The present invention relates to a percutaneous blood pump (1) and an introducer system to be placed in the circulatory system of a patient e.g. using the Seldinger technique without the need of surgical access. The percutaneous blood pump (1) comprises a pump housing (11) inside which a radially pumping impeller (12) is arranged for rotation by means of a rotating flexible cable housed inside a protective flexible catheter (15) and attached to a bearing housing (21) in which a set of radial and axial bearings are housed and arranged for rotation by means of a flexible cable housed inside another protective flexible catheter (25) and driven by an electric motor (30) in a motor housing (31). In addition, an introducer system, comprising an expandable introducer is provided, arranged to facilitate easy and safe introduction of the percutaneous blood pump. The introducer system may comprise a hemostatic valve to limit blood loss during insertion and percutaneous blood pump use. More particularly, the present invention relates to a per-cutaneous blood pump that can be large enough to deliver full circulatory support and is easily and safely introduced into the circulatory system by means of an expandable introducer. The introducer system may include a closure device that is configured to close the incision site after removal of the blood pump and introducer.