Caballero Andrés, Mao Wenbin, McKay Raymond, Sun Wei
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, Connecticut, USA.
Struct Heart. 2020;4(3):179-191. doi: 10.1080/24748706.2020.1740365. Epub 2020 Apr 3.
Mitral regurgitation (MR) is present in a large proportion of patients who undergo transcatheter aortic valve replacement (TAVR). However, existing clinical data on the impact of TAVR on early post-procedural MR severity are contradictory. Using a comprehensive computational engineering methodology, this study aimed to evaluate quantitatively the structural and hemodynamic impact of TAVR on aortic-mitral continuity and MR severity in a rigorously developed and validated patient-specific left heart (LH) computer model with aortic stenosis and concomitant functional MR.
TAVR procedure was virtually simulated using a self-expandable valve (SEV) at three implantation heights. Pre- and post-TAVR LH dynamics as well as intra-operative biomechanics were analyzed.
No significant differences in early MR improvement (<10%) were noted at the three implantation depths when compared to the pre-TAVR state. The high deployment model resulted in the highest stress in the native aortic leaflets, lowest stent-tissue contact force, highest aortic-mitral angle, and highest MR reduction for this patient case. When comparing SEV vs. balloon-expandable valve (BEV) performance at an optimal implantation height, the SEV gave a higher regurgitant volume than the pre-TAVR model (40.49 vs 37.59 ml), while the BEV model gave the lowest regurgitant volume (33.84 vs 37.59 ml).
Contact force, aortic-mitral angle, and valve annuli compression were identified as possible mechanistic parameters that may suggest avenues for acute MR improvement. Albeit a single patient parametric study, it is our hope that such detailed engineering analysis could shed some light into the underlying biomechanical mechanisms of TAVR impact on MR.
在接受经导管主动脉瓣置换术（TAVR）的患者中，很大一部分存在二尖瓣反流（MR）。然而，关于TAVR对术后早期MR严重程度影响的现有临床数据相互矛盾。本研究采用综合计算工程方法，旨在使用一个经过严格开发和验证的、针对患有主动脉瓣狭窄并伴有功能性MR的患者特异性左心（LH）计算机模型，定量评估TAVR对主动脉 - 二尖瓣连续性和MR严重程度的结构及血流动力学影响。
使用自膨胀瓣膜（SEV）在三个植入高度对TAVR手术进行虚拟模拟。分析了TAVR前后的LH动力学以及术中生物力学。
与TAVR术前状态相比，在三个植入深度时早期MR改善情况（<10%）无显著差异。对于该患者病例，高植入模型导致天然主动脉瓣叶应力最高、支架 - 组织接触力最低、主动脉 - 二尖瓣角度最大以及MR降低最多。在最佳植入高度比较SEV与球囊扩张瓣膜（BEV）的性能时，SEV的反流容积高于TAVR术前模型（40.49对37.59 ml），而BEV模型的反流容积最低（33.84对37.59 ml）。
接触力、主动脉 - 二尖瓣角度和瓣环压缩被确定为可能的机制参数，这些参数可能为急性MR改善提供途径。尽管这是一项单患者参数研究，但我们希望这种详细的工程分析能够为TAVR对MR影响的潜在生物力学机制提供一些启示。
