Bioabsorbable self-expanding stent
First Claim
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1. A bioabsorbable implantable stent having a tubular, radially compressible and self-expandable braided and annealed structure comprising:
- a first set of between 5 and 18 filaments each of which extends in a helix configuration along a center line and having a first common direction of winding;
a second set of filaments of the same number as the first set, each of which extends in a helix configuration along the center line and having a second common direction of winding;
the second set of filaments crossing the first set of filaments at an axially directed angle of between about 120 and about 150 degrees when in a first free radially expanded state after being annealed but before being loaded on a delivery device so as to form a plurality of interstices between filaments, and further to determine an annealed diameter, D, of the stent in said first free radially expanded state;
each filament comprising at least one of poly-L-lactide, poly-D-lactide, polyglycolide and combinations thereof, and having a substantially solid and substantially uniform cross-section, a tensile strength of from about 40 ksi to about 120 ksi, a tensile modulus of from about 400,000 psi to about 2,000,000 psi, and an average diameter of from about 0.15 mm to about 0.6 mm;
wherein the first set of filaments and second set of filaments act upon one another to create an outwardly directed radial force sufficient to implant the stent in a body vessel upon deployment from the delivery device; and
wherein said radial force, when the stent is radially constrained to a predetermined fraction of the annealed diameter, varies substantially linearly as a function of the annealed diameter, whereby said annealed diameter, D, is selected to provide a desired radial force when the stent is so radially constrained.
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Abstract
A self-expanding stent formed from helically wound and braided filaments of bioabsorbable polymers such as PLA, PLLA, PDLA, and PGA.
589 Citations
39 Claims
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1. A bioabsorbable implantable stent having a tubular, radially compressible and self-expandable braided and annealed structure comprising:
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a first set of between 5 and 18 filaments each of which extends in a helix configuration along a center line and having a first common direction of winding;
a second set of filaments of the same number as the first set, each of which extends in a helix configuration along the center line and having a second common direction of winding;
the second set of filaments crossing the first set of filaments at an axially directed angle of between about 120 and about 150 degrees when in a first free radially expanded state after being annealed but before being loaded on a delivery device so as to form a plurality of interstices between filaments, and further to determine an annealed diameter, D, of the stent in said first free radially expanded state;
each filament comprising at least one of poly-L-lactide, poly-D-lactide, polyglycolide and combinations thereof, and having a substantially solid and substantially uniform cross-section, a tensile strength of from about 40 ksi to about 120 ksi, a tensile modulus of from about 400,000 psi to about 2,000,000 psi, and an average diameter of from about 0.15 mm to about 0.6 mm;
wherein the first set of filaments and second set of filaments act upon one another to create an outwardly directed radial force sufficient to implant the stent in a body vessel upon deployment from the delivery device; and
wherein said radial force, when the stent is radially constrained to a predetermined fraction of the annealed diameter, varies substantially linearly as a function of the annealed diameter, whereby said annealed diameter, D, is selected to provide a desired radial force when the stent is so radially constrained. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A bioabsorbable implantable endoprosthesis comprising:
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a first set of filaments each of which extends in a configuration about a center line and having a first common direction of winding;
a second set of filaments each of which extends in a configuration about the center line and having a second common direction of winding;
the second set of filaments crossing the first set of filaments at an axially directed angle of between about 120 and about 150 degrees when in a free radially expanded state after being annealed, to determine an annealed diameter, D, of the endoprosthesis in said free radially expanded state;
each filament comprising a bioabsorbable material having a tensile strength of from about 15 ksi to about 120 ksi, a tensile modulus of from about 200,000 psi to about 2,000,000 psi, and an average thickness of from about 0.15 mm to about 0.6 mm;
wherein the first set of filaments and second set of filaments act upon one another to create an outwardly directed radial force and the bioabsorbable implantable endoprosthesis is adapted to substantially degrade in less than about 3 years; and
wherein said radial force, when the endoprosthesis is radially constrained to a predetermined fraction of the annealed diameter, varies substantially linearly as a function of the annealed diameter, whereby the annealed diameter, D, is selected to provide a desired force when the endoprosthesis is so radially constrained. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33)
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34. A bioabsorbable implantable endoprosthesis, including:
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a first set of bioabsorbable filaments wound helically in a first common direction;
a second set of bioabsorbable filaments wound in a second common direction different than the first common direction, and cooperating with the first set of filaments to form a prosthesis structure in which the filaments of the first and second sets cross one another at an axially directed angle when in a free radially expanded state after being annealed, to determine an annealed diameter D of the prosthesis structure in the free radially expanded state; and
wherein the first set of filaments and the second set of filaments cooperate to provide an outwardly directed radial force when the prosthesis structure is radially constrained to a diameter less than the annealed diameter D, and wherein said radial force, when the prosthesis structure is radially constrained to a predetermined fraction of the annealed diameter, varies substantially linearly as a function of the annealed diameter, whereby the annealed diameter D is selectable to provide a desired radial force when the prosthesis structure is radially constrained to said predetermined fraction of the annealed diameter. - View Dependent Claims (35, 36, 37, 38, 39)
said axially directed angle is between about 120 degrees and about 150 degrees.
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36. The endoprosthesis of claim 34 wherein:
each of the filaments of the first and second sets has a tensile strength of from about 15 ksi to about 120 ksi, a tensile modulus of from about 200,000 psi to about 2,000,000 psi, and an average thickness of from about 0.15 mm to about 0.6 mm.
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37. The endoprosthesis of claim 34 wherein:
the prosthesis structure is radially constrained to about half of said annealed diameter D whereby the predetermined fraction is one-half, and the radial force RF exerted in grams, as a function of the annealed diamater D in mm, is defined by the equation RF=−
15D+491+20.
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38. The endoprosthesis of claim 34 wherein:
the filaments include at least one of polydioxanone, polycaprolactone, polygluconate, polylactic acid-polyethylene oxide copolymers, modified cellulose, collagen, poly(hydroxybutyrate), polyanhydride, polyphosphoester, poly(amino acids) and combinations thereof.
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39. Endoprosthesis of claim 34 wherein:
the first and second common directions of winding are opposite one another.
Specification