Self-centering inferior vena cava filter

1. A self-centering inferior vena cava filter, comprising:

a filter portion configured to filter thrombi, comprising at least two layers of filter members extending along a central axis of the self-centering inferior vena cava filter, the at least two layers of filter members being adjacent to each other and staggered around the central axis;

a support portion configured to prevent the self-centering inferior vena cava filter from tilting, extending outwardly radially from a center point of the support portion in a direction towards the filter portion and then curling inwardly radially in a direction away from the filter portion, and configured to be supported on a blood vessel wall by point contact; and

a retrieval portion connected with at least one of the filter portion and the support portion;

wherein

the support portion comprises support struts,

for each of the support struts, a free end of the support strut extends from an apex of the support strut inwardly radially towards the filter portion, and

the apex is farther away from a free end of the filter portion than the free end of the support strut in a direction parallel to the central axis.

2. The self-centering inferior vena cava filter of claim 1 , wherein

each of the at least two layers of the filter members comprises a plurality of struts extending outwardly radially from a center point of the filter members, the plurality of struts of the filter members adjacent to each other being staggered around the central axis, and the plurality of struts of the filter member closest to the support portion being staggered with the support struts of the support portion.

3. The self-centering inferior vena cava filter of claim 2 , wherein

each of the plurality of struts of the filter member closest to the support portion comprises at least a first segment, a second segment, and a third segment extending sequentially radially from the center point of the filter member;

the first segment is in a straight-line shape and parallel to the central axis, each of the second segment and the third segment is in a straight-line shape or a curved-line shape and extends gradually radially;

the slope of the third segment is less than that of the second segment, or the radius of curvature of the third segment is greater than that of the second segment; and

smooth transitions between the first segment, the second segment, and the third segment are provided.

4. The self-centering inferior vena cava filter of claim 3 , wherein the second segment curls radially away from the central axis, and the third segment curls radially toward the central axis.

5. The self-centering inferior vena cava filter of claim 3 , wherein

the third segment further comprises a fourth segment extending outwardly radially, the fourth segment is in a straight-line shape or a curved-line shape; and

the fourth segment further comprises a fifth segment extending parallel to or curling toward the central axis.

6. The self-centering inferior vena cava filter of claim 2 , wherein

each of the plurality of struts of the filter members other than the filter member closest to the support portion comprises at least a first segment, a second segment, and a third segment extending sequentially outwardly radially from the center point of the filter member; and

the first segment is in a straight-line shape and parallel to the central axis, the second segment is in a curved-line shape and curls outwardly radially, and the third segment is in a straight-line shape or a curved-line shape and extends gradually outwardly radially.

7. The self-centering inferior vena cava filter of claim 1 , wherein

the support portion comprises at least three support struts extending outwardly radially from the center point of the support portion and being symmetric about the central axis;

an end of the support strut or a tangent of the end of the support strut, and the central axis define an angle therebetween, and the angle being less than or equal to 180 degrees; and

a maximum outer diameter of the support portion is configured to be substantially coincident with an inner diameter of the blood vessel such that the support struts are configured to be supported on the blood vessel wall by point contact.

8. The self-centering inferior vena cava filter of claim 7 , wherein

each of the support struts comprises a first support segment and a second support segment extending sequentially outwardly radially from the center point of the support portion;

the first support segment or a tangent of each point of the first support segment, and the central axis define an angle therebetween ranging from zero to 90 degrees;

the second support segment or a tangent of each point of the second support segment, and the central axis define an angle therebetween greater than 90 degrees; and

an end of the second support segment or a tangent of the end of the second support segment, and the central axis define an angle therebetween less than or equal to 180 degrees.

9. The self-centering inferior vena cava filter of claim 8 , wherein the second support segment or a tangent of each point of the second support segment, and the first support segment define an angle greater than or equal to 90 degrees.

10. The self-centering inferior vena cava filter of claim 9 , wherein

the second support segment comprises a first sub-segment, a second sub-segment, and a third sub-segment;

the radius of curvature of the second sub-segment is less than that of the first sub-segment; and

the second sub-segment and the central axis define an angle therebetween, the angle increasing along an extending direction of the second sub-segment.

11. The self-centering inferior vena cava filter of claim 9 , wherein

the second support segment comprises a first sub-segment, a second sub-segment, and a third sub-segment; and

the second sub-segment is in a curved-line shape or a polyline shape with a C-shaped or V-shaped opening facing the central axis; each of the first sub-segment and the third sub-segment is in a straight-line shape or a fold-line shape, and the entire second support segment curls away from or toward the filter members.

12. The self-centering inferior vena cava filter of claim 8 , wherein

the second support segment comprises a first sub-segment, a second sub-segment, and a third sub-segment;

the radius of curvature of the second sub-segment is less than that of the first sub-segment; and

the second sub-segment and the central axis define an angle therebetween, the angle increasing along an extending direction of the second sub-segment.

13. The self-centering inferior vena cava filter of claim 8 , wherein

the second support segment comprises a first sub-segment, a second sub-segment, and a third sub-segment; and

the second sub-segment is in a curved-line shape or a polyline shape with a C-shaped or V-shaped opening facing the central axis; each of the first sub-segment and the third sub-segment is in a straight-line shape or a fold-line shape, and the entire second support segment curls away from or toward the filter members.

14. The self-centering inferior vena cava filter of claim 7 , wherein

each of the support struts comprises a first support segment and a second support segment extending sequentially outwardly radially from the center point of the support portion; and

the second support segment or a tangent of each point of the second support segment, and the first support segment define an angle greater than or equal to 90 degrees.

15. The self-centering inferior vena cava filter of claim 7 , wherein the cross-sectional area of each of the support struts of the support portion is gradually reduced toward the end of the support strut.

16. The self-centering inferior vena cava filter of claim 1 , wherein

each of the at least two layers of the filter members comprises a plurality of struts, each of the plurality of struts of the filter member closest to the support portion has a first terminal away from the support portion;

each of the plurality of struts of the filter members other than the filter member closest to the support portion has a second terminal away from the support portion; and

a distance between the first terminal and the central axis is greater than a distance between any part of the support portion and the central axis and less than a distance between the second terminal and the central axis.

17. A self-centering inferior vena cava filter, comprising:

a filter portion configured to filter thrombi, comprising at least two layers of filter members extending along a central axis of the self-centering inferior vena cava filter, the at least two layers of filter members being adjacent to each other and staggered around the central axis;

a support portion configured to prevent the self-centering inferior vena cava filter from tilting, extending outwardly radially from a center point of the support portion in a direction towards the filter portion and then curling inwardly radially in a direction away from the filter portion, and configured to be supported on a blood vessel wall by point contact; and

a retrieval portion connected with both the filter portion and the support portion;

wherein

the support portion comprises support struts,

for each of the support struts, a free end of the support strut extends from an apex of the support strut inwardly radially towards the filter portion, and

the apex is farther away from a free end of the filter portion than the free end of the support strut in a direction parallel to the central axis.

18. The self-centering inferior vena cava filter of claim 17 , wherein

each of the at least two layers of the filter members comprises a plurality of struts extending outwardly radially from a center point of the filter members, the plurality of struts of the filter members adjacent to each other being staggered around the central axis, and the plurality of struts of the filter member closest to the support portion being staggered with the support struts of the support portion.

19. The self-centering inferior vena cava filter of claim 17 , wherein

the support portion comprises at least three support struts extending outwardly radially from the center point of the support portion and being symmetric about the central axis;

an end of the support strut or a tangent of the end of the support strut, and the central axis define an angle therebetween, and the angle being less than or equal to 180 degrees;

a maximum outer diameter of the support portion is configured to be substantially coincident with an inner diameter of the blood vessel such that the support struts are configured to be supported on the blood vessel wall by point contact; and

the end of the support strut extends, in a direction close to the central axis of the self-centering inferior vena cava filter, inwardly radially relative to a portion of the support strut where the support portion has the maximum outer diameter.

20. The self-centering inferior vena cava filter of claim 17 , wherein

each of the at least two layers of the filter members comprises a plurality of struts, each of the plurality of struts of the filter member closest to the support portion has a first terminal away from the support portion;

each of the plurality of struts of the filter members other than the filter member closest to the support portion has a second terminal away from the support portion; and

a distance between the first terminal and the central axis is greater than a distance between any part of the support portion and the central axis and less than a distance between the second terminal and the central axis.