title: Frank-starling control of a left ventricular assist device.
abstract: A physiological control system was developed for a rotary left ventricular assist device (LVAD) in which the target pump flow rate (LVADQ) was set as a function of left atrial pressure (LAP), mimicking the Frank-Starling mechanism. The control strategy was implemented using linear PID control and was evaluated in a pulsatile mock circulation loop using a prototyped centrifugal pump by varying pulmonary vascular resistance to alter venous return. The control strategy automatically varied pump speed (2460 to 1740 to 2700 RPM) in response to a decrease and subsequent increase in venous return. In contrast, a fixed-speed pump caused a simulated ventricular suction event during low venous return and higher ventricular volumes during high venous return. The preload sensitivity was increased from 0.011 L/min/mmHg in fixed speed mode to 0.47L/min/mmHg, a value similar to that of the native healthy heart. The sensitivity varied automatically to maintain the LAP and LVADQ within a predefined zone. This control strategy requires the implantation of a pressure sensor in the left atrium and a flow sensor around the outflow cannula of the LVAD. However, appropriate pressure sensor technology is not yet commercially available and so an alternative measure of preload such as pulsatility of pump signals should be investigated.
authors.affiliation: School of Information Technology and Electrical Engineering, University of Queensland, Brisbane, Australia. michael.c.stevens31@gmail.com
authors.forename: Michael Charles
authors.initials: MC
authors.lastname: Stevens
authors.forename: Nicholas Richard
authors.initials: NR
authors.lastname: Gaddum
authors.forename: Mark
authors.initials: M
authors.lastname: Pearcy
authors.forename: Robert F
authors.initials: RF
authors.lastname: Salamonsen
authors.forename: Daniel Lee
authors.initials: DL
authors.lastname: Timms
authors.forename: David Glen
authors.initials: DG
authors.lastname: Mason
authors.forename: John F
authors.initials: JF
authors.lastname: Fraser
mesh_terms: D016275:Atrial Function / Q000502:physiology*; D032701:Biomimetics / Q000295:instrumentation*; D001794:Blood Pressure / Q000502:physiology; D001795:Blood Pressure Determination / Q000295:instrumentation*; D003198:Computer Simulation; D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005246:Feedback; D025461:Feedback, Physiological / Q000502:physiology; D006353:Heart-Assist Devices; D006801:Humans; D008954:Models, Biological; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016277:Ventricular Function, Left / Q000502:physiology*