Stent construction of rolled configuration

Abstract

A stent for reinforcing a damaged wall in a body passage such as a vascular passage. The stent takes the form of a sheet or metal foil wound tightly around a spool in a multiple layer roll and held in a contracted state by a sheath sleeved around the roll. The spool is inserted into the body passage until the stent is adjacent to the area of the damaged wall. The spool and stent are then advanced while the sheath is held stationary. This pushes the stent out the end of the sheath and releases the stent such that the roll unwinds and expands against the damaged vessel wall.

We claim: 
     
       1. A stent assembly for placement in a body passage to reinforce a damaged wall in the passage, comprising: an elongated core;   an elongated, flexible sheet arranged on said core in a multiple layer roll having expanded and contracted conditions and having a spring force so that said sheet is urged toward the expanded condition, said roll being tightly wound on the core in the contracted condition and presenting in the expanded condition a diameter at least equal to the diameter of the body passage.   said roll being spirally wound on said core and having a tendency to radially expand, said roll presenting a plurality of adjacent, arcuate layers of said sheet in a direction transverse to the longitudinal axis of said core;   releasable means for retaining said roll in the contracted condition on said core while the core is being inserted into the passage to the location of the damaged walls; and   means for effecting release of said releasable means to permit the roll to expand against the damaged wall in the expanded condition of the roll,   said roll in the expanded condition thereof having at least two overlapping layers which overlap and bear against one another over a substantial portion of the circumference of . .a.!. .Iadd.an .Iaddend.inner layer, said expanded roll adapted for securely contacting said damaged wall by virtue of said radial expansion tendency.   
     
     
       2. The stent assembly of claim 1, including a first flange on said core against which one end of said roll is engaged in the contracted condition. 
     
     
       3. The stent assembly of claim 2, including a second flange on said core, said roll being retained between the first flange and said second flange in the contracted condition. 
     
     
       4. The stent assembly of claim 3, wherein said releasable means comprises a pair of control cords having slip knot connections with the respective first and second flanges arranged in a manner to retain the roll in the contracted condition, said slip knot connections being releasable upon pulling of said control cords to thereby release said roll for expansion thereof to the expanded condition. 
     
     
       5. The stent assembly of claim 4, wherein said core comprises a tubular spool having an axial passage therethrough for receiving a guide wire along which the spool may be guided to the location of the damaged wall. 
     
     
       6. The stent assembly of claim 1, wherein said core comprises a tubular spool having an axial passage therethrough for receiving a guide wire along which the spool may be guided to the location of the damaged wall. 
     
     
       7. The stent assembly of claim 1, wherein said sheet is constructed or a metal foil. 
     
     
       8. The stent assembly of claim 1, wherein said sheet is constructed or a stainless steel foil. 
     
     
       9. The stent assembly of claim 1, wherein said releasable means comprises a sheath closely sleeved on said roll, said sheath being movable axially relative to said core to release from the roll. 
     
     
       10. The stent assembly of claim 1, including: a second flexible sheet arranged on said core in a second multiple layer roll spaced from the first mentioned roll, said second roll having a contracted condition wherein the second roll is tightly wound on the core and an expanded condition wherein the second roll presents a diameter substantially equal to the diameter of the body passage, said second roll being urged toward the expanded condition;   releasable means for retaining said second roll in the contracted condition; and   means for effecting release of the releasable means for said second roll.   
     
     
       11. The stent assembly of claim 10, wherein the releasable means for the first and second rolls comprises a sheath closely sleeved on the first and second rolls said sheath being movable axially relative to said core to release from the first and second rolls in succession. 
     
     
       12. Apparatus for reinforcing a damaged wall of a body passage, comprising: an elongated core;   an elongated stent in the form of a flexible sheet spirally wound around the core in a multiple layer roll having contracted and expanded conditions, said sheet being wound tightly on the core in the contracted condition and having a spring force which tends to radially expand toward the expanded condition thereof wherein the sheet assumes a size to contact the damaged wall, and   said roll . .presenting.!. .Iadd.having .Iaddend.a plurality of adjacent, arcuate layers . .of said sheet in a direction transverse top the longitudinal axis of the core.!.;   a sheath fitting closely around said roll to hold the sheet in the contracted condition, said sheet being movable axially relative to the roll to permit the sheath to release from the roll and thereby allow expansion of the sheet against the damaged wall in the expanded condition,   said roll in the expanded condition thereof having at least two overlapping layers, which overlap and bear against one another over a substantial portion of the circumference of the inner layer, said expanded roll adapted for securely contracting said damaged wall by virtue of said radial expansion tendency of the roll.   
     
     
       13. Apparatus as set forth in claim 12, including a flange on said core against which one end of said roll is engaged in the contracted condition. 
     
     
       14. Apparatus as set forth in claim 12, wherein said core comprises a spool having an axial passage therethrough for receiving a guide wire along which the spool may be guided to the location of the damaged wall. 
     
     
       15. Apparatus as set forth in claim 12, wherein said sheet is constructed of a thin metal foil. 
     
     
       16. Apparatus as set forth in claim 12, wherein said sheet is constructed of a thin stainless steel foil. 
     
     
       17. Apparatus as set forth in claim 12, including second stent in the form of a second flexible sheet wound around said core in a second multiple layer roll having contracted and expanded conditions, said second sheet being wound tightly on the core in the contracted condition and being biased toward the expanded condition wherein said second sheet assumes a size to contact the passage wall, said sheath fitting closely on the second roll to hold the second sheet in the contracted condition and being movable axially to release from the second roll and thereby allow the second roll to expand against the wall in the expanded condition. .Iadd. 
     
     
       18.  A stent for placement in a body passage to support a stricture or reinforce a damaged wall in the passage, comprising: an elongated flexible sheet arranged in a multiple layer roll having expanded and contracted conditions and having a spring force, so that when said sheet is in said contracted condition, said spring force urges said sheet to expand toward the expanded condition, said roll presenting in the expanded condition a diameter at least equal to the diameter of the body passage;   said roll presenting in its contracted condition a plurality of adjacent, arcuate layers;   said roll being retained in the contracted condition during an insertion into said passage to the location of said damaged wall by a retaining structure adapted to be inserted into said body passage;   wherein upon release of said roll from said retaining structure at the location of said damaged wall, said spring force urges expansion of said roll into the expanded condition such that said roll contacts said damaged wall, said roll further having in the expanded condition a plurality of overlapping layers which overlap and bear against one another over a substantial portion of the circumference of an inner layer, said expanded roll further having sufficient structural integrity to effect reinforcement or support of said damaged wall. .Iaddend..Iadd.   
     
     
       19.  The stent assembly of claim 18, wherein said sheet is constructed of a metal foil. .Iaddend..Iadd.20. The stent assembly of claim 19, wherein said metal foil is stainless steel. .Iaddend..Iadd.21. The stent assembly of claim 19, wherein prior to insertion into the body passage, said metal foil roll has been heat treated while in said expanded condition to reduce internal stresses within said roll. .Iaddend..Iadd.22. The stent assembly of claim 18, wherein in said contracted condition, said roll has approximately, six or seven adjacent arcuate layers of said sheet. 
     
     
        .Iaddend..Iadd.23.  The stent assembly of claim 18, wherein said retaining structure comprises a sheath which closely overlaps said roll in its contracted condition, said sheath being movable axially with respect to said roll to effect ejection of said roll from said sheath. .Iaddend..Iadd.24. The stent assembly of claim 23, further comprising a flange slidably disposed within said overlapping sheath at a point proximal to said roll, said flange being adapted to provide a force on said roll to eject it from said sheath at a desired location within the 
     
     
        body. .Iaddend..Iadd.25.  A stent assembly for placement in a body vessel for treatment of a vessel abnormality, the stent assembly comprising: a flexible sheet arranged in a multiple layer roll having expanded and contracted conditions and having a spring force, so that when said sheet is in said contracted condition, said spring force urges said sheet to expand toward the expanded condition, said roll presenting in the expanded condition a diameter at least equal to the full diameter of the vessel;   said roll presenting in the contracted condition a plurality of adjacent, arcuate layers;   wherein when said contracted roll is introduced within said vessel at or near said abnormality and is not constrained so as to be maintained in its contracted condition said spring force will urge said stent into said expanded condition, said expanded condition having multiple layers of said sheet that bear against one another over a substantial portion of the circumference of an inner layer, said multiple layers having a frictional force which resists stent contraction thereby enhancing the structural integrity of said stent such that said stent is able to firmly contact the vessel wall to effect treatment of said abnormality. .Iaddend.