Graft dimpling to improve crimp profile and reduce delivery forces
A stent-graft assembly is provided for a variety of medical treatments. The stent-graft assembly includes a stent disposed to and attached between an inner layer of graft material and an outer layer of graft material. One of both of the graft layers includes one or more of a depression, dimple or detent that increases the localized surface area of the graft in one or more portions of the stent otherwise susceptible to graft stretching in the absence of the depression, dimple or detent. There is also described a method of forming dimples in selective locations on one or port graft layers in one or more locations relative to a portion of the stent where a portion of the graft may be susceptible to stretching or tearing during crimping or loading operations.
1. A stent graft assembly, comprising:
a stent structure comprising a luminal surface and an abluminal surface and having at least a first radial opening and a second radial opening, said first and second radial openings extending through said stent structure between said luminal surface and said abluminal surface, wherein said first and second radial openings are spaced apart along a first direction;
a first graft layer having a first thickness disposed along and covering said luminal surface of said stent structure;
a second graft layer having a second thickness disposed along and covering a portion of said abluminal surface of said stent structure; and
one or more dimples formed in the first graft layer and the second graft layer of localized plastically deformed material within radial openings along the first direction, and within the localized plastically deformed material a thickness of the first graft layer is less than the first thickness and a thickness of the second graft layer is less than the second thickness.
2. The stent graft assembly of claim 1 wherein the one or more dimples are formed so as to from a protrusion in a portion of the first graft layer.
3. The stent graft assembly of claim 1 wherein the one or more dimples are formed so as to form a protrusion in a portion of the second graft layer.
4. The stent graft assembly of claim 1 wherein the localized plastically deformed material is positioned relative to the radial openings to accommodate localized stretching of the first and second graft layer when the stent structure is crimped into a stowed configuration.
5. The device of claim 1 wherein the stent graft assembly is adapted and configured for use in clinical applications within lumens of the venous and arterial vasculature including those of the organs and limbs.
6. The device of claim 1 wherein a depth of the one or more dimples is less than 75 microns.
7. The device of claim 1 wherein the first direction is along a longitudinal axis of the stent structure.
8. The device of claim 1 wherein the first direction is along an angled portion of a stent pattern in the stent structure.
9. A stent graft assembly, comprising:
a stent structure having a patterned arrangement of one or more bridges, one or more apexes formed from one or more struts the stent structure having a luminal surface and an abluminal surface and having at least a first radial opening and a second radial opening, said first and second radial openings extending through said stent structure between said luminal surface and said abluminal surface, wherein said first and second radial openings are spaced apart along a first direction;
a graft layer having a thickness disposed along and covering said luminal surface or said abluminal surface of said stent structure; and
one or more dimples formed in the graft layer within the first radial opening and the second radial opening in a pre-selected pattern providing preferential stretching of the graft layer with respect to the patterned arrangement of one or more bridges and one or more apexes, and a thickness of the graft layer where the one or more dimples are formed is less than the graft layer thickness.
10. The stent graft assembly of claim 9 wherein the one or more dimples are formed so as to form a protrusion in a portion of the graft layer.
11. The stent graft assembly of claim 9 wherein the one or more dimples extend from the luminal surface or the abluminal surface of the graft into less than 50% of the thickness of the graft.
12. The stent graft assembly of claim 9 wherein the pre-selected pattern provides localized additional material selected to accommodate localized stretching of the graft layer with respect to the patterned arrangement of one or more bridges and one or more apexes when the stent structure is crimped into a stowed configuration.
13. The stent graft assembly of claim 9 wherein the pre-selected pattern provides localized additional material selected to accommodate localized stretching of the graft layer with respect to the patterned arrangement of one or more struts when the stent structure is crimped into a stowed configuration.
14. The device of claim 9 wherein the one or more dimples formed in a portion of the graft layer has a dimple depth into the graft layer that is selected so that no portion of the dimple forming tool pierces or perforates or induces a weakness resulting in localized failure in proximity to a dimple or dimple zone.
15. A stent graft assembly, comprising:
a stent structure having an patterned arrangement of a plurality of struts arranged into one or more bridges, one or more apexes formed from the plurality of struts the stent structure having a luminal surface and an abluminal surface and having at least a first radial opening and a second radial opening, said first and second radial openings extending through said stent structure between said luminal surface and said abluminal surface, wherein said first and second radial openings are spaced apart along a first direction;
an encapsulating graft layer having a thickness disposed along and covering said luminal surface or said abluminal surface of said stent structure; and
one or more dimples formed in the encapsulating graft layer surrounded by radial openings in a pre-selected pattern of plastic deformation within the graft layer with respect to the stent structure for inducing, providing or enabling folding or deflection of the encapsulating graft material during crimping in those zones of the stent structure having the pre-selected pattern, and a thickness of the graft layer having the one or more dimples is less than the thickness of the encapsulating graft layer.
16. A stent graft assembly of claim 15 the encapsulating graft layer comprising a first graft layer and a second graft layer.