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Publicação
Otimização de Técnicas Endovasculares no Tratamento de Aneurismas Aórticos
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Resumo(s)
Aortic aneurysms are permanent and irreversible dilations of the aortic wall and constitute a potenti ally serious health problem. Currently, several treatment options are available, and the most common is
the endovascular treatment of aneurysms. The challenging anatomy and inadequate landing zones create
limitations to its application. Customized solutions including branched or fenestrated devices are available
and represent a primary option in elective operations. However, urgents, life saving situations may require
the off-label adaptation of off-the-shelf devices. Due to these, advanced endovascular techniques, as
Octopus technique, have been developed. In all of them, a main endograft is used, and inside or outside, it
is deployed parallel endografts to perfuse in the visceral branches involved. However, associated with
these procedures, there are several postoperative complications with a high incidence rate, such as the
migration of the endograft and the formation of endoleaks.
This work aims to develop an algorithm using the MATLAB 2020a platform that recommend the
optimal size of the endograft to decrease the probability of postoperative problems, as endoleaks. To
achieve this, several mathematical and physical concepts were considered, like thin-walled cylinder theory
and fluid mechanics. The algorithm workflow is based on the relationship between the deformation that
each parallel endograft experiences due to the others inside the main endograft.
The developed algorithm has been compared with two methods, the Double Barrel method and the
segmentation of computed tomography images, to validate the results. In the first method, the diameter of
the main endograft was calculated using the developed algorithm and the Double Barrel method. Then
these two values were compared. On the other hand, the second validation method compared the values of
the internal endograft area obtained through the developed algorithm and the segmentation of computed
tomography images.This validation was performed using images that were given to us, from 4 patients
who had already undergone surgery.
The results of the first validation method show that the diameters obtained through the algorithm
are smaller than those obtained through the Double Barrel method. This may be due to the fact that in
the developed algorithm the effect of forces and deformation of the endograft is considered, which in the
Double Barrel method does not happen.
Regarding the second validation method, the results have shown that when the diameter used in the
Octopus procedure and the diameter proposed by the algorithm are equal, the difference between the area
values is not higher than 10%. The observed differences were about 30% and 50% when the diameters
didn’t match. The difference in the diameters can justify that. In the Octopus procedure, the diameter
used is higher than the proposed algorithm. Because of that, the internal endografts have more space to
expand and, therefore, the endografts deformation is lower.
In conclusion, this algorithm can help vascular surgeons choose the optimal endograft diameter to
decrease the probability of having postoperative complications in endovascular procedure, like Octopus
procedure. In the future, it will be crucial to include in this model to be blood pressure and temperature
dependent and validate them in the laboratory, using a phantom model.
Descrição
Tese de mestrado integrado, Engenharia Biomédica e Biofísica (Sinais e Imagens Médicas), Universidade de Lisboa, Faculdade de Ciências, 2022
Palavras-chave
Aneurismas aórticos procedimento endovascular algoritmo sobredimensionamento dimensionamento da endoprótese Teses de mestrado - 2022