Stent type av flow restrictors

2:

• The stent of claim 1 wherein said first end portion and said second end portion include a first collapsed diameter and a second expanded diameter, said second expanded diameter greater than said first collapsed diameter.

3:

• The stent of claim 2 wherein said first end portion and said second end portion are biased toward said second expanded diameter, such that when restraining forces are removed from said first end portion and said second end portion, said first end portion and second end portion automatically transition to said second expanded diameter.

4:

• The stent of claim 2 wherein said first end portion and said second end portion are biased toward said first collapsed diameter, but are able to be flexibly expanded to said second expanded diameter by application of radial forces thereto.

5:

• The stent of claim 4 wherein said central portion has greater resistance to radial expansion than said first end portion and said second end portion.

6:

• The stent of claim 5 wherein said central portion can be radially expanded to a second expanded diameter matching said second expanded diameter of said first end portion and second end portion when sufficient radial expansion forces are applied to said central portion.

7:

• The stent of claim 1 wherein a sheath surrounds said stent before deployment, said sheath sufficiently strong to hold said first end portion and said second end portion in a collapsed configuration.

8:

• The stent of claim 7 wherein said collapsed configuration includes said first end portion, said second end portion and said middle portion having similar diameters.

9:

• The stent of claim 8 wherein said stent includes an expanded configuration wherein said first end portion and said second end portion have similar diameters, and said middle portion has a smaller diameter than said end portions.

10:

• The stent of claim 1 wherein said stent includes a foraminous metal cage forming said first end portion, said second end portion and said middle portion.

11:

• The stent of claim 1 wherein said stent includes at least one non-porous flexible layer adjacent to said metal cage.

12:

• The stent of claim 1 wherein said flexible layer is on an inside surface of said metal cage.

13:

• The stent of claim 1 wherein a second flexible layer is provided on an outside surface of said metal cage.

14:

• The stent of claim 11 wherein said flexible layer includes ePTFE.

15:

• The stent of claim 14 wherein said flexible layer is sufficiently flexible to avoid rupture when said stent is expanded radially.

16:

• The stent of claim 1 wherein each of said end portions and said middle portion each have circular cross-sections along lengths thereof, and wherein said end portions include a conical tapering diameter portion, with smallest diameters adjacent to said central portion.

18:

• The method of claim 17 wherein said stent self-expands when said sheath is retracted during said retracting step.

19:

• The method of claim 17 including the further step of expanding the sheath by expanding a balloon within the stent, with an initial stent radial expansion which expands the first end portion and the second end portion to a greater diameter than the central portion.

20:

• The method of claim 19 including the further step of further expanding the sheath by further expanding the balloon within the stent to cause the central portion to be expanded to a similar diameter as said first end portion and said second portion.