Development of an Absorbable Flow Diverting Stent to Treat Brain Aneurysms
Alim Mitha, Mehdi Jamshidi
Introduction: Metal flow diverting stents are increasingly being used to treat unruptured aneurysms. Although these devices are effective at aneurysm occlusion, the high metal surface area has significant disadvantages include the requirement for lifelong anti-platelet medications and interference with non-invasive imaging.
Objective: We sought to determine whether flow diverting stents could be developed using absorbable biomaterials. The principal objective was to design a device with similar mechanical properties compared to existing metal stents, and without compromising safety, efficacy, delivery, and deployment features.
Methods: Absorbable flow diverting stents were developed. Radial force and thrombogenicity testing was performed and compared to commercial metal stents. Absorbable stents were deployed in rabbit aortas, and in rabbit and pig aneurysm models to determine short-term safety and changes in flow patterns, respectively. Stents were also deployed in a patient-specific aneurysm model, then underwent angiography to determine flow changes including the mean aneurysm flow amplitude (MAFA) ratio.
Results: Compared with commercial metal stents, the absorbable stents had similar mechanical and rheologic properties. In vivo studies demonstrated persistent parent vessel and side branch patency, while animal models of aneurysms treated with the absorbable stent showed contrast patterns consistent with flow diversion. The absorbable stent reduced the MAFA ratio to a value predictive of aneurysm occlusion at three months.
Conclusions: Our absorbable flow diverting stent showed encouraging short-term in vitro and in vivo safety and efficacy results. If shown to be effective in long-term studies, this could represent a promising new technology in the treatment aneurysms, with improved characteristics compared with metal stents.