A Model for Estimating the Blood Flow of the POLVAD Pulsatile Ventricular Assist Device

Objective: The aim of this work was to model the blood flow rate of the POLVAD-MEV pulsatile ventricular assist device (VAD). An adequate flow rate is crucial to restore physiological cardiac output. Unfortunately, during clinical heart support, neither blood flows nor pressures can be measured within the device. In general, the flow rate depends on the control parameters and patient conditions. However, the patient's hemodynamic parameters are not constantly monitored. Therefore, blood flow should be evaluated based on the standard measurements from the device control unit. Methods: The model identification data were taken from a research stand consisting of a VAD connected to a hybrid cardiovascular simulator. The studies were conducted under different work and control conditions. A compound model of a ventricular assist device was proposed. First, the driving pressure waveform for an idle run of the supply unit is modeled. Next, the blood flow is estimated based on the difference between the measured value of driving pressure and the modeled value for an idle run. Results: The quality of the developed model is good (<(R-2)over bar> = 0.92) and similar for all tested cases, confirming the high versatility of the proposed solution. Conclusion: The blood flow rate is estimated based on standard signals from the device control unit; therefore, no additional measurements are necessary. Significance: The developed model application in the VAD control unit will aid the selection of control parameters and might be useful for the development of the adaptive control system. A preliminary version of this work was reported in [1].