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DETERMINANTS OF PULMONARY ARTERY BLOOD VELOCITY PROFILE

肺动脉血流速度的决定因素

基本信息

批准号：
3349237
负责人：
Carol L Lucas
金额：
$ 16.66万
依托单位：
UNIV OF NORTH CAROLINA CHAPEL HILL
依托单位国家：
美国
项目类别：
财政年份：
1986
资助国家：
美国
起止时间：
1986-06-01 至 1993-05-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/3349237
关键词：
blood flow measurement cardiovascular disorder chemotherapy cardiovascular pharmacology disease /disorder model dogs growth /development hemodynamics mathematical model model design /development newborn animals pulmonary artery pulmonary hypertension respiratory airway pressure respiratory disorder diagnosis sheep vascular resistance

项目摘要

Optimal management of patients with congenital heart disease often depends on the ability to monitor pulmonary hemodynamics and assess pulmonary vascular impairment. Need for improved techniques has prompted investigations of relationships between abnormal pulmonary circulations and pulmonary blood velocity patterns, which can be observed noninvasively with pulsed Doppler ultrasound. Features commonly associated with pulmonary hypertension are increased flow reversal in the main pulmonary artery and decreased acceleration time (time from onset of systole to peak velocity). However, recent studies indicate that acceleration time is primarily a function of arterial compliance; flow reversal is directly related to the curvature in the pulmonary outflow tract and/or peripheral vascular resistance. These findings imply that idealized relationships with pressure may exist only in the presence of expected, but not guaranteed, structural changes. Pulmonary vascular impairment is commonly associated with lack of response to vasodilators: however, changes in velocity profiles and the associated pulmonary input impedance spectra may be better indicators of responsiveness. This study will address these issues through experiments designed to identify and quantitate the determinants of the velocity profiles in animal models developed to produce the pulmonary vascular changes associated with either elevated pressure or flow from infancy through childhood. Newborn lambs will be chronically instrumented to measure pulmonary pressures, velocity profiles and axial dimensions from birth to 6 months of age. Elevated pulmonary artery pressure or blood flow will be produced via monocrotaline pyrrole injections or arteriovenous shunts, respectively. Acute interventions designed to assess changes in vascular reactivity will be made during data collection sessions. After natural histories are determined, the ability of long-term pharmacological interventions to alter the high pressure model history will be assessed. Data collected will be used to determine 2- and 3- dimensional velocity profiles, resistance, compliance and shape changes and input impedance spectra. After the terminal hemodynamic study, casts of the right ventricle and proximal pulmonary arteries will be made in situ under hemodynamically matched systolic pressure. The casts will 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, taper, bifurcation angles, and segment dimensions. Experiments designed to test instrumentation and to determine the effects of changes in peripheral vascular resistance as a result of selective embolization of individual lungs will be conducted in acute preparations. Techniques for measuring the pulmonary input impedance spectrum and extracting its salient features will be developed using simple models of the pulmonary vascular bed. Finally, results obtained in the animal models will be compared to available clinical data, thus testing the belief that better understanding of the determinants of the velocity profile will lead to improved patient diagnosis and care.

先天性心脏病患者的最佳治疗通常取决于监测肺血流动力学和评估肺血管损害对改进技术的需求促使肺循环异常与肺动脉高压关系的探讨和肺血流速度模式，用脉冲多普勒超声进行无创性检查。特征通常与肺动脉高压相关的是增加的血流逆转，主肺动脉和加速时间减少（从发作开始的时间）收缩至峰值速度）。然而，最近的研究表明，加速时间主要是动脉顺应性的函数;流量逆转与肺流出道的曲率直接相关和/或外周血管阻力。这些发现意味着理想化的压力关系可能只存在于预期的，但不保证的结构性变化。肺血管损伤通常与对血管扩张剂缺乏反应有关：然而，速度分布和相关肺输入的变化阻抗谱可以是响应性的更好指示。本研究将通过旨在识别和定量动物模型中速度分布的决定因素发展到产生肺血管的变化，从婴儿期到儿童期的压力升高或流动。新生儿将对羔羊进行长期仪器化以测量肺压，从出生到6个月大的速度分布和轴向尺寸。肺动脉压力升高或血流将通过野百合碱吡咯注射或动静脉分流。旨在评估血管反应性变化的急性干预将在数据收集会议期间进行。在自然史之后，确定，长期药物干预的能力，改变高压模型的历史将被评估。收集的数据将用于确定二维和三维速度分布，电阻、顺应性和形状变化以及输入阻抗谱。在终末血流动力学研究后，对右心室和近端肺动脉将在血流动力学条件下原位形成，收缩压匹配将对铸件进行CT扫描，结构提交给计算机内存，从二维和三维可以重建图像。算法将被开发用于量化主干的曲率和扭矩，分流器偏移，锥度，分叉角度和段尺寸。实验旨在测试仪器，并确定外周变化的影响，由于个体的选择性栓塞导致的血管阻力肺将在急性准备中进行。技术来测量肺输入阻抗谱及其特征提取将使用肺血管的简单模型开发功能睡觉了最后，将在动物模型中获得的结果与现有的临床数据，从而测试的信念，更好地了解速度分布的决定因素将导致改善患者诊断和护理。