Occlusion element to occlude a passage in a circulatory system, the occlusion element comprising at least one occlusion body (4, 5) to occlude the passage, an expansion unit (1) comprising at least one fixing structure for fixing the occlusion body within the passage, in which at least a part of the expansion unit (1) expands within said fixing surface, thereby expanding the occlusion body and a blocking unit (2, 3) to block the expansion unit (1) in its expanded state, the expansion unit (2, 3) having a first element and a second element, in which the first and second elements of the blocking unit (2, 3) they can be brought into locking coupling with each other when the occlusion body (4, 5) expands, in which the expansion unit (1) comprises a plurality of elongated members (1) with first and second ends each , in which the first end of each member to argado (1) is fixed to the first element of the blocking unit (2, 3) and the second end of each elongated member (1) is fixed to the second element of the blocking unit (2, 3), in which the elongated members (1) can be twisted to form the at least one fixing structure, in which the at least one occlusion body (4, 5) is a flexible sheet and in which the at least one occlusion body (4 , 5) comprises holes that are penetrated by the elongate members (1), characterized in that the occlusion element comprises a sleeve (6, 7) that envelops at least a part of said expansion unit.Elemento de oclusión para ocluir un paso en un sistema circulatorio, comprendiendo el elemento de oclusión al menos un cuerpo de oclusión (4, 5) para ocluir el paso, una unidad de expansión (1) que comprende al menos una estructura de fijación para fijar el cuerpo de oclusión dentro del paso, en el que al menos una parte de la unidad de expansión (1) se expande dentro de dicha superficie de fijación, expandiendo de esta manera el cuerpo de oclusión y una unidad de bloqueo (2, 3) para bloquear la unidad de expansión (1) en su estado expandido, teniend
