Biodegradable endoprostheses and methods of their fabrication
Inventors
Assignees
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Publication Number
US-9855156-B2
Publication Date
2018-01-02
Expiration Date
Abstract
A biodegradable stent prosthesis formed from a degradable material, having a plurality of luminal, abluminal, and side surface regions, wherein a surface portion extending between the abluminal and luminal surface region of at least some structural elements is convex.
Core Innovation
The invention provides a biodegradable polymeric expandable stent prosthesis comprising structural elements formed by struts joined by crowns. At least some structural elements comprise convex abluminal surface regions and substantially flat or substantially concave luminal surface regions, optionally including a concave section located about midway between the side surfaces. The prosthesis expands from a crimped configuration to an expanded configuration possessing sufficient strength to support a body lumen.
A patterned tubular body forms the stent and undergoes treatment to shape structural elements while retaining substantially unchanged stent weight before and after treatment. In certain embodiments, a coating substantially contours to and maintains the convex abluminal shape of the structural elements. Disclosed structural modifications provide improved radial strength, trackability, stent retention, vessel-wall apposition, and directional drug delivery. The problem being solved is not explicitly described in patent.
Claims Coverage
The claims identify four independent claims covering four inventive features directed to biodegradable expandable stents with defined strut and crown surface geometries, treatment-shaped structural elements, abluminal concave contours, and conforming coatings.
Convex abluminal and flat or concave luminal surfaces
A biodegradable stent prosthesis comprising polymeric material has struts joined by crowns, wherein at least some structural elements have convex abluminal surface regions and substantially flat or substantially concave luminal surface regions in the absence of a coating. The prosthesis expands from a crimped configuration to an expanded configuration having sufficient strength to support a body lumen.
Treated structural elements with substantially unchanged weight
A biodegradable polymeric stent prosthesis is formed from a tubular body patterned into a stent, with structural elements treated to have convex abluminal surface regions and substantially flat or substantially concave luminal surface regions. The stent weight before and after treatment is substantially the same, and the expanded stent has sufficient strength to support a body lumen.
Concave section in the convex abluminal surface
A biodegradable polymeric stent prosthesis comprises structural elements with convex abluminal and substantially flat or concave luminal surface regions, wherein the convex abluminal surface includes a concave section located about midway between side surfaces. The side surfaces extend between the abluminal and luminal surface regions in a continuous convex curve or substantially flat contour, and the stent has sufficient strength to support a body lumen.
Coating that maintains the convex abluminal shape
A biodegradable polymeric stent comprises structural elements with convex abluminal and substantially flat or substantially concave luminal surface regions, and includes a coating that substantially contours to and substantially maintains the convex shape of the abluminal surface regions.
Together, the claims define four inventive features comprising defined convex abluminal and flat or concave luminal surface geometries, treated structural elements that maintain substantially unchanged weight, specific concave abluminal and side-surface contours, and coatings that maintain the convex abluminal shape to support a body lumen.
Stated Advantages
The disclosed geometries can improve radial strength, trackability, stent retention, and vessel-wall apposition.
The disclosed geometries can support directional drug delivery.
Heat treatment is reported to increase radial strength by 15–50% in examples.
Solvent treatment is reported to redistribute polymer with less than 1% mass change, produce up to 43% greater strut thickness, and improve trackability, with a reported maximum push force of 0.89 N versus 0.81 N.
The stent prosthesis has sufficient strength in the expanded configuration to support a body lumen.
Documented Applications
The expandable biodegradable stent prosthesis is configured to support a body lumen in its expanded configuration.
The disclosed stent geometry and coating are described for directional drug delivery.
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