Future horizons in surgical aortic valve replacement: lessons learned during the early stages of developing a...

The aim of this study was to develop a heart valve prosthesis that could be transluminally inserted through the infrarenal aorta in pigs and the femoral artery in humans. Therefore, this valve prosthesis had to be foldable to a diameter of approximately 8 mm, self-expandable when released in the vascular system, and equipped with an anchoring mechanism. For implantation, a suitable catheter delivery system for insertion via the abdominal aorta in pigs also was designed. Furthermore, an operation method, including positioning of the catheter delivery system and deployment of the valved stent under fluoroscopic and echocardiographic control, was developed. A series of different prototypes of the valved stents and catheter delivery systems was produced to optimize design and handling. These prototypes were tested in vitro in a circulation model, and those showing satisfying hemodynamic properties were implanted in pigs as in vivo studies afterwards. The valved stents had a good hemodynamic function in vitro and in vivo with no more than a mild regurgitation or stenosis. Valve movements were satisfying, and the design proved to be generally feasible. However, positioning and anchoring were still difficult; some stents were tilted in the lumen or migrated after implantation.