Active fixation implantable lead with rotation stop features

摘要

An implantable medical electrical lead includes an extendable/retractable active fixation distal tip assembly. The distal tip assembly includes a shell having an internal cavity and a helix guide member extending at least partially across the cavity and including an axial surface. The distal tip assembly also includes a rotatable coupler within the cavity and a fixation helix fixedly attached to the coupler. The fixation helix engages the helix guide member such that rotation of the coupler and the fixation helix causes the coupler and the fixation helix to advance distally relative to the shell. The coupler further includes a distal rotation stop member protruding axially from the coupler configured to abut the axial surface of the helix guide member to delimit rotation and extension of the coupler and the fixation helix.