An implantable permanent filter assembly (1) suitable for deployment in a multifurcated vessel dividing a main vessel into at least two branches, wherein said assembly comprises:
- a) a filtering sleeve (2) which is self-expandable from a radially compressed state defining a delivery configuration to a radially expanded state defining a fully expanded configuration;
- said filtering sleeve comprising, a lumen (21) defined by a wall and extending from a proximal end (2p) to a distal end (2d) of the filtering sleeve, wherein the distal end is configured to extend in one of the at least two branches and the proximal end is configured to extend in the main vessel;
- said wall having a thickness (T2) and made of a braided framework comprising a plurality of wires (25) which are biocompatible and have a diameter (ø25) of at least 20 μm and at most 100 μm;
- the braided framework comprising a lattice of polygonal openings (26) formed by the braided wires;
- said polygonal openings, when observed normal with respect to a wall of the filtering sleeve in the fully expanded configuration, being characterized by an inscribed circle (27) having a mean diameter (ø27) of at least 50 μm and at most 200 μm;
- and a surface coverage ratio (SCR) of said braided framework being more than 40% and less than 90% in the fully expanded configuration;
- and
- b) an expandable main body component (3) formed of a braiding with a plurality of filaments and devoid of any cover layer, the expandable main body component (3) able to expand from a radially compressed state defining a delivery configuration to a radially expanded state defining a fully expanded configuration, the expandable main body component (3) comprising:
- a concaved portion (302) comprising a double-barrelled portion (303) toward a proximal end of the expandable main body component (3);
- middle lines of the concave portion being concave along a longitudinal axis of the expandable main body component (3) and defining two opposing ridges (304) within an interior of the concaved portion (302), each ridge (304) partially contacting the other ridge (304), the two opposing ridges (304) defining:
- a first and second lumens (305) in the double-barrelled portion (303), each of the two lumens (305) extending along an axis;
- and
- c) an extension sleeve (4) which is expandable and comprising:
- a lumen defined by a wall and extending from a proximal end (4p) to a distal end (4d) of the extension sleeve;
- and
- a tip portion (401) able to be inserted into the first lumen of the double-barrelled portion (303),
- characterised in that:
- the braided framework of the filtering sleeve (2) is formed of an interlocked multilayer braiding having a three dimensional structure;
- a ratio (T2/ø25) of the thickness (T2) of the wall of the filtering sleeve (2) to the diameter (ø25) of the wires (25) is at least 3;
- and
- a proximal end diameter (ø2p) of the filtering sleeve (2) is equal to or greater than a maximum diameter (ø3_max) defined as a largest diameter of the expandable main body component (3) in a fully expanded state.