Occluder

1. An occluder for closing a passage in a circulatory system, wherein the occluder has an expandable fixation unit for fixing the occluder on the passage, wherein the occluder can be transferred in the passage from a compact form of appearance to an expanded form of appearance, and wherein the occluder has a distal axial part and a proximal axial part, wherein the fixation unit is held pivotably in the distal axial part and the proximal axial part, wherein the fixation unit has distal fixation arms and proximal fixation arms, wherein the distal fixation arms are pivotably connected to the distal axial part and the proximal fixation arms are pivotably connected to the proximal axial part, and wherein the distal and the proximal fixation arms each have a first free end, wherein the first free ends are connected to one another via connecting members that are moveable relative to the fixation arms, wherein each distal fixation arm is connected to one of said proximal fixation arms by one of said connecting members, wherein each of said distal fixation arms and said proximal fixation arms is U-shaped with two branches and a bridge joining the branches wherein the two branches have second free ends which are held pivotably in the proximal or distal axial part, and wherein the bridges form the first free ends of the distal fixation arms and the proximal fixation arms.

2. The occluder as claimed in claim 1 , wherein the connecting members extend independently of one another between the individual distal and proximal fixation arms.

3. The occluder as claimed in claim 1 , wherein the connecting members intersect in one area, and wherein, in the area, the connecting members extend in an individually displaceable manner in a first sleeve that surrounds the connecting members jointly.

4. The occluder as claimed in claim 1 , wherein the bridges are rectilinear.

5. The occluder as claimed in claim 1 , wherein each bridge is enclosed by and held pivotably in a second sleeve.

6. The occluder as claimed in claim 5 , wherein each connecting member is connected integrally or welded to each respective second sleeve.

7. The occluder as claimed in claim 1 , wherein the fixation arms are wires.

8. The occluder as claimed in claim 1 , wherein the connecting members are wires or strings.

9. The occluder as claimed in claim 1 , further comprising at least one closure body for closing the passage, and wherein the closure body is a membrane, a tampon, or a balloon.

10. The occluder as claimed in claim 9 , wherein the closure body comprises a membrane, and wherein the membrane can be brought to the expanded form of appearance by the fixation arms.

11. The occluder as claimed in claim 9 , wherein the closure body is a compressible elastic tampon.

12. The occluder as claimed in claim 9 , wherein the closure body is a balloon, wherein the balloon extends from the proximal axial part to the distal axial part, and is secured to the two parts and surrounds the fixation arms and connecting members.

13. The occluder as claimed in claim 9 , wherein the closure body is arranged in an area that is defined on one side by the distal fixation arms and on an opposite side by the proximal fixation arms.

14. The occluder as claimed in claim 13 , wherein the closure body is a tampon.

15. The occluder as claimed in claim 1 , wherein the bridges are round.