Vascular filter device
A vascular filter device ( 1 ) has a support frame ( 2 ) and filter elements ( 4 ). The filter elements ( 4 ) extend from the support frame towards filter element ends forming an on-axis apex ( 5 ) at which they are interconnected by a holder ( 6 ). The filter elements ( 4 ) are biased such that if unconnected the filter element ends are located between the support frame and said central axis when the vascular filter device is unconstrained. The filter element unconnected positions are provided by the filter element shapes and the angles at which they extend from the support frame, and in one example this is achieved by laser cutting tubing and heat setting the material.
1. A vascular filter device comprising a support frame defining an outer wall having a proximal end and a distal end, and a plurality of filter elements each having a proximal end fixed to the support frame, the filter elements extending distally from the support frame and having distal filter element ends forming an apex at which they are interconnected, and wherein said apex is located at or near a central axis of the vascular filter device and spaced distally from the distal end of the support frame; wherein the filter elements are biased such that if unconnected the distal filter element ends are located radially between a line extending along and axially beyond the outer wall of the support frame and said central axis when the vascular filter device is unconstrained.
2. A vascular filter device as claimed in claim 1 , wherein the support frame and the filter elements are formed in one piece.
3. A vascular filter device as claimed in claim 1 , wherein the filter element unconnected positions are provided by the filter element shapes and the angles at which they extend from the support frame, and wherein said unconnected positions are located approximately 10% to 50% of the distance from the central axis to the line extending along and axially beyond the outer wall of the support frame.
4. A vascular filter device as claimed in claim 1 , wherein the vascular filter device has an indicated vessel size range, and wherein the filter elements are biased to have positions if unconnected such that: a. when the device is constrained in a vessel defining a vessel wall which lies in an upper sub-range of said indicated range, the distal filter element ends are between the central axis and the vessel wall, b. when the device is constrained in a vessel which lies in a central sub-range of said indicated range the distal filter element ends are approximately on the central axis, and c. when the device is constrained in a vessel which lies in a lower sub-range of said indicated range the distal filter element ends extend through said central axis.
5. A vascular filter as claimed in claim 4 , wherein the filter elements have similar maximum strains in situations when the distal filter element ends are interconnected.
6. A vascular filter as claimed in claim 4 , wherein the filter elements have approximately equal maximum tensile strains in situations when the distal filter element ends are interconnected.
7. A vascular filter device as claimed in claim 1 , wherein the support frame comprises a proximal hoop, a distal hoop and interconnecting struts.
8. A vascular filter as claimed in claim 7 , wherein the proximal hoop has peaks and the filter elements are connected to the support at or adjacent distal peaks of the proximal hoop.
9. A vascular filter device as claimed in claim 7 , wherein the distal hoop comprises an array of V-shaped struts or an array of M-shaped struts, and wherein said struts are not directly interconnected.
10. A vascular filter device as claimed in claim 2 , wherein the distal filter element ends, the filter elements, and the support frame are formed integrally from one piece.
11. A vascular filter device as claimed in claim 2 , wherein the distal filter element ends are formed integrally to provide an integral apex.
12. A vascular filter device as claimed in claim 2 , wherein the distal filter element ends are interconnected by a holder.
13. A vascular filter device as claimed in claim 12 , wherein at least some filter elements have eyelets and the holder is trained through the eyelets.
14. A vascular filter device comprising a support frame defining an outer wall having a proximal end and a distal end, and a plurality of filter elements each having a proximal end fixed to the support frame, the filter elements extending distally from the support frame and having distal filter element ends forming an apex at which they are interconnected, and wherein said apex is located at or near a central axis of the vascular filter device and spaced distally from the distal end of the support frame; wherein the filter elements are biased such that if unconnected the distal filter element ends are located radially between a line extending along and axially beyond the outer wall of the support frame and said central axis when the vascular filter device is unconstrained; wherein the filter elements are interconnected by interlocking features, such as slots and ridges or dovetail features.
15. A method of manufacturing a vascular filter device comprising a support frame defining an outer wall having a proximal end and a distal end, and filter elements, the filter elements extending distally from the support frame and having distal filter element ends forming an apex at which they are interconnected, wherein said apex is located at or near a central axis of the vascular filter device and spaced distally from the distal end of the support frame; wherein the filter elements are biased such that if unconnected the distal filter element ends are located radially between a line extending along and axially beyond the outer wall of the support frame and said central axis when the vascular filter device is unconstrained, wherein the method comprises the steps of: providing a tubing, cutting the tubing, and expanding the tubing.