? Minimally invasive surgical techniques to implant cardiovascular devices for treatment of a variety of valvular, vascular and extra-vascular complications are increasingly exploited to improve patient outcomes, and reduce morbidity and cost. Originally based on simple metals, these devices are now becoming more sophisticated through the use of precisely engineered materials such as metal bimorphs (shape memory alloys) and new polymer structures. Polymers, in particular, exhibit significant advantages in these applications over metals and metal alloys, including ease of surface modification that enhances biocompatibility, greater mechanical flexibility to more accurately simulate native mechanical behavior, and availability of a wide variety of base structural configurations. Manipulation of polymers to produce shape memory characteristics is the most recent evolution, which due to their high degree of shape recoverability (order of magnitude greater than metal alloys) promises significantly greater freedom in designing minimally invasive cardiovascular devices. However, several substantial challenges preclude reliable and direct applications of shape memory polymers (SMPs) as innovative biomaterials for surgical implants. The goal of this project is to remove this limitation in the SMP design process by explicitly quantifying the thermomechanical properties of one promising type of SMP, and infusing this information into a commercially available finite element model (ABAQUS). This will provide designers of cardiovascular devices who wish to use SMPs with two enhancements required to enable exploitation of SMP biomaterials in future surgical devices: (1) new SMP engineering benchmarking characteristics required for rational design and proof-of-concept for SMP-based devices, and (2) a powerful a priori evaluation tool to refine and test device designs prior to fabrication. The model will then be exercised to produce two increasingly complex prototype devices: a vascular stent with significantly greater shape recoverability than currently available using metal shape memory alloys, and a prosthetic heart valve. ? ?
| Yakacki, Christopher M; Shandas, Robin; Safranski, David et al. (2008) Strong, Tailored, Biocompatible Shape-Memory Polymer Networks. Adv Funct Mater 18:2428-2435 |
| Yakacki, C M; Lyons, M B; Rech, B et al. (2008) Cytotoxicity and thermomechanical behavior of biomedical shape-memory polymer networks post-sterilization. Biomed Mater 3:015010 |
| Yakacki, Christopher Michael; Shandas, Robin; Lanning, Craig et al. (2007) Unconstrained recovery characterization of shape-memory polymer networks for cardiovascular applications. Biomaterials 28:2255-63 |
