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

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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.