Modeling, estimation and control of cardiovascular systems with a left ventricular assist device

A dynamic model is developed through theoretical analysis and numerical solutions to approximate the response of human cardiovascular circulatory system. This system model has one critical time-varying parameter, the resistance of blood vessels. An parameter estimation scheme is derived to estimate this parameter, and the parameter estimate is used to implement an adaptive observer to estimate the aortic pressure for physiologic control. An optimal adaptive controller is proposed to control the estimated aortic pressure to track a reference signal updated by a nonlinear function of the pump head to meet the physiologic need. A Matlab simulation model and an experimental mock human circulatory loop are employed as test environments for human cardiovascular circulatory systems with a left ventricular assist device and their physiologic controllers. Different physiologic conditions, such as the variation of left ventricular failures, variation of activities, and left ventricular suction, are evaluated to test the designed physiologic control system. Simulation and experimental results consistently show that the aortic pressure estimation error is small, and that the abnormal hemodynamic variables of a congestive heart failure patient are restored back to the normal physiologic range.