Vascular filter with sleeve

An implantable medical device for therapeutic treatment of a patient, comprising:

• a filter having first and second tubular ends, and a central expandable portion extending between the ends to define a longitudinal axis;
• the central portion tending to resiliently expand in radially outward directions from a compressed initial shape to an expanded deployed shape;
• the filter having proximal and distal ends that are identical and symmetrical;
• wherein the filter defines first and second filtering elements in the expanded shape, the first and second filtering elements each being near the first and second tubular ends, respectively;
• the filter having a central section formed from a plurality of longitudinally oriented rectilinear ribs arranged parallel to the longitudinal axis, the ribs being connected between the first and second filtering elements to enclose a space and form a structure having a longitudinally symmetrical shape, each rib having first and second ends;
• the ribs configured to expand in radially outward directions when the filter expands from the compressed shape to the expanded shape, thereby causing the first and second tubular ends to move toward each other and;
• the filter having a retrieval hook affixed to the first tubular end, for optionally retrieving the filter after implantation to treat a patient;
• the filter having at least one anchor for enhancing position retention, the at least one anchor attached to and extending from the first or second end of at least one of the plurality of ribs;
• and
• a flexible sleeve encircling the plurality of ribs around the longitudinal axis without being penetrated by the at least one anchor, the flexible sleeve being configured so it only covers the central section;
• the sleeve defining a surface area;
• the sleeve configured to expand with the filter central portion to an expanded shape in which the sleeve represents a cylindrical surface for contracting a blood vessel wall, the central section, first and second filtering elements and flexible sleeve forming the filter having a longitudinally symmetrical shape to allow bi-directional filtering.