Low-profile steerable catheter

An apparatus comprising a steerable catheter, the steerable catheter comprising:

• a flexible tube:
• having a proximal portion and a distal portion, at least the distal portion being percutaneously advanceable into a subject, and
• comprising a circumferential wall that defines an elongate lumen between the proximal portion and the distal portion;
• a pull-wire, extending, in association with the wall, from the proximal portion to the distal portion;
• and
• a pull-ring:
• at the distal portion of the tube, coupled to the wall such that the pull-ring circumscribes the lumen,
• coupled to the pull-wire, such that pulling on the pull-wire bends the distal portion of the tube,
• having (i) a first state in which the pull-ring is elliptical and has a first eccentricity, and (ii) a second state in which the pull-ring is elliptical and has a second eccentricity that is smaller than the first eccentricity,
• biased toward assuming the first state, and
• elastically deformable toward the second state.