscript # 1), SB opening, and final POT (manuscript # 3). Finally, we confirmed in vivo, with serial OCT analysis, these excellent mechanical results and the good clinical outcome at mid-term. (manuscript # 5). Thank to this step by step demonstration, from experimental to clinic, we confirmed all benefits of this new provisional stenting sequential technique "rePOT". Thereby, before the last step of the demonstration, rePOT became a reference in Europe for the percutaneous revascularization of coronary bifurcations

Zugl.: Bochum, Univ., Diss., 2009

Bakgrund: Percutan transluminal angioplastik (PTA) är ett ingrepp som syftar till att behandla patienter med besvär orsakade av ateroskleros med förträngningar i artärer. PTA går ut på att vidga kärlets diameter och ibland sätts en stent in i kärlet för att behålla öppenheten. Som röntgensjuksköterska ingår möten med patienter som genomgår PTA före, under och efter ingreppet. Syfte: Litteraturstudiens syfte är att belysa de vanligaste sena komplikationerna som kan uppstå vid PTA. Metod: Det här arbetet är en systematisk litteraturstudie. Inklusionskriterierna var vetenskapliga artiklar skriva mellan 2007 till 2018. Artiklarna var peer-reviewed och etiskt granskade. Databaserna CINAHL och MEDLINE användes vid sökningen. Relevans bedömdes med Critical Appraisal Skills Programme. Resultat: 20 vetenskapliga artiklar inkluderades i studien, samtliga visar på restenos. Stentfraktur förekom i 5 av 20 studier och amputation i 14 av 20 studier. Slutsats: Slutsatsen är att restenos är den vanligaste sena komplikationen oavsett om stent har använts eller inte i samband med PTA av nedre extremiteter. Om stent används finns risken för stentfraktur. Dock är denna risk inte lika stor som risken för restenos. Fortsatt forskning kring läkemedelstäckta ballonger och stentar behövs då det i dagsläget tyder på att färre antal patienter drabbas av restenos vid användandet av dessa. / Background: The purpose of percutanous transluminal angioplasty (PTA) is to treat patients with symptoms and discomfort because of stenosis and occlusions in the arteries caused by atherosclerosis. This is done by dilatation of the vessel diameter and sometimes placing a stent to maintain the patency of the artery. Working as a radiographer includes meeting patients before, during and after PTA. Purpose: The purpose of this study is to illustrate the most common late complications that can occur after PTA. Method: This is a systematic literature study. The inclusion criteria for the articles were to follow a scientific structure, they had to be published between 2007 and 2018 and they had to be peer-reviewed and ethically reviewed. The databases used in this study were CINAHL and MEDLINE. Critical Appraisal Skills Programme was used. Result: 20 scientific articles were included in this study. All of them reported restenosis. Stent fractures occurred in 5 of 20 studies and amputation occurred in 14 of 20 studies. Conclusion: Restenosis was the most common late complication of PTA both with and without stent placement. More research is needed using drug-coated balloons and drug-coated stents to see if there are any beneficial effects.

Made available in DSpace on 2014-07-29T15:07:09Z (GMT). No. of bitstreams: 1 Dissertacao Harley Fernandes Rodrigues.pdf: 5566711 bytes, checksum: 484423a034c8d6a3a3f34650b5036af1 (MD5) Previous issue date: 2011-08-23 / In this work we developed a Dip Coating method that could control the temperature gradient between a substrate and the material that one wants to adsorb at its surface. In particular, the adsorption of biocompatible magnetic nanoparticles at the surface of bare metal Stents, under different experimental conditions, was investigated. The magnetic nanoparticles consisted of magnetite coated with tripoliphosphate (mean diameter 7.68 nm and standard deviation 1.88 nm) dispersed in water at physiological conditions, while the Stent was a CoCr based-one (Cronus stent from Scitech with 16 mm length). Nine series of experiments were performed where it was controlled parameters as: time of adsorption, stent temperature and magnetic fluid temperature. The stents coated with nanoparticles were magnetically characterized using a vibrating sample magnetometer (VSM), which allowed us to determine the number of nanoparticles at the stent surface. The increase of the magnetic moment of the stent with the increase of the adsorption time was theoretically modeled, with an excellent experimental agreement, as a transient diffusion process of nanoparticles at the interface stent-magnetic fluid, which clearly indicates an important diffusive contribution. Strong evidences of thermal diffusion (Soret effect), i.e. nanoparticle diffusion due to temperature gradient between the stent and the magnetic fluid, were shown, suggesting the possibility of nanostructures vectorization through thermal induced mechanisms. The spatial distribution of nanoparticles at the surface of the stent was investigated by Scanning Electron Microscopy (SEM) and X-ray Spectroscopy by Dispersive Energy (EDS). Measurements of the compositional mapping and images of SEM revealed that the nanoparticles are not homogeneously distributed, being concentrated at the edges of the stents for the experimental conditions investigated in this work. As the VSM data, the EDS of the stents revealed an increase of the quantity of adsorbed magnetic nanoparticles at the surface with the increase of the adsorption time. The same theoretical model, know considering the amount of 26Fe in the chemical composition of the coated stent, was able to explain the experimental data. Finally, a comparison was made, using the compositional mapping study of the coated stents, between the Dip Coating and the Spray technique. The later showed a more homogeneous distribution of nanoparticles at the surface of the stent, suggesting that this technique is more adequate on the development of a biomedical nanoproduct for clinical tests. / Neste trabalho foi desenvolvida uma técnica de Dip Coating (deposição por via líquida) que permite controlar o gradiente de temperatura entre o substrato e o material que se quer depositar em sua superfície. Em particular, foi investigado o efeito de adsorção de nanopartículas magnéticas biocompatíveis na superfície de Stents nus em diversas condições experimentais. As nanopartículas magnéticas consistiam de magnetita recobertas com tripolifosfato (diâmetro médio ) dispersas em água em pH fisiológico, enquanto as endopróteses eram Stents de CoCr (Stent Cronus da empresa Scitech com 16mm). Ao todo foram realizadas 9 séries de experimentos onde controlou-se parâmetros como: tempo de adsorção, temperatura do Stent e temperatura do fluido magnético. Os Stents recobertos com nanopartículas foram então caracterizados magneticamente pela técnica de magnetometria de amostra vibrante (VSM Vibrating Sample Magnetometer ), que permitiu determinar o número de nanopartículas magnéticas adsorvidas na superfície da endoprótese. O aumento do momento magnético do Stent com o aumento do tempo de adsorção foi modelado teoricamente, com grande concordância experimental, como um processo de difusão transiente de nanopartículas na interface Stent-fluido magnético, evidenciando a forte contribuição difusiva. Fortes evidências de efeitos termodifusivos (efeito de Soret), ou seja mecanismos de difusão mássica de nanopartículas devido ao gradiente de temperatura entre Stent e FM, foram apresentados, sugerindo a possibilidade de vetorização de nanoestruturas por meio de fenômenos termoinduzidos. A distribuição das nanopartículas na superfície dos Stents foi investigada por medidas de Microscopia Eletrônica de Varredura (MEV) e espectroscopia de raios-X por energia dispersiva (EDS). As medidas de mapeamento composicional e imagens de MEV revelaram que as nanopartículas estão distribuídas de maneira não homogênea, estando concentradas nas bordas dos Stents para as condições experimentais utilizadas neste trabalho. Assim como os dados de MAV, o EDS dos Stents recobertos revelou um aumento da quantidade de nanopartículas magnéticas adsorvidas em sua superfície com o aumento do tempo de adsorção. O mesmo modelo teórico, agora considerando o percentual de 26Fe na composição química do revestimento, foi capaz de explicar os dados experimentais. Finalmente, foi feita uma comparação, por meio do mapeamento composicional de Stents recobertos, entre as técnicas de Dip Coating e Spray. Esta última apresentou uma distribuição de nanopartículas mais homogênea na superfície da endoprótese, sugerindo que possa ser mais adequada para a confecção de um nanoproduto médico voltado a testes clínicos.

Hintergrund: Diese Studie wurde initiiert, um die langfristige Wertigkeit der Implantation von selbstexpandierenden Nitinol-Stents in der Arteria femoralis superficialis zu untersuchen. Die Effektivität wurde anhand von Primärerfolg, Offenheitsraten und klinischem Erfolg überprüft. Komplikationsraten und unerwünschte Folgeereignisse definierten die Sicherheit dieser interventionellen Therapiemethode. Methoden: Retrospektiv wurden 278 Zielextremitäten von 263 Patienten über durchschnittlich 4,7 ± 1,9 Jahre hinweg beobachtet. Die Daten wurden aus internen Krankenakten sowie externen Befunden gewonnen. Gruppenvergleiche wurden mit t-Test, Fisher-Exact-Test und multivariater logistischer Regression durchgeführt. Überlebenszeitanalysen wurden mit der Kaplan-Meier-Methode berechnet. Univariate Risikofaktoren wurden mit dem Log-Rank-Test bestimmt und anschließend in das multivariate Cox-Model eingeschlossen. Ergebnisse: Das Durchschnittsalter der Patienten betrug 67,2 ± 9,5 Jahre, 74,1 % waren männlich, 21,2 % litten an einer kritischen Extremitätenischämie. Die mittlere Läsionslänge maß 11,5 ± 7,9 cm. Es handelte sich in 21,1 % um Restenosen und in 31,6 % um TASC-II-C/D-Läsionen. Der primäre technische Erfolg der Stentimplantation belief sich auf 96,8 %. Nach ein, drei und fünf Jahren lagen die primären Offenheitsraten bei 77 %, 56 % und 46 %, die sekundären Offenheitsraten bei 98 %, 94 % und 89 % sowie die Majoramputations-raten bei 0,4 %, 1,4 % und 4,2 %. Das Rutherford-Stadium ist von 3 ± 0,9 auf 1,8 ± 1,8 gesunken. Ein Todesfall war Folge eines Stentverschlusses. Signifikante Risikofaktoren für verkürzte Stentoffenheiten waren lange Gefäßläsionen, TASC-II-C/D-Läsionen sowie Luminexx®-Stents. Diabetes mellitus, Adipositas und kritische Extremitätenischämie waren mit erhöhten Amputationsraten assoziiert. Fazit: Hohe technische Erfolgsraten, relativ niedrige Komplikationsraten, befriedigende kurz- und mittelfristige Offenheitsraten sowie zufriedenstellender klinischer Erfolg zeichnen die Stentimplantationen in der Arteria femoralis superficialis aus. Langfristig stellen die Entstehung von In-Stent-Restenosen und damit verbundene Folgen jedoch ein Problem dar. Allerdings ist die Einführung von medikamenten-freisetzenden Ballons zur Sekundärbehandlung in dieser Hinsicht erfolgversprechend.

Background: Drug eluting stents (DES) are preferred over bare metal stents (BMS) for native coronary artery revascularization unless contraindicated. However, the preferred stent choice for saphenous venous graft (SVG) percutaneous coronary interventions (PCI) is unclear due to conflicting results. Methods: PubMed, Clinical trials registry and the Cochrane Center Register of Controlled Trials were searched through June 2018. Seven studies (n = 1639) comparing DES versus BMS in SVG-PCI were included. Endpoints were major adverse cardiac events (MACE), cardiovascular mortality, all-cause mortality, myocardial infarction (MI), target vessel revascularization (TVR), target lesion revascularization (TLR), in-stent thrombosis, binary in-stent restenosis, and late lumen loss (LLL). Results: Overall, during a mean follow up of 32.1 months, there was no significant difference in the risk of MACE, cardiovascular mortality, all-cause mortality, MI, stent thrombosis, TVR and TLR between DES and BMS. However, short-term follow up (mean 11 months) showed lower rate of MACE (OR 0.66 [0.51, 0.85]; p = 0.002), TVR (OR 0.47 [0.23, 0.97]; p = 0.04) and binary in-stent restenosis (OR 0.14 [0.06, 0.37]; p < 0.0001) in DES as compared with BMS. This benefit was lost on long-term follow up with a mean follow up 35.5 months. Conclusion: In this meta-analysis of SVG-PCI, DES use was associated with similar MACE, cardiovascular mortality, all-cause mortality, MI, in-stent thrombosis, TVR and TLR compared with BMS during long-term follow up. There was high incidence of MACE noted in both DES and BMS suggesting a need for exploring novel strategies to treat SVG disease to improve clinical outcomes.

Coronary artery disease (CAD) affects every fifth person in the world. The gold-standard treatment for CAD is stent implantation, however, the existing therapy is not sufficient due to many reasons. For instance, in-stent restenosis, biocompatibility, controlled degradation rate, protein adsorption, and adequate endothelialization are still the main concerns. In the last two decades, the field of stent technology has been grown rapidly and many new stent types and in vitro testing methods for stent characterization have been developed to minimize the aforementioned issues. In this vicinity, there are still many unaddressed issues: i) the quantitative analysis of corrosion is conducted with simpler samples made of stent material instead of stents, in most cases due to the absence of a mathematical model to calculate the entire stent surface area (ESSA); ii) in vitro stent testing in environments that are very far from actual physiological environments; iii) Evaluation of the influence of in-vitro test conditions on coated metallic stents; iv) absence of flow-induced shear stress (FISS) corrosion model, to mention a few. This thesis presents the novel ESSA model, the fluid dynamic experimental setup with the integration of various sensors and pH control, the influence of in vitro degradation behavior of the titanium oxynitride (TiOxNy) coated stainless steel stents and anodized AZ31 samples, and the FISS corrosion model. The results show some important contributions in this field, however, there is still a huge potential for the development of promising stent characterization solutions. / Die koronare Herzkrankheit (KHK) betrifft jeden fünften Menschen auf der Welt. Der Goldstandard bei der Behandlung von KHK ist die Stent-Implantation, doch die bestehende Therapie ist aus vielen Gründen nicht ausreichend. So sind beispielsweise die Restenose im Stent, die Biokompatibilität, die kontrollierte Abbaugeschwindigkeit, die Proteinadsorption und die angemessene Endothelialisierung nach wie vor die Hauptprobleme. In den letzten zwei Jahrzehnten hat sich die Stenttechnologie rasant weiterentwickelt, und es wurden viele neue Stenttypen und In-vitro-Testmethoden zur Stentcharakterisierung entwickelt, um die oben genannten Probleme zu minimieren. In dieser Umgebung gibt es noch viele ungelöste Probleme: i) die quantitative Analyse der Korrosion wird mit einfacheren Proben aus Stentmaterial anstelle von Stents durchgeführt, in den meisten Fällen aufgrund des Fehlens eines mathematischen Modells zur Berechnung der gesamten Stentoberfläche (ESSA); ii) In-vitro-Stent-Tests in Umgebungen, die sehr weit von der tatsächlichen physiologischen Umgebung entfernt sind; iii) Bewertung des Einflusses von In-vitro-Testbedingungen auf beschichtete metallische Stents; iv) Fehlen eines FISS-Korrosionsmodells (flow-induced shear stress), um nur einige zu nennen. In dieser Arbeit werden das neuartige ESSA-Modell, der strömungsdynamische Versuchsaufbau mit der Integration verschiedener Sensoren und pH-Kontrolle, der Einfluss des In-vitro-Degradationsverhaltens der mit Titanoxynitrid (TiOxNy) beschichteten Edelstahlstents und anodisierten AZ31-Proben sowie das FISS-Korrosionsmodell vorgestellt. Die Ergebnisse zeigen einige wichtige Beiträge in diesem Bereich, jedoch gibt es noch ein großes Potenzial für die Entwicklung von vielversprechenden Lösungen zur Charakterisierung von Stents.

Les endoprothèses sont devenues une solution thérapeutique de choix pour les anévrismes aortiques. Même si leur bénéfice à long terme face à la chirurgie ouverte reste incertain, elles permettent de réduire la mortalité et les complications postopératoires précoces. Elles sont toutefois soumises à un certain nombre de contraintes anatomiques. Il y a encore quinze ans, elles étaient contre-indiquées dans le traitement des anévrismes débutant au niveau ou au-dessus des artères rénales, à savoir les anévrismes juxta et suprarénaux (AJSR) et les anévrismes thoraco-abdominaux (ATA). Le développement d'endoprothèses fenêtrées et/ou branchées (EPFB) a permis de proposer une solution endovasculaire à ces patients. Il s'agit d'endoprothèses munies d'orifices ou de branches latérales destinées à maintenir la perfusion des artères rénales et viscérales. Plusieurs études rétrospectives ont rapporté des résultats encourageants à court et moyen terme. Il s'agit néanmoins de techniques complexes, exposées à la survenue de problèmes techniques au niveau des artères cibles (rénales et viscérales) et des voies d'accès fémorales. Les résultats des EPFB nous semblent améliorables par une optimisation de la sélection des patients, par des innovations techniques apportées aux dispositifs implantables, ainsi que l'amélioration des techniques d'imagerie et de navigation endovasculaire. En raisons des délais de fabrication (> 6 semaines), les patients nécessitant un traitement rapide (anévrismes douloureux ou volumineux) échappent par ailleurs aux EPFB manufacturées.Les objectifs de cette thèse étaient: (1) d'évaluer dans notre expérience la fréquence et la nature des problèmes techniques peropératoires, et d'analyser leur impact sur les suites cliniques immédiates; (2) d'évaluer la faisabilité et les performances sur modèle in vitro de la navigation endovasculaire utilisant un système de navigation électromagnétique (StealthStation®, Medtronic); (3) d'évaluer la faisabilité et la sureté de la navigation robotique au cours de la mise en place d'une EPFB; (4) d'analyser les résultats à court terme des endoprothèses avec fenêtres créées à façon par le chirurgien pour des patients porteurs d'anévrismes complexes nécessitant un traitement rapide.Au cours de ce travail, nous avons tout d'abord montré qu'en début d'expérience (113 premiers patients), les problèmes techniques peropératoires n'étaient pas rares (30 % des patients) et que ceux-ci aboutissaient dans plus de la moitié des cas à des complications postopératoires. Ces problèmes techniques sont certes en partie évitables par l'amélioration de la sélection des patients et l'expertise de l'équipe soignante, mais nous pensons que le développement de nouveaux outils d'imagerie et de navigation pourrait également jouer un rôle clé. C'est sur ce dernier point que nous avons accentué nos recherches. Bien qu'une amélioration des performances techniques de la navigation électromagnétique soit nécessaire, nous avons pu montrer qu'elle permettait de fournir des informations complémentaires à la fluoroscopie, notamment lors des étapes de déploiement de l'endoprothèse et de cathétérisme des artères cibles. Plus que concurrente de la fluoroscopie, elle pourrait être utilisée de façon combinée dans le but de diminuer l'irradiation par les rayons X et d'améliorer les performances de la navigation. Nous avons également pu montrer les bénéfices potentiels de la navigation robotique lors de la mise en place d'endoprothèses branchées et ses limites actuelles pour assister de façon efficace les procédures fenêtrées. Enfin, dans une série limitée (n=11) de patients porteurs d'ATA, nous avons montré que l'utilisation d'endoprothèses avec fenêtres créées à façon par le chirurgien était à même de fournir des résultats précoces comparables (mortalité hospitalière : 9%, ischémie médullaire : 9%) à ceux des EPFB, et constituait une solution à considérer pour les patients nécessitant un traitement rapide. / Aortic stent grafts have gained widespread acceptance for the treatment of aortic aneurysms. When compared with open repair, they have been shown to reduce significantly postoperative mortality and complication rates. However, these benefits remain uncertain in the long-term and aortic stent grafts are still limited by anatomic restrictions. Fifteen years ago, patients with complex aneurysms such as juxtarenal, suprarenal and thoracoabdominal aneurysms were not eligible for endovascular repair. With the development of fenestrated and branched stent grafts (FBSG), it is now possible to offer an endovascular solution to these patients. FBSG contains holes (fenestrations) or lateral branches. Their purpose is to allow the proximal margin of the device to sit higher than standard infrarenal devices and allow uninterrupted blood flow to renal and visceral vessels. Retrospective studies have shown encouraging short-term and mid-term results. However, fenestrated/ branched stent grafting remains a complex procedure, associated with significant risks of technical problems such as target vessel loss and difficulties with iliac or femoral accesses. Results of FBSG could be further improved by optimizing patient selection, technical innovation to optimize currently available devices, and developments of new imaging and navigation tools. In addition, due to manufacturing delays (6-10 weeks), FBSG are not applicable to high-risk patients who need rapid treatment (painful or large aneurysms).The objectives of this thesis were: (1) to evaluate the incidence and define the nature of unexpected intraoperative adverse events and analyse their impact on the postoperative outcome; (2) to evaluate in vitro the feasibility and the performances of electromagnetic navigation using a new device (StealthStation®, Medtronic); (3) to evaluate the feasibility and safety of robotic navigation for target vessel cannulation; (4) to analyse short-term results of physician modified stent grafts for patients with complex aortic aneurysms needing rapid treatment.During this work, we showed that intraoperative adverse events were not rare (30% of the first 113 patients) during our early experience. They were responsible for postoperative complications in more than 50 % of cases. Optimal patient selection and increased experience of the medical staff may reduce the incidence of technical problems. However, we believe the development of new imaging modalities and navigation tools could play a key role to limit their occurrence. Although further developments are mandatory, the use of electromagnetic navigation as a complementary imaging modality, as tested with the StealthStation®, might be beneficial in terms of radiation exposure, cannulation performances, and accuracy in the positioning of FBSG. We also showed that robotic cannulation of renal and visceral vessels during complex endovascular aortic procedures is feasible and safe. In our experience, it was more effective for branches than for fenestrations. Finally, we used physician modified stent grafts in a limited series of eleven patients with thoracoabdominal aortic aneurysms. With a 9% in-hospital mortality rate and a 9% rate of spinal cord ischemia, they provided similar results to those of manufactured FBSG, suggesting they might be an option to consider for high-risk patients needing rapid treatment.

O Brasil é um país em desenvolvimento que luta para reduzir sua desigualdade social extrema. Isso se reflete na falta de infraestrutura de cuidados de saúde, principalmente para a classe de baixa renda, que depende exclusivamente do sistema de saúde pública. No Brasil, menos de 1% dos pacientes com acidente vascular cerebral (AVC) têm acesso a trombólise intravenosa em uma unidade especializada de AVC e as limitações para a implementação da trombectomia mecânica nos hospitais públicos aumentam a carga social do AVC. Objetivo: Avaliar a viabilidade da trombectomia mecânica como parte do tratamento de rotina em um hospital universitário público brasileiro. Pacientes e Métodos: Foram coletados dados prospectivos de todos os pacientes com acidente vascular cerebral isquêmico (AVCI) agudo tratados por trombectomia mecânica de junho de 2011 a março de 2016. A trombectomia combinada foi realizada em pacientes elegíveis para trombólise intravenosa e com presença de oclusão de grandes artérias. Para os pacientes não elegíveis para trombólise intravenosa, foi realizada a trombectomia mecânica desde que não existisse evidência de isquemia significativa de circulação anterior (escala de pontuação Alberta Stroke Program Early CT > 6), dentro de uma janela de tempo de 6 horas; e também para pacientes com AVCI ao desperdar ou de circulação posterior, independente do tempo de início dos sintomas. Resultados: Um total de 161 pacientes foram avaliados, resultando em uma taxa de recanalização global bem sucedida de 76% e taxa de hemorragia intracraniana sintomática de 6,8%. Após 3 meses, 36% dos pacientes apresentaram um índice da Escala de Rankin modificada inferior ou igual a 2. A taxa de mortalidade geral foi de 23%. Conclusão: Nosso estudo foi a primeira série grande de trombectomia mecânica no Brasil e demonstrou resultados aceitáveis de eficácia e segurança, mesmo em condições restritas, fora do cenário ideal dos estudos clínicos randomizados. / Brazil is a developing country struggling to reduce its extreme social inequality, which is reflected on shortage of health-care infrastructure, mainly to the low-income class, which depends exclusively on the public health system. In Brazil, less than 1% of stroke patients have access to intravenous thrombolysis in a stroke unit, and constraints to the development of mechanical thrombectomy in the public health system increase the social burden of stroke. Objective: Report the feasibility of mechanical thrombectomy as part of routine stroke care in a Brazilian public university hospital. Patients and methods: Prospective data were collected from all patients treated for acute ischemic stroke with mechanical thrombectomy from June 2011 to March 2016. Combined thrombectomy was performed in eligible patients for intravenous thrombolysis if they presented occlusion of large artery. For those patients ineligible for intravenous thrombolysis, primary thrombectomy was performed as long as there was no evidence of significant ischemia for anterior circulation stroke (Alberta Stroke Program Early CT score >6) within a 6-hour time window, and also for those patients with wake-up stroke or posterior circulation stroke, regardless of the time of symptoms onset. Results: A total of 161 patients were evaluated, resulting in an overall successful recanalization rate of 76% and symptomatic intracranial hemorrhage rate of 6.8%. At 3 months, 36% of the patients had modified Rankin Scale score less than or equal to 2. The overall mortality rate was 23%. Conclusion: Our study, the first ever large series of mechanical thrombectomy in Brazil, demonstrates acceptable efficacy and safety results, even under restricted conditions outside the ideal scenario of trial studies.