| Endovascular embolization of cerebrovascular lesions has become a minimally invasive alternative to neurosurgery. However, high risk factors underscore the need for improved endovascular treatments and treatment materials. The specific aims of the research were to develop an improved embolization material and create a chronic embolization model. First, the in vitro and in vivo mechanical stability, biocompatibility, and flow characteristics of a new endovascular polymer injectate, calcium alginate, were tested. Second, a chronic model was created to investigate endovascular injection techniques, radiographic visualization of alginate injections, and long-term polymer occlusion stability and biocompatibility.; Reacted alginate compressive resistance, rheology, and polymer yield were assessed. Unreacted alginate injection properties were determined from endovascular microcatheters flow rate and pressure data. The chronic model was developed from the rete mirabile vasculature in the skullbase of swine. The chronic model incorporated a surgical anastomosis procedure to shunt blood flow to the rete vessels. The surgical and injection techniques were modified to improve animal recovery post-anastomosis and post-embolization.; Purified alginates with high guluronic acid content (PHG) exhibit optimal material characteristics. The optimal alginate solution was 1.6 wt% 37 mPas PHG alginate dissolved in 1:1 Conray to water and mixed with 1 g tantalum powder per 4 ml alginate to enhance radiographic visualization. Complete occlusion was achieved with staged alginate injections into the rete. Partial occlusion was achieved by focally delivering alginate to the rete entrance, thereby blocking blood flow from the main feeding artery. Partial occlusion allowed additional blood flow to perfuse the cerebrovasculature and sustain the animal. Chronic post-embolization histology showed minor bioactive responses to the alginate, resulting in alginate encapsulation and increased polymer stability. No signs of vessel damage or adhesion were observed.; Results suggest that calcium alginate exhibits adequate flow properties and biocompatibility in its unreacted form and overall stability in its reacted form. The research resulted in a new and effective chronic swine model for assessing alginate injectability and stability. The combination of a new embolic material and a new chronic occlusion model may improve future developments of endovascular treatments for arteriovenous malformations (AVMs), aneurysms, tumor blood supply, and vascular hemorrhaging. |
