Nielsen Sten Lyager, Timek Tomasz A, Green G Randall, Dagum Paul, Daughters George T, Hasenkam J Michael, Bolger Ann F, Ingels Neil B, Miller D Craig
Department of Cardiothoracic and Vascular Surgery and Institute of Experimental Clinical Research, Aarhus University Hospital, Skejby Sygehus, Aarhus, Denmark.
Circulation. 2003 Jul 29;108(4):486-91. doi: 10.1161/01.CIR.0000080504.70265.05. Epub 2003 Jul 14.
The contribution of anterior mitral leaflet second-order ("strut") chordae tendineae to left ventricular (LV) systolic mechanics is debated; we measured the in vivo contribution of anterior chordae tendineae (ACT) and posterior chordae tendineae (PCT) to regional and global LV contractile function.
Eight sheep had radiopaque markers implanted in the LV epicardium, partitioning the ventricle into 12 regions. Microminiature force transducers and snares were sutured to anterior leaflet "strut" chordae originating from ACT and PCT papillary muscles. Chordal tension, marker images, and hemodynamic data were acquired before and after (CUT) severing ACT and PCT. Fractional area shrinkage and slope of the regional end-diastolic area-regional stroke work relation (r-PRSW) were computed for each LV region. CUT did not affect global LV systolic function but reduced FAS in LV segments near the PCT insertion site: equatorial posterior lateral (19+/-2% versus 16+/-2%, P<0.05), apical posterior lateral (23+/-4% versus 19+/-4%, P<0.05), and posterior medial LV segments (16+/-2% versus 13+/-2%, P<0.05). r-PRSW fell near both the ACT (equatorial anterior medial [84+/-8 versus 62+/-11 mm Hg, P<0.05] and lateral [73+/-7 versus 53+/-9 mm Hg, P<0.05]) and PCT (apical posterior medial [91+/-12 versus 67+/-17 mm Hg, P<0.05] and lateral [72+/-8 versus 59+/-9 mm Hg, P<0.05]) LV insertion sites. Maximum tension in PCT was higher than in ACT (0.81+/-0.1 versus 0.52+/-0.08N, P<0.01).
Dividing anterior leaflet strut chordae in sheep was associated acutely with regional LV systolic dysfunction near the chordal insertion sites. Caution is necessary when embarking on procedures that cut second-order chordae to treat ischemic mitral regurgitation, since this may compromise LV systolic function in ventricles that are already impaired.
二尖瓣前叶二级（“支柱”）腱索对左心室（LV）收缩力学的贡献存在争议；我们测量了前腱索（ACT）和后腱索（PCT）对局部和整体左心室收缩功能的体内贡献。
8只绵羊在左心室心外膜植入不透射线的标记物，将心室分为12个区域。将微型力传感器和圈套器缝合到源自ACT和PCT乳头肌的前叶“支柱”腱索上。在切断ACT和PCT之前和之后（CUT）采集腱索张力、标记物图像和血流动力学数据。计算每个左心室区域的面积缩小分数和区域舒张末期面积 - 区域搏功关系（r - PRSW）的斜率。CUT不影响整体左心室收缩功能，但降低了PCT插入部位附近左心室节段的面积缩小分数：赤道后外侧（19±2%对16±2%，P<0.05）、心尖后外侧（23±4%对19±4%，P<0.05）和左心室后内侧节段（16±2%对13±2%，P<0.05）。ACT（赤道前内侧[84±8对62±11 mmHg，P<0.05]和外侧[73±7对53±9 mmHg，P<0.05]）和PCT（心尖后内侧[91±12对67±17 mmHg，P<0.05]和外侧[72±8对59±9 mmHg，P<0.05]）左心室插入部位附近的r - PRSW均下降。PCT中的最大张力高于ACT（0.81±0.1对0.52±0.08N，P<0.01）。
在绵羊中切断前叶支柱腱索与腱索插入部位附近的局部左心室收缩功能障碍急性相关。在进行切断二级腱索治疗缺血性二尖瓣反流的手术时需要谨慎，因为这可能会损害已经受损心室的左心室收缩功能。
