An impeller (152) and a method of manufacture thereof are provided. An impeller frame includes proximal and distal end portions (164) and at least two helical elongate elements (166) that wind from the proximal end portion to the distal end portion. A film of material (168) is coupled to the at least two helical elongate elements (166), such that the helical elongate elements (166) with the material (168) coupled thereto define a blade of the impeller. The film of material (168) is an elastomer that is shaped to define a hollow central lumen therethrough. Other applications are also described.
