Mitral leaflet geometry perturbations with papillary muscle displacement and annular dilatation: an in-vitro study of ischemic mitral regurgitation.
Mitral leaflet geometry perturbations with papillary muscle displacement and annular dilatation: an in-vitro study of ischemic mitral regurgitation.
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发表时间：
2003-05
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通讯作者：
Shengqiu He;J. Jimenez;Zhaoming He;A. Yoganathan
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作者：
Shengqiu He;J. Jimenez;Zhaoming He;A. Yoganathan
研究背景和目的瓣叶几何形状的扰动是左心室（LV）缺血导致二尖瓣瓣叶闭合不完全和二尖瓣返流（MR）的最终终点。观察到的瓣膜或瓣下结构改变的几何不一致性提出了几个问题。方法建立了一种新的体外左室柔性袋模型，以观察和分析模拟病理缺血MR条件下瓣叶几何变化。结果：乳头肌（PM）移位和瓣环扩张缩短了瓣叶对合长度，导致显著MR。对称PM移位使对合线向瓣叶边缘移动，并沿该线产生沿着中心间隙。不对称PM位移产生直径不均匀的接合，在系留PM侧有帐篷形瓣叶，而瓣叶在相对侧朝向左心房凸出。结论瓣叶收缩期的几何形状受瓣下结构的影响。可能发生在局部或急性心肌梗死中的不对称PM位移导致瓣叶接合线不规则变形，并因此导致栓系侧的MR。在这些模拟病理条件下直接观察瓣叶扰动可能有助于理解缺血性MR中存在的机制。
BACKGROUND AND AIM OF THE STUDY Perturbations of leaflet geometry are the final end point through which left ventricular (LV) ischemia causes incomplete mitral leaflet closure and resultant mitral regurgitation (MR). Geometric inconsistencies observed with valvular or subvalvular structural alterations raise several questions. METHODS A new in-vitro LV flexible bag model was developed in order to visualize and analyze leaflet geometric changes under simulated pathological ischemic MR conditions. RESULTS Papillary muscle (PM) displacement and annular dilatation decreased leaflet coaptation length, leading to significant MR. Symmetrical PM displacement shifted the coaptation line towards the leaflet edges and created central gaps along this line. Asymmetric PM displacement generated diametrically uneven coaptation with a tent-shaped leaflet at the tethered PM side, while the leaflet bulged at the opposite side towards the left atrium. CONCLUSION Leaflet geometry during systole is affected by subvalvular structures. Asymmetric PM displacement, which may occur in regional or acute myocardial infarction, induces irregular deformation of the leaflet's coaptation line and, as a result, MR at the tethered side. Direct visualization of leaflet perturbation under these simulated pathological conditions may promote understanding of mechanisms present in ischemic MR.