Kunzelman K S, Reimink M S, Cochran R P
Division of Cardiothoracic Surgery and Center for Bioengineering University of Washington, Seattle 98195, USA.
Cardiovasc Surg. 1997 Aug;5(4):427-34. doi: 10.1016/s0967-2109(97)00045-8.
The purpose of this study was to examine the effects of annular dilatation on coaptation, and leaflet and chordal stresses, using a three dimensional finite element computer model. To do this, the whole mitral valve was simulated using ANSYS 4.4A software. Normal model geometry, collagen fiber orientation, tissue thickness, and material properties were determined from fresh porcine valves. For annular dilatation, the annular circumference was increased by 18% versus normal. Isovolumic contraction and rapid ventricular ejection were simulated. Data showed that, in the annular dilatation model, the stress magnitudes increased more than two-fold compared with normal in both the anterior leaflet and posterior leaflet. Coaptation was greatly delayed in the dilatation model, and the leaflets never fully coapted. Chordal stresses were also greatly increased in the dilatation model. In conclusion, increased stress due to annular dilatation may lead to tissue disruption, further dilatation, delayed coaptation, and increased regurgitation, in a 'closed-loop' degenerative process.
本研究的目的是使用三维有限元计算机模型来研究瓣环扩张对瓣叶贴合以及瓣叶和腱索应力的影响。为此，使用ANSYS 4.4A软件对整个二尖瓣进行模拟。正常模型的几何形状、胶原纤维方向、组织厚度和材料特性由新鲜猪瓣膜确定。对于瓣环扩张，瓣环周长相对于正常增加了18%。模拟了等容收缩期和快速心室射血期。数据显示，在瓣环扩张模型中，前叶和后叶的应力大小与正常相比增加了两倍多。在扩张模型中，瓣叶贴合大大延迟，且瓣叶从未完全贴合。扩张模型中的腱索应力也大大增加。总之，瓣环扩张导致的应力增加可能会在一个“闭环”退变过程中导致组织破坏、进一步扩张、贴合延迟和反流增加。
