Timek T A, Nielsen S L, Green G R, Dagum P, Bolger A F, Daughters G T, Hasenkam J M, Ingels N B, Miller D C
Department of Cardiovascular and Thoracic Surgery, Stanford University School of Medicine, California 94305-5247, USA.
Ann Thorac Surg. 2001 Aug;72(2):535-40; discussion 541. doi: 10.1016/s0003-4975(01)02783-7.
Chordal transposition is used in mitral valve repair, yet the effects of second-order chord transection on valve function have not been extensively studied. We evaluated leaflet coaptation, three-dimensional anterior mitral valve leaflet shape, and valve competence after cutting anterior second-order chordae.
In 8 sheep radiopaque markers were affixed to the left ventricle, mitral annulus, and leaflets. Animals were studied immediately with biplane videofluoroscopy and echocardiography before (Control) and after (Cut2) severing two anterior second-order "strut" chordae. Leaflet coaptation was assessed as separation between leaflet edge markers in the midleaflet and near each commissure (anterior commissure, posterior commissure). Anterior leaflet geometry was determined 100 milliseconds after end-diastole from three-dimensional coordinates of 13 markers.
Anterior leaflet geometry changed only slightly after chordal transection without inducing mitral regurgitation. Leaflet coaptation times were 79+/-17 and 87+/-22 milliseconds at the anterior commissure; 72+/-21, 72+/-19 milliseconds at midleaflet, and 71+/-12 and 75+/-8 milliseconds at the posterior commissure (p = NS) for Control and Cut2, respectively.
Cutting anterior second-order chordae did not cause delayed leaflet coaptation, alter leaflet shape, or create mitral regurgitation. These data indicate that transposition of second-order anterior chordae ("strut" chordae) is not deleterious to anterior leaflet motion per se.
腱索转位用于二尖瓣修复，但二级腱索横断对瓣膜功能的影响尚未得到广泛研究。我们评估了切断前叶二级腱索后瓣叶对合情况、二尖瓣前叶三维形状及瓣膜功能。
在8只绵羊身上，将不透X线的标记物固定于左心室、二尖瓣环及瓣叶。在切断两根前叶二级“支柱”腱索之前（对照）和之后（Cut2），立即用双平面视频荧光透视法和超声心动图对动物进行研究。瓣叶对合情况通过测量瓣叶边缘标记物在瓣叶中部及每个瓣环（前瓣环、后瓣环）附近的间距来评估。舒张期末100毫秒后，根据13个标记物的三维坐标确定前叶几何形状。
腱索横断后，前叶几何形状仅有轻微改变，未诱发二尖瓣反流。对照和Cut2组在前瓣环处的瓣叶对合时间分别为79±17毫秒和87±22毫秒；在瓣叶中部为72±21毫秒、72±19毫秒；在后瓣环处为71±12毫秒和75±8毫秒（p=无显著性差异）。
切断前叶二级腱索不会导致瓣叶对合延迟、改变瓣叶形状或产生二尖瓣反流。这些数据表明，转位前叶二级腱索（“支柱”腱索）本身对前叶运动无害。
