Feedback controller for restoring the basal hemodynamic condition with a rotary blood pump used as left ventricular assist device

Abstract

This work deals with the use of pulsatility indices in designing a ventricular assist device (VAD) control system. The control objective is to restore the patient's basal hemodynamic energy. The proposed control system structure comprises a hierarchy of cascaded control loops. At the highest level, there is the pressure feedback control loop, and at the lowest level, there are feedback control loops for both the rotational speed and the armature current. The reference signal for the high-level controller has a pulsatile profile. The generation of this pulsatile profile employs a procedure that takes into account the fulfillment of physiological specifications. Among the considered physiological requirements, there is the mean arterial pressure (MAP), the energy equivalent pressure (EEP), or the surplus hemodynamic energy (SHE). The gains of the low-level controllers are calculated based on the time-domain specification and the VAD mathematical model parameters. On the other hand, high-level controller gains are determined by using integral performance error criteria as tuning rule. The results obtained in silico indicate the feasibility of the proposed control system as well as its related design procedure. With the generated reference pump profile, it is possible to restore the basal hemodynamic condition for a heart failure patient. Besides, the restored basal hemodynamic condition is quite robust since it is maintained even under variations of the systemic resistance and heartbeat rate.