Device for cutting tissue
A catheter which includes a cutting element having one or more raised elements is provided. The cutting element has a cup-shaped surface at the distal end that may be smooth and continuous except for the raised elements. The raised elements have a surface that tends to direct cut particles of material towards one or more of the axis of rotation of the cutting element, the catheter axis, or a particle collection chamber. In further aspects of the invention, a cutting element oscillates in a direction roughly parallel to the axis of rotation of the cutting element.
1. An atherectomy catheter comprising:
a rotatable shaft; and
a cutting element coupled to the rotatable shaft for rotating the cutting element about an axis of rotation, the cutting element having an annular cutting edge and a raised element radially inward of the annular cutting edge, the raised element having opposite first and second walls extending generally axially relative to the axis of rotation and an axial wall extending between and intersecting the first and second walls at a free axial end of the raised element, wherein the first wall and the axial wall define a raised-element edge at the intersection of the first wall and the axial wall, the raised-element edge and the first wall have inner and outer ends relative to the axis of rotation of the cutting element,
wherein the raised-element edge and the first wall curve inwardly toward the second wall from the inner ends of the respective raised-element edge and first wall toward the outer ends of the respective raised-element edge and first wall,
wherein the raised-element edge of the raised-element does not intersect the annular cutting edge.
2. The atherectomy catheter of claim 1 , wherein the raised element is configured to direct cut particles of material toward the axis of rotation of the cutting element.
3. The atherectomy catheter of claim 1 , wherein the annular cutting edge is at a radially outer edge of the cutting element.
4. The atherectomy catheter of claim 1 , wherein the raised element has a third wall extending generally axially relative to the axis of rotation and intersecting and extending between the first and second walls and intersecting the axial wall.
5. The atherectomy catheter of claim 4 , wherein the axial wall of the raised element is recessed axially from the annular cutting edge by an axial distance.
6. The atherectomy catheter of claim 5 , wherein the axial wall of the raised element is recessed axially from the annular cutting edge by an axial distance of 0.0010 to 0.0050 inch (0.0025 to 0.0127 cm).
7. The atherectomy catheter of claim 4 , wherein an interior surface of the cutting element comprises a cup-shaped surface of the cutting element, the cup-shaped surface being smooth and uninterrupted throughout at least 300 degrees when viewed along the axis of rotation of the cutting element.
8. The atherectomy catheter of claim 7 , wherein the cup-shaped surface of the cutting element is smooth and uninterrupted for at least 90% of the surface area of the cutting element when viewed along the axis of rotation of the cutting element.
9. The atherectomy catheter of claim 7 , wherein the cup-shaped surface of the cutting element has an outer radius when viewed along the axis of rotation of the cutting element, the cup-shaped surface being continuous and uninterrupted from the axis of rotation to at least half the distance to the outer radius.
10. The atherectomy catheter of claim 7 , wherein the cup-shaped surface of the cutting element has a surface area, wherein the raised element comprises a plurality of raised elements, the plurality of raised elements altogether occupying less than 5% of the surface area of the cup-shaped surface when viewed along the axis of rotation of the cutting element.
11. The atherectomy catheter of claim 1 , wherein the raised element is recessed axially from the annular cutting edge by an axial distance.
12. The atherectomy catheter of claim 1 , wherein the first wall curves from a relatively tangential angle with the annular cutting edge at a radially outer edge of the cutting element to a relatively radial angle closer to the axis of rotation of the cutting element.
13. The atherectomy catheter of claim 12 , wherein the axial wall extends from the raised-element edge to a second edge at the intersection of the second wall and the axial wall, the axial wall forming an angle of less than 90 degrees with respect to the axis of rotation of the cutting element.
14. The atherectomy catheter of claim 13 , wherein a minimum radial distance between the raised-element edge and the annular cutting edge of the cutting element is less than a minimum radial distance between the second edge and the annular cutting edge of the cutting element.
15. The atherectomy catheter of claim 13 , wherein an included angle between the first wall and the axial wall is an obtuse angle.
16. The atherectomy catheter of claim 1 , wherein the first wall is shaped to direct the cut particles of material towards the axis of rotation of the cutting element.
17. The atherectomy catheter of claim 1 , wherein the raised element comprises a plurality of raised elements, the plurality of raised elements being 2, 3, 4, 6, or 8 raised elements.
18. The atherectomy catheter of claim 1 further comprising an elongate body, wherein the shaft is coupled to the body.
19. The atherectomy catheter of claim 1 , wherein the outer end of the raised-element edge is spaced apart inward from the annular cutting edge relative to the axis of rotation of the cutting element.
20. The atherectomy catheter of claim 1 , is recessed axially from the annular cutting edge relative to the axis of rotation of the cutting element.
21. The atherectomy catheter of claim 1 , wherein the raised-element edge and the first wall curve from the inner ends of the respective the raised-element edge and the first wall to the outer ends of the respective the raised-element edge and the first wall.