Abstract: The catheter to be inserted into a vein (4) of the blood circulation, comprising a conduit (7) with at least one expandable anchoring element (13) at its distal end (8) for anchoring in the vein wall, and a tube-shaped jacket (sheet 14) that is pushed onto the conduit (7) and can be at least partially withdrawn in a proximal direction once the conduit (7) has been inserted into the vein (4), thereby releasing the at least one anchoring element (13), so that it can expand. The conduit (7) comprises a bottleneck (17) at the distal end of its lumen (8) and the catheter comprises a tube-shaped element (pusher 15) to be pushed onto a guiding wire (11). The front end of said element bearing against the bottleneck.