二尖瓣支架与心脏共振的模态分析研究

Research on Modal Analysis of Resonance between Mitral Stents and Heart

研究经导管二尖瓣瓣膜置换术(Transcatheter Mitral Valve Replacement, TMVR)术后,三种不同结构的二尖瓣支架与心脏共振的可能性,为支架的设计和优化提供理论依据。建立三种二尖瓣支架和心脏的有限元模型。分别完成在心脏搏动周期中,支架模型、心脏模型和支架–心脏整体模型的模态分析,比较分析各模型的1~10阶固有频率。在心脏搏动周期中,三种支架模型的前6阶固有频率均在1~1.6 Hz之间,而人体心脏搏动频率范围为1~1.66 Hz。心脏模型的第9阶和第10阶固有频率约为606 Hz和844 Hz,II型支架–心脏整体模型的第9阶和第10阶固有频率约为605 Hz和658 Hz,III型支架–心脏整体模型的第9阶和第10阶固有频率约为463 Hz和464 Hz。结果表明,在TMVR术后初期,心脏搏动作为一种激励,易引起支架与心脏的共振,进而导致心颤。在TMVR术后远期,与心脏模型相比,支架–心脏整体模型的固有频率较低,患者在日常生活中更易遇到相近频率的外部激励,导致支架–心脏整体与外部激励发生共振。三种不同结构的支架中,开环支架的稳定性低于闭环支架,开环数越多,支架稳定性越差。

To study the possibility of resonance between three types of mitral valve stents with different structures and the heart after transcatheter mitral valve replacement (TMVR), so as to provide theoretical basis for the design and optimization of mitral valve stents. The finite element models of three types of mitral valve stents and the heart were established. The modal analysis of mitral valve stent models, cardiac model and stent-cardiac models were completed in the heartbeat cycle, and the 1st to 10th order natural frequencies of each model were compared and analyzed. In the heart-beat cycle, the first six natural frequencies of the three types of mitral valve stent models are all between 1~1.6 Hz, while the range of human heart beat frequency is 1~1.66 Hz. The 9th and 10th natural frequencies of the cardiac model are about 606 Hz and 844 Hz, the 9th and 10th natural frequencies of the type II stent-cardiac model are about 605 Hz and 658 Hz, and the 9th and 10th natural frequencies of the type III stent-cardiac model are about 463 Hz and 464 Hz. The results show that, in the early stage after TMVR, cardiac beating as an incentive can easily cause the resonance between the stents and the heart, and then lead to cardiac fibrillation. In the long term after TMVR, compared with the cardiac model, the natural frequency of the stent-cardiac model is lower, and patients are more likely to encounter similar frequency external excitation in daily life, which leads to the resonance between the stent-heart and the external excitation. Among the three types of stents with different structures, the stability of open-loop stents is lower than that of closed-loop stents, and the more open-loop stents are, the worse the stability of stents is.