An Adaptive Cardiac Output Control for the Total Artificial Heart Using a Self-Tuning Proportional-Integral-Derivative (PID) Controller

Summary

The development of a control method for the totally implantable artificial heart (TAH) to regulate cardiac output according to the change in physiological demand was the goal of this study. The conventional proportional-integral-derivative (PID) controller was used for the automatic regulation of the cardiac output. Furthermore, using a fuzzy gain-tuning algorithm, the PID controller parameters were adaptively tuned to the optimal operating point of the process, which varied with hemodynamic disturbances. To determine the physiological demand, the interventricular pressure (IVP) inside the TAH was used to estimate inflow conditions. The negative peak value of the IVP at each diastolic period has a linear relation to the corresponding atrial pressure. Based on the relationship of atrial pressure to the IVP, the automatic control algorithm proposed regulates the optimal pump rate in terms of sufficient cardiac output delivery under a given venous return. To maintain a well-balanced left and right pump output from the volumetrically coupled, circular moving actuator type TAH, the automatic control also adjusts an asymmetric amount of the moving actuator stroke angle, which provides a different net output of the ventricles. The in vitro performance of the newly developed automatic control method was assessed using a mock circulatory system. Over a physiological range of preload, -3–15 mmHg of right atrial pressure (RAP) and 80–120 mmHg of aortic pressure (AoP), the cardiac output varied from 4.2 to 6.31/min with the left atrial pressure (LAP) maintained below 15 mmHg.