Ventricular assist device

An apparatus comprising:

• a blood pump configured to be placed inside a body of a subject, the blood pump comprising:
• an impeller comprising:
• proximal and distal bushings;
• two or more helical elongate elements that extend from the proximal bushing to the distal bushing;
• an axial structure that is disposed inside of the two or more helical elongate elements, and along an axis around which the helical elongate elements wind;
• and
• a film of material supported between the helical elongate elements and the axial structure such that each of the helical elongate elements with the film of material coupled thereto defines a respective blade of the impeller;
• and
• an impeller-overexpansion-prevention element, the impeller-overexpansion-prevention element being a single integrated structure comprising a ring disposed around the axial structure, and a plurality of elongate elements,
• each of the elongate elements extending from the ring to a respective helical elongate element and being coupled to the respective helical elongate element so as to prevent radial expansion of the impeller.