Assembly (10) for inserting a catheter (22) into a body lumen, the assembly (10) comprising an insertion device (11) to be introduced into an opening of the body lumen, an elongated fixing element (16) having a proximal and distal end, where with its distal end the fixing element (16) is fixable to the introduction device (11), and where a fastening device (14) is provided at the proximal end of the fixing element (16). , whose clamping device (14) comprises a clamping unit (17) for fixing a guide wire (27) in relation to the insertion device (11) and whose clamping unit (17) comprises a passage for the guide wire (27), characterized in that the assembly (10) comprises a catheter (22) having a proximal end and a distal end, wherein the proximal end comprises means (29) for releasingly releasing the fixing unit (17), and where by means of the effort of the means (29) of catheter (22) with the clamping unit (17) the guide wire (27) is movable through the insertion device (11) and where with the performance of the means (29) of the catheter (22) of the clamping unit ( 17) the guide wire (27) is fixed in a non-mobile manner with respect to the introduction device (11).Conjunto (10) para insertar un catéter (22) en un lumen corporal, comprendiendo el conjunto (10)un dispositivo de introducción (11) para ser introducido en una abertura del lumen corporal,un elemento de fijación alargado (16) que tiene un extremo proximal y uno distal, en donde con su extremo distal elelemento de fijación (16) es fijable al dispositivo de introducción (11), y en donde en el extremo proximal delelemento de fijación (16) se proporciona un dispositivo de sujeción (14), cuyo dispositivo de sujeción (14) comprendeuna unidad de sujeción (17) para fijar un hilo guía (27) en relación al dispositivo de introducción (11) y cuya unidadde sujeción (17) comprende un paso para el hilo guía (27),caracterizado porqueel conjunto (10) comprende un catéter (22) que tiene un extremo proximal y un extremo dist
