Division of Cardiothoracic Surgery, Emory University School of Medicine, Atlanta, GA, USA.
J Thorac Cardiovasc Surg. 2012 Sep;144(3):624-633.e2. doi: 10.1016/j.jtcvs.2011.10.032. Epub 2011 Dec 7.
Transection of the secondary chordae on the anterior leaflet of the mitral valve to relieve leaflet tethering and reduce regurgitation is an experimentally proven procedure to correct functional mitral regurgitation. In the present study, we sought to investigate whether transecting the secondary chordae would have an effect on the marginal chordal force on the same leaflet.
Adult porcine mitral valves (n = 8) were studied in a pulsatile heart simulator, in which the papillary muscle positions can be precisely positioned. Miniature transducers were inserted into the anterior marginal chordae to measure the chordal forces. Each valve was studied under baseline conditions, 3 different tethering conditions (apical, apical-lateral, and apical-lateral-posterior), and after chordal cutting in the 3 tethering conditions. The temporal changes and peak and average marginal chordal forces under each condition are reported.
Apical tethering increased the marginal chordal force by an average of 96% but remained unchanged after chordal cutting. With apical-lateral tethering, the marginal chordal force increased by 210% from baseline and increased further to 350% of baseline after chordal cutting. After apical-lateral-posterior tethering, the marginal chordal force increased to 335% of baseline before transection and by 548% after transection.
The increase in the marginal chordal force after secondary chordal cutting depends on the location of the papillary muscles and the extent of leaflet tethering. Although chordal cutting might not alter the valve mechanics under minimal leaflet tethering, it significantly affects the mechanics when the leaflet tethering is more pronounced, which is typically seen in patients with functional mitral regurgitation.
切开二尖瓣前叶的次级腱索以缓解瓣叶牵拉，减少反流，这是一种经实验证实可纠正功能性二尖瓣反流的方法。本研究旨在探讨切开次级腱索是否会对同一瓣叶的边缘腱索力产生影响。
在脉动心脏模拟器中研究了 8 个成年猪二尖瓣，其中乳头肌位置可精确定位。将微型换能器插入前缘腱索以测量腱索力。每个瓣膜在基线条件、3 种不同的牵拉条件（心尖、心尖-外侧和心尖-外侧-后）以及在 3 种牵拉条件下进行腱索切割后进行研究。报告了每种情况下的时间变化和峰值及平均边缘腱索力。
心尖牵拉使边缘腱索力平均增加 96%，但腱索切割后保持不变。心尖-外侧牵拉使边缘腱索力从基线增加 210%，腱索切割后进一步增加到基线的 350%。心尖-外侧-后牵拉后，边缘腱索力在未切割前增加到基线的 335%，切割后增加到基线的 548%。
次级腱索切割后边缘腱索力的增加取决于乳头肌的位置和瓣叶牵拉的程度。尽管腱索切割在最小瓣叶牵拉时可能不会改变瓣膜力学，但当瓣叶牵拉更明显时，它会显著影响力学，这在功能性二尖瓣反流患者中很常见。
