Pump system for pumping a fluid and method for operating a pump system

A ventricular assist device for continuously assisting a heart of a patient with heart failure and/or Fontan circulation and maintaining organ perfusion, the ventricular assist device comprising a pump system for pumping a fluid, the pump system comprising:

• a first diaphragm fluid pump;
• a first inlet cannula connected to the first diaphragm fluid pump for supplying a fluid to the first diaphragm fluid pump;
• a first outlet cannula connected to the first diaphragm fluid pump for discharging the fluid out of the first diaphragm fluid pump;
• a first working pump, which is connected via a first pressure line to the first diaphragm fluid pump and is configured to drive the first diaphragm fluid pump via the first pressure line;
• a first inlet flow sensor for detecting a first inlet flow of the fluid in the first inlet cannula and/or a first outlet flow sensor for detecting a first outlet flow of the fluid in the first outlet cannula;
• and
• a control unit configured to control the first working pump based on the detected first inlet and/or outlet flow as a closed-loop control in order to achieve a preset for the first inlet and/or outlet flow, wherein the preset for the first inlet and/or outlet flow comprises a preset for a time average or a time behavior of the first inlet and/or outlet flow;
• wherein the first working pump has a working piston movable in an oscillatory manner in a working chamber and a balancing valve for changing a mass of a working fluid in the working chamber and/or a pressure in the working chamber, the working chamber being in a pressure exchange connection with the first pressure line, and
• wherein the control unit is configured, based on the detected first inlet flow and/or first outlet flow, to determine a preset for one or more of a mean pressure in the working chamber, a preset for a pressure amplitude in the working chamber, a preset for a pumping rate, a preset for a stroke of the working piston, a preset for a force of the working piston, a preset for a relative emptying duration, a preset for a filling duration, a preset for an emptying pressure, and a preset for a filling pressure in the working chamber, and to control movement of the working piston and the balancing valve according to the preset for the one or more of the mean pressure, the preset for the pressure amplitude, the preset for the pumping rate, the preset for the stroke, the preset for the force, the preset for the relative emptying duration, the preset for the filling duration, the preset for the emptying pressure, and the preset for the filling pressure so that a predetermined first inlet flow and/or first outlet flow is achieved.