Development and characterization of vascular prosthetics for controlled bioabsorption
Abstract
One million intravascular stent installations are performed each year in the United States, with increasing numbers deployed in noncoronary vasculature. Targets of intervention range broadly from compliant pulmonary vessels of children with congenital heart disease (CHD), to atherosclerotic popliteal arteries of older patients with critical limb ischemia (CLI). Stented lesions may be long and tortuous as in the case of severe infrainguinal lesions, or short and relatively uniform as in mild pulmonary artery stenoses. The range of pathologies treated by intravascular stents has risen as technology has become more diverse: compact delivery platforms have allowed access of the peripheral artery system for the treatment of CLI while smaller, more exible stents have enabled treatment of congenital vascular defects and cerebrovascular stenoses. Naive stenting applications have illuminated new problems. Permanent bare metal stents (BMSs) in children are susceptible to relative occlusion and fracture as the anatomy proceeds through natural growth. Stenting in infrainguinal arteries is frequently associated with fracture risk and in-stent-restenosis (ISR) related to lower limb mobility of physically active implant-recipients. Bioabsorbable stent designs hold promise towards mitigation of these effects by disappearing after restoring vessel patency once post-operative vessel healing has occurred. Bioabsorbable design efforts have focused primarily on balloon-expandable technology for coronary pathologies. New designs are needed which service the unique demands of non-coronary vasculature. This proposed and ongoing research is towards design and characterization of high strength, bioabsorbable metallic, intravascular stents. Novel nutrient-metal-composites and alloys of pure iron, manganese and magnesium are proposed in order to control the biodegradation rate as well as mechanical properties. Characterizations including fatigue testing, biodegradation under mechanical stimulation, vascular cell attachment, proliferation and cytotoxicity, are completed in order to illuminate future strategies towards optimized clinical utility. Preliminary in vitro data are presented which evidence protein-environment-dependent fatigue strength and biodegradation rate as well as cytocompatibility of the proposed composite stents.
Degree
Ph.D.
Advisors
Stanciu, Purdue University.
Subject Area
Biomedical engineering|Mechanical engineering|Materials science
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