Mechanical Issues in Pulsatile Blood Flow

本提案的目的是深入了解下面每个血液供应系统中涉及的基本流体动力学设计，与临床研究人员密切合作，以确保解决的问题是相关的。 1.心肌灌注。起源于心外膜的血管树必须以一种尚未完全了解的特定模式到达心室壁深处的高度活跃组织。与马约诊所合作的一项试点研究已经成功完成，在这项研究中，我们使用了显微CT成像和专用血管树计算机分析程序的组合。本研究仅限于宏观尺度的血管系统，目的主要是测试方法。我们现在计划使用这种方法来研究一系列心肌组织活检中的微血管。该主题对于更好地理解心肌内的缺血事件是重要的。 2.压力反射控制血流。压力反射介导心率的变化以响应血压的变化。我与西方的一个神经血管研究小组积极合作，我使用时间序列分析来研究心率和血压记录之间的相关性。在一项初步研究中，我们表明，目前的压力反射功能理论，基于开环控制模型，是不符合生理数据。我们的目标是制定和测试一个闭环模型。该主题与压力反射敏感性随年龄或疾病的恶化有关是重要的。 3.颅骨刚性边界内的脉动血流。由于无法进入，这种流动的机制尚未得到充分了解。临床焦点主要是颅内压（ICP），其影响尚不清楚。在一项试点研究中，与西方的神经血管小组合作，我使用傅立叶分析表明，ICP只是这种流动机制中的一个要素，另一个要素是血管内和血管外顺应性的组合。我的目标是在这些早期发现的基础上建立一个分析模型。这门学科对于脑震荡和脑积水的潜在机制很重要。 4.子宫胎盘血流。子宫的血液供应涉及一组螺旋动脉，这些动脉在怀孕期间经历戏剧性的转变。我应位于密苏里州圣刘易斯的华盛顿大学医学院的研究人员的邀请，进行了一项关于这个系统的基本流体力学的合作研究。我们已经完成了一项初步研究的结果，在该研究中，我们检查了曲率和增加的长度对螺旋动脉中的流动的影响。我们的下一步是建立妊娠过程的模型，从而使螺旋动脉的增加部分转化为开放的漏斗。我的目标是建立一个计算机模型的流体动力学的这种螺旋漏斗组合。该主题与先兆子痫中该血液供应系统的故障有关。

The aim of this proposal to gain insight into the underlying fluid dynamic design involved in each of the blood supply systems below, working in close collaboration with clinical researchers to ensure that the issues being addressed are pertinent. 1. Myocardial Perfusion. Vascular trees originating at the epicardium must reach highly active tissue deep within the ventricular wall in a specific pattern which is not fully understood. A pilot study in collaboration with the Mayo Clinic, in which we used a combination of micro-CT imaging and a dedicated vascular tree computer analysis program, has been successfully completed. The study was limited to vasculature on the macro scale and the aim was mainly to test the methodology. We plan now to use this methodology to study the microvasculature in a series of myocardial tissue biopsies. The subject is important for a better understanding of ischemic events within the myocardium. 2. Baroreflex Control of Blood Flow. The baroreflex mediates changes in heart rate in response to changes in blood pressure. I have an active collaboration with a neurovascular research group at Western in which I use time series analysis to examine the correlation between heart rate and blood pressure recordings. In a pilot study we showed that current theory of baroreflex function, based on an open-loop control model, is inconsistent with physiological data. Our aim is to formulate and test a closed-loop model. The subject is important in relation to the deterioration of baroreflex sensitivity with aging or disease. 3. Pulsatile Blood Flow Within the Rigid Confines of the Skull. Mechanics of this flow are not fully understood because of lack of access. Clinical focus is largely on intracranial pressure (ICP), the effects of which are still unclear. In a pilot study, in collaboration with the neurovascular group at Western, I used Fourier analysis to show that ICP is only one element in the mechanics of this flow, another is a combination of intravascular and extravascular compliance. My aim is to build an analytical model based on these early findings. The subject is important in relation to the underlying mechanics of concussion and hydrocephalus. 4. Uteroplacental Blood Flow. Blood supply to the uterus involves a group of spiral arteries which undergo dramatic transformation during pregnancy. I was invited by researchers at Washington University School of Medicine in St Louis MO for a collaborative study of the underlying fluid mechanics of this system. The results of a pilot study in which we examined the curvature and added length effects on the flow in a spiral artery has been completed. Our next step is to model the course of pregnancy whereby an increasing portion of the spiral artery is converted into an open funnel. My aim is to build a computerized model of the fluid dynamics of this spiral-funnel combination. The subject is important in relation to the failure of this blood supply system in preeclampsia.