An implantable intravascular anchor for supporting a device inside a vascular lumen, the anchor comprising a first part configured to expand when extending from a catheter, and to collapse upon retraction into said catheter; a second part for supporting the device in the lumen and a third part, proximal to the first part, and configured so that, upon release from the catheter, it expands in width to engage an interior wall of the lumen and is adapted for securing the anchor against axial movement along the lumen.