ANASTOMOSIS OF A LEFT VENTRICULAR ASSIST DEVICE

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。列出的机构是 研究中心，而研究中心不一定是研究者所在的机构。 左心室辅助装置（LVAD）已被广泛用于辅助或替代衰竭的左心脏的功能。LVAD通常通过LVAD流入套管连接到左心室心尖之间的自体心脏，并通过LVAD流出套管连接到主动脉。根据心脏的状态，LVAD可以在串联或并联状态下工作。主动脉中的血流可能会受到吻合术的高度干扰。通常不采用降主动脉流出吻合术，因为其可能在主动脉瓣附近产生与血栓形成相关的停滞流动（DiGiorgi等人，2004年）。然而，升主动脉吻合术可在主动脉中产生高度扰动的流动，导致主动脉弓上的射流冲击、主要次级血管之间不可预测的流动划分、主动脉根附近的停滞流动，甚至在特定操作条件下的湍流。这些高剪切湍流可能导致血小板活化和溶血。因此，重要的是要研究在主动脉的流动模式的基础上不同的LVAD吻合configuration.The本研究的目的是了解流出套管吻合的影响，在连续和脉动流条件下，使用面向对象的CFD软件工具包OpenFOAM（开放现场操作和操纵）来计算流场。层流和湍流的串行和并行条件下进行了研究。假设主动脉仅在一个平面内弯曲。通过应用阻力流出边界条件来对次级血管之间的流动分配进行建模（Figueroa等人，2006; Vignon-Clementel等人，2006年）。考虑了两种不同的流出套管吻合配置，包括近端和远端位置。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Left ventricular assist devices (LVADs)have been used extensively to assist or replace the function of a failing left heart. The LVAD is usually connected to the native heart between the apex of the left ventricle by the LVAD inflow cannula and to the aorta by the LVAD outflow cannula. Depending on the state of the heart, the LVAD can work in either serial or parallel conditions.Blood flow in the aorta can be highly disturbed by the anastomosis. A descending aortic outflow anastomosis is usually not employed due to its potential to generate stagnant flows associated thrombosis near the aortic valves (DiGiorgi et al., 2004). An ascending aortic anastomosis, however, can produce highly disturbed flows in the aorta, resulting in jet impingement on the aortic arch, unpredictable flow partitioning between the major secondary vessels, stagnant flow near the aortic root, and even turbulent flow under specific operating conditions. These high shear turbulent flows might cause platelet activation and hemolysis. Therefore, it is important to study flow patterns in the aorta based on different LVAD anastomotic configurations.The goal of the present study is to understand the influence of the outflow cannula anastomosis, in continuous and pulsatile flow conditions, using an object-oriented CFD software toolkit OpenFOAM (Open Field Operation and Manipulation) to compute the flow field. Both laminar and turbulent flows are studied under serial and parallel conditions. The aorta is assumed to be curved in one plane only. The flow partitioning between the secondary vessels is modeled by applying a resistance outflow boundary condition (Figueroa et al., 2006; Vignon-Clementel et al., 2006). Two different outflow cannula anastomotic configurations, including both proximal and distal positions, are considered.