Methods and devices for cutting tissue
A catheter is provided, which includes a cutting element having one or more raised elements. The cutting element has a cup-shaped surface at the distal end that may be smooth and continuous except for the raised elements.
1. An atherectomy catheter, comprising:
a body having opposite proximal and distal ends;
a rotatable shaft coupled to the body;
a cutting element adjacent the distal end of the body and coupled to the rotatable shaft, such that the rotatable shaft is able to rotate the cutting element through a complete rotation about a longitudinal axis of the cutting element, the cutting element having opposite distal and proximal ends, a concave surface and a cutting edge, the concave surface defining a concave cavity, the cutting edge extending circumferentially at the distal end of the cutting element; and
a raised element extending distally from the concave surface of the cutting element, the raised element having a first wall extending generally radially, and a distal wall including distal surface which intersects the first wall to form a raised edge of the raised element, wherein an entirety of the distal surface of the raised element is recessed proximally from the cutting edge.
2. The catheter of claim 1 , wherein:
the distal surface of the raised element is recessed proximally from the cutting edge by a longitudinal distance of 0.0010-0.0020 inch.
3. The catheter of claim 1 , wherein:
the concave surface of the cutting element is smooth and uninterrupted throughout at least 300 degrees when viewed from the longitudinal axis.
4. The catheter of claim 1 , wherein:
the concave surface of the cutting element is smooth and uninterrupted for at least 95% of its surface area.
5. The catheter of claim 1 , wherein:
the concave surface of the cutting element has an outer radius when viewed from the longitudinal axis, the concave surface being continuous and uninterrupted from the longitudinal axis to at least half the distance to the outer radius.
6. The catheter of claim 1 , further comprising:
a plurality of raised elements, the plurality of raised elements altogether occupying an area less than 60 degrees of the concave surface when viewed from the longitudinal axis.
7. The catheter of claim 6 , wherein:
the plurality of raised element altogether occupy less than 5% of the surface area of the concave surface.
8. The catheter of claim 7 , wherein:
the concave surface is smooth and uninterrupted for at least 95% of its surface area.
9. The catheter of claim 1 , wherein:
the body has an opening, less than 90 degrees of the cutting element is exposed to cut tissue relative to the opening in the body.
10. The catheter of claim 1 , further comprising:
a plurality of raised elements, the plurality of raised elements being 2 to 6 raised elements.
11. The catheter of claim 1 , wherein:
the raised element has a trailing edge and the raised edge is a leading edge when the cutting edge is rotated, both the leading edge and trailing edge being 0.0010 to 0.0050 inch from the cutting edge.
12. The catheter of claim 11 , wherein:
the distal surface is formed between the raised edge and trailing edge, and the distal surface forms an angle with the longitudinal axis of 30 to 90 degrees.
13. The catheter of claim 1 , wherein:
the raised element comprises 4 raised elements.
14. The catheter of claim 1 , wherein:
the entire raised element is within the concave cavity.
15. The catheter of claim 1 , wherein:
the distal surface of the raised element forms an angle with the longitudinal axis of 30 to 90 degrees.
16. A method of removing material from a blood vessel, comprising:
providing a catheter comprising:
a body having opposite proximal and distal ends;
a rotatable shaft coupled to the body;
a cutting element adjacent the distal end of the body and coupled to the rotatable shaft, such that the rotatable shaft is able to rotate the cutting element through a complete rotation about a longitudinal axis of the cutting element, the cutting element having opposite distal and proximal ends, a concave surface and a cutting edge, the concave surface defining a concave cavity, the cutting edge extending circumferentially at the distal end of the cutting element; and
a raised element extending distally from the concave surface of the cutting element, the raised element having a first wall extending generally radially, and a distal wall including distal surface which intersects the first wall to form a raised edge of the raised element, wherein an entirety of the distal surface of the raised element is recessed proximally from the cutting edge; and
moving the catheter in a distal direction within a blood vessel, as the rotatable shaft is rotating the cutting element, to cut tissue.
17. The method of claim 16 , wherein:
the providing step is carried out with the raised element being recessed proximally from the cutting edge by a longitudinal distance of 0.0010-0.0020 inch.
18. The method of claim 16 , wherein:
the providing step is carried out with the distal surface of the raised element being recessed proximally from the cutting edge by a radial distance of 0.0010-0.0020 inch.
19. The method of claim 16 , wherein:
the providing step is carried out with the concave surface of the cutting element being uninterrupted throughout at least 300 degrees when viewed from the longitudinal axis.
20. The method of claim 16 , wherein:
the providing step is carried out with the concave surface being uninterrupted for at least 95 percent of its surface area.
21. The method of claim 16 , wherein:
the providing step is carried out with the concave surface having an outer radius at the cutting edge, the concave surface being continuous and uninterrupted from the longitudinal axis to at least half the distance to the cutting edge.
22. The method of claim 16 , wherein:
the providing step is carried out with a plurality of said raised elements, at least a portion of each raised element being within the concave cavity, and which together occupy an area less than 60 degrees of the concave surface when viewed from the longitudinal axis and together occupy less than 5% of the surface area of the concave surface; and
the concave surface being smooth and uninterrupted for at least 95% of its surface area.
23. The method of claim 16 , wherein:
the providing step is carried out with less than 90 degrees of the cutting element being exposed to cut tissue relative to the opening in the body.
24. The method of claim 16 , wherein:
the providing step is carried out with a plurality of said raised elements on the concave surface of the cutting element, at least a portion of each raised element being within the concave cavity, the plurality of raised elements being 2 to 6 raised elements.
25. The method of claim 16 , wherein:
the providing step is carried out with the raised element having a trailing edge and the raised edge being a leading edge when the cutting element is rotated, both the leading edge and trailing edge being 0.0010 to 0.0050 inch from the cutting edge.
26. The method of claim 25 , wherein:
the providing step is carried out with the distal surface being formed between the raised edge and trailing edge, the distal surface forming an angle with the longitudinal axis of 30 to 90 degrees.
27. The method of claim 16 , wherein:
the providing step is carried out with 4 of said raised elements.
28. The method of claim 16 , wherein:
the providing step is carried out with the entire raised element being within the concave cavity.