A Multi-Scale CFD-FSI Model of the Hybrid Norwood Palliative Treatment for Hypopl

描述（由申请人提供）：先天性心脏病发生在150个活产儿中。左心发育不全综合征（HLHS）是此类缺陷中最复杂的一种，在此类婴儿中发病率为4%至5%。该建议侧重于新型混合诺伍德（HN）策略，该策略已成为HLHS新生儿的替代第一干预措施。HN是一种侵入性较小的手术，与传统方法相比，它提供了许多手术优势，例如在新生儿期间避免了体外循环。我们的团队已经成功地开发了一个内部的多尺度计算流体动力学（CFD）模型，以阐明由此产生的复杂且远非直观的血流动力学，并应用于一个接受混合诺伍德姑息治疗的新生儿的合成几何代表。具体目标-在证明了我们的方法论后，我们目前的重点是扩展和发展我们目前的模型，以满足以下具体目标：建立一个患者特异性的几何模拟，并建立不同程度的主动脉弓远端阻塞对动脉导管支架置入的冠状动脉、肺和颈动脉血流的影响。2. 探索患者特定的HN拓扑结构，以确定反向BT分流器的最佳尺寸和可能的位置，以增加冠状动脉和颈动脉循环，减轻异常壁应力、停滞区和异常血流。3. 建立一个HN拓扑案例，结合流体结构相互作用来研究血管超弹性顺应性对血流动力学和心室功能的影响。目标1和目标2的结果将与先前基于合成HN拓扑的计算结果进行比较，目标3的结果将为我们小组在最先进的心血管手术模拟方面的未来研究铺平道路，最终将成为手术计划中宝贵的一步。方法-建议利用HN循环的多尺度计算模型，实现患者特定的mri衍生几何结构，以解决特定目标中概述的关键问题。随后，血管和分流的顺应性将被完全建模为“流固相互作用”（FSI）：流场通过有限体积法求解，并提供导致顺应性血管壁机械响应的应力载荷，这些应力载荷将通过有限元法计算。通过血管和分流的经验应力-应变关系来计算顺应性。在之前的Norwood循环CFD研究中，没有考虑到柔顺性容器的完整建模，这是一项新颖的工作。

DESCRIPTION (provided by applicant): Congenital heart disease occurs in one in 150 live births. Hypoplastic Left Heart Syndrome (HLHS), one of the most complex such defects, occurs in 4 to 5 percent of such infants. This proposal focuses on the novel Hybrid Norwood (HN) strategy which has emerged as an alternative first intervention for neonates with HLHS. The HN is a less invasive procedure that provides numerous surgical advantages over the conventional method, such as avoiding cardiopulmonary bypass during neonatal period. Our team has been successful in developing an in-house multi-scale computational fluid dynamics (CFD) model to elucidate the resulting complex and far from intuitive hemodynamics applied to a synthetic geometry representative of a neonate undergoing Hybrid Norwood palliation. Specific Aims - Having proven our methodology to this initial case our present focus is to expand and evolve our current model to address the following specific aims: 1. Develop a patient-specific geometry simulation and establish the effects on coronary, pulmonary, and carotid blood flow of various degrees of distal aortic arch obstruction proximal to the ductus arteriosus stenting. 2. Explore the patient-specific HN topologies to identify an optimal size and possible placement of the reverse BT shunt that provides an increase in coronary and carotid circulation and mitigates the abnormal wall stresses, stagnation zones, and anomalous flow. 3. Develop a HN topology case incorporating the use of Fluid Structure Interaction to study the effect of vascular hyper-elastic compliance on hemodynamics and ventricular performance. A comparison of results from aims 1 and 2 to previous computations based on a synthetic HN topology will be made and results from aim 3 will pave the way for the future research of our group in state-of-the-art cardiovascular procedure simulations that eventually will become an invaluable step in surgical planning. Methods - It is proposed to utilize a multi-scale computational model of the HN circulation with the implementation of a patient-specific MRI-derived geometry to address critical issues outlined in the specific aims. Subsequently, vascular and shunt compliance will be fully modeled as "fluid-structure interaction" (FSI): the flow field is resolved by the finite volume method and provides the stress loads that result in the mechanical response of the compliant vessel walls that will be calculated by the finite element method. Compliance is accounted for via empirical stress-strain relationship of the vessels and shunt. The full modeling of compliant vessels has not been accounted for in prior CFD studies of the Norwood circulation, and this is a novelty of the proposed work.