It is a kind of foldable, intravascular pluggable blood pump (10) include it is folding, radial transport impeller (20) are in foldable shell or shell (24). The axial rear gap (60) with impeller in forward position be provided at the shell (24) of impeller (20) and front and rear wall (32,62), which is at least 0.2 millimeters, it is preferable that the impeller (20) in the space (54) limited between adjacent blades is opened the shell (60) 0 towards antetheca (32).