for anchoring inside the body lumen 3 having a lateral dimension larger than the lateral dimension of said compressed configuration fig1 represents a further embodiment of the present invention in which the implantable device comprises two flexible arms 66 joined as to form a flexible u201c u u201d and the join section fixed on the curved section of the u201c u u201d fig1 shows an application of the present invention in which the implantable device 2 is inserted in a permanent or semipermanent angioplasty stent 15 in this case the particular embodiment of fig1 is shown inside a tubular stent 15 the skilled person will understand however that all presented embodiment of the invention may be adapted for use in this manner in this particular application the device of the invention can for example be placed for a limited time after an angioplasty operation in the expanded body vessel thanks to this aspect of the invention it is possible to monitor or log blood pressure flow constriction or other clinical parameters or deliver drugs in situ independently from the expansive action of the stent 15 it may be desirable in certain cases to provide for an interface element 15 between the implantable device 2 and the walls of the body lumen into which the device 2 is placed the interface element 15 may include for example a cylindrical sleeve as represented on fig1 optionally treated with appropriate substances for preventing or limiting a tissue growth at the implant site thereby reducing the risk of embolism during the recovery of the device 2 the interface element 15 may be recovered with the device 2 or may be left in situ permanently or until a later moment other forms of interface elements are however possible and readily devisable by.