A blood pump (1) comprises a pump casing (2) having a blood flow inlet (5) and a blood flow outlet (6) connected by a passage (7), and an impeller (3) arranged in said pump casing (2) so as to be rotatable about an axis of rotation (9). The impeller (3) is provided with blades (4) sized and shaped for conveying blood along the passage (7) from the blood flow inlet (5) to the blood flow outlet (6), the impeller (3) being rotatably supported in the pump casing (2) by at least one contact-type bearing (20) comprising a bearing surface of the impeller (3) facing a bearing surface of the pump casing (2). At least one wash out channel (30) extends through the impeller (3) and is in fluid connection with the passage (7) via a first opening (34) and with the bearing (20) via a second opening (35). The wash out channel (30) is operatively associated with a secondary pump for pumping blood through the wash out channel (30) towards the bearing (20), wherein the secondary pump is formed at least partially by said at least one wash out channel (30) extending through the impeller (3) along a direction having at least one tangential directional component.
