Implanted cardiovascular polymers: Natural, synthetic and bio-inspired

This review details the use of polymeric biomaterials used in implantable cardiovascular devices. Specifically, the role of the polymer in two major types of device, the vascular graft and the cardiovascular stent, is examined critically. In these two devices, the device performance is critically dependent on the polymer; the material requirements are detailed, and the shortcomings of currently used polymers highlighted with a view to furthering the development of new materials. In each category, synthetic polymers, polymers of natural origin, and polymers that mimic proteins but are synthesized, have all been evaluated with varying degrees of success. We find that the totally artificial graft is still the preferred option when autologous vessels are not available; the development of a completely tissue-engineered graft awaits improvements in scaffold materials as well as in tissue reactor engineering. In the field of stents, current consensus is driving the substitution of a biodegradable, polymeric stent for the biostable metallic one. Although various biodegradable polymers have been evaluated, the hydrolytically degradable polyesters continue to be the polymer of choice. New developments in biodegradable polymers are highlighted, and their performance in terms of biocompatibility and controlled degradability are presented. The outlook for the next decade appears hopeful, with improvements in cell-seeding and cell growth techniques expected to enhance the performance of both types of implanted device.