Heart valve replacement in pediatric patients continues to require an invasive surgical approach including cardiopulmonary bypass, a midline sternotomy, and significant rehabilitation. The recovery after these surgeries creates a disruption in the socialization and development of affected children. The development of a heart valve amenable to placement in children with transcatheter technology, rather than with surgery, could allow children to avoid this process. Although percutaneous valve replacement has become a reality in adults and teenagers, transcatheter heart valves suitable for use in neonates and younger children do not exist. Nitinol (TiNi), a titanium-nickel alloy, has shape-memory and super-elastic characteristics. It is biocompatible, very strong, and resists fatigue. An expertise in the production of very thin-film TiNi suitable for use in catheter-based artificial heart valves has been developed. An entirely nitinol catheter-based heart valve will be designed for use in small children and tested in vitro and in an animal model. Masking and etching modifications of high temperature TiNi sputtering techniques will be used to produce thin-film nitinol heart valve leaflets resistant to developing rips during transcatheter insertion and long-term function. A contoured scaffolding, also composed entirely of nitinol, has been designed to support the leaflets of an entirely nitinol trileaflet valve. Thin-film TiNi leaflets will be sputtered directly onto this scaffold. In phase I studies, in vitro testing, not including fatigue testing, will be performed to confirm that thin-film TiNi can function adequately as a heart valve. The vortices created by the TiNi valves, valvar stenosis and insufficiency will be assessed in vitro. To gauge in vivo feasibility, valves will be implanted both percutaneously and surgically into a series of animals. In vivo valve function will be assessed by angiography, echocardiography and post-mortem gross and microscopic examination. Phase II studies will focus on accelerated wear testing, long-term in vivo animal testing, and manufacturing issues. ? ?
