Abstract: A centrifugal pump system for a cardiac assist device employs a disc-shaped impeller having an outer circumference adapted to be rotatably driven in a pumping direction. A pump housing has a pumping chamber receiving the impeller, wherein the pumping chamber defines an outlet volute having a separation edge spaced from the outer circumference to provide a limited backflow path coinciding with the pumping direction. A motor drives the impeller in response to a voltage provided to the motor. A current sensor measures current flow within the motor in response to the voltage. A controller estimates a pump flow rate in response to a predetermined relation between the measured current and the pump flow rate, wherein the predetermined relation includes a positive slope from a predetermined backflow rate to a zero pump flow rate.

Abstract: A centrifugal pump system for a cardiac assist device employs a disc-shaped impeller having an outer circumference adapted to be rotatably driven in a pumping direction. A pump housing has a pumping chamber receiving the impeller, wherein the pumping chamber defines an outlet volute having a separation edge spaced from the outer circumference to provide a limited backflow path coinciding with the pumping direction. A motor drives the impeller in response to a voltage provided to the motor. A current sensor measures current flow within the motor in response to the voltage. A controller estimates a pump flow rate in response to a predetermined relation between the measured current and the pump flow rate, wherein the predetermined relation includes a positive slope from a predetermined backflow rate to a zero pump flow rate.