Restrepo Maria, Crouch A Colleen, Haggerty Christopher M, Rossignac Jarek, Slesnick Timothy C, Kanter Kirk R, Yoganathan Ajit P
Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta.
School of Material Sciences and Engineering, Georgia Institute of Technology, Atlanta.
Ann Thorac Surg. 2016 Jan;101(1):183-9. doi: 10.1016/j.athoracsur.2015.07.012. Epub 2015 Oct 1.
A Fontan Y-shaped graft using a commercially available aortoiliac graft has been used to connect the inferior vena cava (IVC) to the pulmonary arteries. This modification of the Fontan procedure seeks to improve hepatic flow distribution (HFD) to the lungs. However, patient-specific anatomical restrictions might limit the space available for graft placement. Altering the superior vena cava (SVC) positioning is hypothesized to provide more space for an optimal connection, avoiding caval flow collision. Computational modeling tools were used to retrospectively study the effect of SVC placement on Y-graft hemodynamics.
Patient-specific anatomies (N = 10 patients) and vessel flows were reconstructed from retrospective cardiac magnetic resonance (CMR) images after Fontan Y-graft completion. Alternative geometries were created using a virtual surgery environment, altering the SVC position and the offset in relation to the Y-graft branches. Geometric characterization and computational fluid dynamics simulations were performed. Hemodynamic factors (power loss and HFD) were computed.
Patients with a higher IVC return showed less sensitivity to SVC positioning. Patients with low IVC flow showed varied HFD results, depending on SVC location. Balanced HFD values (50% to each lung) were obtained when the SVC lay completely between the Y-graft branches. The effect on power loss was patient specific.
SVC positioning with respect to the Y-graft affects HFD, especially in patients with lower IVC flow. Careful positioning of the SVC at the time of a bidirectional Glenn (BDG) procedure based on patient-specific anatomy can optimize the hemodynamics of the eventual Fontan completion.
一种使用市售主髂动脉移植物的Fontan Y形移植物已被用于连接下腔静脉（IVC）和肺动脉。Fontan手术的这种改良旨在改善肝脏血流向肺部的分布（HFD）。然而，患者特定的解剖限制可能会限制移植物放置的可用空间。假设改变上腔静脉（SVC）的位置可为最佳连接提供更多空间，避免腔静脉血流碰撞。使用计算建模工具回顾性研究SVC放置对Y形移植物血流动力学的影响。
在Fontan Y形移植物完成后，从回顾性心脏磁共振（CMR）图像重建患者特定的解剖结构（N = 10例患者）和血管血流。使用虚拟手术环境创建替代几何形状，改变SVC位置以及相对于Y形移植物分支的偏移。进行几何特征分析和计算流体动力学模拟。计算血流动力学因素（功率损失和HFD）。
IVC回流较高的患者对SVC定位的敏感性较低。IVC血流较低的患者根据SVC位置显示出不同的HFD结果。当SVC完全位于Y形移植物分支之间时，可获得平衡的HFD值（两肺各占50%）。对功率损失的影响因患者而异。
SVC相对于Y形移植物的定位会影响HFD，尤其是在IVC血流较低的患者中。在双向格林（BDG）手术时，根据患者特定的解剖结构仔细定位SVC可以优化最终Fontan手术完成时的血流动力学。
