Tissue Mechanics Laboratory, The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA.
Division of Cardiology, The Hartford Hospital, Hartford, CT, USA.
J R Soc Interface. 2019 Aug 30;16(157):20190355. doi: 10.1098/rsif.2019.0355. Epub 2019 Aug 14.
The aortic and mitral valves function in a reciprocal interdependent fashion. However, the impact of transcatheter aortic valve replacement (TAVR) on the aortic-mitral continuity and severity of mitral regurgitation (MR) are poorly understood. In this study, a comprehensive engineering analysis was performed to investigate the impact of TAVR on MR severity and left heart dynamics in a retrospective patient case who harbours bicuspid aortic valve stenosis and concomitant functional MR. The TAVR procedure was computer simulated using a balloon-expandable valve, and the impact of three implantation heights on aortic-mitral coupling, MR severity and device performance were analysed. The accuracy and predictability of the computer modelling framework were validated with pre- and post-operative echo data. The highest deployment model resulted in higher stresses in the native leaflets, contact radial force and stent recoil, while the midway implantation model gave better haemodynamic performance and MR reduction in this patient case. Although the regurgitant volume decreased (less than 10%) for the three deployment configurations, no significant differences in MR severity improvement and mitral leaflet tethering were found. Acute improvement in MR was (i) due to the mechanical compression of the stent against the aortic-mitral curtain, (ii) due to an immediate drop in the ventricular pressure and transmitral pressure gradient. Albeit a single real clinical case, it is our hope that such detailed engineering computational analysis could shed light on the underlying biomechanical mechanisms of TAVR impact on MR.
主动脉瓣和二尖瓣以相互依存的方式发挥功能。然而，经导管主动脉瓣置换术（TAVR）对主动脉-二尖瓣连续性和二尖瓣反流（MR）严重程度的影响仍知之甚少。在这项研究中，对一名患有二叶式主动脉瓣狭窄和功能性二尖瓣反流的回顾性患者病例进行了全面的工程分析，以研究 TAVR 对 MR 严重程度和左心动力学的影响。使用球囊扩张瓣膜对 TAVR 手术进行了计算机模拟，并分析了三种植入高度对主动脉-二尖瓣偶联、MR 严重程度和器械性能的影响。使用术前和术后的超声心动图数据验证了计算机建模框架的准确性和可预测性。最高的部署模型导致原生瓣叶、接触径向力和支架回缩的应力更高，而中间植入模型在该患者病例中给出了更好的血液动力学性能和 MR 减少。尽管三种部署配置的反流量都有所减少（少于 10%），但在 MR 严重程度改善和二尖瓣瓣叶牵拉方面没有发现显著差异。MR 的急性改善是由于（i）支架对主动脉-二尖瓣幕的机械压迫，以及（ii）心室压力和跨瓣压力梯度的立即下降。尽管这只是一个真实的临床病例，但我们希望这种详细的工程计算分析能够阐明 TAVR 对 MR 影响的潜在生物力学机制。
