Valve for medical implant delivery system

1. A valve for use in delivering a medical device, the valve including:

a body having a first end and a second end disposed along a longitudinal axis, and a wall defining a passage between the first and second ends,

a flexible member disposed about the passage, the flexible member being spaced from each of the first and second ends and defining an aperture along the passage, the aperture having a first diameter when in an unstressed state, wherein:

(1) the first diameter is less than the internal diameter of the passage at one or both of the first and second ends, and

(2) when an element having an external diameter greater than the first diameter is inserted into the aperture, the diameter of the aperture increases to accommodate the element and to create a seal around the element,

wherein the valve is fixed in a twisted state:

a. with the flexible member under a fixed degree of torsion,

b. with the first end of the body being nonrotatably secured relative to the second end,

c. with the wall defining the passage being in longitudinal tension between the first and second ends of the body, and

without any element being within the aperture of the flexible member.

2. The valve of claim 1 wherein the aperture has a first diameter of up to 1 mm.

3. The valve of claim 1 wherein the first diameter is less than the internal diameter of the passage at both the first and the second ends.

4. The valve of claim 1 wherein the wall is configured so that the passage is hour-glass shaped.

5. The valve of claim 1 wherein the flexible member is integrally formed as a single piece with the body.

6. The valve of claim 1 wherein the flexible member is formed of the same material as the wall.

7. The valve of claim 1 wherein the first end is rotatable relative to the second end about the longitudinal axis so as to apply torsion to the flexible member.

8. The valve of claim 1 wherein the first end is locked into a position in which it has been rotated 360° relative to the second end.

9. The valve of claim 1 wherein the flexible member is in a permanent state of torsion, such that the aperture has a diameter which is less than the first diameter.

10. The valve of claim 1 further including resistance means for resisting increase of the diameter of the aperture.

11. The valve of claim 10 wherein the resistance means comprises an annular element formed of a resilient material, the annular element being disposed around the flexible member.

12. The valve of claim 1 wherein the body is stretched along its longitudinal axis to a length which is from 120%-150% of its length when not under longitudinal tension.

13. The valve of claim 1 having several flexible members disposed sequentially between the first and second ends.

14. The valve of claim 1 further including a tubular liner.

15. A valve for use in delivering a medical device, the valve including:

a body having a wall defining a passage extending between a first end and a second end, the passage converging inwardly from the first end and from the second end to define a narrowed aperture between the first and second ends,

wherein the wall is flexible about the aperture, whereby the aperture seals about an element of a medical device inserted therein if the element has a diameter greater than the diameter of the aperture,

wherein the valve is fixed in a twisted state, with one of the first and second ends of the body being twisted and nonrotatably fixed with respect to the other such that:

a. the body is in a fixed degree of torsion, and

b. the wall defining the passage is in longitudinal tension between the first and second ends of the body,

without any element being in the aperture, whereby the diameter of the aperture is reduced prior to subsequent insertion of any element therein.

16. The valve of claim 15 wherein the body is formed of elastomeric material.

17. The valve of claim 15 wherein the internal diameter of the aperture, when the valve is not in a twisted state and the wall defining the passage is not in longitudinal tension between the first and second ends of the body, is less than the internal diameter of the passage at one or both of the first and second ends.

18. The valve of claim 15 wherein the internal diameter of the aperture, when the valve is not in a twisted state and the wall defining the passage is not in longitudinal tension between the first and second ends of the body, is less than the internal diameter of the passage at both of the first and second ends.

19. A method of delivering a medical device using the valve of claim 15 , the method including the step of inserting a medical device within the reduced-diameter aperture.

20. The method of claim 19 further including the step, prior to any element being in the aperture, of tensioning the body between the first and second ends until the length of the body between the first and second ends is at least 120% of the length of the body when untensioned.