A method and device to assist the performance of a heart with at least one pump that is formed as a rotary pump and driven via magneto coupling. The pump includes a magnetically driven rotor rotatable within a surrounding rotor housing to act upon blood flowing from an inflow tube toward the magnetically driven rotor, and a second magnetic device axially aligned with the inflow tube and positioned to magnetically drive rotation of the magnetically driven rotor via the magneto coupling.