Magnetic Bearing In Incor Axial Blood Pump Acts As Multifunctional Sensor

The INCOR blood pump is an axial pump with a magnetically suspended impeller. Since June of 2002, it has been successfully used more than 115 times in Europe and in Asia to treat patients with severe leftventricular heart failure. The magnetic-suspension bearings of the combined rotor and impeller operate with passive radial and active axial position stabilization. Active stabilization is based on the determination of the rotor’s axial motion. In operation, fluid-dynamic forces associated with the active pumping function and the remaining activity of the assisted heart act on the rotor in addition to the magnetic bearing forces. The pressure head across the pump can be deduced directly from the electrical parameters which are sensed in order to operate the magnetic bearings. The blood flow rate through the pump can be determined from the fluid-dynamic characteristics and the pump impeller speed. The pressure gradient and the flow rate information can be used to adapt the pump speed ideally to the patient’s needs. The speed can be varied synchronously to the patient’s heartbeat in order to simulate the natural heart’s blood flow. Modulating the control parameter of the magnetic bearing with a higher-frequency signal will cause the rotor to oscillate in an axial direction in relation to the superimposed signal. The amplitude of the oscillations provide information on the viscosity of the blood. This makes it possible to diagnose the patient’s liquid balance continually and thus take suitable and timely counteractive measures in critical situations. The INCOR blood pump’s magnetic bearings thus enable the pressure head, the blood flow and the blood viscosity to be determined without the need for additional sensors. This means that it provides information which is essential for optimizing the patient’s road to recovery.