The present invention relates to an injectable aqueous viscous solution for treating varicose veins. It also relates to a catheter system with cannulas for vascular puncture with double or triple cut tip comprising, (i) an outer cannula (non-cutting element), a tube-like construction which is slightly flexible, (a) the tip zone being tapered to ease introduction, (b) the edges being optionally rounded to provide atraumatic advancement (c) optionally with a Luer-lock connector (ii) a hollow needle which is flexible and bendable (c) optionally with a transparent flashback chamber, wherein (d) the diameter of the needle is below the diameter of the catheter, wherein (iii) the needle and outer cannula are connected by a temporary lock to ensure the needle tip is fixed in adequate position outside the outer cannula outer cannula during skin puncture and introduction towards the target region.
