Catheters with enhanced flexibility and associated devices, systems, and methods

A catheter comprising:

• a first helically wound elongate member;
• a second helically wound elongate member, the first helically wound elongate member being disposed within the second helically wound elongate member, at least one of the first helically wound elongate member or the second helically wound elongate member comprising a plurality of filaments wound in parallel, and the second helically wound elongate member being counter-wound relative to the first helically wound elongate member;
• and
• an outer jacket positioned over at least one of the first or second helically wound elongate members.

A catheter comprising:

• a first helically wound elongate member comprising a first plurality of filaments wound in parallel;
• a second helically wound elongate member comprising a second plurality of filaments wound in parallel, the first helically wound elongate member being concentric with the second helically wound elongate member, one of the first helically wound elongate member or the second helically wound elongate member comprising a right-hand helical coil and the other of the first helically wound elongate member or the second helically wound elongate member comprising a left-hand helical coil;
• and
• an outer jacket positioned over at least one of the first or second helically wound elongate members.