A Continuous Flow Centrifugal Ventricular Assist Device
- 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.