Cette étude à pour but de développer un concept de stent atraumatique pour le remplacement percutanée de la valve aortique. Le stent est obtenu à partir de brins de Nitinol tressés, ce qui lui permet, de part sa géométrie et sa structure, d'être compressible, auto-expansible, et atraumatique. Le principe de fabrication des prototypes et les contraintes qui lui est associé sont présentées. Les performances de ces prototypes, en terme d'ancrage, de régurgitation statique et de régurgitation dynamique sont ensuite évaluées par des essais in vitro, pour lesquel le banc de test en flux pulsé a été optimisé afin de prendre en considération la compliance de la racine aortique. Les résultats obtenus permettent de mettre en évidence les différents paramètres de fabrication stent, tant au niveau dimensionnel (hauteur du cylindre, angle du cône...) qu'au niveau structurel (rigidité), qui ont une influence significative sur le comportement de l'endoprothèse. / The goal of this work is to develop an atraumatic stent concept for percutaneous aortic valve replacement. Shape setted braided nitinol wires, thanks to their specific geometry and elasticity, allows stent's compressibility, self deployment and aortic root preservation. Prototypes manufacturing technique and relatives constraints are presented. Performance of the obtained prototypes are evaluated in vitro, in terms of sealing, static and dynamic regurgitation. More specifically, the pulsatile bench testing has been optimized to take in account the compliant constraint of the aortic valve environment. The results bring to the fore which are the dimensions (head height, cone angle...) and the structures features that do influence the endoprosthesis behavior significantly.

Mitral valve disease is widely prevalent among pediatric and adult population across the world, and it encompasses a spectrum of lesions which include congenital valve defects, degenerative valve lesions, and valve dysfunction due to secondary pathologies. Though replacement of the diseased mitral valves with artificial heart valves has been the standard of care until early 1990's, current trends have veered towards complete surgical repair. These trends are encouraging, but current repair techniques are plagued with lack of durability and high rates of failure within 10 years after repair. With increasing number of patients receiving mitral valve repair, there is now an immediate need to understand the mechanisms of repair failure, and assess the role of several clinical risk factors on valve repair. In this thesis, an in vitro pulsatile left heart simulator was developed to mimic the congenital and adult mitral valve pathological morphologies in normal porcine valves, and simulate the pathological valve hemodynamics and mechanics. Different surgical repair techniques were used to correct the valve lesions, and the post repair valve hemodynamics, mechanics and geometry were assessed using quantitative measurement techniques. The extent to which each repair restores physiological valve function and mechanics was assessed, and the impact of different pathological risk factors on repair failure mechanisms was investigated. It is expected that the knowledge from this thesis would play an important role in the evolution of mitral valve surgical repair, and guide the development of more effective and long-lasting heart valve repair technologies.

Thesis (M.S.)--New Jersey Institute of Technology, Dept. of Biomedical Engineering, 2003. / HFT20030804. Includes bibliographical references (p. 75-76). Also available via the World Wide Web.

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Thesis (Ph. D.)--University of New South Wales, 2002.

Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographical references (leaves [127]-138).