[Research on Control of the Cardiovascular System Based on a Left Ventricular Assist Device]

We propose a control model of the cardiovascular system coupled with a rotary blood pump in the present paper.A new mathematical model of the rotary heart pump is presented considering the hydraulic characteristics and the similarity principle of pumps.A seven-order nonlinear spatial state equation adopting lumped parameter is used to describe the combined cardiovascular-pump model.Pump speed is used as the control variable.To achieve sufficient perfusion and to avoid suction,a feedback strategy based on minimum(diastolic)pump flow is used in the control model.The results showed that left ventricular assist device(LVAD)could improve hemodynamics of the cardiovascular system of the patient with heart failure in open loop.When rotation speed was 9,000r/min,cardiac output reached 82mL/s while the initial cardiac output was only 34mL/s without the LVAD support.When the rotation speed was above 12 800r/min,suction was found because the high rotating speed resulted in insufficient venous return volume.Suction was avoided by adopting the feedback control.The model reveals the interaction of LVAD and the cardiovascular system,which provides theoretical basis for the therapy of heart failure in the left ventricular and for the design of a physiological control strategy.