Understanding the regulatory control of complex blood flow in conduit arteries and veins

几十年来，心血管研究人员一直在研究大动脉和大静脉直段的血液流动，发现血液流动模式如何影响血管的功能。然而，在现实中，我们的血管系统中很少有区域是由直管组成的，并且可以包含独特的特征，例如一个血管分成两个血管的分叉区，或者防止血液从心脏回流的静脉瓣膜。虽然我们知道这样的区域更有可能包含“复杂”的血液流动特征(例如，分流、流动射流、回流区)，但我们对什么条件产生复杂的流动现象以及这些流动模式如何影响血管功能了解很少。因此，这项研究计划的长期目标是更好地了解复杂的血液流动在整个人体动脉和静脉中的调节和影响。为了实现这一目标，将致力于三个短期研究目标：1)开发生物医学超声技术，用于估计人类的复杂血流；2)确定血管阻力、压力和管壁僵硬如何影响动脉分叉中复杂血流行为的大小；以及3)确定静脉瓣膜的存在如何影响主要静脉的复杂血流。上述目标将通过先进的成像技术和人体非侵入性实验测试相结合来实现，例如肢体加热、呼吸动作、下半身吸气和单肢锻炼。该计划将结合尖端超声技术，允许对复杂的血流进行可视化和量化，以研究动脉分叉和静脉瓣膜，这是临床单位通常使用的常规超声无法实现的。这项工作将为多个科学领域提供模型人体数据，为血管疾病的复杂流体动力学模拟提供信息，建立人体模型以研究血流异常的病理生理学，并为不断增长的加拿大超声行业开发新的超声应用。参加这项研究计划的学生将在应用人体生理学和先进成像技术的开发方面获得宝贵的经验，参与灵活的培训环境，以支持学术和行业职业道路。重点将放在应用编程技能和创造性的研究设计上，以针对人类心血管控制的特定方面，如血管压力、动脉僵硬和血液流动。在明确的长期目标和以学生为中心的培训计划的推动下，这项研究计划寻求发展血管生理学的一个新分支，产生关于如何在人体最难以接近和复杂的血管区域控制血液流动的基础知识。

For decades, cardiovascular researchers have studied blood flow in straight segments of large arteries and veins, making discoveries in how blood flow patterns impact the function of our vessels. However, in reality, few regions of our vascular system are made of straight tubes, and can contain unique features such as bifurcation regions in which one vessel branches into two, or venous valves that act to prevent the backflow of blood away from the heart. While we know such regions are more likely to house `complex' blood flow features (e.g., splitting flow streams, flow jets, recirculation zones), we have a poor understanding of what conditions create complex flow phenomena and how these flow patterns impact vascular function. Accordingly, the long-term objective of this research program is to better understand the regulation and impact of complex blood flow throughout human arteries and veins. To achieve this goal, three short-term research objectives will be addressed: 1) to develop biomedical ultrasound techniques for the estimation of complex blood flow in humans; 2) to determine how vessel resistance, pressure, and wall stiffness contribute to the magnitude of complex blood flow behaviour in arterial bifurcations; and 3) to determine how the presence of venous valves impacts complex blood flow in the major veins. The above objectives will be met using a combination of advanced imaging techniques and non-invasive experimental tests in humans such as limb heating, breathing maneuvers, lower body suction, and single-limb exercise. This program will incorporate cutting-edge ultrasound techniques that allow the visualization and quantification of complex blood flow to study arterial bifurcations and venous valves, which is not achievable by conventional ultrasounds typically found in clinical units. This work will benefit multiple scientific domains by providing model human data to inform sophisticated fluid dynamics simulations of vascular disease, establishing human models to study the pathophysiology of blood flow abnormalities, and developing novel ultrasound applications for the growing Canadian ultrasound industry. Students who participate in this research program will gain valuable experience in both applied human physiology and development of advanced imaging technology, engaging in a flexible training environment to support both academic- and industry-track career paths. Emphasis will be placed on applied programming skills, and creative study design to target specific aspects of human cardiovascular control, such as vascular pressure, arterial stiffness, and blood flow. Motivated by a clear long-term objective and student-focused training plan, this research program seeks to develop a new branch of vascular physiology, generating foundational knowledge about how blood flow is controlled in the most inaccessible and complicated vascular regions of the human body.