US Patent 7751905 Active fixation cardiac lead

An active fixation cardiac electrode lead having a fixation helix movably placed in a housing at the electrode lead's distal end so as to be extended out of the housing's distal end and retraced into an inner space enclosed by the housing. The housing has a wall and a protrusion formed in the wall that protrudes into the inner space into interspaces between windings of the fixation helix. The protrusion causes an axial movement of the helix when the helix is rotated around its longitudinal axis. The protrusion is an integral part of the housing's wall which is bent or embossed to form the protrusion.