In one representative embodiment, a steerable catheter device comprises a shaft comprising a proximal portion, a distal portion, and a pull-wire lumen that extends at least partially through the proximal and distal portions. A pull wire extends through the pull-wire lumen and has a proximal end portion and a distal end portion, wherein the distal end portion of pull wire is fixed to the distal end portion of the shaft. An adjustment mechanism is operatively connected to the proximal end portion of the pull wire and configured to increase and decrease tension in the pull wire to adjust the curvature of the distal portion of the shaft. An axially non-compressible pull-wire sleeve extends co-axially through the pull-wire lumen and over the pull wire.