Development of bioabsorbable braided vascular scaffolds for the intracranial circulation
Date
2019-05-29
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Abstract
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.
Description
Keywords
Intracranial aneurysm, Flow-diverting stent, Bioabsorbable stent
Citation
Jamshidi, M. (2019). Development of bioabsorbable braided vascular scaffolds for the intracranial circulation (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.