A steerable stylet for use within a lumen of an intravascular device includes a stylet assembly and a handle. The stylet assembly has a distal end portion and a proximal end portion and includes a stylet wire having a lumen and a core wire positioned within the lumen with the distal end portion secured to the stylet wire proximate the distal end portion of the stylet wire. The handle includes a hand-held housing structure connected to one of the proximal end portion of the stylet wire or the core wire. In one embodiment, an adjustable tensioner is connected to the other of the proximal end portion of the stylet wire or the core wire to adjust a relative tension force applied between the stylet wire and the core wire. A tension limiter is arranged to limit the tension force to a limit force that is less than a breaking stress force of the stylet wire when the stylet wire is positioned within the lumen of the intravascular device.