Department of Biomedical Engineering, Imperial College London, L2 Bessemer Building, South Kensington Campus, London, SW7 2AZ, UK.
BHF Centre of Research Excellence, Imperial College London, London, UK.
Biomech Model Mechanobiol. 2024 Oct;23(5):1433-1448. doi: 10.1007/s10237-024-01848-0. Epub 2024 Apr 29.
Fetal critical aortic stenosis with evolving hypoplastic left heart syndrome (CAS-eHLHS) can progress to a univentricular (UV) birth malformation. Catheter-based fetal aortic valvuloplasty (FAV) can resolve stenosis and reduce the likelihood of malformation progression. However, we have limited understanding of the biomechanical impact of FAV and subsequent LV responses. Therefore, we performed image-based finite element (FE) modeling of 4 CAS-eHLHS fetal hearts, by performing iterative simulations to match image-based characteristics and then back-computing physiological parameters. We used pre-FAV simulations to conduct virtual FAV (vFAV) and compared pre-FAV and post-FAV simulations. vFAV simulations generally enabled partial restoration of several physiological features toward healthy levels, including increased stroke volume and myocardial strains, reduced aortic valve (AV) and mitral valve regurgitation (MVr) velocities, reduced LV and LA pressures, and reduced peak myofiber stress. FAV often leads to aortic valve regurgitation (AVr). Our simulations showed that AVr could compromise LV and LA depressurization but it could also significantly increase stroke volume and myocardial deformational stimuli. Post-FAV scans and simulations showed FAV enabled only partial reduction of the AV dissipative coefficient. Furthermore, LV contractility and peripheral vascular resistance could change in response to FAV, preventing decreases in AV velocity and LV pressure, compared with what would be anticipated from stenosis relief. This suggested that case-specific post-FAV modeling is required to fully capture cardiac functionality. Overall, image-based FE modeling could provide mechanistic details of the effects of FAV, but computational prediction of acute outcomes was difficult due to a patient-dependent physiological response to FAV.
胎儿严重主动脉瓣狭窄伴进行性左心发育不良综合征（CAS-eHLHS）可进展为单心室（UV）出生畸形。基于导管的胎儿主动脉瓣成形术（FAV）可解决狭窄并降低畸形进展的可能性。然而，我们对 FAV 的生物力学影响及其随后的 LV 反应知之甚少。因此，我们对 4 例 CAS-eHLHS 胎儿心脏进行了基于图像的有限元（FE）建模，通过迭代模拟来匹配基于图像的特征，然后反向计算生理参数。我们使用 FAV 前模拟进行虚拟 FAV（vFAV），并比较了 FAV 前和 FAV 后的模拟。vFAV 模拟通常能够使几个生理特征部分恢复到健康水平，包括增加的每搏量和心肌应变，降低主动脉瓣（AV）和二尖瓣反流（MVr）速度，降低 LV 和 LA 压力，以及降低峰值肌纤维应力。FAV 通常会导致 AV 反流（AVr）。我们的模拟表明，AVr 可能会损害 LV 和 LA 的减压能力，但它也可以显著增加每搏量和心肌变形刺激。FAV 后的扫描和模拟表明，FAV 只能部分降低 AV 耗散系数。此外，LV 收缩性和外周血管阻力可能会因 FAV 而发生变化，与狭窄缓解相比，这会阻止 AV 速度和 LV 压力的降低。这表明需要针对特定病例的 FAV 后建模来全面捕获心脏功能。总的来说，基于图像的 FE 建模可以提供 FAV 影响的机制细节，但由于患者对 FAV 的生理反应依赖于个体，因此急性结果的计算预测很困难。
