The invention relates to a stent pump for intravascular, intraventricular or intraatrial placement inside the human heart comprising: —a preferably tubular housing having an inlet and an outlet, —an impeller, and —a stream former, wherein the impeller and optionally the stream former are arranged within the housing, characterized in that the stream former is arranged downstream of the impeller, and the housing, the stream former and/or the impeller are deployable from a first position, in which the housing, the stream former and/or the impeller are folded for being arranged within a delivery device, into a second, expanded position, in which the housing, the stream former and/or the impeller are deployed.