Stent with protected barbs

1. An endoluminal prosthesis comprising:

a stent configurable between a compressed configuration within a sheath and an expanded configuration and having at least one strut;

at least one barb secured to the at least one strut and comprising a distal tip, the at least one barb having a retracted configuration toward the strut and an extended configuration biased away from the strut, wherein the at least one barb is moveable between the retracted configuration and the extended configuration; and

at least one degradable barb guard disposed about the at least one strut and the at least one barb and covering at least a portion of the barb and holding it in the retracted configuration and protecting the distal tip when the stent is in the compressed configuration;

wherein the barb guard comprises a degradable structure that degrades to expose the distal tip of the barb when the stent is placed in a vessel.

2. The prosthesis of claim 1 , where the guard comprises a dissolvable structure.

3. The prosthesis of claim 2 , where the guard covers the distal tip of the barb.

4. The prosthesis of claim 1 , where the guard comprises a frangible structure.

5. The prosthesis of claim 4 , where the frangible structure comprises a score and is configured to break at the score.

6. The prosthesis of claim 4 , wherein the guard comprises a dissolvable structure.

7. The prosthesis of claim 1 , wherein the guard is attached directly to the barb.

8. An endoluminal prosthesis deployment system comprising:

a sheath having a sheath lumen; and

a prosthesis disposed within the sheath lumen and comprising a stent having at least one strut and at least one barb secured to the at least one strut, the at least one barb and the at least one strut having a circumference, wherein the at least one barb comprises a distal tip; and

at least one degradable barb guard disposed substantially about the circumference of the at least one strut and the at least one barb and covering at least a portion of the barb and preventing direct contact between the distal tip of the and the sheath;

wherein the guard comprises a degradable structure that degrades to expose the distal tip of the barb after the stent is released from the sheath; and

wherein the at least one barb is movable between a retracted configuration and an extended configuration.

9. The deployment system of claim 8 , wherein the guard contacts the sheath.

10. The deployment system of claim 8 wherein when the barb is in the extended configuration it has a bias force that is greater than the strength of the guard so that the guard breaks when the stent is released from the sheath.

11. The deployment system of claim 10 , wherein the guard comprises a frangible structure.

12. The deployment system of claim 8 , wherein the guard comprises a dissolvable structure.

13. The deployment system of claim 8 , wherein the guard comprises a blunt cover that covers the distal tip of the barb.

14. The deployment system of claim 13 , wherein the guard comprises a frangible structure.

15. The deployment system of claim 14 , wherein the frangible structure comprises a score and is configured to break at the score.

16. The deployment system of claim 8 , wherein the guard is attached directly to the barb.

17. A method of deploying in a lumen an endoluminal prosthesis covered by a sheath, the endoluminal prosthesis having a plurality of struts and at least one barb attached to a strut of the plurality of struts, the barb having a first configuration toward the strut and a second configuration biased away from the strut, and

a degradable structure disposed about the strut and the at least one barb and holding the barb in the first configuration and preventing direct contact between each barb and the sheath, the method comprising:

retracting the sheath to expose the endoluminal prosthesis;

expanding said endoluminal prosthesis to an expanded state;

degrading the degradable structure and

moving the barb from the first configuration to the second configuration thereby engaging each barb with the lumen.

18. The method of claim 17 wherein the endoluminal prosthesis is self expanding.

19. The method of claim 17 wherein the endoluminal prosthesis is balloon expandable.

20. The method of claim 17 wherein the degradable structure is frangible and wherein the degradable structure is degraded by breaking the degradable structure.