Impeller for blood pump

An apparatus comprising:

• a blood pump configured to be placed inside a body of subject, the blood pump comprising:
• an impeller comprising:
• proximal and distal bushings;
• at least one helical elongate element that extends from the proximal bushing to the distal bushing;
• a spring that is disposed inside of the helical elongate element, and
• along an axis around which the helical elongate element winds;
• and
• a film of material supported between the helical elongate element and the spring;
• a frame configured to be disposed around the impeller,
• wherein the impeller further comprises at least one flexible elongate element configured to extend radially from the spring to the helical elongate element, the flexible elongate element being configured to maintain the helical elongate element within a given distance from the spring, to thereby maintain a gap between an outer edge of a blade of the impeller and an inner surface of the frame, during rotation of the impeller.