Helical and segmented stent-graft
The stent-graft described herein generally includes a substrate, a helix disposed about the substrate, a covering disposed over at least a portion of the helix, and a support member coupled to the covering.
1. An implantable prosthesis, comprising:
a generally tubular substrate;
a helix disposed over an outer surface of the substrate along a longitudinal axis, the helix having a first thickness;
a covering separate from the tubular substrate disposed over at least a portion of the helix; and
a support member coupled to an outer surface of the covering, the support member having a second thickness greater than the first thickness and overlapping at least a portion of the helix.
2. The implantable prosthesis according to claim 1 , wherein the helix comprises a continuous member helically disposed along a longitudinal axis from a first end to a second end to define a plurality of spaced apparat helical windings that are not interconnected.
3. The implantable prosthesis according to claim 2 , wherein a space between helical windings at the first end and the second end is different from a space between helical windings along a mid-region of the generally tubular substrate when the implantable prosthesis is in a relaxed condition.
4. The implantable prosthesis according to claim 1 , wherein the generally tubular substrate and covering comprise ePTFE.
5. The implantable prosthesis according to claim 4 , wherein the covering is an elongate strip of material arranged helically over the helix.
6. The implantable prosthesis according to claim 5 , wherein the helix is disposed about the generally tubular substrate at a first angle with respect to the longitudinal axis and the elongate strip of material is disposed about the helix at a second angle with respect to the longitudinal axis different from the first angle.
7. The implantable prosthesis according to claim 4 , wherein the covering comprises a plurality of annular rings, which are not interconnected, spaced apart along the longitudinal axis.
8. The implantable prosthesis according to claim 7 , further comprising at least one elongate strip of ePTFE material arranged generally parallel to the longitudinal axis.
9. The implantable prosthesis according to claim 1 , wherein the covering comprises ultra high molecular weight polyethylene fibers woven or knitted into a network of cells and links.
10. The implantable prosthesis according to claim 9 , wherein the network of cells and links includes a central opening defining a hexagonal shape.
11. The implantable prosthesis according to claim 9 , wherein the network of cells are arranged along the longitudinal axis in a first row and a second row spaced circumferentially approximately 180 degrees from the first row.
12. The implantable prosthesis according to claim 11 , wherein adjacent cells along the first row are connected by a longitudinal link and adjacent cells along the second row are connected by a longitudinal link.
13. The implantable prosthesis according to claim 12 , wherein the first row cells are connected to the second row cells at approximately the same axial position along the longitudinal axis by a first circumferential link and a second circumferential link spaced approximately 180 degrees from the first circumferential link.
14. The implantable prosthesis according to claim 13 , wherein the first and second circumferential links are rotated approximately 90 degrees with respect to the longitudinal links.
15. The implantable prosthesis according to claim 1 , further comprising a polymeric adhesive disposed over at least a portion of the helix and a tetrahydrofuran (THF) solvent disposed over at least a portion of the covering.
16. The implantable prosthesis according to claim 1 , wherein the first thickness is in a range of about 50 microns to about 1000 microns, and wherein the second thickness is in a range of about 0.5 mm to about 2.0 mm.
17. The implantable prosthesis according to claim 1 , wherein the support member is disposed substantially coincident with the outer surface of the covering.
18. The implantable prosthesis according to claim 1 , wherein the support member is disposed substantially coincident with the covering outer surface.
19. A stent-graft, comprising:
a helix disposed over an outer surface of a substrate, a material of the helix having a first stiffness;
a covering separate from the substrate and disposed over at least a portion of the helix; and
a support member coupled to the covering, a material of the support member having a second stiffness greater than the first stiffness and overlapping at least a portion of the helix.
20. A stent-graft, comprising:
a self-expanding helix disposed over an outer surface of an ePTFE substrate;
a covering separate from the ePTFE substrate and disposed over at least a portion of the helix; and
a plurality of spaced apart expandable segments coupled to the covering and overlapping at least a portion of the helix.