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.