Magnevad status of design improvements human blood results and preliminary sheep trial

Magnevad II is an improved version of Magnevad I and both are fourth-generation axial flow left ventricular assist devices. A major simplification has been implemented and tested. Magnevad I used a magnetically suspended rotor requiring active axial control. Magnevad II is completely passive but otherwise similar. A self-washing radial hydrodynamic bearing suspends the rotor. In the axial direction, noncontact axial stiffness is provided by opposing pairs of repulsion magnets ( called bumper magnets). Rotor location shifts in response to differential pressure. A low-cost position sensor measures this motion to provide pump differential pressure. This is used to create pulsating flow and physiologic control ( like Magnevad I). Hemolysis of Magnevad II using human blood was very low with a normalized index of hemolysis at 0.001-0.002 g/100 L. Our first sheep trial took place in September 2004. No thrombus or deposits were found in the disassembled pump. Longer sheep trials are scheduled in March 2005 at the Foundation Cardio-Infantil in Bogota, Colombia.