into a movement in a second degree of freedom as a result a combined movement at the distal end of the catheter can be produced particularly simply for compression and release of a functional element application_number US 201013147880 A description in the embodiment the application of the invention to a catheter is described in particular which catheter carries a pump at the end thereof and can be introduced into the bloodstream of a patient pumps of this type which are introduced for example into the heart of a patient and serve to convey blood for supporting the heart are basically known it is thereby also known to construct such pump structures such that they can be widened in diameter after introduction into the ventricle it is sensible and essentially an application advantage of the present invention to provide thereby a mechanism which can release the functional element which in the present case comprises the pump so that it is potentially widened automatically and can also compress in order to be able to remove the functional element the pump with the catheter again from the body in the interim the entire device should advantageously remain in the body and should neither damage the patient in this state nor impede the flow of blood through the catheter beyond a tolerable degree basically the catheter 1 which is represented merely schematically in fig1 is introduced through an incision 2 by means of a lock 3 into the blood vessel is pushed through the latter until the end 5 of the.