Yajima Shin, Zhu Yuanjia, Stark Charles J, Wilkerson Robert J, Park Matthew H, Stefan Elde, Woo Y Joseph
Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif.
Department of Bioengineering, Stanford University, Stanford, Calif.
JTCVS Open. 2023 May 6;15:164-172. doi: 10.1016/j.xjon.2023.04.011. eCollection 2023 Sep.
This study aimed to biomechanically evaluate the force profiles on the anterior primary and secondary chordae after neochord repair for anterior valve prolapse with varied degrees of residual mitral regurgitation using an ex vivo heart simulator.
The experiment used 8 healthy porcine mitral valves. Chordal forces were measured using fiber Bragg grating sensors on primary and secondary chordae from A2 segments. The anterior valve prolapse model was generated by excising 2 primary chordae at the A2 segment. Neochord repair was performed with 2 pairs of neochords. Varying neochord lengths simulated postrepair residual mitral regurgitation with regurgitant fraction at >30% (moderate), 10% to 30% (mild), and <10% (perfect repair).
Regurgitant fractions of baseline, moderate, mild, and perfect repair were 4.7% ± 0.8%, 35.8% ± 2.1%, 19.8% ± 2.0%, and 6.0% ± 0.7%, respectively ( < .001). Moderate had a greater peak force of the anterior primary chordae (0.43 ± 0.06 N) than those of baseline (0.19 ± 0.04 N; = .011), mild (0.23 ± 0.05 N; = .041), and perfect repair (0.21 ± 0.03 N; = .006). In addition, moderate had a greater peak force of the anterior secondary chordae (1.67 ± 0.17 N) than those of baseline (0.64 ± 0.13 N; = .003), mild (0.84 ± 0.24 N; = .019), and perfect repair (0.68 ± 0.14 N; = .001). No significant differences in peak and average forces on both primary and secondary anterior chordae were observed between the baseline and perfect repair as well as the mild and perfect repair.
Moderate residual mitral regurgitation after neochord repair was associated with increased anterior primary and secondary chordae forces in our ex vivo anterior valve prolapse model. This difference in chordal force profile may influence long-term repair durability, providing biomechanical evidence in support of obtaining minimal regurgitation when repairing mitral anterior valve prolapse.
本研究旨在使用体外心脏模拟器，对不同程度残余二尖瓣反流的前叶瓣膜脱垂进行新腱索修复后，对前叶主要和次要腱索上的力分布进行生物力学评估。
实验使用8个健康猪的二尖瓣。使用光纤布拉格光栅传感器测量来自A2节段的主要和次要腱索上的腱索力。通过切除A2节段的2条主要腱索建立前叶瓣膜脱垂模型。用2对新腱索进行新腱索修复。通过改变新腱索长度模拟修复后残余二尖瓣反流，反流分数>30%（中度）、10%至30%（轻度）和<10%（完美修复）。
基线、中度、轻度和完美修复的反流分数分别为4.7%±0.8%、35.8%±2.1%、19.8%±2.0%和6.0%±0.7%（P<0.001）。中度时前叶主要腱索的峰值力（0.43±0.06N）大于基线（0.19±0.04N；P=0.011）、轻度（0.23±0.05N；P=0.041）和完美修复（0.21±0.03N；P=0.006）时。此外，中度时前叶次要腱索的峰值力（1.67±0.17N）大于基线（0.64±0.13N；P=0.003）、轻度（0.84±0.24N；P=0.019）和完美修复（0.68±0.14N；P=0.001）时。在基线与完美修复以及轻度与完美修复之间，未观察到前叶主要和次要腱索的峰值力和平均力有显著差异。
在我们的体外前叶瓣膜脱垂模型中，新腱索修复后中度残余二尖瓣反流与前叶主要和次要腱索力增加有关。腱索力分布的这种差异可能影响长期修复耐久性，为二尖瓣前叶脱垂修复时获得最小反流提供生物力学证据。
