Control method of a rotary blood pump for a left ventricular assist device

Abstract

The aim of the investigation is to develop a control method of a rotary blood pump (RBP) to solve the following problems: estimation of the pump flow rate, achievement and maintaining of the desired flow level through the continuous adjustment of pump speed and prevention of adverse effects on the cardiovascular system. Results. Functional chart of RBP control consists of several units: a unit for evaluation of instantaneous pump flow rate, unit for estimation of approximate and actual pump flow rate and identification of pumping states, and unit for speed adjustment forming a new speed value of the desired flow rate and current pumping state. The core of the functional chart is RBP unit presented by a mathematical model of RBP. Waveforms of pump flow and speed changes and indices for RBP state identification are given in the work. Hemodynamic curves (the flow rate through aortic valve and minimum volume of the left ventricle during a cardiac cycle) are used to evaluate accuracy of pumping states identification. The possibility to adjust pump flow in various physiological conditions (variation of the heart rate and left ventricular contractility) is demonstrated. Control of the pumping states allows to avoid adverse conditions in the cardiovascular system, and to estimate physiological changes in its work such as aortic valve closure. Conclusion. The proposed control method of a RBP allows to achieve and maintain the desired pump flow rate under various physiological conditions. This method is supposed to be used in the development of control system for the left ventricular assist devices.