One embodiment of the invention provides a variable pitch impeller for a blood pump. The variable pitch impeller includes: a flexible polymer defining a plurality of blades extending from a first end to a second end, the blades having a resting non-zero pitch an external shaft coupled to a first end of the flexible polymer and an internal shaft received within the external shaft and coupled to the second end of the flexible polymer. The internal shaft and the external shaft are rotatable with respect to each other to achieve a blade pitch between about 0.0001° and about 2,880°.
