Patent ID: 8478429

Claim:
An implantable lead comprising: a flexible body extending between a proximal end and a distal end; and a distal assembly coupled to the distal end of the body and including: a housing having a wall having an external surface and an internal surface defining an inner lumen, a distal end and a proximal end, the proximal end fixedly coupled to the distal end of the body, the housing having an axial shoulder extending radially inward relative to the internal surface at or near the distal end of the housing; a coupler rotatably disposed within the housing, the coupler having a proximal end and a distal end; a helical electrode fixedly secured to the distal end of the coupler, wherein the coupler and the helical electrode are configured to translate relative to the housing between a retracted position and a fully extended position; and a resilient seal fixedly secured to the coupler between the proximal and distal ends thereof and able to translate with the coupler relative to the housing, the seal positioned to sealingly engage the internal surface of the housing wall, wherein when the helical electrode is in the fully extended position, the seal is positioned proximate the shoulder of the housing to substantially seal off the inner lumen of the housing.