A medical device for being inserted into a patient's body lumen, comprising: an elongate tubular substrate; a shielded twisted pair of conductors located on said substrate, said shielded twisted pair of conductors comprising: a twisted pair of conductors including two conductor layers (54, 58) comprising conductive material and a layer of nonconductive material disposed between the two conductor layers (54, 48); and an insulator comprising a lower insulator layer (76 1) and an upper insulator layer (76 2), wherein said conductor layers (54,58) are located between said lower insulator layer (76 1) and said upper insulator layer (76 2), said lower insulator layer (76 1) and said upper insulator layer (76 2) surrounding said twisted pair of conductors to form an insulated twisted pair of conductors, said twisted pair of conductors positioned on an upper surface of said lower insulator layer (76 1), said upper insulator layer (76 2) being formed on said twisted pair of conductors; and a shield comprising a lower shield layer (78 1) and an upper shield layer (78 2), wherein said insulated twisted pair of conductors is located between said lower shield layer (78 1) and said upper shield layer (78 2), said lower shield layer (78 1) and said upper shield layer (78 2) surrounding said insulated twisted pair of conductors (52, 80), said upper shield layer (78 2) being located over said upper insulator layer (76 2), said lower shield layer (78 1) and said upper shield layer (78 2) being in electrical contact with each other, and a plurality of contact rings (46, 46 1, 46 2, 46 N) at a proximal end of the substrate, the contact rings comprising a layer of conductive material and being electrically connected to the twisted pair of conductors, wherein the contact rings (46, 46 1, 46 2, 46 N) are configured to be operably connectable to a control unit. an elongate tubular substrate; a shielded twisted pair of conductors located on said substrate, said shielded twisted pair of conductors comprising: a twisted pair of conductors including two conductor layers (54, 58) comprising conductive material and a layer of nonconductive material disposed between the two conductor layers (54, 48); and an insulator comprising a lower insulator layer (76 1) and an upper insulator layer (76 2), wherein said conductor layers (54,58) are located between said lower insulator layer (76 1) and said upper insulator layer (76 2), said lower insulator layer (76 1) and said upper insulator layer (76 2) surrounding said twisted pair of conductors to form an insulated twisted pair of conductors, said twisted pair of conductors positioned on an upper surface of said lower insulator layer (76 1), said upper insulator layer (76 2) being formed on said twisted pair of conductors; and a shield comprising a lower shield layer (78 1) and an upper shield layer (78 2), wherein said insulated twisted pair of conductors is located between said lower shield layer (78 1) and said upper shield layer (78 2), said lower shield layer (78 1) and said upper shield layer (78 2) surrounding said insulated twisted pair of conductors (52, 80), said upper shield layer (78 2) being located over said upper insulator layer (76 2), said lower shield layer (78 1) and said upper shield layer (78 2) being in electrical contact with each other, and a twisted pair of conductors including two conductor layers (54, 58) comprising conductive material and a layer of nonconductive material disposed between the two conductor layers (54, 48); and an insulator comprising a lower insulator layer (76 1) and an upper insulator layer (76 2), wherein said conductor layers (54,58) are located between said lower insulator layer (76 1) and said upper insulator layer (76 2), said lower insulator layer (76 1) and said upper insulator layer (76 2) surrounding said twisted pair of conductors to form an insulated twisted pair of conductors, said twisted pair of conductors positioned on an upper surface of said lower insulator layer (76 1), said upper insulator layer (76 2) being formed on said twisted pair of conductors; and a shield comprising a lower shield layer (78 1) and an upper shield layer (78 2), wherein said insulated twisted pair of conductors is located between said lower shield layer (78 1) and said upper shield layer (78 2), said lower shield layer (78 1) and said upper shield layer (78 2) surrounding said insulated twisted pair of conductors (52, 80), said upper shield layer (78 2) being located over said upper insulator layer (76 2), said lower shield layer (78 1) and said upper shield layer (78 2) being in electrical contact with each other, and a plurality of contact rings (46, 46 1, 46 2, 46 N) at a proximal end of the substrate, the contact rings comprising a layer of conductive material and being electrically connected to the twisted pair of conductors, wherein the contact rings (46, 46 1, 46 2, 46 N) are configured to be operably connectable to a control unit.