Polymeric endoprosthesis and method of manufacture

Abstract

Improved polymeric endoprostheses and methods of making endoprostheses are disclosed. Said endoprostheses exhibit improved overall compliance, selective regional compliance, and selective radial strength without varying the geometries of selected regions. Numerous other physical characteristics of said endoprostheses may be selectively varied during manufacture. Some embodiments may comprise one or more erodible material. Some embodiments may comprise one or more therapeutics incorporated into said endoprosthesis via a solvent in a supercritical state.

We claim:  
     
         1 . An endoprosthesis comprising one or more erodible materials, a first region and a second region, wherein said first region comprises a first degree of overall compliance and said second region comprises a second degree of overall compliance, wherein said first degree of overall compliance is greater than said second degree, whereby when said endoprosthesis is disposed within a body lumen comprising walls comprising irregular morphology, said first region is substantially compliant with said walls.  
     
     
         2 . The endoprosthesis of  claim 1  wherein said endoprosthesis comprises a first end and a second end, and wherein said first region is proximate said first end.  
     
     
         3 . The endoprosthesis of  claim 1 , wherein said endoprosthesis comprises an endoprosthesis element and a lumen defined therethrough, wherein said endoprosthesis element comprises a cross section in said first region and in said second region, and wherein said cross section in said first region is substantially similar to said cross section in said second region.  
     
     
         4 . The endoprosthesis of  claim 1  wherein said endoprosthesis comprises a plurality of endoprosthesis elements and a lumen defined therethrough, wherein said endoprosthesis elements comprise linear dimensions in said first region and in said second region, and wherein said linear dimensions of said first region are substantially similar to said linear dimensions of said second region.  
     
     
         5 . An endoprosthesis comprising one or more erodible materials, a first region and a second region, wherein said first region comprises a first degree of radial conformability and said second region comprises a second degree of radial conformability, wherein said first degree of radial conformability is greater than said second degree of radial conformability.  
     
     
         6 . The endoprosthesis of  claim 5  wherein said endoprosthesis comprises a first end and a second end, and wherein said first region is proximate said first end.  
     
     
         7 . The endoprosthesis of  claim 5  wherein said endoprosthesis comprises an endoprosthesis element and a lumen defined therethrough, wherein said endoprosthesis element comprises a cross section in said first region and in said second region, and wherein said cross section in said first region is substantially similar to said cross section in said second region.  
     
     
         8 . The endoprosthesis of  claim 5  wherein said endoprosthesis comprises a plurality of endoprosthesis elements and a lumen defined therethrough, wherein said endoprosthesis elements comprise linear dimensions in said first region and in said second region, and wherein said linear dimensions of said first region are substantially similar to said linear dimensions of said second region.  
     
     
         9 . The endoprosthesis of  claim 5  wherein said endoprosthesis further comprises one or more connecting members, and said first region is proximate said one or more connecting members.  
     
     
         10 . An endoprosthesis comprising one or more erodible materials, a first region and a second region, wherein said first region comprises a first outward radial force and said second region comprises a second outward radial force, wherein said second outward radial is greater than said first outward radial force.  
     
     
         11 . The endoprosthesis of  claim 10  wherein said endoprosthesis comprises a first end and a second end, and wherein said first region is proximate said first end.  
     
     
         12 . The endoprosthesis of  claim 10  wherein said endoprosthesis comprises an endoprosthesis element and a lumen defined therethrough, wherein said endoprosthesis element comprises a cross section in said first region and in said second region, and wherein said cross section in said first region is substantially similar to said cross section in said second region.  
     
     
         13 . The endoprosthesis of  claim 10  wherein said endoprosthesis comprises a plurality of endoprosthesis elements and a lumen defined theretbrough, wherein said endoprosthesis elements comprise linear dimensions in said first region and in said second region, and wherein said linear dimensions of said first region are substantially similar to said linear dimensions of said second region.  
     
     
         14 . The endoprosthesis of  claim 10  wherein said endoprosthesis further comprises one or more connecting members, and said first region is proximate said one or more connecting members.  
     
     
         15 . An endoprosthesis comprising one or more erodible materials, a first region and a second region, wherein said first region comprises a first axial flexibility and said second region comprises a second axial flexibility, wherein said first axial flexibility is greater than said second axial flexibility.  
     
     
         16 . The endoprosthesis of  claim 15  wherein said endoprosthesis comprises a first end and a second end, and wherein said first region is proximate said first end.  
     
     
         17 . The endoprosthesis of  claim 15  wherein said endoprosthesis comprises an endoprosthesis member and a lumen defined therethrough, wherein said endoprosthesis member comprises a cross section in said first region and in said second region, and wherein said cross section in said first region is substantially similar to said cross section in said second region.  
     
     
         18 . The endoprosthesis of  claim 15  wherein said endoprosthesis comprises a plurality of endoprosthesis elements and a lumen therethrough, wherein said endoprosthesis elements comprise linear dimensions in said first region and in said second region, and wherein said linear dimensions of said first region are substantially similar to said linear dimensions of said second region.  
     
     
         19 . An endoprosthesis comprising at least one erodible polymer, a first region and a second region, wherein said at least one erodible polymer comprises a first density in said first region and a second density in said second region that is greater than said first density.  
     
     
         20 . The endoprosthesis of  claim 19  wherein said endoprosthesis comprises a first end and a second end, and wherein said first region is proximate said first end.  
     
     
         21 . The endoprosthesis of  claim 19  wherein said endoprosthesis further comprises one or more connecting members, and said first region is proximate said one or more connecting members.  
     
     
         22 . An endoprosthesis comprising a first region and a second region, wherein said first region comprises a first diffusion coefficient and said second region comprises a second diffusion coefficient that is greater than said first diffusion coefficient.  
     
     
         23 . The endoprosthesis of  claim 22  wherein said endoprosthesis comprises a luminal surface and a vascular surface, and said first region is disposed on said luminal surface, and said second region is disposed on said vascular surface.  
     
     
         24 . An endoprosthesis comprising one or more polymeric materials, a first and a second region, wherein said one or more polymeric materials comprise a first degree of crystallinity in said first region and a second degree of crystallinity in said second region that is greater than the first degree of crystallinity.  
     
     
         25 . The endoprosthesis of  claim 24  wherein said endoprosthesis further comprises one or more connecting members, and said first region is proximate said one or more connecting members.  
     
     
         26 . An endoprosthesis comprising one or more erodible materials and one or more endoprosthesis elements, wherein said one or more endoprosthesis elements comprises a trapezoidal cross-section.  
     
     
         27 . The endoprosthesis of  claim 26  wherein said endoprosthesis comprises a vascular surface area, and said surface area is 10% or more greater than the surface area of an endoprosthesis comprising equivalent non-trapezoidal endoprosthesis elements.  
     
     
         28 . An expandable endoprosthesis comprising one or more endoprosthesis elements, said endoprosthesis elements comprising a plurality of apices alternating with a plurality of straight sections, said apices comprising a first width and said straight sections comprising a second width, wherein the second width is greater than said first width.  
     
     
         29 . The endoprosthesis of  claim 28  wherein upon expansion, said endoprosthesis elements bend preferentially at said apices.  
     
     
         30 . The endoprosthesis of  claim 29  wherein following expansion, said apices comprise an angle of between 40 and 65 degrees.  
     
     
         31 . The endoprosthesis of  claim 30  wherein said endoprosthesis comprises a first material, wherein said first material undergoes strain induced crystallization upon expansion.  
     
     
         32 . An expandable endoprosthesis comprising means for limiting expansion of said endoprosthesis.  
     
     
         33 . The endoprosthesis of  claim 32  wherein said endoprosthesis comprises an endoprosthesis element comprising a plurality of apices, said apices comprising one or more stop portions, wherein said stop portions are separate from one another prior to expansion, and abut one another upon expansion of said endoprosthesis.  
     
     
         34 . The endoprosthesis of  claim 32  comprising one or more stop elements, wherein said one or more stop elements comprise a curved configuration prior to expansion and a linear configuration following expansion, wherein said linear configuration prevents the further expansion of said endoprosthesis.  
     
     
         35 . An endoprosthesis comprising one or more erodible materials, wherein said endoprosthesis comprises one or more endoprosthesis elements and one or more reinforcing elements.  
     
     
         36 . The endoprosthesis of  claim 35  wherein said reinforcing elements comprise a biocompatibly corrosive metal.  
     
     
         37 . The endoprosthesis of  claim 35  wherein said reinforcing element is encapsulated by said one or more endoprosthesis elements.  
     
     
         38 . The endoprosthesis of  claim 35  wherein said endoprosthesis comprises a luminal surface and a vascular surface, and wherein said reinforcing element is disposed on said luminal surface.  
     
     
         39 . The endoprosthesis of  claim 35  wherein said reinforcing element encapsulates said one or more endoprosthesis elements.  
     
     
         40 . An expandable endoprosthesis comprising poly-lactic acid and polycaprolactone in a ratio of between 80:20 and 95:5.  
     
     
         41 . The endoprosthesis of  claim 40  wherein said endoprosthesis is annealed at a temperature of between 50 and 200 degrees C. for a duration of between one half and 24 hours.  
     
     
         42 . The endoprosthesis of  claim 41  wherein said endoprosthesis undergoes strain induced crystallization upon expansion.  
     
     
         43 . The endoprosthesis of  claim 42  wherein said endoprosthesis comprises an endoprosthesis element comprising a plurality of apices alternating with a plurality of straight sections wherein said endoprosthesis undergoes strain induced crystallization upon expansion proximate the apices.  
     
     
         44 . The endoprosthesis of  claim 43  wherein said apices define an included angle between straight sections comprise of between 40 and 90 degrees following expansion of the endoprosthesis.  
     
     
         45 . An endoprosthesis comprising one or more polymeric materials that undergo plastic deformation between 3 and 20 ksi.  
     
     
         46 . The endoprosthesis according to  claim 45  wherein said one or more polymeric materials continues to strengthen following plastic deformation until the point of material failure.  
     
     
         47 . The endoprosthesis of  claim 1  further comprising one or more therapeutic substances incorporated into the endoprosthesis using a solvent in a supercritical state.  
     
     
         48 . The endoprosthesis of  claim 47  wherein said endoprosthesis is formed from one or more curable materials using a first set of first set of parameters to achieve said first set of physical properties and using a second set of parameters to achieve said second set of physical properties.  
     
     
         49 . A method of manufacture of an endoprosthesis comprising: 
 providing a mold;    placing a first material into said mold;    placing a second material into said mold;    apply heat and pressure to mold to form film;    removing said film from said mold; and    forming a cylinder from said film to define said endoprosthesis.    
     
     
         50 . The method of  claim 49  wherein said mold comprises a first region and a second region, and wherein said first material is placed in said first region and said second material is placed in said second region.  
     
     
         51 . The method of  claim 50  wherein said first material comprises a first set of properties and said second material comprises a second set of properties.  
     
     
         52 . The method of  claim 51  wherein said properties comprise material density, modulus of elasticity, rate of erosion, extensibility, compressibility, mechanical strength, tensile strength, degree of crystallinity, diffusion coefficient, and permeability.  
     
     
         53 . A method of manufacture of an endoprosthesis comprising the steps of: 
 coextruding a first material and a second material to form a generally tubular structure; and    selectively removing portions of said first material from said tube.    
     
     
         54 . The method of  claim 53  comprising the additional step of selectively removing portions of said second material.  
     
     
         55 . The method of  claim 54  wherein said first material comprises a first set of properties and said second material comprises a second set of properties.  
     
     
         56 . The method of  claim 55  wherein said properties comprise material density, modulus of elasticity, rate of erosion, extensibility, compressibility, mechanical strength, tensile strength, degree of crystallinity, diffusion coefficient, and permeability.  
     
     
         57 . The method of  claim 49  wherein the method further comprises the step of immersing said endoprosthesis and a hydrophilic therapeutic agent in water beneath a blanket of carbon dioxide in its supercritical state, whereby said hydrophilic therapeutic agent is incorporated into said endoprosthesis.  
     
     
         58 . The method of  claim 49  wherein the method further comprises the step of immersing said endoprosthesis and a hydrophobic therapeutic agent in carbon dioxide in its supercritical state, whereby said hydrophobic therapeutic agent is incorporated into said endoprosthesis.  
     
     
         59 . The method of  claim 53  wherein the method further comprises the step of immersing said endoprosthesis and a hydrophilic therapeutic agent in water beneath a blanket of carbon dioxide in its supercritical state, whereby said hydrophilic therapeutic agent is incorporated into said endoprosthesis.  
     
     
         60 . The method of  claim 53  wherein the method further comprises the step of immersing said endoprosthesis and a hydrophobic therapeutic agent in carbon dioxide in its supercritical state, whereby said hydrophobic therapeutic agent is incorporated into said endoprosthesis.