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Sobre a definição do processo de simulação do comportamento mecânico da Aorta Torácica Ascendente
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Segundo a Organização Mundial de Saúde as doenças cardiovasculares são uma das
principais causas de morte da atualidade. Destas fazem partes os aneurismas da aorta
torácica. Entre estes os mais comuns são os da aorta torácica ascendente, representando
certa de 60% dos casos. Estes devem ser monitorizados e controlados, sendo que perante
a sua rotura a probabilidade de morte é de até 94%. Atualmente, o método de decisão
cirúrgica baseia-se somente na avaliação do diâmetro do aneurisma, sendo que quando
este é superior a 5,5 cm é recomendada intervenção cirúrgica. Este método tem-se re-
petidamente demonstrado falível, visto que existem consideráveis quantidades de casos
em que se dá a rotura ou disseção do aneurisma antes da verificação deste critério. As-
sim, surge a necessidade de implementar novos métodos de avaliação e análise de risco
dos aneurismas. A necessidade de estudar melhor o aneurisma de forma a melhorar a
qualidade de vida e taxa de sobrevivência de pacientes por ele afetados é uma grande
motivação para o desenvolvimento deste projeto e dissertação. A presente dissertação
insere-se num projeto multidisciplinar que tem como objetivo o desenvolvimento de um
modelo robusto que permita determinar/prever o comportamento mecânico da artéria
aorta, considerando a definição de intervalos de simulação.
Assim, esta dissertação foca-se no estudo e criação de uma geometria e modelo de
elementos finitos capaz de simular o comportamento mecânico da parede da artéria
aorta ascendente, considerando a incerteza inerente aos processos de criação. Para tal
foi implementado um método de análise de variabilidade do processo de obtenção da
geometria a partir de exames médicos, onde se obtém uma métrica que permite comparar
e quantificar a variabilidade do processo. Posteriormente foi desenvolvido e analisado um
modelo de elementos finitos. A dissertação contém uma extensa pesquisa bibliográfica,
que visa a construir uma base sólida para o desenvolvimento futuro do projeto no qual
está incluída.
According to the World Health Organization cardiovascular diseases are one of the main causes of death of the modern world. The thoracic aorta aneurysms are part of this group of diseases. The most common of these are the ascending thoracic aorta aneurysms, which represent 60% of the cases. These should be monitored and controlled because in case of rupture they present a rate of mortality up to 94%. Currently the method on which the decision is made upon relies only on the aneurysm diameter, being recomended surgical intervention when the diameter is above 5.5 cm. This metric has been continu- ously shown to be flawed as there is a considerable amount of cases (about 60%) in which the aneurysm ruptures before the diameter reaches 5.5 cm. Due to this there comes a necessity to come up with a new and better criteria fot the evaluation of aneurysms. The main motivation in the studying of this condition is the improvement of the quality of life and survival chance of pacients affected by it. This thesis is part of a multidisciplinary project which goal is to develop a robust model that is capable of predicting and deter- mine the mechanical behavior of the human ascending aorta, considering the definition of simulation intervals. This thesis focuses on the studying creation of a geometry and finite element model capable of simulating the mechanical behavior of the ascending aorta walls, considering the uncertainty inherent to the creation process. To this end an analysis method was implemented to determine the variability of the geometry creation process from medical exams, where the output is a metric that can compare and quantify the process variability. Then a finite element model was developde and analysed. This dissertation contains a extensive amount of research done with the goal of estabilishing a solid foundation for the future development of the project in with it is included.
According to the World Health Organization cardiovascular diseases are one of the main causes of death of the modern world. The thoracic aorta aneurysms are part of this group of diseases. The most common of these are the ascending thoracic aorta aneurysms, which represent 60% of the cases. These should be monitored and controlled because in case of rupture they present a rate of mortality up to 94%. Currently the method on which the decision is made upon relies only on the aneurysm diameter, being recomended surgical intervention when the diameter is above 5.5 cm. This metric has been continu- ously shown to be flawed as there is a considerable amount of cases (about 60%) in which the aneurysm ruptures before the diameter reaches 5.5 cm. Due to this there comes a necessity to come up with a new and better criteria fot the evaluation of aneurysms. The main motivation in the studying of this condition is the improvement of the quality of life and survival chance of pacients affected by it. This thesis is part of a multidisciplinary project which goal is to develop a robust model that is capable of predicting and deter- mine the mechanical behavior of the human ascending aorta, considering the definition of simulation intervals. This thesis focuses on the studying creation of a geometry and finite element model capable of simulating the mechanical behavior of the ascending aorta walls, considering the uncertainty inherent to the creation process. To this end an analysis method was implemented to determine the variability of the geometry creation process from medical exams, where the output is a metric that can compare and quantify the process variability. Then a finite element model was developde and analysed. This dissertation contains a extensive amount of research done with the goal of estabilishing a solid foundation for the future development of the project in with it is included.
Descrição
Palavras-chave
Aneurisma Aorta Ascendente Método dos Elementos Finitos (FEM) 3D Slicer Simulia Abaqus Análise de Sensibilidade (SA)