Le but de cette étude est d’évaluer la faisabilité de l’analyse tomodensitométrique 3D des bioprothèses aortiques pour faciliter leur évaluation morphologique durant le suivi et d’aider la sélection de cas et améliorer la planification d’une procédure valvein-valve. Le challenge était représenté par le rehaussement des feuillets valvulaires, en raison d’images très bruitées. Un angio-scanner synchronisé était réalisé chez des patients porteurs d’une bioprotèses aortique dégénérée avant réintervention (images in-vivo). Différentes méthodes pour la réduction du bruit étaient proposées. La reconstruction tridimensionnelle des bioprothèses était réalisée en utilisant des méthodes de segmentation de régions par "sticks". Après réopération ces méthodes étaient appliquées aux images scanner des bioprothèses explantées (images ex-vivo) et utilisées comme référence. La réduction du bruit obtenue par le filtre stick modifié montrait meilleurs résultats en rapport signal/bruit en comparaison aux filtres de diffusion anisotropique. Toutes les méthodes de segmentation ont permis une reconstruction 3D des feuillets. L’analyse qualitative a montré une bonne concordance entre les images obtenues in-vivo et les altérations des bioprothèses. Les résultats des différentes méthodes étaient comparés par critères volumétriques et discutés. Les bases d'une première approche de visualisation spatio-temporelle d'images TDM 3D+T de la prothèse valvulaire ont été proposés. Elle implique des techniques de rendu volumique et de compensation de mouvement. Son application à la valve native a aussi été envisagée. Les images scanner des bioprothèses aortiques nécessitent un traitement de débruitage et de réduction des artéfacts de façon à permettre le rehaussement des feuillets prothétiques. Les méthodes basées sticks semblent constituer une approche pertinente pour caractériser morphologiquement la dégénérescence des bioprothèses. / The aim of the study was to assess the feasibility of CT based 3D analysis of degenerated aortic bioprostheses to make easier their morphological assessment. This could be helpful during regular follow-up and for case selection, improved planning and mapping of valve-in-valve procedure. The challenge was represented by leaflets enhancement because of highly noised CT images. Contrast-enhanced ECG-gated CT scan was performed in patients with degenerated aortic bioprostheses before reoperation (in-vivo images). Different methods for noise reduction were tested and proposed. 3D reconstruction of bioprostheses components was achieved using stick based region segmentation methods. After reoperation, segmentation methods were applied to CT images of the explanted prostheses (exvivo images). Noise reduction obtained by improved stick filter showed best results in terms of signal to noise ratio comparing to anisotropic diffusion filters. All segmentation methods applied to the best phase of in-vivo images allowed 3D bioprosthetic leaflets reconstruction. Explanted bioprostheses CT images were also processed and used as reference. Qualitative analysis revealed a good concordance between the in-vivo images and the bioprostheses alterations. Results from different methods were compared by means of volumetric criteria and discussed. A first approach for spatiotemporal visualization of 3D+T images of valve bioprosthesis has been proposed. Volume rendering and motion compensation techniques were applied to visualize different phases of CT data. Native valve was also considered. ECG-gated CT images of aortic bioprostheses need a preprocessing to reduce noise and artifacts in order to enhance prosthetic leaflets. Stick based methods seems to provide an interesting approach for the morphological characterization of degenerated bioprostheses.

Novel biomaterials provide a spectrum of possibilities. They can be engineered in different forms to understand how they would perform as different bioprosthetic conduits. Bacterial cellulose membranes may be suitable candidates as prosthetic valve leaflets in valve replacement surgeries due to their functional properties (hemodynamics, resistant to thrombosis). Biomaterials used for most bioprosthetic heart valves are cut, trimmed and sutured. A major challenge for the bi-leaflet configuration is that the cutting and suturing of biopolymers fabricated as sheets into a cylindrical form increases failure risk due to greater number of suture points and irregular coaptation. The objective was to culture the bacterial cellulose membrane as a continuous cylindrical construct and evaluate its mechanical properties. Various design features of the fabrication process such as culturing media and the hollow carrier-mandrel characteristics were evaluated. A comparative study of how bacterial cellulose grows on different hollow carrier membranes was conducted and thin smooth surface silicone tubes fabricated in the lab were found to be most suitable. A bioreactor for culturing cylindrical bacterial cellulose tubes on the outer surface of the hollow carrier was designed and fabricated. The mechanical properties of the fabricated tubes, specifically, their tensile strength, flexure, suture retention and tear resistance were characterized. Mechanical characterization studies showed the cylindrical bacterial cellulose tubes to be anisotropic, with preferential properties in the longitudinal (axial) direction of the tube. Preliminary results show that cylindrical bacterial cellulose tubes can be a promising candidate for use in prosthetic valve conduits.

The aim of the study was to assess the feasibility of CT based 3D analysis of degenerated aortic bioprostheses to make easier their morphological assessment. This could be helpful during regular follow-up and for case selection, improved planning and mapping of valve-in-valve procedure. The challenge was represented by leaflets enhancement because of highly noised CT images. Contrast-enhanced ECG-gated CT scan was performed in patients with degenerated aortic bioprostheses before reoperation (in-vivo images). Different methods for noise reduction were tested and proposed. 3D reconstruction of bioprostheses components was achieved using stick based region segmentation methods. After reoperation, segmentation methods were applied to CT images of the explanted prostheses (exvivo images). Noise reduction obtained by improved stick filter showed best results in terms of signal to noise ratio comparing to anisotropic diffusion filters. All segmentation methods applied to the best phase of in-vivo images allowed 3D bioprosthetic leaflets reconstruction. Explanted bioprostheses CT images were also processed and used as reference. Qualitative analysis revealed a good concordance between the in-vivo images and the bioprostheses alterations. Results from different methods were compared by means of volumetric criteria and discussed. A first approach for spatiotemporal visualization of 3D+T images of valve bioprosthesis has been proposed. Volume rendering and motion compensation techniques were applied to visualize different phases of CT data. Native valve was also considered. ECG-gated CT images of aortic bioprostheses need a preprocessing to reduce noise and artifacts in order to enhance prosthetic leaflets. Stick based methods seems to provide an interesting approach for the morphological characterization of degenerated bioprostheses.

O pericárdio bovino tratado com glutaraldeído (GTA) e armazenado em formaldeído tem sido utilizado para confecção de biopróteses cardíacas ao longo das últimas décadas, já se tendo acumulado grande experiência com seu manuseio. Sabemos, no entanto, que o uso do GTA associadamente à presença de restos celulares existentes em meio às fibras de colágeno e elastina do pericárdio, são fatores indutores de resposta inflamatória e de enucleação de cristais de cálcio, o que compromete a durabilidade da bioprótese in vivo a longo prazo. No presente trabalho, tivemos como objetivo comparar a resistência mecânica do pericárdio decelularizado com o pericárdio convencional, assim como avaliar sua capacidade de induzir resposta inflamatória em modelo experimental com ratos. Para estudar as duas técnicas, dividimos os pericárdios em dois grupos: Grupo I - pericárdio submetido a tratamento convencional com GTA e Grupo II - pericárdio submetido a tratamento de decelularização previamente ao tratamento convencional com GTA. Após o processamento químico dos pericárdios, as amostras do Grupo II foram histologicamente avaliadas para confirmar a eficácia da decelularização. A seguir, analisamos a resistência mecânica nos dois grupos de pericárdio através dos testes de tração e de desnaturação térmica. Em nossa casuística, os dois grupos tiveram desempenho semelhante. A capacidade de induzir resposta inflamatória foi avaliada em estudo experimental em 50 ratos Wistar, machos, com 3 meses de idade, os quais foram submetidos a implante subcutâneo no abdome de fragmentos de pericárdio dos dois grupos. Igualmente, não evidenciamos diferença significativa. Nossa terceira etapa de avaliação consistiu em confeccionar 3 biopróteses (mitral n. 29) com o pericárdio decelularizado e que foram submetidas a avaliação hidrodinâmica juntamente com uma bioprótese convencional de teste. As biopróteses decelularizadas mostraram ter desempenho hidrodinâmico semelhante à prótese de teste e ao padrão de avaliação de próteses já conhecido da Braile Biomédica (S.J.Rio Preto-SP), todas atingindo a marca de 150 milhões de ciclos. A avaliação histológica do pericárdio das próteses ao fim da ciclagem mostrou padrão microscópico habitual, não tendo havido ruptura ou fragmentação anormal induzida por estresse mecânico. Temos como conclusão que a técnica de decelularização mantém a resistência física do pericárdio em comparação àquele convencionalmente preparado, não levando à fragmentação da matriz de colágeno e elastina e nem à perda de sua resistência mecânica tanto estática quanto dinâmica, além de não ter induzido resposta inflamatória diferente daquela habitualmente encontrada no pericárdio convencional / The bovine pericardium treated with glutaraldehyde (GTA) and stored in formaldehyde has been used in the manufacturing of cardiac bioprosthesis through the past decades, and a great knowledge has been acquired in this field. We know however that the use of the GTA and the presence of cell debris among the collagen and elastin fibers are triggers to induce inflammatory response and calcium deposition in the tissue, what compromises the long term durability of bioprosthesis in vivo. In this paper, our objective was to compare the decellularized and the conventional pericardium mechanical resistance and also its capability of inducing inflammatory response in an animal experimental model. In order to study these two techniques, we divided the pericardia into two groups: Group I- pericardia conventionally treated with GTA and Group II - pericardia previously decellularized and then conventionally treated with GTA. At first, after the pericardia chemical treatment, we performed histological analysis of Group II to certify the efficacy of the decellularization process. Afterwards, we analyzed the mechanical resistance in both groups using the stretching and shrinkage tests. In our samples, both groups had the same performance. The capacity of inducing inflammatory response was evaluated in an experimental study with 50 Wistar rats, male, 3 months old, which were operated to receive the pericardia patches of both groups underneath the dermal layer in the abdomen. We also did not find any difference between the groups. The third step of evaluation was to manufacture three decellularized bioprosthesis and one no decellularized one that were submitted to hydrodynamic tests. The decellularized and the test prosthesis showed the same performance and there was also no difference when compared with the known performance of the Braile Biomédica\'s (S.J.R. Preto-SP) bioprosthesis. They all reached 150 million cicles. The histological avaluation of the bioprosthesis showed the usual microscopic pattern, and there was no abnormal rupture or fragmentation caused by mechanical stress. We have therefore reached to the conclusion that the decellularization technique keeps the physical resistance of the pericardium when compared with the conventionally prepared. It does not cause damage or fragmentation of the collagen and elastin fibers and does not lead to loss of the mechanical resistance. And also, there was no difference in both groups regarding to inflammatory response studied in the animal model

Este trabalho descreve a reação de reticulação alternativa do pericárdio bovino com os acetais do glutaraldeído, preparados a partir da solução de glutaraldeído na presença do etanol em meio ácido. Os acetais difundem para dentro da matriz colagênica, e a reticulação ocorre após a desproteção dos grupos aldeídicos com uma amina terciária. O material obtido sob estas condições mostrou as propriedades biológicas e mecânicas similares ou superiores àqueles descritos para o pericárdio bovino reticulado pelo procedimento convencional com glutaraldeído, e provavelmente, com resultados de uma distribuição e natureza química mais homogênea das reticulações formadas, devido à ausência das reticulações polímeros de glutaraldeído. As biopróteses manufaturadas com pericárdio reticulado com acetais do glutaraldeído, também mostraram durabilidade superior e foi menos suscetível ao processo de calcificação, como determinado em implantes subcutâneos em ratos. Resultados preliminares de teste à fadiga e performance hidrodinâmica foram caracterizados por um comportamento similar àqueles materiais tratados convencionalmente sugerindo que, o pericárdio reticulado com acetais do glutaraldeído pode ser um procedimento alternativo e mais eficiente na manufatura das biopróteses, particularmente com respeito à calcificação, um dos maiores problemas encontrados pós-implante. / This work describes the cross-linking of bovine pericardium with glutaraldehyde acetals, which are its protected forms. The acetals, prepared from a glutaraldehyde solution in the presence of ethanol in acidic media was al/owed to diffuse within the collagen matrix, and cross-linking achieved by deprotection with a tertiary amine. The material obtained under this conditions showed biological and mechanical properties similar or superior to those described for bovine pericardium crosslinked by conventional procedure with glutaraldehyde, and probably, as a results of a more homogeneous distribution and chemical nature of the formed crosslinks, that is the absence of polymeric cross-links. Bioprostheses manufactured with glutaraldehyde acetals cross-linked bovine pericardium, also showed higher durability and was less susceptible to calcification process, as determined in subcutaneous implant in rats. Preliminary results on fatigue test and hydrodynamic performance were characterized by a behavior similar to those observed for conventional/y treated materials suggesting that, glutaraldehyde acetals crosslinked bovine pericardium may be an alternate and more efficient procedure in the manufacture of bioprostheses, particularly in respect to calcification, one of the major problems found post-implantation.

O revestimento completo das superfícies das biopróteses cardíacas por uma camada protetora de células endoteliais do hospedeiro ainda não foi relatado. As próteses cardíacas de uso corrente são comumente preservadas em glutaraldeído, o qual é citotóxico para as células do hospedeiro evitando a endotelização espontânea. O objetivo deste estudo é demonstrar o potencial para a endotelização in vivo das próteses cardíacas tratadas por um processo alternativo de preservação tecidual (L-Hydro™). O processo de preservação L-Hydro™ consiste na extração controlada de substâncias antigênicas do tecido valvar e na incorporação de um agente antiinflamatório e anti-trombótico. Sete biopróteses porcinas com suporte tratadas pelo processo L-Hydro™ (grupo teste) e três fixadas em glutaraldeído (grupo controle) foram implantadas na posição mitral de ovelhas jovens. As próteses foram avaliadas pela ecocardiografia e angiografia antes do sacrifício aos cinco meses. As próteses explantadas foram avaliadas quanto ao aspecto radiológico, histológico e histoquímico. O teste-t não-pareado de Student e o teste exato de Fisher foram utilizados para a análise estatística. Não houve diferença hemodinâmica entre os grupos, exceto pela pressão capilar mais elevada no grupo controle. Entretanto, a microscopia óptica e a eletrônica de varredura e transmissão mostraram o revestimento quase completo de células endoteliais na superfície de todos os folhetos das próteses tratadas pelo L-Hydro™ após cinco meses de implante. As células endoteliais estavam em contato direto com a camada do colágeno subjacente e expressaram antígenos ligados ao fator von Willebrand. As superfícies das próteses tratadas pelo glutaraldeído encontravam-se cobertas por depósitos de fibrina, macrófagos, cálcio e material trombótico. Apenas células endoteliais esparsas foram observadas neste grupo, e o contato destas células com o colágeno subjacente foi incompleto. Estes dados indicam que a preservação tecidual não-aldeídica (L-Hydro™) utilizada neste estudo é capaz de induzir a endotelização espontânea evidenciada pela boa adesividade celular do novo endotélio à matriz do colágeno, e pela maior resistência à trombose e à calcificação. / A protective layer of endothelial cells of host origin on the entire surfaces of bioprosthetic heart valves has never been reported. Current commercial bioprosthetic heart valves are commonly preserved in glutaraldehyde which is cytotoxic to host cells preventing spontaneous endothelialization. The aim of this study is to demonstrate the potential for in vivo endothelialization of heart valves treated by an alternative tissue preservation process (L-Hydro). L-Hydro preservation process consists of controlled extraction of antigenic substances from the valvular tissue and incorporation of an anti-inflammatory and a anti-thrombotic agent. Seven stented porcine heart valves treated by the L-Hydro™ process (test group) and three glutaraldehyde-fixed porcine heart valves (control group) were implanted in the mitral position of juvenile sheep. The valves were evaluated echocardiographically and angiographically prior to sacrifice at five months. Recovered valves were also radiologically, histologically and histochemically evaluated. Unpaired t-test of Student and Fisher’s exact test were performed for statistical analysis. There were no hemodynamic differences between groups except for a higher pulmonary artery wedge pressure in the control group. However, optical microscopy, scanning and transmission electron microscopy showed a nearly complete coverage of endothelial cells on the surfaces of all leaflets in the L-Hydro™ treated valves after five months of implantation. The endothelial cells were in direct contact with the underlying collagen layer and expressed von Willebrand-related antigens. The surfaces of the glutaraldehyde-treated valves were covered by fibrin deposition, macrophages, calcium and thrombotic material. Only sparse endothelial cells were observed in this group, and contact of the endothelial cells with the underlying tissue was incomplete. These data indicate that the non-aldehyde tissue preservation (L-Hydro) utilised in this study is capable of inducing spontaneous endothelialization with evidence of strong cell attachment of the new endothelium to the collagen tissue matrix, and it also provides a greater resistance to thrombosis and calcification.

O revestimento completo das superfícies das biopróteses cardíacas por uma camada protetora de células endoteliais do hospedeiro ainda não foi relatado. As próteses cardíacas de uso corrente são comumente preservadas em glutaraldeído, o qual é citotóxico para as células do hospedeiro evitando a endotelização espontânea. O objetivo deste estudo é demonstrar o potencial para a endotelização in vivo das próteses cardíacas tratadas por um processo alternativo de preservação tecidual (L-Hydro™). O processo de preservação L-Hydro™ consiste na extração controlada de substâncias antigênicas do tecido valvar e na incorporação de um agente antiinflamatório e anti-trombótico. Sete biopróteses porcinas com suporte tratadas pelo processo L-Hydro™ (grupo teste) e três fixadas em glutaraldeído (grupo controle) foram implantadas na posição mitral de ovelhas jovens. As próteses foram avaliadas pela ecocardiografia e angiografia antes do sacrifício aos cinco meses. As próteses explantadas foram avaliadas quanto ao aspecto radiológico, histológico e histoquímico. O teste-t não-pareado de Student e o teste exato de Fisher foram utilizados para a análise estatística. Não houve diferença hemodinâmica entre os grupos, exceto pela pressão capilar mais elevada no grupo controle. Entretanto, a microscopia óptica e a eletrônica de varredura e transmissão mostraram o revestimento quase completo de células endoteliais na superfície de todos os folhetos das próteses tratadas pelo L-Hydro™ após cinco meses de implante. As células endoteliais estavam em contato direto com a camada do colágeno subjacente e expressaram antígenos ligados ao fator von Willebrand. As superfícies das próteses tratadas pelo glutaraldeído encontravam-se cobertas por depósitos de fibrina, macrófagos, cálcio e material trombótico. Apenas células endoteliais esparsas foram observadas neste grupo, e o contato destas células com o colágeno subjacente foi incompleto. Estes dados indicam que a preservação tecidual não-aldeídica (L-Hydro™) utilizada neste estudo é capaz de induzir a endotelização espontânea evidenciada pela boa adesividade celular do novo endotélio à matriz do colágeno, e pela maior resistência à trombose e à calcificação. / A protective layer of endothelial cells of host origin on the entire surfaces of bioprosthetic heart valves has never been reported. Current commercial bioprosthetic heart valves are commonly preserved in glutaraldehyde which is cytotoxic to host cells preventing spontaneous endothelialization. The aim of this study is to demonstrate the potential for in vivo endothelialization of heart valves treated by an alternative tissue preservation process (L-Hydro). L-Hydro preservation process consists of controlled extraction of antigenic substances from the valvular tissue and incorporation of an anti-inflammatory and a anti-thrombotic agent. Seven stented porcine heart valves treated by the L-Hydro™ process (test group) and three glutaraldehyde-fixed porcine heart valves (control group) were implanted in the mitral position of juvenile sheep. The valves were evaluated echocardiographically and angiographically prior to sacrifice at five months. Recovered valves were also radiologically, histologically and histochemically evaluated. Unpaired t-test of Student and Fisher’s exact test were performed for statistical analysis. There were no hemodynamic differences between groups except for a higher pulmonary artery wedge pressure in the control group. However, optical microscopy, scanning and transmission electron microscopy showed a nearly complete coverage of endothelial cells on the surfaces of all leaflets in the L-Hydro™ treated valves after five months of implantation. The endothelial cells were in direct contact with the underlying collagen layer and expressed von Willebrand-related antigens. The surfaces of the glutaraldehyde-treated valves were covered by fibrin deposition, macrophages, calcium and thrombotic material. Only sparse endothelial cells were observed in this group, and contact of the endothelial cells with the underlying tissue was incomplete. These data indicate that the non-aldehyde tissue preservation (L-Hydro) utilised in this study is capable of inducing spontaneous endothelialization with evidence of strong cell attachment of the new endothelium to the collagen tissue matrix, and it also provides a greater resistance to thrombosis and calcification.

À l’heure actuelle, plusieurs centres de chirurgie cardiaque ont noté une augmentation du nombre de patients âgés orientés pour une chirurgie. Les baisses majeures de la natalité et de la mortalité dans tous les groupes d’âge ont contribué au vieillissement progressif des populations des pays industrialisés. Il est bien connu que la prévalence des pathologies cardiovasculaires augmente avec l’âge et fait en sorte que ce groupe de patients âgés soit à haut risque opératoire. Trois études ont été réalisées dans le cadre de ce travail dédié aux deux types de chirurgie les plus fréquemment pratiquées pour ce groupe de population : la chirurgie de la valve aortique et la chirurgie de revascularisation coronarienne. Le substitut valvulaire aortique idéal pour une personne âgée considérée à risque opératoire élevé suscite toujours un débat. Depuis quelques années, avec les progrès technologiques en chirurgie cardiaque, les valves sans suture (V-SS) en général et la Perceval en particulier, constituent une excellente alternative à la prothèse standard chez ce sous-groupe de patients. Tout en diminuant le temps opératoire, la Perceval ne compromet ni la qualité ni la sécurité de l’acte chirurgical et elle présente des bénéfices cliniques et hémodynamiques aussi bien à court et à long terme. Pour le démontrer nous vous présentons les résultats d’une étude de cohorte regroupant 215 patients consécutifs qui a permis d’évaluer l’efficacité et la durabilité de la Perceval. Notre étude se veut l’appui qui soutiendra la place et l’apport de la Perceval dans l’arsenal thérapeutique du remplacement valvulaire aortique (RVA). Comme toutes les bioprothèses, la Perceval est soumise à un risque faible, mais constant à long terme de dégénérescence structurale et qui pourrait éventuellement nécessiter une réintervention. Pour clarifier cette problématique, nous vous présentons une étude descriptive rapportant notre expérience dans la prise en charge de la détérioration structurale de la prothèse Perceval. De plus, cette étude a permis de mettre en lumière la complémentarité parfois inattendue (dans des conditions urgentes) de ces approches thérapeutiques ( TAVI et Perceval) chez les patients à risque élevé. De nos jours, un certain pourcentage des malades orientés vers une revascularisation chirurgicale présente une pathologie coronarienne assez diffuse et complexe qui peut compromettre la revascularisation coronarienne souhaitable. A cet effet, l’endartériectomie coronarienne (EC), une ancienne technique largement utilisée auparavant, puis délaissée par la suite, mérite d’être reconsidérée chez ces patients. La troisième étude présentée dans ce mémoire rapporte les résultats d’une cohorte de 147 patients atteints de maladie coronarienne diffuse. En plus d’être sécuritaire, notre étude documente la perméabilité à court et à moyen terme d’un sous groupe de patient étudié avec un angioscanner coronaire. / Currently, several cardiac surgery centers have noted an increase in the number of elderly patients referred for surgery. The major decline in birth rates and deaths in all age groups has contributed to the gradual aging of populations in industrialized countries. It is well known that the prevalence of cardiovascular pathologies increases with age and puts this group of elderly patients at high risk for surgery. Three studies were carried out as part of this work dedicated to the two types of surgery most frequently performed for this population group: aortic valve surgery and coronary revascularization surgery. The ideal aortic valve substitute for an elderly person considered to be at high operative risk is still a subject of debate. In recent years, with technological advances in cardiac surgery, sutureless valves (V-SS) in general and the Perceval in particular have been an excellent alternative to the standard prosthesis in this subgroup of patients. While reducing operating time, Perceval does not compromise the quality or safety of the surgical procedure and it offers clinical and hemodynamic benefits both in the short and long term. To demonstrate this, we present to you the results of a cohort study involving 215 consecutive patients which made it possible to evaluate the effectiveness and durability of Perceval. Our study is intended to support the place and contribution of Perceval in the therapeutic arsenal of aortic valve replacement (AVR). Like all bioprostheses, Perceval is subject to a low, but constant long-term risk of structural degeneration which may eventually require reoperation. To clarify this problem, we present to you a descriptive study reporting our experience in the management of structural deterioration of the Perceval prosthesis. In addition, this study shed light on the sometimes unexpected complementarity (in urgent conditions) of these therapeutic approaches (TAVI and Perceval) in high-risk patients. Nowadays, a certain percentage of patients referred for surgical revascularization present a fairly diffuse and complex coronary pathology which can compromise the desirable coronary revascularization. To this end, coronary endarterectomy (CE), an old technique widely used before, then abandoned thereafter, deserves to be reconsidered in these patients. The third study presented in this thesis reports the results of a cohort of 147 patients with diffuse coronary artery disease. In addition to being safe, our study documents the short- and medium-term patency of a subgroup of patients studied with a coronary CT angiography.