Siefert Andrew W, Rabbah Jean-Pierre M, Pierce Eric L, Kunzelman Karyn S, Yoganathan Ajit P
The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia.
Department of Mechanical Engineering, University of Maine, Orono, Maine.
Cardiovasc Eng Technol. 2014 Mar 1;5(1):35-43. doi: 10.1007/s13239-014-0175-9.
Computational models of the heart's mitral valve (MV) exhibit potential for preoperative surgical planning in ischemic mitral regurgitation (IMR). However challenges exist in defining boundary conditions to accurately model the function and response of the chordae tendineae to both IMR and surgical annuloplasty repair. Towards this goal, a ground-truth data set was generated by quantifying the isolated effects of IMR and mitral annuloplasty on leaflet coaptation, regurgitation, and tethering forces of the anterior strut and posterior intermediary chordae tendineae.
MVs were excised from ovine hearts (N=15) and mounted in a pulsatile heart simulator which has been demonstrated to mimic the systolic MV geometry and coaptation of healthy and chronic IMR sheep. Strut and intermediary chordae from both MV leaflets (N=4) were instrumented with force transducers. Tested conditions included a healthy control, IMR, oversized annuloplasty, true-sized annuloplasty, and undersized mitral annuloplasty. A2-P2 leaflet coaptation length, regurgitation, and chordal tethering were quantified and statistically compared across experimental conditions.
IMR was successfully simulated with significant increases in MR, tethering forces for each of the chordae, and decrease in leaflet coaptation (p<.05). Compared to the IMR condition, increasing levels of downsized annuloplasty significantly reduced regurgitation, increased coaptation, reduced posteromedial papillary muscle strut chordal forces, and reduced intermediary chordal forces from the anterolateral papillary muscle (p<.05).
These results provide for the first time a novel comprehensive data set for refining the ability of computational MV models to simulate IMR and varying sizes of complete rigid ring annuloplasty.
心脏二尖瓣（MV）的计算模型在缺血性二尖瓣反流（IMR）的术前手术规划中显示出潜力。然而，在定义边界条件以准确模拟腱索对IMR和手术瓣环成形术修复的功能和反应方面存在挑战。为了实现这一目标，通过量化IMR和二尖瓣瓣环成形术对前支柱和后中间腱索的瓣叶贴合、反流和系绳力的单独影响，生成了一个真实数据集。
从羊心脏（N = 15）中切除MV，并安装在脉动心脏模拟器中，该模拟器已被证明可模拟健康和慢性IMR绵羊的收缩期MV几何形状和贴合情况。两个MV瓣叶的支柱和中间腱索（N = 4）都配备了力传感器。测试条件包括健康对照、IMR、过大瓣环成形术、真实尺寸瓣环成形术和过小二尖瓣瓣环成形术。在不同实验条件下，对A2 - P2瓣叶贴合长度、反流和腱索系绳进行了量化和统计比较。
成功模拟了IMR，MR显著增加，每条腱索的系绳力增加，瓣叶贴合减少（p <.05）。与IMR条件相比，逐渐减小尺寸的瓣环成形术水平显著降低了反流，增加了贴合，降低了后内侧乳头肌支柱腱索力，并降低了前外侧乳头肌的中间腱索力（p <.05）。
这些结果首次提供了一个新颖的综合数据集，用于提高计算MV模型模拟IMR和不同尺寸完整刚性环瓣环成形术的能力。
