Modeling and Analysis of Human Cardiovascular Dynamics

Abstract

In this thesis, mathematical modeling was applied to the cardiovascular system of the human body, a simple cardiovascular model was developed to an extended cardiovascular model, including major organs, and a controller was added to apply a blood flow homeostasis maintenance system. The blood flow homeostasis maintenance system is an essential element in applying various situations such as aging, rest, and exercise. The blood flow and blood pressure flowing through each part were considered in the mathematical modeling of the cardiovascular system, and the heart was modeled as a pump that prevents the backflow. A simple cardiovascular model could obtain results that match the actual human blood pressure, blood flow, and cardiac output. The extended cardiovascular model, including major organs, was modeled by considering the percentage of blood flow through each organ. As a result, the blood flow through each organ was consistent with physiological data. A controller was designed to apply the system for maintaining blood flow in this model. The controller consists of a heart rate controller and a heart contractility controller, and a PI controller that is widely used in the industry was used. To prevent the variance of heart rate during a heartbeat, it is designed to be controlled after the heartbeat. And we confirmed that the controller works properly using a step response. Aging was applied to the model, which includes the homeostasis system. When aging occurs, the function of the heart and blood vessels radius decreases. According to the papers on the degree of aging according to the age 25, 40, 55 years old – 15 years of age interval was applied to the model. As a result, it was possible to confirm the phenomenon that occurs when the actual human body aging progresses through simulation. Finally, we simulated with medium intensity exercise condition according to the aging of the cardiovascular system. It was confirmed that the heart rate and cardiac output increased as the exercise was performed, and the heart rate decreased as taking a rest. This result is accordant with the actual human body. As a result, by using simulation, actual changes in the human body, according to aging, rest, and exercise, were applied to the simulation model. We validated the current model by applying actual aging, rest, and exercise situations. In further studies, this model will be extended by adding new loops – such as gas exchange, blood sugar control, and electrolyte balance maintenance. Establishing the presented model has been very worthwhile since this could be key to any extended model by adding various factors.