Optimisation and 3D Printing of Paediatric Stents

Abstract

Aortic coarctation is a congenital heart defect that occurs 3 per 10,000 live births with a life expectancy of 35 years if left untreated. Stenting is a common treatment method, but devices are not specifically designed for paediatric patients, leading to off label stent use and potentially hazardous device modifications. The combination of unique pathologies and low patient numbers associated with aortic coarctation leads to little commercial incentive to develop devices for this patient cohort. This study has the overarching aim of investigating the feasibility of developing devices for this population with additive manufacturing (AM). A stent design inspired by commercial devices was adapted and produced by AM. A post-processing parameter study was conducted to enable the manufacture of an open cell varied diameter stent not easily fabricated with typical stent manufacturing techniques. Furthermore, these devices were tested mechanically to analyse their radial strength and flexibility. Geometric properties such as strut thickness and surface roughness were also measured to gain insight into the relationship between post-processing technique parameters and stent properties.

These devices were compared to contemporary commercial and additively manufactured stents previously presented in the literature. Analysis of surface roughness and strut thickness showed the stents produced in this work have the lowest surface roughness and strut thickness for AM stents to date and are comparable to commercial devices. The analysis of mechanical properties showed these devices are less radially stiff and more flexible than contemporary commercial stents and AM stents to date. Overall, these results prove the feasibility of using AM to produce stents with a wide range of geometric and mechanical properties with AM.

In summary, this work pushes the boundaries of AM fabrication showing the feasibility of developing devices with an open-cell design and varied diameter. The use of AM and the post-processing techniques presented in this work proves the viability of developing stents with tuneable local mechanical and geometric properties. AM enables rapid prototyping and feasible manufacture of these devices which may enable the commercial viability of disease or patient specific devices in future work.