Mitral valve coaptation plate for ischemic mitral regurgitation

描述(由申请人提供)：拟议研究的目的是证明一种新的二尖瓣和二尖瓣粘合机制的可行性(正在申请专利)，该机制基于二尖瓣和二尖瓣粘合的功能性和流固相互作用来预防缺血性二尖瓣反流。缺血性二尖瓣反流是由于缺血左心室重构，导致乳头肌移位，瓣环扩张，继而二尖瓣叶被拴住，限制了二尖瓣叶的关闭。目前的手术策略包括瓣环成形术、乳头肌再定位、弦和小叶操作，这些都是基于小叶接触和排列的MV胶合机制。到目前为止，没有一种方法能提供长期的可靠性。缺乏有效的治疗导致50%的二尖瓣返流在5年内复发。在这项建议中，PI提出了一种新的MV接合机制，即MV接合板的概念，用于治疗缺血性二尖瓣返流。通过将二尖瓣吻合板插入二尖瓣口，并利用流体-结构相互作用的新知识，可以更好地治疗缺血型二尖瓣返流。接合板接合机构的新概念不需要小叶相互接触，而是使小叶接触接合板，作为小叶之间的中间桥梁，并密封小叶间隙。具体目的有两个：1)评价二尖瓣吻合板预防二尖瓣关闭时缺血性二尖瓣反流的效果；2)评价二尖瓣关闭时应用二尖瓣吻合板的缺血型二尖瓣关闭不全患者的左心室和二尖瓣血流动力学。测量和分析了中压叶的空间形态、缝隙大小、压降、叶的接合深度和阀门关闭时的泄漏情况，证明了接合板的有效性。采用计算流体力学方法对中膜、接合板和左心室进行了研究，以评价跨中膜压降、切应力、速度、旋涡模式和左心室内的能量耗散。由接合板引入的新的MV接合概念挑战了目前基于叶接触和排列的MV接合机制，该机制依赖于叶和环的大小以及弦和乳头的空间构型。新的粘接板的粘合机制不需要两个MV叶之间的接触或对齐，也不需要通过瓣环成形术获得正常或过小的环，因为粘合板的几何形状补偿了由于环扩张和索系系导致的叶移位。一旦这种新的粘合机制被证明是有效和可行的，它将极大地冲击现有的MV修复模式，并导致改进的手术方法和新的医疗设备的开发，不仅可以预防缺血性二尖瓣反流，而且还可以预防其他原因的二尖瓣反流。 公共卫生相关性：拟议的研究旨在证明一种由二尖瓣吻合板(正在申请专利)引入的新的二尖瓣缝合机制的可行性，该机制基于二尖瓣和吻合板的功能和流固相互作用来预防缺血性二尖瓣反流。一旦粘接板的粘合机制被证明是有效的，它将极大地冲击现有的MV修复模式，并导致改进的手术操作和新的医疗器械的开发，以长期可靠地防止二尖瓣返流，降低患者的发病率和死亡率。

DESCRIPTION (provided by applicant): The objective of the proposed research is to prove feasibility of a novel mitral valve (MV) coaptation mechanism introduced by coaptation plate (patent pending) to prevent ischemic mitral regurgitation based on functionality and fluid-structure interaction of the MV and coaptation plate. Ischemic mitral regurgitation results from remodeling of the ischemic left ventricle, leading to displacement of the papillary muscles, annulus dilatation and consequent tethering of the MV leaflets, which restrict the closure of the mitral leaflets. Current surgical strategies include annuloplasty, repositioning of papillary muscles, chordal and leaflet manipulation, which are all based on MV coaptation mechanism of the leaflet contact and alignment. Until now, none of them offers long term reliability. Lack of effective treatment leads to 50% mitral regurgitation recurrence in 5 years. In this proposal, the PI proposes a novel MV coaptation mechanism, a concept of MV coaptation plate, to treat ischemic mitral regurgitation. It is hypothesized that ischemic mitral regurgitation can be better treated by inserting the coaptation plate into the MV orifice and utilizing new knowledge of fluid-structure interaction in an ischemic MV with the coaptation plate. The novel concept of coaptation mechanism of the coaptation plate does not require leaflets contacting each other, but induces leaflets to contact the coaptation plate as an intermediate bridge between leaflets, and seals the leaflet gap. The 2 specific aims are: 1) evaluate efficacy of the MV coaptation plate to prevent ischemic mitral regurgitation during valve closure; 2) evaluate left ventricle and MV fluid mechanics in the ischemic MV with the coaptation plate during valve opening. MV leaflet spatial configuration, gap size, pressure drop, leaflet coaptation depth and leakage during valve closure are measured and analyzed to prove efficacy of the coaptation plate. A computational fluid dynamic study on the MV, coaptation plate and left ventricle is conducted to evaluate pressure drop across the MV, shear stress, velocity, vortex pattern, and energy dissipation in the left ventricle. The novel coaptation concept of the MV introduced by the coaptation plate challenges the current MV coaptation mechanism based on leaflet contact and alignment, which depends on leaflet and annulus sizes, and chordal and papillary spatial configuration. The new coaptation mechanism of the coaptation plate requires neither touch or alignment between two MV leaflets, nor a normal or undersized annulus achieved by annuloplasty because geometry of the coaptation plate compensates leaflet displacement due to annulus dilatation and chordae tethering. Once this novel coaptation mechanism is proved to be effective and feasible, it would greatly impact current MV repair paradigms, and lead to improved surgical procedures and development of novel medical devices to prevent not only ischemic mitral regurgitation, but also mitral regurgitation of other etiologies. PUBLIC HEALTH RELEVANCE: The proposed research aims to prove feasibility of a novel mitral valve coaptation mechanism introduced by coaptation plate (patent pending) to prevent ischemic mitral regurgitation based on functionality and fluid-structure interaction of the mitral valve and coaptation plate. Once the coaptation mechanism of the coaptation plate is proved to be effective, it will greatly impact current MV repair paradigms, and lead to improved surgical procedures and development of novel medical devices to prevent mitral regurgitation with long-term reliability and decrease patient morbidity and mortality.