Post-implantation contractible or expandable devices and method of using and making the same
Devices and methods for the controlled over-expansion of a body conduit and controlled constriction or expansion of a vessel in a patient are disclosed. The devices and methods can employ a bio-corrodible expandable support structure and an implant coaxially adjacent the support structure. The support structure can have a delivery diameter and an expanded supporting diameter. The implant can have a collapsed deformed diameter, an undeformed neutral diameter and an over-expanded deformed diameter. Contraction of the implant can occur when the support structure is bioabsorbed.
1. A device comprising:
an expandable, bioabsorbable support structure, the support structure having a delivery diameter and configured to be plastically deformed to an expanded supporting diameter; and
an implant coaxially adjacent and secured to the support structure, the implant comprising a graft structure defining a lumen adapted to support fluid flow and a stent structure secured to the graft structure and adapted to provide support to the graft structure, the stent structure being self-expanding and non-bioabsorbable and the implant having a collapsed deformed diameter corresponding to the delivery diameter of the support structure, an undeformed neutral diameter and an over-expanded deformed diameter corresponding to the expanded supporting diameter of the support structure, the support structure configured to provide secondary support to maintain the implant at the over-expanded deformed diameter for a limited period of time, the support structure providing reducing secondary support over time as the support structure bioabsorbs, the stent structure of the implant tending to elastically return the implant to the undeformed neutral diameter from the over-expanded deformed diameter in an absence of the secondary support from the support structure as the support structure bioabsorbs,
the collapsed deformed diameter being less than the undeformed neutral diameter, the undeformed neutral diameter being less than the over-expanded deformed diameter and the over-expanded deformed diameter being approximately equal to the supporting diameter.
2. The device of claim 1 , wherein expansion of the expandable support structure from the collapsed delivery diameter to the expanded supporting diameter radially forces the expansion of the implant from the collapsed deformed diameter to the over-expanded deformed diameter.
3. The device of claim 1 , wherein a contraction of the implant from the over-expanded deformed diameter to the undeformed diameter occurs by at least one of bio-corrosion and structural breakdown of the support structure.
4. The device of claim 1 , wherein at least one of bio-corrosion and structural breakdown of the support structure results in a contraction of the implant from the over-expanded deformed diameter to the undeformed neutral diameter.
5. The device of claim 1 , wherein the support structure comprises a non-shape memory alloy.
6. The device of claim 1 , wherein at least one of the implant and the support structure comprises a bio-corrodible metal alloy comprising an iron alloy.
7. The device of claim 1 , wherein at least one of the implant and the support structure comprises a bio-corrodible metal alloy comprising an iron alloy having greater than at least one of about 50% iron, about 60% iron, about 70% iron, about 80% iron, about 90% iron, and about 95% iron.
8. The device of claim 1 , wherein at least one of the implant and the support structure comprises a bio-corrodible metal alloy comprising: from 0 to about 40% manganese; 0 to about 5% chromium; 0 to about 10% nickel; 0 to about 25% cobalt; 0 to about 1% aluminum; 0 to about 5% molybdenum; 0 to about 3% titanium; 0 to about 3% zirconium; 0 to about 1% carbon; 0 to about 1% silicon; 0 to about 3% niobium; 0 to about 1% nitrogen; and 0 to about 1% yttrium, with the remainder being iron.
9. The device of claim 1 , wherein the implant comprises a shape memory alloy.
10. The device of claim 1 , wherein the implant comprises a Ni—Ti alloy.
11. The device of claim 1 , wherein the implant comprises a bio-corrodible metal alloy.
12. The device of claim 1 , wherein the implant is balloon expandable.
13. The device of claim 1 , wherein the implant is self-expanding from the collapsed delivery diameter to the undeformed neutral diameter.
14. The device of claim 1 , further comprising a constraining sleeve coaxially surrounding the implant.
15. The device of claim 1 , further comprising a balloon catheter; and wherein the support structure and the implant coaxially surround the balloon.
16. The device of claim 15 , wherein balloon-assisted radial expansion of the expandable support structure from the collapsed delivery diameter to the expanded supporting diameter concomitantly forces the expansion of the implant from the collapsed deformed diameter to the over-expanded deformed diameter.
17. A method for maintaining an implant in an over-expanded state in a lumen for a period of time comprising:
locating in the lumen the device of claim 1 ;
expanding the expandable support structure from the collapsed delivery diameter to the expanded supporting diameter with concomitant radial expansion of the implant from the collapsed deformed diameter to the over-expanded deformed diameter; and
allowing the support structure to at least one of bio-corrode and structurally breakdown over the period of time.
18. The device of claim 1 , wherein the device comprises an outer surface having a material which facilitates tissue in growth.
19. The device of claim 18 , wherein the outer surface comprises an open ePTFE microstructure.
20. An implantable endoluminal device comprising:
an expandable, bioabsorbable support structure, the support structure having a delivery diameter and configured to be plastically deformed to expand to a supporting diameter; and
an implant coaxially adjacent and secured to the support structure, the implant including a stent structure and a graft structure to which the stent structure is secured, the stent structure being self-expanding and non-bioabsorbable and the implant having neutral diameter and an over-expanded deformed diameter corresponding to the expanded supporting diameter of the support structure, the stent structure biasing the implant to the neutral diameter and the support structure configured to provide radial support to the implant at the over-expanded deformed diameter for a limited time, the support structure providing reducing secondary support over time as the support structure bioabsorbs, such that the radial support degrades over time in vivo and the implant tends to return to the neutral diameter from the over-expanded deformed diameter as the support structure bioabsorbs,
the neutral diameter being less than the over-expanded deformed diameter and the over-expanded deformed diameter approximately equal to the supporting diameter.