CARDIOPULMONARY GEOMETRY AND BLOOD FLOW IN GROWING LAMBS

生长中羔羊的心肺几何形状和血流

• 批准号: 3360073
• 负责人: Carol L Lucas
• 金额: $ 21.17万
• 依托单位: UNIV OF NORTH CAROLINA CHAPEL HILL
• 依托单位国家: 美国
• 财政年份: 1989
• 资助国家: 美国
• 起止时间: 1989-07-01 至 1992-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3360073
• 关键词: growth /development; hemodynamics; infant animal; mathematical model; online computer; pulmonary artery; respiratory airway pressure; respiratory circulation; respiratory circulation disorder; respiratory disorder diagnosis; respiratory imaging /visualization; sheep; tissue /cell culture; ultrasound blood flow measurement

The potential for measuring pulmonary blood velocity noninvasively with pulsed Doppler ultrasound has stimulated interest in relationships between velocity patterns and abnormal pulmonary hemodynamics. Unfortunately, clinical and experimental studies have found that characteristics reported in correlate well with abnormal pulmonary pressure and/or resistance are often observed in normal subjects. For example, the prominent backflow along the right posterior wall of the pulmonary trunk in patients with pulmonary hypertension, which has been attributed to enhanced curvature of the main pulmonary artery, has also been observed in normal lambs, dogs and humans. The similarity of animal velocity profiles in vivo to profiles obtained in pulsatile flow studies in curved tubes suggests that geometry plays a role as important as hemodynamics in determining velocity patterns. Thus, understanding the relationships 1) between normal maturation and geometry and 20 between geometry and fluid dynamics is essential if techniques for diagnosing altered fluid dynamics induced by congenital heart defects in infants and children, in whom pulmonary geometries will be changing rapidly, are to be improved. Using a series of developing lambs ranging from 1 day to 1 year in age, this study will address these issues by performing in vivo, in situ and in vitro experiments. (A) During the in vivo phase, velocity profiles will be obtained in the main and branch pulmonary arteries using 20 MHz pulsed Doppler devices. Data collected will be used to project normal -or-age 2- and 3-dimensional velocity profiles and input impedance spectra and to verify the authenticity of profiles determined in vitro in later studies. (B) Casts of the right ventricle and proximal pulmonary arteries will be made in situ under normal physiologic pressure. The casts, which reveal the importance of the subvalvar infundibular region, can be CT scanned and their structure committed to computer memory, from which 2- and 3-dimensional images can be reconstructed. Algorithms will be developed for quantifying curvature and torque of the main trunk, flow divider offset, bifurcation angles, taper, and segment dimensions. Data obtained will be used to quantitate age-related changes in geometry and intra-age variability. (C) In vitro studies in glass and silicone rubber models will be components of a sophisticated pulse duplicator system designed to match the pressure and flow characteristics of the right ventricle. Flow patterns will be visualized using a laser light source and velocity measured with a laser Doppler anemometer system and pulsed Doppler devices similar to those used in vivo. In vitro studies provide flexibility not available in vivo; flow patterns can be observed under conditions of 1) constant geometry and variable hemodynamics, 2) constant hemodynamics and variable geometry, and 3) resting hemodynamics and geometry but variable compliance. Unification of results obtained should answer clearly the questions implied: 1) how do the geometries of the right ventricle and major pulmonary arteries change from birth to adult life? and 2) how do geometric variations resulting from normal aging and/or individual variability affect flow dynamics?

无创测量肺血流速度的可能性 脉冲多普勒超声激发了人们对 流速模式和肺血流动力学异常之间的联系 不幸的是，临床和实验研究发现， 报告的特征与肺部异常密切相关 压力和/或阻力通常在正常受试者中观察到。为 例如，沿着右后壁的显著回流沿着 肺动脉高压患者的肺动脉干， 归因于主肺动脉的曲率增强， 在正常的羔羊、狗和人类中观察到。动物的相似性 在脉动流研究中获得的速度分布 在弯曲的管道中，几何形状的作用与 血流动力学测定速度模式。因此，了解 关系1）正常成熟和几何形状之间的关系和20之间的关系 几何学和流体动力学是必不可少的， 婴儿先天性心脏缺陷引起的流体动力学改变， 肺几何形状将迅速变化的儿童， 完善使用一系列发育中的羔羊， 年的年龄，这项研究将解决这些问题，通过在体内进行， 原位和体外实验。(A)在体内阶段，速度 将使用以下方法获得主肺动脉和分支肺动脉的轮廓 20 MHz脉冲多普勒设备。收集的数据将用于项目 正常或年龄二维和三维速度剖面和输入阻抗 光谱，并验证在体外确定的配置文件的真实性， 后来的研究。(B)右心室和近端肺动脉的铸型 在正常生理压力下原位制造动脉。的 显示瓣下漏斗区重要性的铸型， 可以进行CT扫描，并将其结构提交到计算机存储器中， 可以重建2维和3维图像。算法将 开发用于量化主干、流量 分隔器偏移、分叉角度、锥度和段尺寸。数据 获得的数据将用于量化几何学中与年龄相关的变化， 年龄内变异(C)玻璃和硅橡胶中的体外研究 模型将是一个复杂的脉冲复制系统的组成部分， 设计用于匹配右侧的压力和流量特性， 脑室将使用激光光源可视化流型 用激光多普勒风速计系统测量速度， 多普勒器械与体内使用的器械相似。体外研究提供了 体内不具备灵活性;在下可以观察到流动模式 1）恒定几何形状和可变血流动力学，2）恒定 血流动力学和可变几何形状，以及3）静息血流动力学和 几何形状，但可变的顺应性。所获结果的统一应 明确回答隐含的问题：1）如何做的几何形状的 从出生到成年，右心室和主要肺动脉发生变化 生活？以及2）正常老化导致的几何变化如何 和/或个体变异性影响血流动力学？