BME Seminar Series: Dr. Frederic Heim, Université de Haute Alsace
"Heart Valves from Fibers: Remaining Challenges "
Over 300.000 heart valves are replaced every year in western countries and valve therapy represents today one of the most common surgical procedures performed in the world. While open chest surgery remains the gold standard to replace a faulty valve, less invasive approaches have been developed over the last decade. Actually, the rapid developments and success in percutaneous vascular stents implantation over the last 2 decades to treat vessel stenosis has made this technique attractive today even for aortic valve replacement. The principle is to implant a stented valve prosthesis by going through the vascular network of the patients. With this new technique, patients are not exposed to the risks of surgery, and transcatheter aortic valve implantation (TAVI) has become highly suitable for an increasing elderly population and has become an accepted alternative technique to surgical valve replacement for over 150,000 patients worldwide. Despite minor issues related to the implantation of the device, this non-invasive technique is cost-effective and provides increased comfort to patients, relative to traditional surgical valve implantation. In a fast growing global market, where TAVI related survival rates depend highly on the initial patient’s health, one can expect that more less-critical patients could be treated successfully with TAVI in the coming years. Currently, the valve material used in TAVI is biologic tissue, such as bovine or porcine pericardium. However, once assembled inside the metallic stent and crimped at low diameter for catheter insertion, studies have shown that the biological materials may become degraded. Textile polyester (PET) could be considered as an alternative material to replace TAVI biological valve leaflets. In particular, woven textile constructions have outstanding folding and resistance properties and as a result, these materials are easy to crimp and insert, even in low profile devices. Moreover, woven materials are discontinuous, mitigating the risk of a catastrophic rupture. Rupture propagation is isolated to the single filament. Recent works showed that woven textile materials could resist up to over 200 million cycles in vitro under accelerated cyclic loading and 6 months in vivo successful implantations were reported with fabric valve prototypes implanted in juvenile sheep models. However, despite the high potential of the material, challenges remain before textile can be considered as a durable valve replacement solution.