An implant designed to be placed in a blood circulation passage, and to be fastened on a tissue, and comprising: - a proximal sleeve, generally tubular around a central axis, extending longitudinally between a proximal end and a distal end, the proximal sleeve being deployable between a contracted configuration and a deployed configuration, - a plurality of proximal arms, each extending between a first end connected to the distal end of the proximal sleeve, and a second free end designed to bear on a first face of the tissue, each proximal arm extending in the direction of the central axis such that its free end is positioned beyond the distal end of the proximal sleeve, - a distal sleeve, with a generally tubular shape around the central axis, deployable between a contracted configuration and a deployed configuration, designed to be assembled with the proximal sleeve to form a tubular armature together, that armature defining an internal blood circulation conduit when the proximal sleeve and the distal sleeve are assembled and each in the deployed configuration, - a plurality of distal arms, supported by the distal sleeve, and extending substantially perpendicular to the central axis in the deployed configuration, designed to bear on a second face of the tissue, such that the tissue is then pinched between the proximal arms and the distal arms, characterized in that: - at least one proximal arm is elastically deformable, between a separating position and an anchoring position, such that, when there is no outside bias, the radial distance between its free end and its connected end is larger in the separated position rather than in the anchoring position, this proximal arm being elastically returned toward its anchoring position, - the implant includes means for maintaining said at least one deformable proximal arm in its separating position, comprising: • a first stop, supported by that proximal arm, and • a second stop, designed to cooperate with the first stop when the proximal sleeve is in the contracted configuration to keep that proximal arm in its separating position, and to release that first stop when the proximal sleeve is in the deployed configuration to allow the proximal arm to move toward its anchoring position. - a proximal sleeve, generally tubular around a central axis, extending longitudinally between a proximal end and a distal end, the proximal sleeve being deployable between a contracted configuration and a deployed configuration, - a plurality of proximal arms, each extending between a first end connected to the distal end of the proximal sleeve, and a second free end designed to bear on a first face of the tissue, each proximal arm extending in the direction of the central axis such that its free end is positioned beyond the distal end of the proximal sleeve, - a distal sleeve, with a generally tubular shape around the central axis, deployable between a contracted configuration and a deployed configuration, designed to be assembled with the proximal sleeve to form a tubular armature together, that armature defining an internal blood circulation conduit when the proximal sleeve and the distal sleeve are assembled and each in the deployed configuration, - a plurality of distal arms, supported by the distal sleeve, and extending substantially perpendicular to the central axis in the deployed configuration, designed to bear on a second face of the tissue, such that the tissue is then pinched between the proximal arms and the distal arms, - at least one proximal arm is elastically deformable, between a separating position and an anchoring position, such that, when there is no outside bias, the radial distance between its free end and its connected end is larger in the separated position rather than in the anchoring position, this proximal arm being elastically returned toward its anchoring position, - the implant includes means for maintaining said at least one deformable proximal arm in its separating position, comprising: • a first stop, supported by that proximal arm, and • a second stop, designed to cooperate with the first stop when the proximal sleeve is in the contracted configuration to keep that proximal arm in its separating position, and to release that first stop when the proximal sleeve is in the deployed configuration to allow the proximal arm to move toward its anchoring position. • a first stop, supported by that proximal arm, and • a second stop, designed to cooperate with the first stop when the proximal sleeve is in the contracted configuration to keep that proximal arm in its separating position, and to release that first stop when the proximal sleeve is in the deployed configuration to allow the proximal arm to move toward its anchoring position.