Cutting balloon catheter

Abstract

A system for removing matter from a partially or totally occluded stent includes a cutter that is urged radially outward toward the inner surface of the stent. Preferably, the cutter has a hardness that is less than or equal to the hardness of the material used to make the stent. Aspiration may be provided to remove portions of the occluding material from the vessel.

Claims

1. A .[.system for removing deposits from a partially or totally occluded stent.]. .Iadd.balloon catheter.Iaddend., comprising: .Iadd.a catheter shaft configured to be routed over a guidewire;.Iaddend. an expandable cutter .[.disposed over a guide wire.]. .Iadd.coupled to the catheter shaft.Iaddend., the cutter including a coiled member .Iadd.having a proximal end directly affixed to a distal end of the catheter shaft and a distal end directly affixed to a distal bearing through which the guidewire is routed.Iaddend.; and a balloon disposed within the coiled member that expands to urge the cutter radially outward, .Iadd.the balloon being a separate component from the expandable cutter, a proximal end of the balloon directly affixed to the distal end of the catheter shaft proximate the proximal end of the coiled member and a distal end of the balloon directly affixed to the distal bearing proximate the distal end of the coiled member, .Iaddend.wherein the balloon is inflated .[.when the cutter is within the occluded stent to urge the cutter toward an inner wall of the occluded stent, the expandable cutter being rotatable in the occluded stent to remove occluding matter.]. .Iadd.with a fluid delivered through the catheter shaft.Iaddend..

2. The .[.system.]. .Iadd.balloon catheter .Iaddend.of claim 1, wherein the coiled member is a .[.diamond coated.]. helical wire.

3. The .[.system.]. .Iadd.balloon catheter .Iaddend.of claim 1, wherein the coiled member is a flat spring .[.having a sharpened outer edge.]..

4. The .[.system.]. .Iadd.balloon catheter .Iaddend.of claim 1, wherein the coiled member is a semi-cylindrical wire .[.having a sharpened edge.]..

.[.5. A method for removing restenotic tissue from within a stent, comprising: advancing a cutter into the stent, the cutter being secured to a drive shaft and including an expandable coil having a cutting surface, wherein the cutting surface is positioned on the coil such that the cutting surface does not contact the stent when removing restenotic tissue from within the stent; rotating the cutter; and aspirating ablated particles of the restenotic tissue..].

.Iadd.6. The balloon catheter of claim 1, wherein the cutter is rotatable to remove occluding matter during use..Iaddend.

.Iadd.7. A medical device, comprising: a catheter shaft having a proximal and a distal end, the catheter shaft being configured to be routed over a guidewire; an inflatable balloon having a proximal end directly affixed to the distal end of the catheter shaft and a distal end directly affixed to a distal member through which the guidewire is routed; and a helical cutter disposed over a portion of the inflatable balloon such that the balloon is disposed within the helical cutter, the helical cutter being a separate component from the inflatable balloon, a proximal end of the helical cutter being directly affixed to the distal end of the catheter shaft proximate the proximal end of the inflatable balloon and a distal end of the helical cutter being directly affixed to the distal member proximate the distal end of the inflatable balloon; wherein the inflatable balloon is inflated with a fluid delivered through the catheter shaft to move the helical cutter radially outward..Iaddend.

.Iadd.8. The medical device of claim 7, wherein the helical cutter includes an abrasive..Iaddend.

.Iadd.9. The medical device of claim 8, wherein the abrasive is a diamond coating..Iaddend.

.Iadd.10. The medical device of claim 7, wherein the helical cutter is a flat spring..Iaddend.

.Iadd.11. The medical device of claim 7, wherein the helical cutter is a wire..Iaddend.

.Iadd.12. The medical device of claim 7, wherein the helical cutter is rotatable to remove occluding matter during use..Iaddend.

.Iadd.13. The medical device of claim 7, wherein the distal member is a distal bearing..Iaddend.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:

(2) FIG. 1 shows a system for removing material from an occluded stent in accordance with one embodiment of the present invention;

(3) FIGS. 2 and 3 illustrate a cutter in accordance with another aspect of the present invention;

(4) FIG. 4 illustrates a cutter for removing material from an occluded stent in accordance with yet another embodiment of the present invention;

(5) FIG. 5 illustrates a helical cutter in accordance with another aspect of the present invention;

(6) FIGS. 5A-5C illustrate various embodiments of helical cutters in accordance with other aspects of the present invention; and

(7) FIG. 6 illustrates a system for operating the helical cutter in accordance with another aspect of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(8) FIG. 1 illustrates one embodiment of a system 10 for removing occluding matter 12 from a stent 14 that is positioned within a vessel 16 according to the present invention. As indicated above, the occluding material 12 is typically different from the occluding material generally associated with arteriosclerosis or other vascular diseases. Once the stent 14 is positioned in the vessel 12, the material 12 that re-occludes the stent is typically a smooth-celled growth that may continue to grow until the lumen or passage through the stent 14 is totally blocked.

(9) To remove the occluding material 12 from the stent, the present invention includes a cutter 20 that is rotated by a drive shaft 22. The drive shaft 22 is advanced and rotated by an advancer/rotational drive 23 at the maximal end of the drive shaft 22. The cutter 20 and the drive shaft 22 are routed within a catheter 30 that is coupled to a source of negative pressure to provide a corresponding negative pressure or slight vacuum within the vessel 16 at the location of the stent. The catheter 30 may have a mechanism for sealing the catheter within the vessel such as a self-expanding stent 32 that is covered with an elastomeric coating such that when the stent 32 expands, the vessel is sealed. Alternatively, inflatable balloons at the end of the catheter 30 or other mechanisms may be used to seal the vessel in order to provide proper aspiration of the ablated particles.

(10) To ensure that the cutter 20 clears a passage with a fairly large diameter, the cutter 20 is preferably routed over a guide wire 40 that is helical or otherwise shaped to force the cutter 20 toward the inner surface of the stent 14 when the cutter is advanced over the guide wire.

(11) In some instances, it may be desirable to deliver a saline solution or other liquid through the drive shaft 22 and/or the cutter 20 to provide additional liquid volume in the vessel so that the vessel 16 doesn't collapse during aspiration. Saline and blood aspirated from the vessel are received in a collecting jar 42 and returned by a pump 44 to the patient via an intravenous drip or other mechanism.

(12) In order to prevent damage to the stent, the cutter 20 as shown in FIG. 2 is preferably made of a material that is soft or softer than the material from which the stent is made. Typically, the stent 14 is made is made of Nitinol™ or stainless steel. Therefore, the cutter 20 is preferably made of a material having a hardness less than or equal to Nitinol™ or stainless steel. As shown in FIG. 3, the cutter 20 has a number of recessed blades 50 that lie within corresponding channels 52. The blades 50 are positioned such that the outer surface of the cutter 20 is relatively smooth and will not catch or cut the inner surface of the stent 14. However, any occluding matter 12 that enters or is forced into the channels 52 is cut by the one or more blades 50 as the cutter 20 is rotated by the drive shaft 22. The channels 52 may be spiralled around the outer surface of the cutter 20 in order to force ablated material proximally as the burr is rotated in order to aid aspiration of the ablated tissue.

(13) FIG. 4 shows an alternative embodiment of a system for removing occluding matter from a stent. Here, a stent 60 is positioned within a vessel 62. The stent is shown as being fully blocked by occluding material 64. To remove the occluding material 64, a catheter 70 is inserted into the vessel. The catheter 70 has a self-expanding stent 72 at its distal end that is preferably covered with an elastomeric or other non-porous material 74 to seal the vessel when the stent 72 expands. One or more extendable cutting knives or blades 76, 77 are secured to the stent 72 such that when the stent is expanded, the one or more knives 76 are urged radially outward toward the vessel wall. In operation, the catheter 70 can be placed within or adjacent to the occluded stent 60. The self-expanding stent 72 is allowed to expand such that the one or more knives 76, 77 are positioned within the stent 60. Thereafter, the catheter 70, self-expanding stent 72, and one or more cutting knives 76, 77 are rotated within the stent to remove portions of the occluding matter 64. Aspiration can be applied to the catheter 70 to remove portions of the occluding material that are cut by the one or more cutting knives 76, 77.

(14) To further hold the catheter 70 in position within the stent, a guide wire 80 has one or more hooks 82 (that may or may not be barbed) at its distal end that can be implanted into the occluding matter 64. The guide wire 80 serves an anchor against which the catheter 70 can be pulled in order to advance the one or more cutting knives 76, 77 within the occluded stent 60. Once the one or more cutting knives 76, 77 are rotated 360° in the stent 60, the guide wire 80 can be further advanced into the occluding material 64 and the process repeated.

(15) FIG. 5 shows yet another alternative embodiment of a system for removing occluding matter from a stent in accordance with the present invention. In this embodiment, a helical cutter 90 extends around a guide wire 92 that is routed within a catheter 94. The cutter 90 extends from the end of the catheter 94 to a distal bearing 96 that is positioned on the guide wire 92. Within the helical cutter 90 is a balloon 98 .Iadd.(shown in phantom lines).Iaddend.. The balloon 98 can be inflated with the saline or other material that is delivered through the catheter 94 .Iadd.(shown by arrows).Iaddend.. Preferably, the catheter 94 is sealed along its length to prevent loss of the material used to inflate the balloon. Inflating the balloon 98 urges the helical cutter 90 radially outward toward the inner surface of a stent.

(16) FIGS. 5A-5C show three of many possible embodiments of the helical cutter 90. The helical cutter 90 can comprise a generally round wire 100 that is selectively coated with an abrasive material such as diamond grit 102 as shown in FIG. 5A. The diamond grit is plated to a wire selectively such that the grit is not exposed on the surfaces that contact the stent itself, if the plated wire momentarily engages the stent, but only cuts deformable restenosis tissue that deforms in the abrasive.

(17) Alternatively, as shown in FIG. 5B, the helical cutter 90 can comprise a relatively flat spring 104 having an outer edge 106 that is sharpened to provide a cutting surface. The material used to make the flat spring 104 preferably has a hardness that is less than or equal to the hardness of the material used to make the stent to be cleared.

(18) Alternatively, as shown in FIG. 5C, the helical cutter 90 can comprise a cutaway tube, such as a hypotube, having a sharpened outer edge 110. The tube is wound into a helical coil around the guide wire. The material used to make the tube should have a hardness less or equal to the hardness of the material used to make the stent.

(19) FIG. 6 shows how a helical cutter 90 of a type shown in FIG. 5 is used within a vessel. The helical cutter 90 is positioned within a partially or totally occluded stent 120 that is within a vessel 122. A catheter 130 is advanced into the vessel 122 and a sealing mechanism such as one or more balloons 134 at the distal end of the catheter is used to seal the vessel. A catheter 94 that contains the helical cutter 90 is then advanced through the catheter 94. The helical cutter 90 is expanded radially outward once it is within the stent 120 by inflating the balloon 98. The catheter 94 is then rotated by a prime mover such as gas turbine or an electric motor (not shown) at the proximal end of the catheters 94 and 130. Rotation of the helical cutter 90 removes the occluding material 124 from the stent 120. In addition, aspiration can be provided to the catheter 130 and/or 94 to remove portions of the ablated, occluding material 124. The aspirated material can be removed from the vessel using a pump 140 and a filter 144 before the aspirated liquid is returned to the patient.

(20) While the preferred embodiment of the invention has been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention. It is therefore intended that the scope of the invention be determined from the following claims and equivalents thereto.