Systems, methods and devices for embolic protection
Embodiments of the present disclosure are directed to systems, methods and devices for providing embolic protection in a patient. In some embodiments, the device is configured for implantation in a body vessel including fluid flow. The device may assume, or be constrained to assume, an undeployed state and a deployed state. In the undeployed state, the device or a portion thereof has a substantially linear shape configured to reside in the lumen of a thin needle having a diameter of less than about 0.5 mm (for example), in the deployed state, the device has a primary axis. When the device is implanted the primary axis is approximately perpendicular to the fluid flow. In some embodiments, the device comprises a thin filament body. In the deployed state the filament takes a helical shape. Emboli that are larger than the distance between consecutive turns or windings of the helix are thus filtered by the device and are prevented from causing deleterious conditions such as stroke or pulmonary embolism. The device may be made of a super-elastic alloy. Thus, the device may transition between the undeployed and the deployed states without plastic deformation. Delivery systems and method for implanting such devices are also disclosed.
1. An embolic filtering device for deployment at a human blood vessel, the device comprising:
a filament having proximal and distal ends, the filament being configured to include un-deployed and deployed states,
wherein:
in the un-deployed state, at least a portion of the filament is configured to fit within the lumen of a needle; and
in the deployed state,
the filament is configured to form a shape comprising a helix including a plurality of windings and having a length and an axis, and a linear segment at the proximal end and arranged approximately collinear with the axis,
the helix is configured for implantation within the blood vessel such that after implantation the axis aligns approximately perpendicular to the direction of flow in the blood vessel and the helix length corresponds to approximately the inner diameter of the blood vessel, and
the linear segment is configured after implantation to breach the wall of the blood vessel at an angle approximately perpendicular to the direction of flow;
and
an anchor configured for positioning within tissue and outside of the blood vessel after implantation.
2. The device of claim 1 , wherein the thickness of the filament is between about 50 and 350 microns.
3. The device of claim 1 , wherein in the deployed state, the radius of curvature anywhere along the filament exceeds a critical value equal to the thickness of the filament divided by about twice the critical strain of the material from which the filament is made.
4. The device of claim 3 , wherein the critical value is greater than about 0.6 mm.
5. The device of claim 1 , wherein the windings vary in diameter.
6. The device of claim 1 , wherein the helix includes between two and twenty windings.
7. The device of claim 1 , wherein the windings that approximately trace the shape of a shell of a body of revolution.
8. The device of claim 5 , wherein the plurality of windings includes at least one winding having a maximal diameter which is less than or equal to the diameter of the vessel.
9. The device of claim 1 , wherein the distance between consecutive windings is greater than about 0.7 mm.
10. The device of claim 1 , wherein the distance between consecutive windings is less than about 1.5 mm.
11. The device of claim 1 , further comprising one or more of a radiopaque marker, an echogenic marker, a radioactive marker, a magnetic marker, and a magnetic resonance marker.
12. The device of claim 1 , wherein the filament is made from at least one of: a metal, a plastic, a natural polymer, a shape memory alloy, a super elastic alloy, a biodegradable material, a bioresorbable material, and a bioabsorbable material.
13. The device of claim 1 , further comprising one or more additional filaments.
14. The device of claim 13 , wherein the one or more additional filaments each have a helical shape.
15. The device of claim 1 , wherein part of the device is configured to protrude out from the skin of a patient.
16. The device of claim 1 , wherein part of the device is configured for arrangement immediately below the skin of a patient.
17. The device of claim 1 , wherein in the deployed state the shape further comprises a second linear segment approximately collinear with the axis and distal to the helix, and wherein the second linear segment breaches the vessel wall.
18. A method for providing embolic protection in a patient, the method comprising implanting the device of claim 1 .
19. The device of claim 1 , further comprising a bearing.
20. The device of claim 19 , wherein the bearing and anchor are integral with one another.
21. An embolic filtering device for deployment at a human blood vessel, the device comprising:
a filament having proximal and distal ends, the filament being configured to include un-deployed and deployed states; and
a bearing,
wherein:
in the un-deployed state, at least a portion of the filament is configured to fit within a lumen of a needle; and
in the deployed state,
the filament is configured to form a shape comprising a helix for implantation within the blood vessel, the helix including a plurality of windings and having a length and an axis, and a linear segment at the proximal end and arranged approximately collinear with the axis,
the helix is configured such that after implantation the axis aligns approximately perpendicular to the direction of flow in the blood vessel and the helix length corresponds to approximately the inner diameter of the blood vessel,
the linear segment is configured after implantation to breach the wall of the blood vessel at an angle approximately perpendicular to the direction of flow,
the bearing is affixed to the proximal end of the filament, and
at least a portion of the bearing is arranged externally to the blood vessel lumen after implantation.