Apparatus and methods for material capture and removal
Catheters, kits, and methods are provided for removing material from a body lumen. The catheters and methods may be used in a variety of body lumens, including but not limited to coronary and other arteries. In general, the catheter has a cutting element that cuts material while the material is engaged by a material capture device on the catheter body. Preferably, the material capture device tensions the material during cutting, which reduces the amount of cutting force required. The material capture device typically follows a path that draws material into the catheter body. Preferably, but not necessarily, the material capture device may be arranged on the catheter body to advance along a path outwardly from the catheter body into the material and then inwardly towards the catheter body to tension the material. The cutting element on the catheter body moves between a first position and a second position to cut the material while in tension.
BACKGROUND OF THE INVENTION
The present invention relates generally to apparatus and methods for removing occluding materials from body lumens. More particularly, the present invention relates to the construction and use of atherectomy catheters for excising atheroma and other materials from blood vessels.
Cardiovascular disease frequently arises from the accumulation of atheromatous material on the inner walls of vascular lumens, particularly arterial lumens of the coronary and other vasculature, resulting in a condition known as atherosclerosis. Atherosclerosis occurs naturally as a result of aging, but may also be aggravated by factors such as diet, hypertension, heredity, vascular injury, and the like. Atheromatous and other vascular deposits restrict blood flow and can cause ischemia which, in acute cases, can result in myocardial infarction. Atheromatous deposits can have widely varying properties, with some deposits being relatively soft and others being fibrous and/or calcified. In the latter case, the deposits are frequently referred to as plaque.
Atherosclerosis can be treated in a variety of ways, including drugs, bypass surgery, and a variety of catheter-based approaches which rely on intravascular widening or removal of the atheromatous or other material occluding a blood vessel. Of particular interest to the present invention, a variety of methods for cutting or dislodging material and removing such material from the blood vessel have been proposed, generally being referred to as atherectomy procedures. Atherectomy catheters intended to excise material from the blood vessel lumen generally employ a rotatable and/or axially translatable cutting blade which can be advanced into or past the occlusive material in order to cut and separate such material from the blood vessel lumen. In particular, side-cutting atherectomy catheters generally employ a housing having an aperture on one side, a blade which is rotated or translated by the aperture, and a balloon or other deflecting structure to urge the aperture against the material to be removed.
Although atherectomy catheters have proven to be very successful in treating many types of atherosclerosis, some catheter designs suffer from certain limitations. For example, many side-cutting atherectomy catheters have difficulty in capturing occluding material in the cutting aperture. To facilitate material capture, the cutting aperture is frequently elongated. Although improving material capture, such lengthening makes it more difficult to introduce the distal end of the catheter through torturous regions of the vasculature. Additionally, it is often difficult for conventional atherectomy cutters to apply the requisite pressure to cut off the targeted material. When higher pressures are applied, damage to the artery (barotrauma) can occur. High pressures can also compress plaque, subsequently reducing the cutter's ability to capture the occlusive material. This decreases the effectiveness of these cutters and limits the cutter and catheter designs.
For these reasons, it is desired to provide atherectomy catheters which can access small, tortuous regions of the vasculature and which can remove atheromatous and other occluding materials from within blood vessels in a controlled fashion with minimum risk of injuring the blood vessel wall. In particular, it is desired to provide atherectomy catheters which can facilitate capturing of occlusive material. It would also be particularly desirable to decrease the amount of force required to cut off occlusive material from the body. At least some of these objectives will be met by the catheter and method of the present invention described hereinafter and in the claims.
SUMMARY OF THE INVENTION
The present invention provides catheters, kits, and methods for removing material from a body lumen. The catheters and methods of the present invention are for use in a variety of body lumens, including but not limited to intravascular lumens such as the coronary artery and other blood vessels. In general, the catheter of the present invention has a cutting element that cuts material engaged by a material capture device on the catheter body. Preferably, the material capture device tensions the material during cutting, which reduces the amount of cutting force required. The material capture device typically follows a path that draws material into the catheter body. Preferably, but not necessarily, the material capture device is arranged on the catheter body to advance along a path outwardly from the catheter body into the material and then inwardly towards the catheter body to tension the material. In some embodiments, the material capture device may extend in an outwardly direction but not beyond the outer diameter of the catheter body. The cutting element on the catheter body moves between a first position and a second position to cut the material while in tension, where motion of the cutting element urges the material capture device to draw cut material into the catheter body.
Desirably, the blade or blades of the catheter will be actuable with the application of reasonable mechanical forces which are capable of being transmitted along even rather lengthy catheters. Further desirably, the catheters will be suitable for directional removal of occluding material and may include mechanisms for engaging cutting blades against selected portions of a vascular wall. Optionally, the engaging mechanisms should permit blood perfusion during performance of an atherectomy procedure.
In one embodiment, the catheter of the present invention uses a material capture device in the form of a material capture needle. The needle will be deployed in a radially outward direction from the catheter body. Preferably, but not necessarily, the needle will capture material while the catheter remains stationary. Some embodiments may use a plurality of material capture needles. The material capture needle may follow a path outwardly from the catheter body in various manners. In one embodiment, the needle has a portion that advances through an elongate slot on the catheter body to move the needle along a path outwardly from the catheter body. Another embodiment uses a curved needle rotatably mounted about a pivot pin. As the needle is rotated, it will protrude outwardly from the catheter body. A preferred embodiment uses a needle having a bias element which urges the needle outwardly when the catheter is in position. Typically, a material cutting element will engage the material that has been captured and sheer off the material into the catheter.
In a further embodiment, a material capture device of the present invention uses a penetrating member mounted to extend through an aperture on the catheter body to penetrate material in advance of the cutting blade and to draw material into the catheter body as the cutting blade is advanced past the aperture. The penetrating member is rotatably mounted to the slidable cutting blade on the catheter body. A cam surface on the catheter body engages a surface of the penetrating member to guide the member along a path to engage the material and draw the material into the catheter body. In a still further embodiment, an abutment or raised portion on the catheter body is mounted to engage one end of the penetrating member. This contact caused the penetrating member to rotate about its pivot point on the cutting blade and thus engage material and draw material into the catheter body.
In another aspect of the present invention, a method is provided for excising occlusive material from within a body lumen. The method involves engaging the occlusive material with a material capture device on a catheter body. The material is drawn in a radially inward direction by the device to tension the material to be cut. A blade is advanced through the tensioned material to sever the material from the body lumen. As mentioned previously, tensioning the material reduces the amount of cutting force required. The tensioning of the occlusive material may also comprise moving the material capture device towards a catheter body while the material capture device is in contact with the occlusive material. Typically, the engaging and tensioning steps may also be performed with a single motion by the user to facilitate cutting.
In a still further aspect, kits according to the present invention will comprise a catheter having a material capture device. The kits will further include instructions for use setting forth a method as described above. Optionally, the kits will further include packaging suitable for containing the catheter and the instructions for use. Exemplary containers include pouches, trays, boxes, tubes, and the like. The instructions for use may be provided on a separate sheet of paper or other medium. Optionally, the instructions may be printed in whole or in part on the packaging. Usually, at least the catheter will be provided in a sterilized condition. Other kit components, such as a guidewire, may also be included.
A further understanding of the nature and advantages of the invention will become apparent by reference to the remaining portions of the specification and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
DESCRIPTION OF THE SPECIFIC EMBODIMENTS
The present invention provides devices, methods, and kits for use in removing material from a body lumen. The present invention may be used in a variety of body lumens, including but not limited to coronary and other arteries. Advantageously, the present invention reduces the amount of force required to cut material and facilitates material capture into apertures of the catheter.
Apparatus according to the present invention will comprise catheters having catheter bodies adapted for intraluminal introduction to the target body lumen. The dimensions and other physical characteristics of the catheter bodies will vary significantly depending on the body lumen which is to be accessed. In the exemplary case of atherectomy catheters intended for intravascular introduction, the catheter bodies will typically be very flexible and suitable for introduction over a guidewire to a target site within the vasculature. In particular, catheters can be intended for “over-the-wire” introduction when a guidewire lumen extends fully through the catheter body or for “rapid exchange” introduction where the guidewire lumen extends only through a distal portion of the catheter body.
Catheter bodies intended for intravascular introduction will typically have a length in the range from 50 cm to 200 cm and an outer diameter in the range from 1 French (0.33 mm; Fr.) to 12 Fr., usually from 3 Fr. to 9 Fr. In the case of coronary catheters, the length is typically in the range from 125 to 200 cm, the diameter is preferably below 8 Fr., more preferably below 7 Fr., and most preferably in the range from 2 Fr. to 7 Fr. Catheter bodies will typically be composed of an organic polymer which is fabricated by conventional extrusion techniques. Suitable polymers include polyvinylchloride, polyurethanes, polyesters, polytetrafluoroethylenes (PTFE), silicone rubbers, natural rubbers, and the like. Optionally, the catheter body may be reinforced with braid, helical wires, axial filaments, or the like, in order to increase rotational strength, column strength, toughness, pushability, and the like. Suitable catheter bodies may be formed by extrusion, with one or more lumens being provided when desired. The catheter diameter can be modified by heat expansion and shrinkage using conventional techniques. The resulting catheters will thus be suitable for introduction to the vascular system, often the coronary arteries, by conventional techniques.
The cutting blades used in the present invention will usually be formed from a metal, but could also be formed from hard plastics, ceramics, or composites of two or more materials, which can be honed or otherwise formed into the desired cutting edge. In the exemplary embodiments, the cutting blades are formed as coaxial tubular blades with the cutting edges defined in aligned apertures therein. It will be appreciated that the present invention is not limited to such preferred cutting blade assemblies, in a variety of other designs, such as the use of wiper blades, scissor blades or the like. Optionally, the cutting edge of either or both the blades may be hardened, e.g., by application of a coating. A preferred coating material is titanium nitride, available from Brycoat, Inc., which may be applied according to manufacturer's instructions.
Referring now to
With the material capture needle 23 deployed as shown in
The catheter 70 is quite useful and an improvement over conventional atherectomy catheters even without incorporation of the material capture needle 74. The decrease in the rigid length of the distal portion of catheter 70 is a significant advantage, particularly when the catheter is introduced to the highly tortuous regions of the coronary vasculature. Once at a desired location, however, the rigid cutter portion of the catheter can be extended in length by 50% or more, with a theoretical limit of 100% for a two-portion telescoping region. In the illustrated embodiment, the cutting aperture 76 is defined only on one of the cutter blades. In other embodiments, it will possible to define the aperture on both of the cutting blades and/or in a variety of configurations. While the cutting blades will preferably employ the cutting edges at each end, the advantages of the telescoping cutter can be enjoyed even without the cutting edges.
Referring now to
In a still further embodiment of the cutting mechanism,
Referring now to
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As seen in
Referring now to
The embodiments of
The positioning wires 510 form from a resilient material, typically stainless steel ribbon or a shape memory alloy ribbon, such as nitinol. The proximal ends of each wire are attached in slots formed near the proximal end of the outer tubular cutter 506 and extend inwardly through openings (not shown) so that their distal ends extend radially inwardly into the interior of the outer tubular cutter, as shown in the left-hand side of
Once positioned at the treatment location, the inner cutting blade 504 may be distally retracted, both opening a cutter window 514 and causing the cam surface 518 on the penetrating member 502 to engage a cam element 520, causing the penetrating tip of the penetrating element 502 to emerge through the cutter window 514 as generally described with the embodiments of
Referring now to
As seen in
Referring now to
Referring now to
While all the above is a complete description of the preferred embodiments of the inventions, various alternatives, modifications, and equivalents may be used. For example, the cutters and material capture devices may be oriented in a variety of angles on the catheter body. As seen in
17. A catheter as in claim 1 wherein said material capture device comprises:
- a penetrating member rotatably mounted on said cutting element; and
- an abutment disposed on said catheter body to engage one end of the penetrable member and cause rotation of the penetrating member from a first, open position to a second, closed position.
18. A catheter as in claim 17 further comprising a tether coupled to said penetrating member to control positioning of the penetrating member.
19. A catheter as in claim 1 wherein said material capture device comprises a penetrating member rotatably mounted on said catheter body and fixedly secured relative to said slidable cutting element;
- a pushing element mounted on said cutting element to engage said penetrating member to move said member between a first position to a second tissue-engaging position.
20. A catheter as in claim 1 wherein said material capture device is configured to be deployed from an aperture in the side wall of the catheter body.
21. A catheter as in claim 20 wherein said cutting element includes an material imaging device mounted to be in an imaging position when said aperture is closed by said cutting element.
22. A catheter as in claim 1 wherein said cutting element includes a first cutting blade having at least one penetrating point.
23. A catheter as in claim 1 wherein said cutting element has a first cutting blade opposed to a second cutting blade for removing said material.
24. A catheter as in claim 1 wherein said cutting element comprises a tubular inner cutter slidably mounted within an outer cutter of the catheter body, said inner cutter coupled to a drive wire actuated by a user.
25. A catheter as in claim 1 wherein said material capture device extends an extension distance outward from the catheter body to engage material, said extension distance equal to the diameter of the catheter body.
26. A catheter as in claim 1 wherein said material capture device includes a barbed distal tip to retain material on the capture device.
27. A catheter as in claim 1 wherein said cutting element further comprises a material imaging device.
28. A catheter as in claim 27 wherein said material imaging device comprises an ultrasound transducer array.
29. A catheter as in claim 1 wherein said material capture device comprises means for penetrating said material.
30. A catheter as in claim 29 wherein said means for penetrating material comprises a curved needle biased outwardly from the catheter body.
31. A catheter as in claim 29 wherein said means for penetrating material comprises a penetrating member rotatably mounted about a pivot pin on said cutting element.
32. A catheter as in claim 29 wherein said means for penetrating material is configured to engage a raised portion on said catheter body to move said means to engage material and then retract material into the catheter body.
33. A catheter as in claim 32 wherein said raised portion comprises a cam surface having a plurality of tracks, wherein each track has a funneled entrance to guide said penetrating member therein.
34. A catheter for removing material from the wall of a body lumen, said catheter comprising:
- a catheter body having a proximal end and a distal end;
- a side aperture on the catheter body;
- a cutting blade adapted to advance past the aperture to sever material which intrudes through the aperture; and
- a penetration member mounted to extend through the aperture to penetrate material in advance of the cutting blade and to draw material into the catheter body as the cutting blade is advanced past the aperture.
35. A catheter as in claim 34 further comprising a cam surface mounted on said catheter body, said cam surface having a surface configured to guide said penetration member into said material when said blade is advanced.
36. A catheter for removing material from a body lumen, said catheter comprising:
- a catheter body having a proximal end and a distal end;
- a material capture device arranged on said catheter body to advance along a path radially outwardly from the catheter body into said material and then inwardly towards the catheter body to tension said material; and
- a cutting element on said catheter body moving between a first position and a second position to cut said material while said material is in tension.
Filed: Jun 19, 2006
Publication Date: Oct 19, 2006
Inventors: Tim Corvi (Belmont, CA), Stephen Boyd (Moss Beach, CA), Brett Follmer (Santa Clara, CA), John Stine (San Jose, CA), David Snow (San Carlos, CA), Darren Doud (San Jose, CA)
Application Number: 11/455,995
International Classification: A61B 10/00 (20060101);