The invention relates to an implantable medical device (1) comprising a flexible band (2) intended for being placed around an organ to tightly bind the latter, said medical device being characterised in that it includes a positioning means (10) provided with a curved stiffening element with a rigidity greater than that of the flexible band, said positioning means (10) being designed to be inserted around the organ in order to substantially mark the path for placing said flexible band (2) around said organ. The invention can be used in the field of implantable medical devices.