New generation of aortic bioprosthesis: technology specifications
One important point in tissue valve engineering is the ability to develop new biological prosthesis with less static configurations and more biologically active tissues. So far, recent technologies have achieved better fixation and storage procedures (Table 1), but all of them fail to mimic biological activity of heart valve cells. Recently, two new bioprosthesis (Inspiris® from Edwards Lifesciences® and Perceval Plus® from Livanova®) with two novel tissue treatments (Resilia® and FREE®, respectively) have been launched expecting less calcification and improved tissue durability.
Perceval Plus® is a bovine pericardial heart valve with a novel tissue treatment to reduce calcification: the FREE® treatment. FREE treatment uses an alcohol mixture for phospholipids removal, combined with a post-sterilization amino-acid treatment for the neutralization of unbound aldehydes, and final storage with an aldehyde-free solution (80). FREE-treated tissues have a reduced content of phospholipids up to 96%, comparing to Glut-treated tissues, combined with a significant improvement in the removal and neutralization of unbound Glut (80). Tissues have less propensity to mineralization while maintaining the same mechanical and biochemical performance and stability of the conventional Glut-treated prosthesis (80). In theory, FREE treatment is an effective strategy to reduce bioprosthesis dysfunction. However, long-term outcomes in humans still unknown.
Resilia® is also a new tissue preservation technology, that uses stable functional group capping, ethylene oxide sterilization, and preservation by glycerolization (81). This innovative technology does not avoid Glut use but reduces phospholipids content and residual chemicals from the valve tissues. There are also differences considering the storage of the tissues, using dry storage, which reduces the contact of the prosthesis with aldehyde-enriched solutions.
Despite all these new and exciting tissue treatments to prevent calcification, we should keep in mind that it will take longer to have the 15-20 year outcomes we now have for conventional Glut-treated tissues. Moreover, all these strategies are based on the reduction of free aldehyde groups and phospholipids content, reducing the chemical effects of Glut. As previously discussed here, chemical changes are just part of the complex process of biological prosthetic valves dysfunction, and new strategies to address mechanical and immunological changes in valve tissues must be addressed.