Steffens T G, Hagan A D
Am J Cardiol. 1984 Jan 1;53(1):153-6. doi: 10.1016/0002-9149(84)90700-8.
Study of 16 normal and 33 flail mitral valves provides evidence of the active participation of chordae tendineae in mitral valve opening. The normal valves have straight chordae at all phases of opening. During isovolumic relaxation and progressive opening phases, the smooth configuration of the mid-anterior mitral leaflet is broken by a sharp outward "tenting." This tenting is localized at chordal insertions, reflecting significant tension at these points. Flail mitral valves allow comparison of opening motion between mitral segments with normal chordal attachment and flail segments without chordal support. Posterior flail leaflets demonstrate delay in initiation of opening motion relative to the normal anterior leaflet. The most dramatic examples of this delay reveal a maximal opening excursion of the anterior leaflet before the flail posterior leaflet initiates opening motion. The untethered free margins of opening flail anterior leaflets produce the appearance of the flail segment trailing the body of the anterior leaflet with a sharp break in leaflet contour between the supported and unsupported segments. These configurational expressions of mitral valve opening are inconsistent with a passive hemogenic mechanism. They support an active myogenic process mediated through direct traction on the valve by the chordae tendineae.
对16个正常二尖瓣和33个连枷样二尖瓣的研究提供了腱索积极参与二尖瓣开放的证据。正常瓣膜在开放的各个阶段都有笔直的腱索。在等容舒张期和逐渐开放阶段，二尖瓣前叶中部的平滑形态被尖锐的向外“帐篷样”改变所打破。这种帐篷样改变位于腱索附着处，反映了这些部位存在显著张力。连枷样二尖瓣使得能够比较有正常腱索附着的二尖瓣节段与没有腱索支持的连枷节段之间的开放运动。后叶连枷的二尖瓣显示相对于正常前叶，开放运动起始延迟。这种延迟最显著的例子是在连枷后叶开始开放运动之前，前叶出现最大开放位移。开放的连枷前叶的无束缚游离缘使得连枷节段看起来落后于前叶主体，在受支持节段和无支持节段之间的小叶轮廓处有明显的中断。二尖瓣开放的这些形态学表现与被动血液动力学机制不一致。它们支持一种由腱索直接牵拉瓣膜介导的主动肌源性过程。
