Patent ID: 8209035

Claim:
A lead assembly comprising: a lead body extending from a distal end portion to a proximal end portion; at least one conductor disposed within the lead body and extending from the proximal end portion; an electrically conductive terminal pin disposed at the proximal end portion of the lead body, the electrically conductive terminal pin coupled with the at least one conductor; an active fixation mechanism disposed proximate to the distal end portion of the lead body and including a fixation helix that is an electrode; the active fixation mechanism including a movement assembly coupled therewith that extends and retracts the active fixation mechanism, the movement assembly including a shell, wherein the shell includes an inner surface having an internal helical threaded portion including internal threads extending along a length of the inner surface of the shell; and a collar disposed within the shell, wherein the collar includes an outer surface having an external helical threaded portion including external threads extending along a length of the outer surface of the collar, wherein the external threads threadingly engage the internal threads of the shell such that the internal helical threaded portion of the shell provides a helical path for the external helical threaded portion of the collar.