Mitral Saddle Shape Preservation Improves Valvuloplasty

描述(由申请人提供)： 在过去的三十年里，Carpentier开创了标准化的外科技术，使所有类型的叶状、索状和环状畸形的二尖瓣得到可靠的修复。这些技术的使用在世界各地的中心都产生了良好的效果。虽然这些维修的耐久性是可以接受的，但长期失败率为10%至16%。已报道的失败模式涉及机械应力作为病因因素。在人类和动物身上的成像技术显示，二尖瓣环具有明显的鞍形；这种形状在哺乳动物中是保守的。最先进的数学模型表明，这种鞍形赋予小叶曲率，将小叶的应力和由此产生的应变降至最低。大多数成熟的二尖瓣修复技术包括放置扁平的二尖瓣成形环。虽然平环通过减少瓣环面积和改善瓣叶粘合来改善早期瓣膜功能，但环形扁平可能会减小瓣叶曲率，并对瓣叶组织、肌腱索和修复缝合线产生不必要的应力和应变，从而限制修复的耐用性。我们假设与标准的扁平瓣环成形术相比，鞍形瓣环成形术可以减少瓣叶应力。三维超声心动图将在绵羊模型上评估瓣环成形环形状对正常瓣叶曲率的影响。此外，用于心脏成像和应变测量的声学显微阵列定位技术将用于评估瓣环成形环形状对整个心脏周期中二尖瓣瓣叶应变的影响。来自这两种技术的数据将允许对连接环状形状、叶片曲率和叶片张力的机制进行定量评估。了解这一关系将有助于更合理地设计瓣环成形术，提高目前已有的瓣膜修复技术的使用寿命。

DESCRIPTION (provided by applicant): During the past thirty years Carpentier has pioneered and standardized surgical techniques that allow reliable repair of mitral valves with all types of leaflet, chordal and annular deformities. Use of these techniques has produced good results at centers all over the world. Although the durability of these repairs has been acceptable there is a 10 to 16% long-term failure rate. Reported modes of failure implicate mechanical stress as an etiologic factor. Imaging techniques in humans and animals have shown the mitral annulus to have a pronounced saddle shape; this shape is conserved across mammalian species. State-of-the-art mathematical modeling indicates that this saddle shape imparts curvature to the leaflets, minimizing leaflet stress and resulting strain. Most established mitral valve repair techniques include placement of a flat annuloplasty ring. While a flat ring improves early valve competence by reducing annular area and improving leaflet coaptation, annular flattening may reduce leaflet curvature and produce unnecessary stress and strain on leaflet tissue, chordae tendenae and repair suture lines, limiting repair durability. We hypothesize that saddle-shape annuloplasty will diminish leaflet stress when compared with standard flat annuloplasty, Three-dimensional echocardiography will be used to assess the effect of annuloplasty ring shape on normal leaflet curvature in an ovine model. In addition, sonomicrometry array localization, a technique for cardiac imaging and strain measurement, will be used to assess the effect of annuloplasty ring shape on mitral valve leaflet strain throughout the cardiac cycle. Data from these two techniques will allow a quantitative assessment of the mechanism linking annular shape, leaflet curvature, and leaflet strain. An understanding of this relationship will allow a more rational design of annuloplasty rings, improving the longevity of currently established valve repair techniques.