Long-term retrievable medical filter

Abstract

A medical filter has more than one pair of struts extending along an undulating path between a first and second end, which cooperate to define a first and second filter element having a plurality of cells, connected by a central portion with longitudinal strut sections. The struts extend between the first and second ends, and the struts tend to resiliently expand in radially outward directions from a compressed initial shape to an expanded deployed shape. In the expanded shape, the undulating path is defined by (i) a first portion of each pair of ribs extends substantially adjacent to each other for a distance from the first end, (ii) a second portion of each pair of ribs extends substantially adjacent to each other for a distance from the second end; and (iii) an intermediate portion of each one of a pair of ribs extends to curve away from each other.

1 . A medical filter for therapeutic treatment of a patient, comprising: a first and second end defining a longitudinal axis; more than one pair of ribs extending between the first and second ends, the ribs tending to resiliently expand in radially outward directions from a compressed initial shape to an expanded deployed shape; wherein in the compressed initial shape, the ribs each follow a path substantially parallel to the longitudinal axis; wherein in the expanded deployed shape, the ribs each follow an undulating path, such that a first portion of each pair of ribs extends substantially adjacent to each other for a distance from the first end, and a second portion of each pair of ribs extends substantially adjacent to each other for a distance from the second end; and an intermediate portion of each one of a pair of ribs tends to curve away from each other in the expanded deployed shape; wherein in the expanded deployed shape, the filter defines a first and second filtering portion near the first and second end, respectively. 
     
     
         2 . The filter of  claim 1 , wherein in the expanded shape, the intermediate portion of each one of a pair of ribs tends to curve away from each other and touch one of another pair of ribs. 
     
     
         3 . The filter of  claim 1 , wherein in the expanded shape, a central portion of each rib tends to extend parallel to the longitudinal axis. 
     
     
         4 . The filter of  claim 1 , wherein the filter has at least three pairs of ribs. 
     
     
         5 . The filter of  claim 1 , wherein the filter has six pairs of ribs. 
     
     
         6 . The filter of  claim 1 , wherein the filter is made of nitinol. 
     
     
         7 . A method of making a medical filter for therapeutic treatment of a patient, comprising the steps of: a) providing a tubular form defining a longitudinal axis and having a first and second end; b) cutting more than one pair of struts in the tubular form, so as to define the struts extending between a first and second end of the filter; and c) treating the struts so that they tend to resiliently expand from a compressed shape to an expanded shape: by expanding a central portion of the struts in radially outward directions; such that a gap is defined between the pairs of struts, and the individual struts of each pair follow a path which is substantially adjacent to the other strut of that pair; and by bending a central portion of each of the ribs to follow an undulating path in the expanded shape, such that in the expanded shape a first portion of each pair of ribs extends substantially adjacent to each other for a distance from the first end, and a second portion of each pair of ribs extends substantially adjacent to each other for a distance from the second end; wherein an intermediate portion of each one of a pair of ribs is bent to curve away from each other in the expanded shape; wherein in the expanded deployed shape, the filter defines a first and second filtering portion near the first and second end, respectively.