L'anévrisme de l'aorte abdominale est une pathologie devant être traitée par chirurgie quand son diamètre atteint 5.5cm, en raison d’un risque de rupture qui est souvent mortelle. La chirurgie endovasculaire consiste à déployer une endoprothèse dans l’anévrisme pour l’exclure de la circulation sanguine. Cette chirurgie souffre cependant d'un taux relativement élevé de complications post-opératoires à long terme, nécessitant des interventions coûteuses. Ces complications sont principalement d’origine mécanique et pourraient être anticipées grâce à la simulation numérique.Cette thèse a pour objectif d'élaborer une méthodologie de simulation personnalisée de déploiement d'endoprothèses dans des anévrismes, dans le but final de fournir un outil d'aide à la décision aux praticiens hospitaliers pour améliorer leur planning pré-opératoire.Une méthodologie permettant de déployer numériquement des endoprothèses bifurquées, composées de plusieurs modules, dans des anévrismes aortiques personnalisés, de géométries quelconques, a été conçue. Des simulations numériques ont été effectuées sur cinq cas cliniques réels, dont des cas fortement tortueux et complexes àplanifier pour les praticiens hospitaliers. La méthodologie a été validée par comparaison des résultats numériques avec la position des stents sur les scanners post-opératoires.La capacité de la méthodologie numérique à simuler le déploiement d’endoprothèses dans des géométries personnalisées d’anévrismes aortiques a été démontrée. Ces simulations possèdent un fort potentiel, en pouvant permettre de mieux adapter les endoprothèses aux patients et d’anticiper les complications post-opératoires dès le planning pré-opératoire. / Abdominal aortic aneurysm is a pathology which needs to be treated by surgery when its diameter reaches 5.5cm, due to high risk of rupture that is often lethal. Endovascular repair consists in deploying a stent-graft inside the aneurysmal sac to exclude it from the blood flow. However, the drawback of this surgery is the relatively important post-operative complication rate at long-term, requiring costly secondary interventions. The origin of these complications is mainly related to mechanics and therefore, they could be prevented thanks to numerical simulation.The objective of this thesis is to elaborate a simulation methodology to deploy in silico stent-grafts in patient-specific aneurysms. The ultimate goal is to provide practioners with a computer aided decision tool to improve their pre-operative planning.A methodology was developed to simulate the deployment of bifurcated stent-grafts, composed of several modules, in patient-specific aortic aneurysms, whatever their geometry. Finite-element analyses were performed on several clinical cases from real patients, some of them which were highly tortuous and complex for practioners to achieve an accurate preoperative planning. The methodology was validated by comparing numerical results with the position of the stents in the post-operative scans.The ability of finite-element analyses to simulate stent-graft deployment in patient-specific aortic aneurysm geometries was proved in this thesis. Simulations have great potential for adapting stent-grafts to each patient and for anticipating possible post-operative complications at the stage of pre-operative planning.

Economic evaluations provide a tool to estimate costs and health consequences of competing medical technologies, ultimately to aid decision makers when deciding which medical technologies should be funded from available resources. Such decisions inevitably need to be taken under uncertainty and it is not clear how to approach them in health care decision-making. Recent work in economic evaluation has proposed an analytic framework where two related, but conceptually different decisions need to be considered: (1) should a medical technology be adopted given existing evidence; and (2) whether more evidence should be acquired to support the adoption decision in the future. The proposed analytic framework requires a decision-analytic model appropriately representing the clinical decision problem under consideration, a probabilistic analysis of this model in order to determine cost-effectiveness and characterise current decision uncertainty, and estimating the value of additional information from research to reduce decision uncertainty. The main aim of this thesis is to apply the analytic framework on three case studies concerning treatment strategies for cardiovascular disease in order to establish whether the treatment strategies should be adopted given current available information and if more information should be acquired to support the adoption decisions in the future. The implications for policy and methodology of utilising the analytic framework employed in the case studies are also discussed in this thesis. The results of the case studies show that a screening programme for abdominal aortic aneurysm in 65-year-old men is likely to be cost-effective in a Swedish setting and there appears to be little value in performing further research regarding this decision problem; an early interventional strategy in non-ST-elevation acute coronary syndrome is cost-effective for patients at intermediate to high risk of further cardiac events in a UK setting; endarterectomy in patients with an asymptomatic carotid artery stenosis is cost-effective for men around 73 years of age or younger in a Swedish setting and conducting further research regarding this decision problem is potentially worthwhile. Comparing the results of the present analyses with current clinical practice shows a need for changing clinical practice in Sweden regarding screening for abdominal aortic aneurysm and endarterectomy in patients with asymptomatic carotid artery stenosis. Furthermore, employing the analytic framework applied in the case studies can improve treatment guidelines and recommendations for further research. In particular, treatment guidelines ought to consider in which particular subgroups of patients an intervention is cost-effective. The case studies indicate that it is feasible to apply the analytic framework for economic evaluation of health care. Methodological development can improve the accuracy with which cost-effectiveness and value of information is estimated, but may also lead to comprehensive and complex evaluations. The nature of the decision problem should determine the level of comprehensiveness required for a particular evaluation.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Colonic ischaemia (CI), Intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS) are devastating complications after abdominal aortic aneurysm (AAA) surgery. The aims of this thesis were to study the incidence and clinical consequences of IAH/ACS and the association between CI and intra-abdominal pressure (IAP) among patients undergoing OR for ruptured AAA (rAAA), to compare extraluminal pHi monitoring, with standard intra-luminal monitoring among patients operated on for AAA, and to study the frequency and clinical consequences of IAH/ACS after endovascular repair (EVAR) for rAAA. The incidence of ACS was 26% in a retrospective study of 27 patients undergoing OR for rAAA. Consensus definitions on IAH/ACS were appropriate for patients after OR for rAAA: 78% (7/9) of patients with IAH grade III or IV developed organ failure and all patients who developed CI had some degree of IAH. Active fluid resuscitation treating hypovolaemia to avoid CI may partly cause IAH. The association between CI and IAP was investigated in a prospective study on 29 patients operated on for rAAA, 86% (25/29) were treated for hypovolaemia and ten (34%) had both IAH and CI. Since monitoring colonic perfusion is very important and there is no ideal method, a new technique, extraluminal colonic tonometry to detect colonic perfusion was compared with standard intraluminal tonometry. Although, this new method was not able to determine the severity of ischaemia it may serve as a screening test. EVAR of rAAA is feasible and patients may benefit from this less invasive procedure. Of 29 patients treated with this technique, 10% developed ACS, and all patients except one with preoperative shock developed some degree of IAH. In conclusion, IAP/ACS is common after both OR and EVAR for rAAA, and is associated with adverse outcome. Monitoring IAP and colonic perfusion with timely intervention may improve outcome.

L'objectif de cette thèse est de développer de nouveaux textiles biomimétiques pour réaliser des prothèses vasculaires au comportement mécanique proche de celui de l'aorte native, afin de limiter les problèmes post-opératoires observés actuellement. Afin d'établir le cahier des charges, un modèle de comportement de l'AA inspiré d'un modèle multicouches a été ajusté sur des essais biaxiaux de la littérature réalisés sur des échantillons d'AA excisés, pour trois groupes d'âge distincts. Ce modèle a ensuite été implémenté dans un code de calculs par éléments finis afin de simuler le comportement mécanique de l'aorte saine soumise à un ensemble de sollicitations mécaniques, tant à l'échelle du matériau (traction uni et biaxiale, flexion) qu'à celle de la structure (gonflement avec pré-élongation, flexion, compression diamétrale). Dans un second temps, des essais de caractérisation couplés à des mesures par imagerie ont été mis en œuvre sur des prothèses du commerce, avec les mêmes conditions limites et de chargement que les simulations numériques. Ces essais ont permis d'identifier les écarts de comportement mécanique entre les prothèses actuelles et l'aorte native. Afin de pallier à cela, la dernière partie de ce travail a été consacrée au développement de nouveaux textiles biomimétiques, i.e mimant le comportement mécanique de l'aorte native ainsi que ses principales caractéristiques histologiques (« ondulation » et « orientations de fibres privilégiées»), réalisables à l'échelle industrielle par technologie « tricot maille jetée ». Dans un premier temps, le comportement mécanique de plusieurs multifilaments en PET avec différents titres, nombres de filaments et différentes textures, a été étudié après plusieurs traitements (thermique…). Ceci a permis de sélectionner un fil en particulier pour la réalisation des textiles. Par la suite, une première optimisation des paramètres de fabrication (armure, densité de mailles, jauge) a été réalisée pas-à-pas à travers plusieurs campagnes de réalisations et de caractérisations de tricots plans en sollicitation uniaxiale et biaxiale. Enfin, des premiers essais de mise en forme tubulaire ont été réalisés à partir des textiles optimisés. Deux procédés de mise en forme ont été développés : tubes cousus / tubes tramés. La production de « tubes tramés » continus est une technologie innovante à notre connaissance, et prometteuse. Le comportement mécanique des tubes réalisés a été caractérisé en gonflement pour une première évaluation. Plus spécifiquement, l'effet des procédés appliqués sur les textiles médicaux (lavage, traitement thermique, enduction) a été testé sur des échantillons de tube tramé et de textiles plans. Ces premiers essais ont montré qu'en pilotant les paramètres de ces différents traitements et plus particulièrement ceux du traitement thermique, il est possible de moduler le comportement mécanique des tricots afin qu'il s'approche au mieux de celui de l'AA. / This thesis aims at developing new biomimetic textiles to design vascular prostheses with a mechanical behavior close to the one of the host aorta, in order to reduce current post-operative problems. To define the ideal target properties, a AA mechanical model was chosen, based on a multi-layered model from the literature. The model parameters were adjusted on biaxial tensile data reported in the literature, performed on excised AA samples for three different age groups. Then, this model was implemented in a finite element code in order to simulate the mechanical behavior of the healthy aorta submitted to various mechanical loadings, both at the material's scale (uni- and biaxial tensile tests, bending) and at the structure's scale (inflation with prestretch, bending, diametric compression). Secondly, several commercial prostheses were characterized using dedicated experimental devices combined with image recordings. The prostheses were tested under the same boundary and loading conditions as the ones used in the numerical simulations. These tests showed that the actual prostheses are not fully mechanically compatible with the host aorta. In order to solve this problem, the last part of this work was dedicated to the design of new biomimetic textiles, i.e. mimicking the healthy aorta's mechanical behavior and main histologic properties (“wavy fibres” and “preferred fiber orientations”), which can be produced industrially using “warp knitting” technology. Firstly, the mechanical behavior of several PET yarns made of different titers, filament numbers and textures were characterized after several treatments (thermal, etc.). This step enabled to identify one specific yarn to produce the biomimetic textiles. Then, a first optimization of the manufacturing parameters (weave, gauge, density, etc.) was made step by step by means of several textile production and planar tests (uni- and biaxial tensile tests). Finally, several trials were conducted to design tubular structures from the optimized textiles. Two shaping methods were developed: sewed tubes / weaved tubes. The continuously “weaved tubes” production is an innovative and promising technology as far as we know. The mechanical behavior of the new tubes was characterized using inflation tests for a first assessment. More specifically, the effect of the treatments usually applied on medical textiles (cleaning, thermal treatment, coating) was tested on weaved tubes and planar textiles samples. By adjusting the parameters of the several processes - and mostly those of thermal treatments – it was possible to adjust the textiles' mechanical behavior in order to make it the closest to the AA's one.

Dans ce travail de thèse, on s’intéresse au traitement endovasculaire de l’anévrisme de l’aorte abdominale (EVAR). Cette technique mini-invasive couramment utilisée et connaît une croissance importante depuis 10 ans. Elle repose sur l’exclusion du sac anévrismal par le déploiement au niveau de l’anévrisme d’une ou plusieurs endoprothèses introduites par voies fémorales. Au cours de l’intervention, plusieurs types d’outils de rigidité variable sont introduits pour permettre la navigation de l’endoprothèse. La structure vasculaire subit alors des déformations importantes. Ces déformations sont en général sans incidence sur le bon déroulement de l’intervention. Cependant dans certains cas, notamment pour les patients présentant des anatomies défavorables (fortes tortuosités ou angulations, important degré de calcification, longueur importante des artères iliaques communes et externes) les déformations produites par l’insertion des guides rigides peuvent avoir des conséquences sur le déroulement de l’intervention. Actuellement leur anticipation repose principalement sur l’expérience du chirurgien. La simulation mécanique semble être un outil adapté pour fournir des indicateurs plus objectifs et utiles au praticien lors du planning de son intervention : cette pratique permettrait en guidant et sécurisant le geste chirurgical de diminuer potentiellement les risques de complications peropératoires et postopératoires. La première étape du travail a consisté à développer un modèle mécanique de la structure aorto-iliaque et une méthode de simulation permettant de répondre au problème mécanique posé. Ce modèle a été paramétré de façon patient-spécifique à partir des données préopératoires disponibles. Puis la deuxième étape du travail a consisté à valider la modélisation développée en la confrontant à des données peropératoires réelles obtenus sur 28 cas de patients opérés au CHU Rennes. L’ensemble des méthodes développées à enfin été intégré à un module de démonstration du logiciel EndoSize® (Therenva, France). / Endovascular Aneurysm Repair (EVAR) is a mini-invasive technique that is commonly used to treat Abdominal Aortic Aneurysms (AAA). It relies on the exclusion of the aneurysm sac by introducing one or more stent-grafts through the femoral arteries and deploying them inside the aneurysm. During the procedure, several tools of varying stiffness are introduced to enable the delivery of the stent graft to its deployment site. During this process, the vascular structure undergoes major deformations. Usually, these have no consequence on the smooth progress of the procedure. However, in some instances, particularly when the patient presents an unfavorable anatomical profile (major tortuousness or angulation, deep calcification, long length of the common and external iliac arteries), the deformation caused by the insertion of stiff guidewires can have major consequences. Today, their prediction relies mainly on the surgeon’s experience. Numerical simulation appears to be an appropriate tool to give the practitioner more objective and more useful indicators when planning the procedure: guiding the surgical act and making it safer using such an approach would potentially reduce the risks of intraoperative and postoperative complications. In the first step of the work, we developed a mechanical model of the aorto-iliac vascular structure and a simulation methodology to answer the mechanical problem. This patient-specific model has been parametrized based on available preoperative data. Then the second step of the work consisted in the validation of this model by confronting the simulation results to real intraoperative 3D data that were collected on 28 cases of patients operated at the University Hospital of Rennes. All the methods that were developed during this PhD were integrated in demonstration module of EndoSize® software (Therenva, France).

Dissertation Abstract Abdominalaortic aneurysm (AAA) is a serious disease. Its prevalence is in the developed countries about 3%. As an aneurysm is considered a dilatation of all layers of a vessel wall over 3 cm. Majority of AAA are small and asymptomatic, and although the risk of rupture increases with the size of aneurysm sack, even the small aneurysms rupture. The rupture mortaliry ranges about 70 %. Surgical treatment is indicated in the asymptomatic patients in diameter of AAA over 5 cm. The average speed of growth of AAA is 0.3 cm per year, e.g. in the early diagnosed patients there is a several years interval for a pharmacolocical influencing of the progression of this disease. Knowledge of pathogenesis is essential for any targeted pharmacological treatment. Our prospective, non-randomised studies are based on the application of the stereological methods for the histopathological assessment of the AAA samples. The acquired data enable the statistical analysis, including the null hypothesis testing. In our study analyzing the histopathology of AAA aortae of 65 patients (65 walls and 55 thrombi) and 6 normal abdominal aortae from the organ donors we assessed the following parameters: the area fractions of collagen and elastin, and the length density of elastin in intima and media, the area...

L'objectif de ce travail est de contribuer à une meilleure prédiction de la rupture des Anévrismes de l'Aorte Abdominale. Pour ce faire, des simulations par éléments finis ont été mises en oeuvre sur des anévrismes modèles dans des conditions proches de la réalité physiopathologique, i.e. en tenant compte de l'anisotropie de la paroi anévrismale, du caractère poreux du thrombus et des Interactions Fluide-Structure. Dans la première partie, une étude statique en l'absence du thrombus a permis de mettre en évidence l'influence de la géométrie de l'anévrisme et du comportement mécanique (isotrope ou anisotrope) de la paroi sur la distribution des contraintes, i.e. la rupture potentielle de l'anévrisme, ainsi que sur l'évolution du module de Peterson. Dans la seconde partie, une modélisation poro-hyperélastique du thrombus est proposée, en s'appuyant sur des données expérimentales de la littérature. La prise en compte de ce comportement et des Interactions Fluide-Structure montre que la pression intra-thrombus demeure du même ordre de grandeur que la pression intra-luminale, conformément à des mesures in vivo réalisées par ailleurs. Enfin, nous montrons que ceci n'est pas en contradiction avec une réduction du risque de rupture potentielle de l'anévrisme. / The aim of this work is to contribute to a better prediction of the Abdominal Aortic Aneurysm rupture (AAA). For that purpose, finite elements simulations have been performed on idealized AAA models under physiopathological like conditions, by taking into account the aneurysmal wall anisotropy, the intra-luminal thrombus porosity and the Fluid-Structure Interactions. In the first part, the influence of the aneurysm geometry and its wall properties (isotropic or anisotropic hyperelasticity) on the wall stress distribution and the Peterson's modulus has been studied in a static analysis and without taking into account the thrombus. In the second part, based on the experimental results from the litterature, a porohyperelastic model has been proposed for the thrombus. By considering such behavior for the thrombus and the Fluid-Structure Interactions, we observe that the intra-thrombus pressure is the same order as the intra-luminal pressure, which is consistent with in vivo measurements. Our results show that despite this unchanged pressure, the maximum wall stress decreases leading to a decrease of the aneurysm potential rupture.

Les maladies cardiovasculaires sont la première cause de mortalité dans le monde chez les personnes âgées de plus de 65 ans. Parmi les maladies artérielles, l'anévrisme, maladie asymptomatique, est une dilatation localisée et permanente de la paroi d'une artère aboutissant à la formation d'une poche de taille variable. Soumis aux impulsions sanguines, l'anévrisme augmente progressivement et lorsqu'il se rompt, provoque une hémorragie interne pouvant entraîner la mort. Ce projet de recherche concerne le traitement endovasculaire des Anévrismes de l'Aorte Thoracique dont le traitement consiste à déployer une endoprothèse par voie fémorale. Actuellement, les chirurgiens planifient leurs interventions uniquement à partir d'informations issues de l'imagerie médicale. Cette procédure n'est pas totalement fiable et des limites liées à des configurations anatomiques complexes et à la difficulté du geste minimalement invasif persistent. Dans ce contexte, l'objectif est de développer un outil numérique réalisant des simulations virtuelles de ce traitement endovasculaire. Afin d'appréhender le comportement mécanique complexe du tissu artériel, des expérimentations avec une technique de corrélation d'images ont été réalisées sur des prélèvements humains d'aortes thoraciques. Des simulations d'écoulement sanguin dans l'aorte thoracique ont ensuite été réalisées chez un patient sain avec le logiciel OpenFOAM dans lequel un modèle rhéologique prenant en compte les effets viscoélastique et rhéofluidifiant du sang a été développé. En parallèle et en prévision de la modélisation complète de l'acte chirurgical, des calculs numériques sur la montée des outils chirurgicaux dans l'aorte thoracique ont été réalisés en se basant sur des travaux précédents au laboratoire sur la montée des outils dans l'aorte abdominale. L'approche envisagée s'inscrit ainsi dans le cadre des gestes médicaux et chirurgicaux assistés par ordinateur afin de proposer une solution personnalisée opérationnelle pour le choix d'un système de largage et d'une endoprothèse adaptés. / Cardiovascular diseases are the leading cause of death worldwide. Their analysis leads to multidisciplinary problems that require diversity, transversal and complementary approaches. This contribution is part of a research project in Computer Aided Surgery and intends to contribute to the improvement of TEVAR procedures in terms of accuracy and optimization of the operating strategy. In this study, stereocorrelation technique is used to measure the strain field under a human aortic arch in order to identify its mechanical behaviour. Blood flow simulations in the thoracic aorta were then carried out for a healthy patient using the open source OpenFOAM software. A rheological model derived from polymer rheology, considers viscous, shear thinning and other stress overshoot behaviours. In parallel and in anticipation of the complete modeling of the surgical procedure, numerical calculations ofthe rise of the surgical tools in the thoracic aorta were carried out based on previous work in the laboratory regarding the abdominal aorta. This study aims to virtually simulate the whole endovascular stent graft procedure for an aortic aneurysm. This procedure has a high rate of short-term success and its indication compared to open surgery is increasing. Despite many benefits such as reduced blood loss and reduced recovery time, the hindsight is insufficient and there are limitations related to complex anatomical configurations. This procedure therefore needs to be more reliable and secure. In this context, it is important to identify the mechanical behavior of the aorta for further numerical simulations.

Submitted by José Elias da Silva Júnior null (jedsjunior@hotmail.com) on 2018-02-28T17:41:26Z No. of bitstreams: 1 TESE FINAL CORRIGIDA.pdf: 992178 bytes, checksum: 6cf7663fc6a01c288850e2c6ea550472 (MD5) / Approved for entry into archive by ROSANGELA APARECIDA LOBO null (rosangelalobo@btu.unesp.br) on 2018-03-05T17:48:49Z (GMT) No. of bitstreams: 1 silvajunior_je_me_bot.pdf: 992178 bytes, checksum: 6cf7663fc6a01c288850e2c6ea550472 (MD5) / Made available in DSpace on 2018-03-05T17:48:49Z (GMT). No. of bitstreams: 1 silvajunior_je_me_bot.pdf: 992178 bytes, checksum: 6cf7663fc6a01c288850e2c6ea550472 (MD5) Previous issue date: 2017-08-25 / INTRODUÇÃO: A correção endovascular do aneurisma de aorta abdominal (EVAR) modificou o tratamento desta patologia, reduzindo a mortalidade e as complicações, á curto prazo quando comparada à cirurgia aberta. Ainda assim, os pacientes necessitam de seguimento rigoroso a fim de reconhecer as possíveis complicações. O crescimento do diâmetro do saco aneurismático pós-EVAR está relacionado ao risco de rotura ou necessidade de reabordagem, sendo que alguns fatores pré-operatórios podem prever esse aumento. OBJETIVO:Identificar se os sintomas pré-tratamento EVAR podem ser um fator preditivo para a continuidade da expansão do saco aneurismático após tratamento, no seguimento em 12 meses. MATERIAL E MÉTODOS: Estudo retrospectivo realizado através da coleta de dados do prontuário dos pacientes em seguimento na Faculdade de Medicina de Botucatu e que preencheram critérios de inclusão. Os pacientes foram separados em dois grupos de estudos: G1- Pacientes assintomáticos quanto a presença do aneurisma de aorta infrarenal; G2- Pacientes sintomáticos quanto a presença do aneurisma de aorta infrarenal. Todos os grupos foram acompanhados por 12 meses e avaliados quanto ao crescimento do saco aneurismático após o procedimento endovascular, através de AngioTC e Duplex Scan e coleta do exame “proteína C Reativa” para avaliação inflamatória relacionada ao EVAR. RESULTADOS: Foram 9 estudados 112 pacientes. A faixa etária apresentou uma média de 68,6 anos. 80% eram do sexo masculino e 95% brancos. A maioria dos pacientes eram hipertensos e fumantes, 74,1% e 67% respectivamente. No total houve 22,3% de endoleak e o aumento do saco aneurismático foi de 26,8%. Avaliando todos os pacientes, ocorreu diminuição do diâmetro do AAA em média de 0,8cm, entre o pré e pós-operatório. Observou se que 25,3% dos assintomáticos e 30% dos sintomáticos tiveram crescimento do saco aneurismáticos. A presença de endoleak ocorreu em 19% dos assintomáticos e 41,2% dos sintomáticos. No total, 40 % dos pacientes que evoluíram com aumento do saco aneurismático apresentavam endoleak. CONCLUSÃO: Os pacientes que tiveram dor no pré-operatório, portanto, sintomáticos, apresentaram uma taxa numérica maior do crescimento do saco aneurismático em relação ao grupo que não apresentava sintomas, mas este achado não foi estatisticamente significante. A presença do endoleak não foi a única causa do crescimento dos AAAs. Não houve diferença do PCR colhido no pré-operatório em relação ao crescimento do AAA em ambos os grupos. A hipertensão arterial foi a comorbidades mais frequente na nossa casuística. / BACKGROUND: The endovascular repair of abdominal aortic aneurysm (EVAR) modified its treatment, reducing the mortality and complications in short-term compared to open repair. Even though, patients need strict follow-up to identify possibly complications. The sac aneurysm enlargement after EVAR is related to the risk of rupture or reintervention, with some preoperative factors can predict this enlargement. OBJECTIVE: Identify if the AAA symptons, especially pain, are predictors of abdominal aortic aneurym sac enlargement after EVAR. METHODS: Retrospective study through the gathering of data about the patientes in follow-up in Botucatu School Medicine. The patients were separated in two groups: G1 – assymptomatics in the preoperative; G2 – syptomatic in the preoperative. Both groups were followed-up for 12 months to the sac enlargement through AngioCT, duplex scan and Reative-C-Protein. RESULTS: 112 patientes were analysed. The age average was 68,6 years. 80% were male and 95% white. Most of them were hypertensive and smoker, 74,1% and 67% respectively. There was 22,3% of endoleaks and 26,8% sac enlargement ratio. 25,3% of the assymptomatics and 30% of the symptomatics had sac enlargement. 19% of the assymptomatics compared with 41,2% of the symptomatics had endoleak. 40% of the patients with sac enlargement had endoleaks. CONCLUSION: The symptomatics preoperative patients has a higher risk compared with assymptomatic group. The endoleak is not the only 11 reason for the AAA sac enlargement. There was no difference between the groups G1 and G2 related to AAA sac enlargement and Reative-CProtein. Hypertension was the most prevalent comorbidity in our study.