FLUID DYNAMICS OF RIGHT HEART BYPASS OPERATIONS

右心搭桥手术的流体动力学

• 批准号: 2655261
• 负责人: Carol L Lucas
• 金额: $ 32.01万
• 依托单位: UNIV OF NORTH CAROLINA CHAPEL HILL
• 依托单位国家: 美国
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-02-01 至 2000-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2655261
• 关键词: biomaterial compatibility; biomaterial evaluation; biomaterial interface interaction; blood flow measurement; clinical research; computed axial tomography; hemodynamics; human data; human subject; mathematical model; model design /development; physical model; sheep

DESCRIPTION: (Adapted from the applicant's abstract) Success of surgical interventions performed to improve pulmonary blood flow in infants with congenital defects that interrupt the pulmonary circulation depends on the procedures and materials selected and the ability of the intervention to accommodate for patient growth. Repair options include creation of atrio- and cavopulmonary connections and implantation of cryopreserved valve homografts or extracardiac conduits. However, conduits and homografts don't grow, optimal positions for connections are controversial, and late results from clinical and autopsy studies show high incidence of conduit failure due to fibromuscular ingrowth, valvular degeneration and pseudointimal peel formation. Thus, despite significant advances, answers are still needed to many important questions concerning how to 1) prevent conduit failure, 2) maintain sufficient energy to move blood through a low pressure system, 3) appropriately distribute flow to both lungs, and 4) prepare for reasonable growth. Answers to these general questions require answers to basic questions regarding relationships between fluid mechanics and the involved geometries: How do 1) conduit design and shape affect shear stresses, secondary flow and flow separation, 2) curves, kinks, pouches and bends affect energy losses, 3) anastomotic geometries influence flow distribution? This study will address pertinent issues through a series of in vivo, in situ, and computational experiments. (A) In the in vivo phase, hemodynamic studies will be performed in 1-month and 3-month old lambs before and implanting an extracardiac shunt or establishing an atrio- or cavopulmonary connection. The importance of respiration and atrial contractions to blood transport will be evaluated. (B) Silicone rubber casts of the vena cava connections, right heart and proximal pulmonary arteries will be made in situ. (C) In vitro studies will be performed in various flow through models, velocity patterns visualized using dye injections and laser light and velocity measured with laser and pulsed Doppler devices. In vitro studies provide flexibility not available in vivo; conduit design features will be tested in a range of hemodynamic and cardiopulmonary geometric conditions. (D) Casts made in situ will be CT scanned such that computerized 3D images can be reconstructed and key features extracted. The computerized images will provide the basis for defining geometry for stereolithographic, anatomically correct flow-through models and for computation studies. Finite element techniques for simulating pulmonary blood flow will be developed, expanding the flexibility provided by the in vitro studies, including the ability to project for expected growth. (E) MR images and CT scans of Fontan patients will be used to generate comparable flow-through and finite element models for in vitro and computational studies. unification of results obtained should help identify causes of graft failure and assist surgeons in selecting interventions to establish optimal pulmonary blood flow patterns and make appropriate allowances for patient growth.

描述：（改编自申请人摘要）手术成功 为改善患有肺动脉高压的婴儿的肺血流而进行的干预 中断肺循环的先天性缺陷取决于 选择的程序和材料以及干预措施的能力， 适应患者的成长。 修复选项包括创建心房- 和腔静脉连接以及低温保存瓣膜的植入 同种移植物或心外导管。 然而，导管和同种移植物 增长，连接的最佳位置是有争议的， 从临床和尸检研究表明，导管故障的发生率很高， 纤维肌性长入、瓣膜变性和假内膜剥离 阵 因此，尽管取得了重大进展，但仍然需要找到解决办法， 关于如何1）防止管道故障，2） 保持足够的能量使血液通过低压系统，3） 适当地分配流量到两个肺，以及4）准备合理的 增长 要回答这些一般性问题，需要回答以下基本问题： 关于流体力学和所涉及的 几何形状：1）管道设计和形状如何影响剪切应力， 二次流和流分离，2）弯曲、扭结、囊袋和弯曲 影响能量损失，3）吻合口几何形状影响流量分布？ 本研究将通过一系列的体内、体内和体外研究来解决相关问题。 原位和计算实验。 (A)在体内阶段，血流动力学 研究将在1月龄和3月龄羔羊中进行， 植入心外分流管或建立心房或腔静脉 连接. 呼吸和心房收缩对血液的重要性 运输将得到评估。 (B)腔静脉硅橡胶模型 连接，右心和近端肺动脉将在 原地。 (C)体外研究将在各种流通中进行 使用染料注入和激光可视化的模型、速度模式 用激光和脉冲多普勒装置测量速度。 体外 研究提供了在体内不可用的灵活性;导管设计特征 将在一系列血流动力学和心肺几何学中进行测试 条件 (D)将对原位制作的铸件进行CT扫描， 可以重建计算机化的3D图像并提取关键特征。 的 计算机化图像将为确定几何形状提供基础， 立体平版印刷、解剖学上正确的流通模型和成形 计算研究。 有限元技术在模拟肺 血液流动将得到发展，扩大了内部提供的灵活性， 体外研究，包括预测预期生长的能力。 (E)先生 Fontan患者的图像和CT扫描将用于生成可比较的 用于体外和计算的流通和有限元模型 问题研究 统一所取得的结果应有助于查明 移植失败，并协助外科医生选择干预措施，以建立 最佳肺血流模式，并适当考虑 患者成长