Mechanical Issues in Pulsatile Blood Flow

这项建议的目的是深入了解下面每个血液供应系统所涉及的潜在流体动力学设计，并与临床研究人员密切合作，以确保所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特定的模式到达室壁深处的高度活跃的组织，这一模式尚未完全理解。与梅奥诊所合作的一项试点研究已经成功完成，在该研究中，我们结合使用了微型CT成像和专用的血管树计算机分析程序。这项研究仅限于宏观尺度上的血管系统，目的主要是测试方法学。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系统。这个主题对于更好地了解心肌内的缺血事件是很重要的。 2.压力感受性反射对血流的控制。压力感受器反射调节心率的变化，以响应血压的变化。我与西方大学的一个神经血管研究小组有一个积极的合作，在这个小组中，我使用时间序列分析来检查心率和血压记录之间的相关性。在一项初步研究中，我们发现目前基于开环控制模型的压力感受器反射功能理论与生理数据不一致。我们的目标是制定和测试一个闭环系统模型。这一课题对于压力感受器反射敏感性随年龄增长或疾病的恶化具有重要意义。 3.在坚硬的颅骨范围内有搏动性血流。由于缺乏通道，这种流动的机制还没有完全了解。临床关注的焦点主要是颅内压，其影响尚不清楚。在一项试点研究中，我与WESTERN的神经血管小组合作，使用傅立叶分析表明，颅内压只是这种血流机制中的一个因素，另一个因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。这一主题对于脑震荡和脑积水的潜在机制是重要的。 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了戏剧性的变化。密苏里州圣路易斯的华盛顿大学医学院的研究人员邀请我对这个系统的基本流体力学进行合作研究。我们研究了曲率和附加长度对螺旋动脉中流动的影响的初步研究结果已经完成。我们的下一步是模拟妊娠过程，将螺旋动脉的越来越多的部分转化为开放的漏斗。我的目标是建立一个螺旋-漏斗组合的流体动力学的计算机模型。这一主题与先兆子痫患者血液供应系统的故障有关，具有重要意义。

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.