Retrieval systems and methods for use thereof
The devices and methods described herein relate to improved structures for removing obstructions from body lumens. Such devices have applicability in through-out the body, including clearing of blockages within the vasculature, by addressing the frictional resistance on the obstruction prior to attempting to translate and/or mobilize the obstruction within the body lumen.
1. A medical device for removing an obstruction from a body passage, the medical device comprising:
at least one leading wire having a first end and a second end; and
a capturing portion having a surface extending between an open proximal end and a permeable distal end,
wherein the capturing portion is formed from the at least one leading wire such that the at least one leading wire extends through an interior of the capturing portion and diverges to form the permeable distal end, the at least one leading wire extending back in a proximal direction to form the capturing portion,
wherein the proximal end of the capturing portion is unattached proximally to another portion of the device such that the proximal end can move relative to the at least one leading wire in multiple directions, and
wherein the surface of the capturing portion comprises a translating surface and a capturing surface, each being configured so that a translating surface axial strength is greater than a capturing surface axial strength, wherein application of a tensile force on the at least one leading wire causes axial compression of the capturing surface before causing axial compression and deformation of the translating surface as the capturing portion engages the obstruction.
2. The medical device of claim 1 , where the capturing portion is formed such that articulation of the capturing portion relative to a portion of the at least one leading wire extending through the interior of the capturing portion does not cause the open, unattached proximal end to reduce in size.
3. The medical device of claim 1 , where the capturing surface is configured to generate a spring force against the translating surface when a proximal force applied by the at least one leading wire compresses the capturing surface against the translating surface when encountering resistance from the obstruction, where the capturing surface is configured to have a sufficient axial stiffness to direct the spring force and proximal force to the open, unattached proximal end as the open, unattached proximal end engages the obstruction where the capturing surface is also sufficiently flexible to conform to a shape of the body passage.
4. The medical device of claim 1 , where the capturing portion is configured so that when the open, unattached proximal end of the translating surface engages resistance equal to or greater than a threshold force, proximal movement of the at least one leading wire inverts the capturing surface within the translating surface and reduces a size of the capturing portion.
5. The medical device of claim 4 , where the capturing surface and translating surface are configured to invert upon continued proximal movement of the at least one leading wire such that the translating surface moves distally to the capturing surface.
6. The medical device of claim 1 , where the at least one leading wire is joined to a proximal bundle, where the proximal bundle comprises a stiffness greater than the at least one leading wire and where the at least one leading wire extends for a pre-determined distance from the permeable distal end to allow navigation of a distal portion of the medical device within the cerebral vasculature.
7. The medical device of claim 6 , where the pre-determined distance is at least 20 cm.
8. The medical device of claim 1 , where the capturing surface has an increased frictional resistance as compared to the translating surface, such that the capturing surface engages the obstruction for removal of the obstruction.
9. The medical device of claim 1 , where the open, unattached proximal end further comprises a plurality of flanges extending from the translating surface.
10. The medical device of claim 9 , where the flanges extend radially away from an axis of the capturing portion.
11. The medical device of claim 1 , where the capturing portion is self-expandable.
12. The medical device of claim 1 , where at least a portion of the capturing surface comprises a structure selected from the group consisting of a basket, a filter, a bag, a coil, a helical wire structure, a mesh, a single wound wire, and a plurality of crossing wires or a combination thereof.
13. The medical device of claim 1 , where the at least one leading wire includes at least a first wire and a second wire where the first and second wire each have different characteristics.
14. The medical device of claim 13 , where the characteristics are selected from a group consisting of material, cross-sectional shape, and cross-sectional size.
15. The medical device of claim 1 , where the at least one leading wire includes at least one shape memory alloy wire.
16. The medical device of claim 1 , where the at least one leading wire includes at least one wire selected from the group consisting of a superelastic wire, a polymeric wire, or a metal alloy.
17. The medical device of claim 16 , where the metal alloy comprises an alloy selected from the group consisting of stainless steel, titanium, platinum, gold, iridium, tantalum, nitinol, and combinations thereof.
18. The medical device of claim 1 , further comprising at least one radiopaque material located on the capturing portion.
19. The medical device of claim 1 , where the at least one leading wires comprises a plurality of individual wires and where one of the individual wires comprises a bundle of smaller wires.
20. The medical device of claim 1 , where the capturing portion is jointless.
21. The medical device of claim 1 , where the at least one leading wire is surrounded by a coil or coiled wire.