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Badania ex vivo oraz modelowanie analityczne i numeryczne tętnic mózgowych

Adam Piechna

Abstract

The following PhD thesis describes an unique experimental investigations performed on human cerebral arteries. In total 33 brains, 51 cerebral arteries, 17 adventitias of cerebral arteries and 5 carotid arteries were investigated. The research was conducted on a specially designed and build measurement station. Rupture pressure and ultimate strains values of cerebral arteries were measured. Negative correlation between strain and age was found and evaluated. It has a substantial clinical implications such as planning of an angioplasty. Also material characteristics (stress-strain curves) of cerebral and carotid arteries were obtained. They are a crucial element in performing numerical analysis. In addition to the experiments conducted on the intact artery wall, an experiment on the separated adventitia was also investigated. The main role of adventitia in the artery mechanical strength was highlighted. The adventitia can stand 65% (standard deviation (SD) 13%) of intact wall rupture pressure, despite its thickness is only about 1/3 of intact wall. The presented results have a direct reference to angioplasty, where during mechanical widening of narrowed artery its internal layers are destroyed and adventitia takes its major mechanical role. Ultimate stress of adventitia of cerebral arteries was evaluated. The obtained results are in agreement with the ones presented earlier in the literature for different types of arteries. The experimental results were combined with complementary numerical and mathematical modeling. The analytical model of two layer artery with residual stresses was developed. It enables of precise computation of residual stresses and assessment of stresses during pressure loading. Also numerical modeling was conducted. Its aim was to investigate residual stress phenomenon, which is commonly brought up in the literature but with various conclusions. The method of experimental validation of numerical model was proposed. The series of experiments was performed and influence of residual stresses on the pressure-strain characteristics was confirmed. The obtained results could be also used to validate different numerical models and for testing artificial tissues. Experimental data was fitted to the structural model described by Wuyts et al [102].Waviness values of collagen fibers of the carotid arteries were calculated. Recapitulating, the thesis concluded six year of experimental and theoretical investigation of the mechanical properties of arteries. The obtained results are largely unique and were not found in the literature before.
Record ID
WUT104dde97f5af4023bb7a11ae07806a3b
Diploma type
Doctor of Philosophy
Author
Title in Polish
Badania ex vivo oraz modelowanie analityczne i numeryczne tętnic mózgowych
Language
(pl) Polish
Certifying Unit
Faculty of Mechatronics (FM)
Discipline
biocybernetics and biomedical engineering / (technology domain) / (technological sciences)
Status
Finished
Defense Date
15-04-2015
Title date
22-04-2015
Supervisor
Internal reviewers
External reviewers
Jan Marciniak, prof. Jan Marciniak, prof.,, External affiliation of publication: Faculty of Biomedical Engineering
Zenon Mariak, prof. n. med. Zenon Mariak, prof. n. med.,, External affiliation of publication: Klinika Neurochirurgii UM
Pages
126
Keywords in English
cerebral arteries, adventitia, ex vivo, material characteristic, modeling of biological tissues
Abstract in English
The following PhD thesis describes an unique experimental investigations performed on human cerebral arteries. In total 33 brains, 51 cerebral arteries, 17 adventitias of cerebral arteries and 5 carotid arteries were investigated. The research was conducted on a specially designed and build measurement station. Rupture pressure and ultimate strains values of cerebral arteries were measured. Negative correlation between strain and age was found and evaluated. It has a substantial clinical implications such as planning of an angioplasty. Also material characteristics (stress-strain curves) of cerebral and carotid arteries were obtained. They are a crucial element in performing numerical analysis. In addition to the experiments conducted on the intact artery wall, an experiment on the separated adventitia was also investigated. The main role of adventitia in the artery mechanical strength was highlighted. The adventitia can stand 65% (standard deviation (SD) 13%) of intact wall rupture pressure, despite its thickness is only about 1/3 of intact wall. The presented results have a direct reference to angioplasty, where during mechanical widening of narrowed artery its internal layers are destroyed and adventitia takes its major mechanical role. Ultimate stress of adventitia of cerebral arteries was evaluated. The obtained results are in agreement with the ones presented earlier in the literature for different types of arteries. The experimental results were combined with complementary numerical and mathematical modeling. The analytical model of two layer artery with residual stresses was developed. It enables of precise computation of residual stresses and assessment of stresses during pressure loading. Also numerical modeling was conducted. Its aim was to investigate residual stress phenomenon, which is commonly brought up in the literature but with various conclusions. The method of experimental validation of numerical model was proposed. The series of experiments was performed and influence of residual stresses on the pressure-strain characteristics was confirmed. The obtained results could be also used to validate different numerical models and for testing artificial tissues. Experimental data was fitted to the structural model described by Wuyts et al [102].Waviness values of collagen fibers of the carotid arteries were calculated. Recapitulating, the thesis concluded six year of experimental and theoretical investigation of the mechanical properties of arteries. The obtained results are largely unique and were not found in the literature before.
Thesis file
  • File: 1
    AdamPiechna_doktorat_150914_v3.pdf
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Citation count
2

Uniform Resource Identifier
https://repo.pw.edu.pl/info/phd/WUT104dde97f5af4023bb7a11ae07806a3b/
URN
urn:pw-repo:WUT104dde97f5af4023bb7a11ae07806a3b

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