Clot retrieval device for removing clot from a blood vessel
A clot removal device for removing clot from a body vessel comprises an expandable structure and an elongate member. The expandable structure has a constrained delivery configuration, an expanded clot engaging deployed configuration, and an at least partially constrained clot pinching configuration. At least a portion of the expandable structure is configured to engage clot in the expanded deployed configuration and to pinch clot on movement from the deployed configuration to the clot capture configuration. The expandable structure may comprise a main body portion and a clot pinching structure and a diameter of the clot pinching structure is less than a diameter of the main body portion. The clot pinching structure may be substantially tubular and of spiral form.
1. A clot removal device for removing a clot from a body vessel comprising an expandable structure and an elongate member,
the elongate member having a proximal end and a distal end, the elongate member being connected to the expandable structure at its distal end,
the expandable structure having a constrained delivery configuration, an expanded clot engaging deployed configuration, and an at least partially constrained clot pinching configuration, the expandable structure comprising:
a main body portion comprising a plurality of rings of cells embedding in the clot and positioned between proximal and distal ends of the expandable structure, each ring comprising circumferential cells; and
a clot pinching structure configured to pinch the clot on movement from the deployed configuration to the clot pinching configuration, the clot pinching structure comprising:
a plurality of struts forming clot-receiving cells and extended between rings of the main body portion and comprising a diameter less than a diameter of the main body portion; wherein the struts extend between crowns and are configured to pinch clot located in the cell as the device is moved from the expanded deployed configuration to the at least partially constrained clot pinching configuration, wherein the cell has a proximally facing crown and a distally facing crown and wherein the proximally facing crown has a diameter which is larger than a diameter of the distally facing crown; and
wherein portions between the cells of the rings are configured to deliver relatively low radial force to the vessel with minimized surface contact area between struts of the portions and the clot; and wherein at least a portion of the expandable structure being configured to engage the clot in the expanded deployed configuration and to pinch the clot on movement from the deployed configuration to the clot pinching configuration.
2. The clot removal device as claimed in claim 1 , wherein the clot pinching structure is of spiral form.
3. The clot removal device as claimed in claim 1 , wherein the clot pinching structure is configured to exert an outward radial force when deployed within a lumen having an inner diameter which is lower than that of the expanded deployed configuration, and wherein the clot pinching structure being configured to exert an outward radial force varying in a generally sinusoidal pattern, along the length of the device.
4. The clot removal device as claimed in claim 3 , wherein the generally sinusoidal pattern comprises a wave pattern, and the amplitude of the wave pattern is generally consistent along the length of the device.
5. The clot removal device as claimed in claim 3 , wherein the generally sinusoidal pattern comprises a wave pattern, and the amplitude of the wave pattern decreases along the length of the device, being higher at the proximal end and lower at the distal end of the device.
6. The clot removal device as claimed in claim 1 , wherein the clot pinching structure comprises a plurality of adjacent segments, and wherein the segments are configured such that the radial force exerted by at least two adjacent segments differs from each other.
7. The clot removal device as claimed in claim 1 , wherein adjacent struts define a channel which narrows distally towards the crown joining the struts.
8. The clot removal device as claimed in claim 1 , wherein a size of a clot-receiving cell towards a proximal end of the clot pinching structure is smaller than a cell towards a distal end of the clot pinching structure.
9. The clot removal device as claimed in claim 1 , wherein adjacent struts comprise at least one bend, the bends being configured so that the bends of adjacent struts interengage as the device is moved to the clot pinching configuration.
10. The clot removal device as claimed in claim 1 , wherein the ratio of a diameter of the main body portion to a diameter of the clot pinching structure is from 1.5:1 to 4:1 or from 2:1 to 3:1.
11. The clot retrieval device as claimed in claim 1 , wherein the device comprises a radiopaque marker at a transition between the main body portion and the clot pinching structure.
12. The clot retrieval device as claimed in claim 1 , wherein the device has a longitudinal axis which extends through the main body portion and the clot pinching structure extends around the longitudinal axis in a spiral.
13. The clot removal device as claimed in claim 1 , wherein the clot pinching configuration is achieved by forwarding a microcatheter over the clot retrieval device until a portion of the clot is compressed between a tip of the microcatheter and the proximally facing or the distally facing crown or the strut on the clot removal device.
14. The clot removal device as claimed in claim 1 , wherein 2-5 cells are comprised in each circumferential ring.
15. The clot removal device as claimed in claim 1 , wherein the rings of cells for embedding in the clot comprise a higher radial force compared with the sections of the expandable structure.
16. The clot removal device as claimed in claim 1 , wherein struts connecting the main body portion and the clot pinching structure are curved towards a center-line of the device at a mid-point to further reduce the strut contact force and area with the clot.
17. The clot removal device as claimed in claim 1 , wherein a diameter of the clot pinching structure varies from 30% to 150% of a diameter of the body vessel at a position of the clot.
18. The clot removal device as claimed in claim 1 , wherein the clot removal device is configured to capture clots higher than 40% fibrin content.