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Title:The development of patient-specific vascular stents using computational modeling and optimisation : doctoral disertation
Authors:ID Donik, Žiga (Author)
ID Kramberger, Janez (Mentor) More about this mentor... New window
ID Pocivavsek, Luka (Comentor)
Files:.pdf DOK_Donik_Ziga_2024.pdf (73,27 MB)
MD5: 14DB373D9DD9BE0AFFABAA83D81EC787
 
Language:English
Work type:Doctoral dissertation
Typology:2.08 - Doctoral Dissertation
Organization:FS - Faculty of Mechanical Engineering
Abstract:Minimally invasive endovascular procedures are becoming a preferred approach to treat aortic dissection compared to traditional open surgery. Despite their advantages, endovascular options are currently limited to less complex geometries and are not without challenges. Endoleak, caused by the geometric mismatch between the straight cylindrical endograft and the curved aorta, remain a significant concern and lead to reinterventions. Understanding the underlying physical mechanisms governing the interfacial behavior of the seal zone is crucial to establishing guidelines for optimal stent sizing and developing more reliable endografts. Computational simulations are an essential tool in that regard, offering insights into the mechanical behavior of stents and aiding in their development. A computational study is performed to analyze the effects of endograft oversizing and artery curvature on potential endoleak. Based on identified mechanisms of endoleak creation, an optimal oversizing that minimizes potential endoleak is determined as a function of curvature. The findings will help develop new generations of endografts and define new standards. The Dissertation also involves computational modeling of a novel method to treat aortic arch dissection, where a bare metal stent is employed to expand the true lumen and displace the dissection flap. The simulation is compared to images from surgery, which shows a good agreement of the deformation patterns. An analysis of different dissection flap stiffnesses underscores the potential for this type of endovascular treatment if higher radial force can be provided by the stent. A methodology for lumen characterization is presented, based on which a personalized bare metal stent can be constructed for the aortic arch. Initial tailored stent designs indicate increased flap displacement compared to the original stent but encounter local instabilities at one of the support rings, which poses certain risks. Rectifying this design flaw is essential for advancing patient-specific bare metal stents, which hold the potential to revolutionize aortic arch dissection repair.
Keywords:endovascular aortic repair, TEVAR, vascular stent, endograft, aortic dissection, finite element analysis (FEA)
Place of publishing:Maribor
Place of performance:Maribor
Publisher:[Ž. Donik]
Year of publishing:2024
Number of pages:XIV, 116
PID:20.500.12556/DKUM-88521 New window
UDC:[004.942+519.6]:66.132-77(043.3)
COBISS.SI-ID:212545539 New window
Publication date in DKUM:17.10.2024
Views:160
Downloads:194
Metadata:XML DC-XML DC-RDF
Categories:KTFMB - FS
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Licences

License:CC BY-NC-ND 4.0, Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
Link:http://creativecommons.org/licenses/by-nc-nd/4.0/
Description:The most restrictive Creative Commons license. This only allows people to download and share the work for no commercial gain and for no other purposes.
Licensing start date:08.05.2024

Secondary language

Language:Slovenian
Title:Razvoj pacientu prilagojenih žilnih opornic z računalniškim modeliranjem in optimizacijo
Abstract:Minimalno invazivni znotrajžilni postopki postajajo prednostni pristop za zdravljenje disekcije aorte v primerjavi z uveljavljenimi odprtimi rekonstrukcijskimi posegi. Kljub svojim prednostim so znotrajžilne intervencije trenutno omejene na manj zapletene oblike disekcije in predstavljajo določena tveganja. Puščanje, ki ga povzroči geometrijsko neskladje med ravno cilindrično žilno opornico in ukrivljeno aorto, ostaja velik problem in zahteva ponovno odprto operacijo. Razumevanje osnovnih fizikalnih mehanizmov, ki narekujejo obnašanje tesnilne cone med žilno steno in žilno opornico, je ključnega pomena za določitev smernic za izbiro optimalne velikosti in razvoj zanesljivejših žilnih opornic. Računalniške simulacije predstavljajo pri tem pomembno orodje, saj ponujajo vpogled v mehansko obnašanje žilnih opornic in pomagajo pri njihovem razvoju. Izvedena je računalniška študija za analizo učinka izbire povečane velikosti žilne opornice v primerjavi z arterijo in ukrivljenosti arterije na potencialno puščanje. Na podlagi ugotovljenih mehanizmov nastanka puščanja je kot funkcija ukrivljenosti ugotovljena optimalna velikost žilne opornice, ki zmanjša potencialno puščanje. Ugotovitve bodo pomagale pri razvoju novih generacij žilnih opornic in opredelitvi novih standardov. Disertacija vključuje tudi računalniško modeliranje nove metode za zdravljenje disekcije aortnega loka, kjer se uporablja nepokrita kovinska žilna opornica za razširitev prave svetline s premikom intimalne lehe. Primerjava rezultatov simulacije s slikami iz operacije kaže na dobro ujemanje deformacijskih vzorcev. Analiza različnih togosti intimalne lehe izkazuje potencial za to vrsto znotrajžilnega zdravljenja, če bi bila žilna opornica sposobna zagotoviti večjo radialno silo. Predstavljena je metodologija za karakterizacijo svetline, na podlagi katere je mogoče izdelati pacientu prilagojeno nepokrito žilno opornico za aortni lok. Začetne prilagojene zasnove žilne opornice kažejo povečan premik intimalne lehe v primerjavi z osnovno žilno opornico, vendar pride do lokalnih nestabilnosti na enem izmed podpornih obročev, kar predstavlja določena tveganja. Odprava te konstrukcijske napake je bistvenega pomena za napredek razvoja pacientu prilagojenih nepokritih žilnih opornic, ki kažejo potencial za uveljavitev v znotrajžilnem zdravljenju disekcij aortnega loka.
Keywords:znotrajžilno zdravljenje aorte, žilne opornice, disekcija aorte, metoda končnih elementov (MKE)


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