A temporarily or permanently implantable medical device comprising at least one elongate electric lead having at least two function conductors, which are each multi-stranded, each function conductor being connected to at least one respective function electrode pole to deliver treatment signals or to record diagnostic signals, in which device - a first of the function conductors has at least one first strand, which, in a course of the longitudinal extension of the first function conductor in at least one first longitudinal portion, which forms only part of the longitudinal extension of the function conductor, has a first coupling to a second of the function conductors, which coupling is configured to couple, at least in part, electromagnetic radio-frequency waves guided in the second function conductor into the at least one first strand of the first function conductor and, on account of an inherent physical separation of at least one second strand of the first function conductor, which second strand is different from the first strand, from the second function conductor, not into the at least one second strand, which is different from the first strand, of the first function conductor, and in which - the at least one first strand in the course of the longitudinal extension of the first function conductor in at least one second longitudinal portion different from the first longitudinal portion has a second coupling to the at least one second strand of the first function conductor, which coupling is suitable for coupling, at least in part, electromagnetic radio-frequency waves guided in the at least one first strand into the at least one second strand of the first function conductor, and wherein - the at least one first strand of the first function conductor is guided in the first longitudinal portion at a shorter distance from the second function conductor, suitable for producing the first coupling, than outside the first longitudinal portion of the first function conductor. - a first of the function conductors has at least one first strand, which, in a course of the longitudinal extension of the first function conductor in at least one first longitudinal portion, which forms only part of the longitudinal extension of the function conductor, has a first coupling to a second of the function conductors, which coupling is configured to couple, at least in part, electromagnetic radio-frequency waves guided in the second function conductor into the at least one first strand of the first function conductor and, on account of an inherent physical separation of at least one second strand of the first function conductor, which second strand is different from the first strand, from the second function conductor, not into the at least one second strand, which is different from the first strand, of the first function conductor, and in which - the at least one first strand in the course of the longitudinal extension of the first function conductor in at least one second longitudinal portion different from the first longitudinal portion has a second coupling to the at least one second strand of the first function conductor, which coupling is suitable for coupling, at least in part, electromagnetic radio-frequency waves guided in the at least one first strand into the at least one second strand of the first function conductor, and wherein - the at least one first strand of the first function conductor is guided in the first longitudinal portion at a shorter distance from the second function conductor, suitable for producing the first coupling, than outside the first longitudinal portion of the first function conductor.