Flow diverter devices are small stents used to divert blood flow away from aneurysms in the brain,stagnating flow and inducing intra-aneurysmal thrombosis which in time will prevent aneurysm rupture.Current devices ar...Flow diverter devices are small stents used to divert blood flow away from aneurysms in the brain,stagnating flow and inducing intra-aneurysmal thrombosis which in time will prevent aneurysm rupture.Current devices are formed from thin(~25μm)wires which will remain in place long after the aneurysm has been mitigated.As their continued presence could lead to secondary complications,an absorbable flow diverter which dissolves into the body after aneurysm occlusion is desirable.The absorbable metals investigated to date struggle to achieve the necessary combination of strength,elasticity,corrosion rate,fragmentation resistance,radiopacity,and biocompatibility.This work proposes and investigates a new composite wire concept combining absorbable iron alloy(FeMnN)shells with one or more pure molybdenum(Mo)cores.Various wire configurations are produced and drawn to 25–250μm wires.Tensile testing revealed high and tunable mechanical properties on par with existing flow diverter materials.In vitro degradation testing of 100μm wire in DMEM to 7 days indicated progressive corrosion and cracking of the FeMnN shell but not of the Mo,confirming the cathodic protection of the Mo by the FeMnN and thus mitigation of premature fragmentation risk.In vivo implantation and subsequentμCT of the same wires in mouse aortas to 6 months showed meaningful corrosion had begun in the FeMnN shell but not yet in the Mo filament cores.In total,these results indicate that these composites may offer an ideal combination of properties for absorbable flow diverters.展开更多
There has been growing interest and insight into the histological composition of retrieved stroke emboli.One of the main focuses of the stroke clot analysis literature has been the implications of clot composition on ...There has been growing interest and insight into the histological composition of retrieved stroke emboli.One of the main focuses of the stroke clot analysis literature has been the implications of clot composition on mechanical thrombectomy procedures.However,the holy grail of clot analysis may not be in the field of clot-device interaction,but rather,in understanding mechanisms of fibrinolysis resistance.The mechanisms underlying the low response to fibrinolytic therapy,even with the newer,more powerful agents,remain poorly understood.While factors such as embolus size,location and collateral status influence alteplase delivery and recanalisation rates;compositional analyses focused on histological and ultrastructural characteristics offer unique insights into mechanisms of alteplase resistance.In this review,we strive to provide comprehensive review of current knowledge on clot composition and ultrastructural analyses that help explain resistance to fibrinolysis.展开更多
基金support of Carlo Wolf(School of Mechanical Engineering,University of Applied Sciences Stralsund)for support with the CT analysis and metallographic preparation,Aubrey L.Ehle(Indiana University School of Medicine)for support with the radiopacity assessment,and Amani Gillette(Morgridge Institute for Research)for support with the cytotoxicity analysis.Parts of this study were completed using Michigan Technological University’s Applied Chemical and Morphological Analysis Laboratory.RG and NP were partially supported by NIH R15HL167221.AO is supported by American Heart Association grant 23PRE1012781.
文摘Flow diverter devices are small stents used to divert blood flow away from aneurysms in the brain,stagnating flow and inducing intra-aneurysmal thrombosis which in time will prevent aneurysm rupture.Current devices are formed from thin(~25μm)wires which will remain in place long after the aneurysm has been mitigated.As their continued presence could lead to secondary complications,an absorbable flow diverter which dissolves into the body after aneurysm occlusion is desirable.The absorbable metals investigated to date struggle to achieve the necessary combination of strength,elasticity,corrosion rate,fragmentation resistance,radiopacity,and biocompatibility.This work proposes and investigates a new composite wire concept combining absorbable iron alloy(FeMnN)shells with one or more pure molybdenum(Mo)cores.Various wire configurations are produced and drawn to 25–250μm wires.Tensile testing revealed high and tunable mechanical properties on par with existing flow diverter materials.In vitro degradation testing of 100μm wire in DMEM to 7 days indicated progressive corrosion and cracking of the FeMnN shell but not of the Mo,confirming the cathodic protection of the Mo by the FeMnN and thus mitigation of premature fragmentation risk.In vivo implantation and subsequentμCT of the same wires in mouse aortas to 6 months showed meaningful corrosion had begun in the FeMnN shell but not yet in the Mo filament cores.In total,these results indicate that these composites may offer an ideal combination of properties for absorbable flow diverters.
基金This work was supported by the National Institutes of Health grant number(R01 NS105853).
文摘There has been growing interest and insight into the histological composition of retrieved stroke emboli.One of the main focuses of the stroke clot analysis literature has been the implications of clot composition on mechanical thrombectomy procedures.However,the holy grail of clot analysis may not be in the field of clot-device interaction,but rather,in understanding mechanisms of fibrinolysis resistance.The mechanisms underlying the low response to fibrinolytic therapy,even with the newer,more powerful agents,remain poorly understood.While factors such as embolus size,location and collateral status influence alteplase delivery and recanalisation rates;compositional analyses focused on histological and ultrastructural characteristics offer unique insights into mechanisms of alteplase resistance.In this review,we strive to provide comprehensive review of current knowledge on clot composition and ultrastructural analyses that help explain resistance to fibrinolysis.
