Patent ID: 8391997

Claim:
An implantable lead comprising: a flexible body extending between a proximal end and a distal end; a connector assembly secured to the proximal end for coupling the lead to an implantable medical device, the connector assembly including a terminal pin rotatable relative to the body; a conductor member disposed longitudinally within the body and coupled to the terminal pin, the conductor member rotatable relative to the body; and a distal assembly coupled to the distal end of the body and including: a housing having a distal region and a proximal region, the proximal region fixedly coupled to the distal end of the body, the housing having an inner surface; a coupler rotatably disposed within the housing, the coupler having a proximal end, a distal end and an outer surface, the proximal end connected to the conductor member; a helical electrode fixedly secured to the coupler; and an annular seal disposed between the coupler and housing, the annular seal providing an at least substantially fluid tight seal between the coupler and the housing, the annular seal including: an annular base portion; an annular wiper portion; and a central portion extending between the base portion and the wiper portion, the annular base portion and the annular wiper portion extending axially beyond the central portion to define an annular channel between the annular base portion and the annular wiper portion, the annular seal being disposed and configured such that fluid flow into the annular channel applies a sealing force to the annular wiper portion; wherein the terminal pin is rotatably engaged with the coupler via the conductor member such that rotation of the terminal pin causes the coupler and the helical electrode to rotate and therefore translate relative to the housing.