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由配合板（专利申请中）引入的一种新型二尖瓣（MV）配合机制的可行性，该机制基于二尖瓣和配合板的功能和流-结构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缺血左心室重塑引起的，导致乳头肌移位，心室环扩张和随后的二尖瓣小叶栓系，这限制了二尖瓣小叶的闭合。目前的手术策略包括环成形术、乳头肌的重新定位、脊索和小叶的操作，这些都是基于小叶接触和对齐的MV适应机制。到目前为止，没有一种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。在本提案中，PI提出了一种新的二尖瓣闭合机制，即二尖瓣闭合板的概念，以治疗缺血性二尖瓣反流。我们推测，通过将配合板插入二尖瓣孔，并利用与配合板在缺血性二尖瓣内的流固相互作用的新知识，可以更好地治疗缺血性二尖瓣反流。新概念的贴合板贴合机构不要求小叶相互接触，而是诱导小叶与贴合板接触，作为小叶之间的中间桥梁，密封小叶间隙。2个具体目的是：1)评价中压贴合板在瓣膜关闭过程中预防缺血性二尖瓣返流的效果；2)用配合板评价缺血中压通气时左心室及中压流体力学。通过对阀瓣空间形态、间隙大小、压降、阀瓣闭合深度和阀瓣闭合时泄漏量的测量和分析，验证了阀瓣闭合板的有效性。采用计算流体力学方法对中压、合板和左心室进行了计算流体力学研究，以评估中压压降、剪切应力、速度、涡型和左心室能量耗散。由贴合板引入的新颖贴合概念挑战了目前基于小叶接触和对齐的中叶贴合机制，该机制依赖于小叶和环的大小，以及弦索和乳头状的空间构型。新的配合板的配合机制既不需要两个MV小叶之间的接触或对齐，也不需要通过环成形术获得正常或过小的环，因为配合板的几何形状补偿了由于环扩张和索系索引起的小叶位移。一旦这种新的适应机制被证明是有效和可行的，它将极大地影响当前的二尖瓣修复模式，并导致改进外科手术和开发新的医疗设备，不仅可以预防缺血性二尖瓣反流，还可以预防其他原因的二尖瓣反流。

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.