An implantable device for positioning about a blood vessel bifurcation zone to control flow of embolic material around said bifurcation. The device comprises an anchoring element extending within said zone of bifurcation to anchor said device therein, and a deflecting element, associated with said anchoring element, said deflecting element comprising a mesh having a mesh size sufficient to allow passage of blood without hindrance while occluding passage of embolic material exceeding a predetermined size.