Biomechanics Research Centre, Biomedical Engineering, College of Engineering and Informatics, National University of Ireland Galway, Galway, Ireland.
Boston Scientific, Ballybrit Business Park, Ballybrit, Galway, Ireland.
Biomech Model Mechanobiol. 2019 Feb;18(1):79-88. doi: 10.1007/s10237-018-1069-9. Epub 2018 Aug 20.
It has been proposed that inappropriate positioning of transcatheter aortic valves (TAVs) is associated with procedural complications and decreased device durability. Second-generation TAVs allow for repositioning giving greater control over the final deployment position. However, the impact of positioning on the tissue surrounding these devices needs to be better understood, in particular for the interleaflet triangle in which the conductance system (bundle of His) resides. In this study, we investigate the impact of implantation depth on the frame-tissue interaction for a next-generation repositionable Lotus™ valve. For this purpose, a computational model simulating deployment of the Lotus valve frame into a calcified patient-specific aortic root geometry was generated to predict aortic root stress and frame eccentricity at three different deployment depths. The results of this study predicted that positioning of the Lotus valve had an influence on the stresses in the aortic sinus and frame eccentricity. An analysis of levels of stress arising in the vicinity of the bundle of His, as a function of implantation depth, was conducted, and it was found that, for the specific patient anatomy studied, although the sub-annular position showed reduced peak stress in the aortic sinus, this implantation position showed the highest stress in the area of greatest risks of conductance interference. In contrast, while a supra-annular position increased the peak arterial stress, this implantation position resulted in lower stress in the interleaflet triangle and thus might reduce the risk of conductance interference. These results provide pre-operative information that can inform clinical decision-making regarding TAVI positioning.
有人提出，经导管主动脉瓣（TAV）的不当定位与手术并发症和器械耐久性降低有关。第二代 TAV 允许重新定位，从而更好地控制最终的部署位置。然而，需要更好地了解定位对这些器械周围组织的影响，特别是对于传导系统（希氏束）所在的瓣叶间三角区。在这项研究中，我们研究了植入深度对下一代可重新定位的 Lotus™瓣膜框架组织相互作用的影响。为此，生成了一个计算模型，模拟 Lotus 瓣膜框架在钙化的患者特定主动脉根部几何形状中的部署，以预测三个不同部署深度下的主动脉根部应力和框架偏心度。这项研究的结果预测，Lotus 瓣膜的定位对主动脉窦和框架偏心度的应力有影响。分析了在希氏束附近产生的应力水平，作为植入深度的函数，结果发现，对于研究的特定患者解剖结构，虽然亚瓣环位置显示主动脉窦的峰值应力降低，但该植入位置显示在传导干扰风险最大的区域的最高应力。相比之下，虽然瓣上位置增加了动脉峰值应力，但该植入位置导致瓣叶间三角区的应力降低，从而可能降低传导干扰的风险。这些结果提供了术前信息，可以为 TAVI 定位的临床决策提供信息。
