Patent ID: 8055356

Claim:
A lead system comprising: an elongate lead body extending from a proximal end portion to a distal end portion; a recess formed in the elongate lead body; a low variation friction member held within the recess such that the low variation friction member is held stationary with respect to the elongate lead body, the low variation friction member including an annular spring coil having individual coil windings defining a coil centerline, the coil centerline following an annular path; and an active fixation assembly movable relative to the elongate lead body, the active fixation assembly extending through the annular spring coil with the annular path of the centerline encircling the active fixation assembly such that the active fixation assembly can translate relative to the low variation friction member, the low variation friction member being frictionally engaged with the active fixation assembly in order to provide frictional resistance to translation of the active fixation assembly, the active fixation assembly including a piston having a non circular outer periphery that interacts with the low variation friction member.