Vaso-occlusive devices including a friction element
Vaso-occlusive apparatuses, including implants, and methods of using them to treat aneurysms. The vaso-occlusive implants described herein include one or more soft and expandable braided member coupled to a pushable member such as a coil that maybe inserted and retrieved from within an aneurism using a delivery catheter as well as a friction element between the soft braided member and the coil. The friction element allows the relatively soft and elongate implant to be pushed out of a cannula without binding up within the cannula.
1. A vaso-occlusive device adapted to be pushed through a delivery catheter and out an open distal end of the delivery catheter, the vaso-occlusive device comprising:
an elongate braided tubular outer member having a radially compressed configuration when constrained within the delivery catheter, and a radially expanded configuration when pushed out the open distal end of the delivery catheter so as to no longer be constrained within the delivery catheter;
an elongate pushable inner member disposed within an interior of the braided tubular outer member, wherein the pushable inner member is axially moveable relative to the delivery catheter;
a friction element disposed between the pushable inner member and the braided tubular outer member, wherein at least a portion of the friction element is configured to generate friction between the pushable inner member and an inner surface of the braided tubular outer member when the vaso-occlusive device is constrained within the delivery catheter so as to move the braided tubular outer member axially relative to the delivery catheter as the pushable inner member is moved axially relative to the delivery catheter, and to release the friction between the pushable inner member and the inner surface of the braided tubular outer member when the braided tubular outer member is in the radially expanded configuration such that the pushable inner member can be moved axially independent of the braided tubular outer member; and
wherein the friction element comprises an elongated cylindrical body attached to an outer surface of the pushable inner member such that the elongated cylindrical body is coaxial with the pushable inner member, and the friction element is biased to expand radially outwards from a radially compressed configuration to a radially expanded configuration.
2. The vaso-occlusive device of claim 1 , wherein the friction element in the radially expanded configuration has a larger diameter than a diameter of the pushable inner member such that the friction element extends slightly radially from a surface of the pushable inner member.
3. The vaso-occlusive device of claim 1 , wherein an outer diameter of the friction element is non-uniform.
4. The vaso-occlusive device of claim 1 , wherein the friction element is formed of a material having a high coefficient of friction relative to the pushable inner member and the braided tubular outer member.
5. The vaso-occlusive device of claim 1 , wherein the friction element is flush with an outer diameter of the pushable inner member.
6. The vaso-occlusive device of claim 1 , wherein the friction element has a proximal end and a distal end, and the proximal end of the friction element is axially and radially fixed relative to the pushable inner member and the distal end of the friction element is axially slidable relative to the pushable inner member.
7. The vaso-occlusive device of claim 6 , wherein a middle portion of the friction element radially expands when the distal end of the friction element slides axially towards the proximal end of the friction element.
8. The vaso-occlusive device of claim 1 , wherein the friction element comprises a flared braid, the flared braid having a cylindrical portion and flared prongs extending radially outward from a distal end of the cylindrical portion, wherein the flared prongs engage the braided tubular outer member through opens cells of the braided tubular outer member when the braided tubular outer member is in the radially compressed configuration and the flared prongs release from the braided tubular outer member when the braided tubular outer member is in the radially compressed configuration.
9. The vaso-occlusive device of claim 1 , wherein the friction element is coupled to the pushable inner member.
10. The vaso-occlusive device of claim 1 , wherein the friction element is free-floating in that the friction element is not attached to the pushable inner member or to the braided tubular outer member.
11. The vaso-occlusive device of claim 1 , further comprising a plurality of friction elements wherein the friction elements are arranged at spaced apart locations along a length of the braided tubular outer member.
12. The vaso-occlusive device of claim 1 , wherein the friction element is a braid having one of a flared profile or an hour-glass profile.
13. The vaso-occlusive device of claim 10 , wherein the friction element is formed of a material having a high coefficient of friction relative to the pushable inner member and the braided tubular outer member.