Department of Mechanical Engineering, University of Birmingham, Birmingham, UK.
Filament PD, Level 4 - Skypark 3, Skypark, Glasgow, UK.
Proc Inst Mech Eng H. 2021 Mar;235(3):291-299. doi: 10.1177/0954411920975938. Epub 2020 Nov 27.
The aim of this study was to assess whether the mechanical properties of mitral valve chordae tendineae are sensitive to being cross-linked under load. A total 64 chordae were extracted from eight porcine hearts. Two chordae (posterior basal) from each heart were subjected to uniaxial ramp testing and six chordae (two strut, two anterior basal and two posterior basal) were subjected to dynamic mechanical analysis over frequencies between 0.5 and 10 Hz. Chordae were either cross-linked in tension or cross-linked in the absence of loading. Chordae cross-linked under load transitioned from high to low extension at a lower strain than cross-linked unloaded chordae (0.07 cf. 0.22), with greater pre-transitional (30.8 MPa cf. 5.78 MPa) and post-transitional (139 MPa cf. 74.1 MPa) moduli. The mean storage modulus of anterior strut chordae ranged from 48 to 54 MPa for cross-linked unloaded chordae, as compared to 53-61 MPa cross-linked loaded chordae. The mean loss modulus of anterior strut chordae ranged from 2.3 to 2.9 MPa for cross-linked unloaded chordae, as compared to 3.8-4.8 MPa cross-linked loaded chordae. The elastic and viscoelastic properties of chordae following glutaraldehyde cross-linking are dependent on the inclusion/exclusion of loading during the cross-linking process; with loading increasing the magnitude of the material properties measured.
本研究旨在评估二尖瓣腱索在负荷下交联时的力学性能是否敏感。从 8 只猪心提取了总共 64 根腱索。每只心脏的两根腱索（后基底）进行单轴斜坡试验，6 根腱索（两根支柱、两根前基底和两根后基底）在 0.5 至 10 Hz 之间的频率下进行动态力学分析。腱索在张力下或无负载下交联。在负载下交联的腱索在比未负载交联的腱索更低的应变下从高延伸转变为低延伸（0.07 对 0.22），具有更大的预过渡（30.8 MPa 对 5.78 MPa）和后过渡（139 MPa 对 74.1 MPa）模量。交联未负载的前支柱腱索的平均储能模量范围为 48 至 54 MPa，而交联负载的腱索的平均储能模量范围为 53-61 MPa。交联未负载的前支柱腱索的平均损耗模量范围为 2.3 至 2.9 MPa，而交联负载的腱索的平均损耗模量范围为 3.8-4.8 MPa。戊二醛交联后腱索的弹性和粘弹性特性取决于交联过程中是否包括/排除负载；负载增加了测量的材料性能的幅度。
