There are advantages for biodegradable stents (BDS) to treat cardiovascular disease, but a stent that successfully treats arterial stenosis and then disappears would especially be an advantage in a growing child. The overall goal of this research is to study the characteristics and mechanical performance of a BDS specifically designed for the management of congenital heart disease (CHD). BDS larger than 8mm diameter are required for growing children with CHD but none are in development. Testing of a novel coil based, double opposed helical (DH) stent made of poly-L-lactic acid (PLLA) has shown acceptable mechanical properties with low inflammatory profile in preclinical testing in smaller diameters. This unique design allows manufacture of BDS to large diameters and with alterations to the fiber may be able to overcome problems of worsening mechanical properties with increasing stent diameters.
The aim of this study is to investigate changes in biodegradable fibers by altering strut thickness, then document the BDS performance at large diameters.
The first aim i s to determine the mechanical properties of fiber fabricated with PLLA with strut thickness of 0.25 and 0.30 mm. Then determine the degradation and thermal properties of these fibers. It is expected that thinner polymer fibers will be initially stronger and degradation to be approximately 2 years.
The second aim i s to use these fibers to manufacture DH BDS at diameters of 10, 12, 14, 16, and 20mm. The mechanical properties with regard to expansion, recoil and radial strength will be documented. The mechanical properties throughout degradation will be determined. This is anticipated to provide valuable new knowledge of the behavior of large diameter BDS. Finite element analysis for the 10mm BDS will be compared to the experimental result to determine if structural simulation is valid in this diameter. Comparisons with over- expanded metal stents in clinical use today will be made. The results from this research are anticipated to form the basis for future studies including in-vivo studies t evaluate the effect of the BDS on the vessel wall. Documentation of BDS mechanical characteristics (compared to overinflated metal stents) have the potential to revolutionize the way CHD is managed.
Stents are scaffolds that hold open a blocked artery, in many cases avoiding surgery, but mechanical support is only needed temporarily and after months/years the permanent metal scaffold becomes a disadvantage especially in a growing child. The proposed research combines expertise in bioengineering and interventional cardiology to design and test a biodegradable disappearing stent specifically for use in much larger arteries required in children with congenital heart disease.
