Development of bioabsorbable braided vascular scaffolds for the intracranial circulation

An intracranial (or brain) aneurysm is a life-threatening disease that affects more than 3% of the population. The treatment techniques of cerebral aneurysms have significantly improved in the past decade, transitioning from open surgical procedures to less invasive endovascular procedures. A disruptive technology in aneurysm treatment was the advent of the metal flow-diverting stent, which made it relatively easy to treat the most complicated of brain aneurysms, and avoiding the need for a high-risk open surgical procedure. Despite these improvements, metal stents are still associated with major complications, mostly due to their thrombogenicity as well as their long-term implications. Although the need for a stent to treat aneurysms is only temporary, due to progressive neointima formation over the stent structure, they cannot be removed. This requires patients to remain on lifelong anti-platelet medications, which can cause other health problems. Bioabsorbable stents have been postulated as a way to overcome the long-term disadvantages of metal stents. Commercial bioabsorbable stents have been developed for coronary artery diseases, although the design of coronary stents is different than for intracranial aneurysms. Coronary stents are mostly balloon expandable, and can acquire good wall apposition simply by balloon inflation. Stents used for intracranial applications, on the other hand, are required to be flexible and self-expandable, and they should revert to at least close to their original diameter after deployment from the catheter. The challenges for the design of bioabsorbable flow-diverting stents for the treatment of intracranial aneurysms lies in differences with the deployment mechanism, the poor mechanical properties of bioabsorbable polymers, and their inability to show shape memory behavior. In this study, we designed and fabricated bioabsorbable flow-diverting stents for the treatment of aneurysms. Information acquired from existing stents, as well as the three initial iterations of our design, are reviewed and discussed. The mechanical properties and safety profile of our stents were studied in vitro, and the safety and efficacy were also studied in vivo with pilot animal experiments. The bioabsorbable flow-diverting stent that we developed demonstrated mechanical properties similar to existing intracranial stents. They further showed low potential for hemolysis and thrombus formation on the stent struts, as well as neointimal layer formation and persistent side branch patency in animal models at 1 month follow-up. The performance of the stent in terms of flow-diverting capabilities was also demonstrated in acute small and large animal models of intracranial aneurysms.

Name thesis:degree_name

Doctor of Philosophy (PhD)

Discipline thesis:degree_discipline

Engineering – Biomedical

Grantor dc:publisher.institution

Schulich School of Engineering

Year dc:date.issued

2019

Author dc:creator

• Jamshidi, Mehdi

Advisors dc:contributor.advisor

• Mitha, Alim Pyarali A.
• Sundararaj, Uttandaraman

Committee members dc:contributor.committeemember

• Ronsky, Janet L.
• Di Martino, Elena S.

• Intracranial aneurysm, Flow-diverting stent, Bioabsorbable stent

Statement dc:rights

• University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.

Language dc:language.iso

eng

DOI

http://dx.doi.org/10.11575/PRISM/36621

OAI identifier oai:identifier

oai:ucalgary.scholaris.ca:1880/110472