This is usually a tube-like, long, small-caliber, hollow steel device, used to guide catheters over its outer diameter in angioplasty procedures. From what I can tell its usually used as a segment of a guidewire or a catheter due to both malleability and steerability.
Its sometimes termed as cewnik (catheter) or prowadnica/prowadnik (guidewire) in Polish references. However, to the best of my knowledge hypotubes are hollow devices and therefore shouldnt be referred to as (solid) guidewires.

http://legal.european-patent-office.org/dg3/pdf/t970317eu1.p...