A first aspect of the present invention relates to a guide wire for use in a catheter assembly comprising: a) a distal end expandable assembly, wherein said expandable assembly is capable of being changed from a retracted state to an expanded state and wherein said expandable assembly is arranged in a substantially conical configuration； b) a pivotable joint connecting said expandable assembly to said guide wire. A second aspect of the present invention relates to a catheter assembly comprising a first tube and a guide wire according to the first aspect of the present invention, located within said first tube, optionally wherein said guide wire is located in a second tube positioned within said first tube, wherein said first and/or second tube is made of or covered with a non-sticking material and wherein said first tube comprises one or more side holes. A third aspect of the present invention relates to a guide wire for use in a catheter assembly, comprising: a) an expandable assembly； b) one or a plurality of contacts positioned on said expandable assembly, wherein each contact comprises an electrode element connected to a conductor； c) an electrically conducting pivotable joint connecting said expandable assembly to said guide wire, wherein said guide wire has an insulated conductive core； and d) a power supply capable of selectively generating an electrical signal transmitted to said one or a plurality of contacts via conductive core of said guide wire.Un premier aspect de la présente invention concerne un fil-guide destiné à être utilisé dans un ensemble cathéter comprenant : a) un ensemble extensible au niveau de l'extrémité distale, ledit ensemble extensible pouvant passer d'un état rétracté à un état étendu et ledit ensemble extensible étant agencé dans une configuration pratiquement conique ； b) un joint pivotant reliant ledit ensemble extensible audit fil-guide. Un deuxième aspect de la présente invention concerne un ensemble cathéter comprenant un premier
