Graft apparatus
Stents and methods of using stents are provided. Stents of the invention provide external support structure for a blood vessel segment disposed within, wherein the stents are capable of resilient radial expansion in a manner mimicking the compliance properties of an artery. The stent may be formed of a knitted or braided mesh formed so as to provide the needed compliance properties. A venous graft with the stent and a vein segment disposed within is provided, wherein graft is capable of mimicking the compliance properties of an artery. Methods of selecting stents for downsizing and methods of using the stents of the invention in downsizing and smoothening are provided. Methods of replacing a section of an artery with a venous graft including a stent of the invention are provided. Methods of reducing intimal hyperplasia in implanted vein segment in a venous graft using stents of the invention are provided.
1. A method for preparing an arteriovenous access conduit, said method comprising:
providing a connection forming a fluid passageway between an arterial lumen of an arterial vessel and a venous lumen of a venous vessel, the arterial vessel having a first radial compliance and the venous vessel having a second radial compliance that is different from the first radial compliance, said connection having an ablumenal surface;
providing a radially resilient external support; and
positioning said external support at said ablumenal surface of said connection to form a supported connection, wherein the support has resilient radial expansion and contraction characteristics to provide the supported connection with radial compliance properties mimicking the first radial compliance.
2. A method as in claim 1 wherein the connection exhibits a third radial compliance that is different from the first radial compliance.
3. A method as in claim 1 wherein the connection is selected from the group consisting of an end to side anastomosis, a side to side anastomosis, and an end to end anastomosis.
4. A method as in claim 3 wherein said external support is positioned at the anastomosis site.
5. A method as in claim 1 wherein the connection includes a vessel.
6. A method as in claim 5 wherein the vessel forms a shunt between the arterial vessel and the venous vessel.
7. A method for preparing an exterior access vessel for repeated access to a patient's vascular system, said method comprising:
providing a connection forming a fluid passageway between an arterial lumen of an arterial vessel and a venous lumen of a venous vessel;
providing a radially resilient, generally tubular external support;
positioning said external support in contact with an ablumenal surface of said venous vessel to form the exterior access vessel, the support having resilient radial expansion and contraction characteristics that provide said exterior access vessel with a compliance ranging from 3 to 30%/100 mm Hg.
8. A method as in claim 7 wherein said external support is a fiber mesh having openings between fibers that are sized to receive a hypodermic needle.
9. A method as in claim 8 wherein said openings have a minimum size of between 1.8-2.1 mm.
10. A method as in claim 7 wherein said external support exerts a radially resilient contraction force that is sufficient to close puncture wounds caused by penetration of said exterior access vessel by a hypodermic needle.
11. A method as in claim 7 wherein a difference between an outer diameter of said exterior access vessel and an adjacent vessel section of said patient's vascular system is reduced.
12. A method as in claim 7 wherein an outer diameter of said exterior access vessel is downsized.
13. A method as in claim 7 wherein said external support comprises a braided construction.
14. A method as in claim 13 wherein said external support comprises a shape memory material, a metal wire, a polymer material, or any combination thereof.
15. A method as in claim 14 wherein said braided construction comprises said metal wire and wherein said metal wire is from about 37 to about 170 micrometers in diameter.
16. A method as in claim 14 wherein said braided construction comprises a pitch angle from about 5° to 85° to an axial length of said external support.
17. A method as in claim 7 wherein said positioning further comprises compressing a length of said external support thereby increasing a diameter of said external support.