Quantitative Force Measurements to Optimize Valve Repair for Ischemic MR

描述(申请人提供)：缺血性二尖瓣反流(IMR)是指结构正常的二尖瓣(MV)由于心肌梗死引起的左心室重构而功能不全。IMR对160万至280万美国人产生了影响。二尖瓣环过小平环成形术已成为二尖瓣成形术的首选治疗方法。然而，最近的研究表明，这种方法与手术后6个月内30%的失败率有关。大多数失败是由进行性的叶拴系和瓣环成形术环裂开引起的，这意味着环状和弦状应力分布是一种机制。这些不理想的应力分布部分是由于过小的瓣环成形术可能通过进一步损害基础左心室的几何形状和功能而加剧了左室重构过程。过小的瓣环成形术的不足是因为它未能满足Carpentier成功修复二尖瓣的两个基本要求：它不能重建正常的环状结构，也不能充分恢复瓣叶的活动度。初步工作表明，鞍形瓣环成形术和小叶扩大术在改善IMR修复方面具有良好的前景。然而，目前还没有数据支持关于IMR的最佳修复技术的共识。因此，我们设计了这个项目的具体目标，以检验这样一个假设，即正常化环状几何结构和恢复叶活动的IMR修复技术将通过促进更好的基础左室功能、较少的左室重构恶化和减少环状和索状应力分布而导致更持久的修复。我们对这一关键临床问题的创新方法利用了我们集团外科和工程专业知识的独特组合。我们将利用体内和体外的IMR模型，结合新的成像和力传感器技术，评估瓣环成形术和瓣叶组织扩大术对瓣膜力分布的影响。这种实验方法允许临床前优化IMR的二尖瓣修复程序，因此只需要在患者身上测试最有希望的技术。

DESCRIPTION (provided by applicant): Ischemic mitral regurgitation (IMR) occurs when a structurally normal mitral valve (MV) is rendered incompetent as a result of myocardial infarction induced left ventricular remodeling. IMR effects between 1.6 to 2.8 million Americans. Mitral valve repair with undersized flat ring annuloplasty has become the preferred treatment. However, recent studies have demonstrated this approach is associated with a failure rate of 30% within 6 months of surgery. Most failures result from progressive leaflet tethering and annuloplasty ring dehiscence which implicates annular and chordal stress distribution as a mechanism. These suboptimal stress profiles are due, in part, to the fact that undersized annuloplasty likely accentuates the LV remodeling process by further impairing basal LV geometry and function. The inadequacy of undersized annuloplasty results from its failure to fulfill two of Carpentier's fundamental requirements for successful mitral valve repair: it does no reestablish normal annular geometry nor does it adequately restore leaflet mobility. Preliminary work has demonstrated the promise of saddle-shaped annuloplasty and leaflet augmentation in improving IMR repair. However, there are currently no data to support a consensus as to the optimal repair technique for IMR. Therefore, we have designed the specific aims of this project to test the hypothesis that IMR repair techniques that normalize annular geometry and restore leaflet mobility will result in more durable repairs by promoting better basal LV function, less exacerbation of LV remodeling and reduced annular and chordal stress distribution. Our innovative approach to this critical clinical problem leverages our group's unique combination of surgical and engineering expertise. Using both in vivo and in vitro models of IMR in combination with novel imaging and force transducer technology, we will assess the effect annuloplasty shape and leaflet tissue augmentation on valvular force distribution. Such an experimental approach allows for the preclinical optimization of a mitral valve repair procedures for IMR so only the most promising techniques need to be tested in patients.