Aortic hemodynamics assessment prior and after valve sparing reconstruction: A patient-specific 4D flow-based FSI model
Aortic hemodynamics assessment prior and after valve sparing reconstruction: A patient-specific 4D flow-based FSI model
复制标题
DOI：
10.1016/j.compbiomed.2021.104581
复制
发表时间：
2021-06-24
影响因子：
7.7
通讯作者：
Redaelli, Alberto
中科院分区：
文献类型：
--
作者：
Nannini, Guido;Caimi, Alessandro;Redaelli, Alberto
前言：保留瓣膜的升主动脉根部置换术(VSRR)是治疗主动脉瘤的一种挽救生命的手术，但患者仍有发生涉及下游自然主动脉的术后事件的风险，其机制尚不清楚。升主动脉近端移植物置换术可能会引起降主动脉血流动力学改变，从而引发不良事件。在这里，我们提出了一种基于患者特定几何和边界条件的流体-结构相互作用(FSI)方案，以评估近端主动脉移植物对下游主动脉血流动力学和扩张性的影响。方法：对一名受试者在VSRR前后进行心脏磁共振(CMR)，包括MRA、Cine-CMR和4D血流序列。中心血压在CMR时以非侵入性方式获取：数据用于重建VSRR前后的模型，并在相同设置下为FSI和计算流体动力学(CFD)分析得出患者特定的边界条件。将预测的速度场与主动脉沿线四个标志物上的4D血流数据集进行比较，并将预测的扩张性与电影CMR得出的值进行比较，对结果进行验证。结果：4DFlow和FSI提取的瞬时速度值相似(p>；0.001)，而CFD预测的速度明显高于前者(p<；0.001)，尤其是VSRR前模型的降主动脉(v(Max)分别为73 cm/S、76 cm/S和99 cm/S)。根据Cine-CMR的测量，FSI预测移植后降主动脉扩张性增加(即4.02至5.79 10(-3)mm Hg(-1))。在降主动脉，VSRR后模型表现出速度、主动脉扩张性、应力和应变以及壁切应力的增加。结论：我们的结果表明：1)管壁的扩张性不可忽略，因此FSI方法是获得可靠结果的必要方法；2)移植物植入会导致胸主动脉沿线血流动力学和生物力学的改变，从而可能引发不利的血管重塑。
Introduction: Valve-sparing root replacement (VSRR) of the ascending aorta is a life-saving procedure for the treatment of aortic aneurysms, but patients remain at risk for post-operative events involving the downstream native aorta, the mechanism for which is uncertain. It is possible that proximal graft replacement of the ascending aorta induces hemodynamics alterations in the descending aorta, which could trigger adverse events. Herein, we present a fluid-structure interaction (FSI) protocol, based on patient-specific geometry and boundary conditions, to assess impact of proximal aortic grafts on downstream aortic hemodynamics and distensibility.Methods: Cardiac magnetic resonance (CMR), including MRA, cine-CMR and 4D flow sequences, was performed prior and after VSRR on one subject. Central blood pressure was non-invasively acquired at the time of the CMR: data were used to reconstruct the pre- and post-VSRR model and derive patient-specific boundary conditions for the FSI and a computational fluid dynamic (CFD) analysis with the same settings.Results were validated comparing the predicted velocity field against 4D flow dataset, over four landmarks along the aorta, and the predicted distensibility against the cine-CMR derived value. Results: Instantaneous velocity magnitudes extracted from 4D flow and FSI were similar (p > 0.05), while CFD-predicted velocity was significantly higher (p < 0.001), especially in the descending aorta of the pre-VSRR model (v(max) was 73 cm/s, 76 cm/s and 99 cm/s, respectively). As measured in cine-CMR, FSI predicted an increase in descending aorta distensibility after grafting (i.e., 4.02 to 5.79 10(-3) mmHg(-1)). In the descending aorta, the post-VSRR model showed increased velocity, aortic distensibility, stress and strain and wall shear stress.Conclusions: Our Results indicate that i) the distensibility of the wall cannot be neglected, and hence the FSI method is necessary to obtain reliable results; ii) graft implantation induces alterations in the hemodynamics and biomechanics along the thoracic aorta, that may trigger adverse vessel remodeling.