Catheters for arterial lesion modification

Abstract

Embodiments are disclosed of a catheter system (200) including a catheter and a guidewire trap (216). The catheter includes a catheter axis extending in a longitudinal direction, a sidewall (208) having an inner surface (206) bounding a catheter lumen, and a locking mechanism (214) projecting from the inner surface toward the catheter axis in a radial direction normal to the longitudinal direction. The guidewire trap is positioned in the catheter lumen and has a trap body including a trap lumen (218) extending in the longitudinal direction and adapted to receive a guidewire (220) therein, and a collet formed at a trap distal end. The collet includes a tapered outer surface adapted to engage with the locking mechanism in the catheter lumen. When the guidewire trap is pushed in a distal direction through the catheter lumen, the locking mechanism engages with the tapered outer surface to cause the collet to contract radially toward the catheter axis.

Description

CATHETERS FOR ARTERIAL LESION MODIFICATION

[0001] This application claims the benefit of and priority to U.S. Provisional Patent Application No. 63 / 695,772, filed on September 17, 2024, titled “CATHETER WITH GUIDEWIRE TRAP” and U.S. Provisional Patent Application No. 63 / 695,775, filed on September 17, 2024, titled “BUMP CATHETERS FOR ARTERIAL LESION MODIFICATION,” which are incorporated herein by reference in their entirety to provide continuity of disclosure.TECHNICAL FIELD

[0002] The disclosed embodiments relate generally to catheters used to treat conditions such as critical limb ischemia (CLI). More particularly, but not exclusively, they relate to catheters that modify lesions associated with conditions such as CLI.BACKGROUND

[0003] Critical limb ischemia (CLI) is a severe blockage in a patient’s lower extremities (e.g., in a leg, ankle, foot) that can reduce or stop blood flow to the extremities. In particular, CLI can be the result of narrowing of arteries (or arteries that are calcified) over time due to lesions such as inflamed tissue or a buildup of fatty deposits called plaque. Patients with CLI often have diabetic foot ulcers or gangrene, which results in severe pain, and are at high risk of amputation as a result of these arterial blockages, especially those below the ankle.SUMMARY

[0004] Existing catheters may be unable to effectively access and efficiently dilate a lower extremity artery (e.g., the peroneal artery, the dorsalis pedis artery, plantar arteries, etc.) to address a patient’s CLI. Unlike coronary arteries - for which most, if not all, conventionalcatheters are designed - lower extremity arteries can be more tortuous and thinner. As a result, conventional catheters may not be flexible enough and have a thin enough profile to be able to effectively navigate through a lower extremity artery and penetrate lesions in the artery so that further procedures can be performed where a blockage is located.

[0005] To help penetrate a lesion, some catheters use a guidewire positioned in the catheter. But even guidewires can have difficulty penetrating and modifying a lesion if the lesion is too dense or hard. A dense or hard lesion can cause the guidewire to bend or cause it to be pushed back into the interior of the catheter. Therefore, there is a need for a catheter that can use a guidewire to cross a lesion and / or can modify the lesion to allow navigation through the lesion to perform procedures to address conditions such as CLI.

[0006] In an aspect, a catheter system includes a catheter including a catheter axis extending in a longitudinal direction, a sidewall having an inner surface bounding a catheter lumen, and a locking mechanism projecting from the inner surface toward the catheter axis in a radial direction normal to the longitudinal direction. The catheter system includes a guidewire trap positioned in the catheter lumen, the guidewire trap comprising a trap body including a trap lumen extending in the longitudinal direction and adapted to receive a guidewire therein, and a collet formed at a trap distal end. The collet includes a tapered outer surface that is adapted to engage with the locking mechanism in the catheter lumen. When the guidewire trap is pushed in a distal direction through the catheter lumen, the locking mechanism engages with the tapered outer surface to cause the collet to contract radially toward the catheter axis. The catheter system can therefore support the guidewire within the trap lumen to modify and / or cross a lesion.

[0007] In an aspect, a kit includes a guidewire, and a catheter system. The catheter system includes a catheter axis extending in a longitudinal direction, a sidewall having an inner surface bounding a catheter lumen, and a locking mechanism projecting from the inner surface toward- 2 - Docket No. 15695WOO1the catheter axis in a radial direction normal to the longitudinal direction, and a guidewire trap positioned in the catheter lumen, the guidewire trap comprising a trap body including a trap lumen extending in the longitudinal direction and adapted to receive a guidewire therein, and a collet formed at a trap distal end. The collet includes a tapered outer surface that is adapted to engage with the locking mechanism in the catheter lumen. When the guidewire trap is pushed in a distal direction through the catheter lumen, the locking mechanism engages with the tapered outer surface to cause the collet to contract radially toward the catheter axis.

[0008] In an aspect, a method includes inserting a catheter system into a blood vessel and navigating the catheter system through the blood vessel to a lesion in the blood vessel. The catheter system comprises a catheter having a catheter lumen, a guidewire trap positioned in the catheter lumen, the guidewire trap having a trap lumen, and a guidewire positioned in the trap lumen. The method includes activating the guidewire trap to engage the guidewire. The method includes advancing the engaged guidewire trap and the guidewire through the lesion.

[0009] In an aspect, a bump catheter includes a catheter body having a catheter axis extending in a longitudinal direction, and a sidewall having an interior surface bounding a lumen. The bump catheter includes a first bump set including several first bumps formed on an exterior surface of the sidewall and projecting from the exterior surface in a radial direction normal to the longitudinal direction. The bump catheter includes a second bump set including several second bumps formed on the exterior surface and projecting from the exterior surface in the radial direction. The second bump set is positioned at a different longitudinal location than the first bump set. The bump sets can engage and modify a lesion to facilitate lesion crossing.

[0010] In an aspect, an expandable bump catheter includes a catheter body including a catheter axis extending in a longitudinal direction, and a sidewall having an interior surface bounding a primary lumen. The catheter body includes a proximal section, a distal section longitudinally movable relative to the proximal section along the catheter axis, and an- 3 - Docket No. 15695WOO1expanding section between the proximal section and the distal section. The expanding section includes several slits formed in the sidewall. Interstitial parts of the sidewall between slits form several sidewall columns. A pair of pull wires are positioned in the catheter body. The pair of pull wires is movable relative to the proximal section and is attached to the distal section.

[0011] In an aspect, a method includes inserting a catheter into a blood vessel and navigating the catheter to a lesion in the blood vessel. The method includes modifying the lesion by engaging the lesion with a bump on the catheter.BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Non-limiting and non-exhaustive embodiments of the present invention are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified.

[0013] FIGS. 1A-1B are diagrams of an embodiment of a catheter used to penetrate a lesion in a blood vessel.

[0014] FIGS. 2A-2B are drawings of an embodiment of a catheter including a guidewire trap.

[0015] FIGS. 3A-3D are views of an embodiment of a guidewire trap.

[0016] FIGS. 4A-4D are views of embodiments of locking mechanisms that can be positioned in a catheter lumen to engage a guidewire trap.

[0017] FIGS. 5A-5B are views of other embodiments of locking mechanisms that can be positioned in a catheter lumen to engage a guidewire trap.

[0018] FIG. 6 is a flowchart of an embodiment of a process for using a catheter with a guidewire trap.

[0019] FIGS. 7A-7E are drawings of an embodiment of a bump catheter.- 4 - Docket No. 15695WOO1

[0020] FIGS. 8A-8E are side views of embodiments of bump profdes that can be used in a bump catheter.

[0021] FIGS. 9A-9C are proximal- or distal -facing views of embodiments of bump profdes that can be used in a bump catheter.

[0022] FIGS. 10A-10D are views of an embodiment of an expandable bump catheter.

[0023] FIGS. 11A-1 IB are views of an embodiment of a positioning of pull wires within an expandable bump catheter such as the one shown in FIGS. 10A-10D.

[0024] FIGS. 12A-12B are views of another embodiment of a positioning of pull wires within an expandable bump catheter such as the one shown in FIGS. 10A-10D.

[0025] FIG. 13 is a flowchart of an embodiment of a method for using the bump catheter of FIGS. 7A-7E.

[0026] FIG. 14 is a flowchart of an embodiment of a method for using the expandable bump catheter of FIGS . 10A- 10D .DETAILED DESCRIPTION

[0027] Embodiments are described of a catheter that includes a guidewire trap that resists longitudinal movement of a guidewire. Embodiments are also described of a bump catheter for modification of lesions in a blood vessel. Specific details are described to provide an understanding of the embodiments, but one skilled in the relevant art will recognize that the invention can be practiced without one or more of the described details or with other methods, components, materials, etc. In some instances, well-known structures, materials, or operations are not shown or described in detail but are nonetheless encompassed within the scope of the invention.

[0028] Reference throughout this specification to “one embodiment” or “an embodiment” means that a described feature, structure, or characteristic can be included in at least one- 5 - Docket No. 15695WOO1described embodiment, so that appearances of “in one embodiment” or “in an embodiment” do not necessarily all refer to the same embodiment. Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments.

[0029] As used in this application, directional terms such as “left,” “right,” “front,” “rear,” “upper,” lower,” “top,” “bottom,” “side,” “lateral,” “longitudinal,” etc., refer to the orientations of embodiments as they are presented in the drawings, but any directional term should not be interpreted to imply or require a particular orientation of the described embodiments when in actual use. The use of relative terms throughout the description can denote a relative position or direction. For example, “distal” can indicate a first direction along a longitudinal axis of a catheter system and “proximal” can indicate a second direction opposite to the first direction. Such terms are provided to establish relative frames of reference, but are not intended to limit the use or orientation of the disclosed devices to a specific configuration described in the various embodiments below.

[0030] FIGS. 1A-1B illustrate an embodiment of a catheter 100 used for treatment of conditions such as critical limb ischemia (CLI). During treatment, catheter 100 can be used to penetrate and modify a lesion 110 in a blood vessel 108. Lesion 110 can, for instance, be a deposit such as plaque or can be inflamed tissue, including inflamed tissue that has calcified and hardened. Catheter 100 includes a catheter body 102 with a proximal end 102p and a distal end 102d. A lumen 104 is formed within the catheter body and runs the entire length of the catheter from the proximal end to the distal end. A guidewire 106 is positioned within the lumen. The guidewire is longer than the length of the lumen, so that the guidewire projects out the proximal and distal ends of catheter body 102. In operation, as shown in FIG. 1A, catheter body 102 and guidewire 106 are advanced into blood vessel 108 until just before lesion 110. As shown in FIG. IB, guidewire 106 is then advanced into the bulk of the lesion 110 until the distal end of the guidewire crosses the lesion to be dilated. Catheter body 102 is then advanced- 6 - Docket No. 15695WOO1through the lesion over the previously-introduced guidewire until the catheter is properly positioned across the lesion, thus modifying the lesion to allow further procedures to be performed.

[0031] FIGS. 2A-2B together illustrate an embodiment of a catheter system 200 that includes a guidewire trap. FIG. 2A shows the guidewire trap in an open state and FIG. 2B shows the guidewire trap in a closed state.

[0032] Catheter system 200 includes a catheter body 202. The catheter body is a flexible tube with a proximal end 202p, a distal end 202d, an outer surface 204 and an inner surface 206. The material between the outer and inner surfaces defines a sidewall 208 of the catheter, and inner surface 206 forms the boundary of a catheter lumen 210 within the catheter body. Catheter lumen 210 runs the entire length of the catheter body from proximal end 202p to distal end 202d. A longitudinal axis, e.g., a catheter axis 212, runs along the center of catheter body 202 and, if catheter lumen 210 is centered in the catheter body, also along the center of the catheter lumen.

[0033] In various embodiments, catheter body 202 can be made from a hard but flexible material such as a polyamide or polytetrafluoroethylene (PTFE). Embodiments of catheter body 202 need not have constant stiffness, but can instead have a stiffness profile — that is, the stiffness of the catheter body can vary with longitudinal position along the catheter body. In the illustrated embodiment the catheter is straight, so that catheter axis 212 is also straight. But because the catheter can be flexible and can be bent into shapes that are not straight, catheter axis 212 also need not be straight.

[0034] Catheter body 202 includes a locking mechanism 214. The locking mechanism is positioned at or near distal end 202d of the catheter and projects radially inward, e.g., in a radial direction normal to the longitudinal direction, from inner surface 206 toward catheter axis 212. Embodiments of locking mechanism 214 are discussed below in connection with FIGS. 4A-4D and 5A-5B.- 7 - Docket No. 15695WOO1

[0035] A guidewire trap 216 is positioned in catheter lumen 210 and can move longitudinally (e.g., substantially along catheter axis 212 in both proximal and distal longitudinal directions) through the catheter lumen. Guidewire trap 216 includes a trap lumen 218 within which a guidewire 220 is positioned. In one embodiment, guidewire 220 is a thin wire, such as a 0.014 inch metal wire with constant stiffness, but in other embodiments guidewire 220 need not have constant stiffness but can instead have a stiffness profile — that is, the stiffness of the guidewire can vary with longitudinal position along the guide wire. In one example of a guide - wire stiffness profile, the guidewire can be less stiff at the distal end than at more proximal positions, so that the distal end of the guidewire can bend more easily around curves in a blood vessel. Guidewire trap 216 includes a tapered section 222 at its distal end. Tapered section 222 forms a collet that can be used to grip or trap a guidewire 220. Further details of tapered section 222 are discussed below in connection with FIGS. 3A-3D.

[0036] In operation of catheter system 200, the catheter body 202, guidewire trap 216, and guidewire 220 are inserted into a blood vessel and navigated to the location of a lesion to be penetrated. Normally the guidewire can then be used for initial penetration of the lesion, as also shown in FIGS. 1A-1B. But in some cases, the lesion can be too dense or hard and the distal end of the guidewire can have difficulty penetrating the lesion. For example, the distal end of the guidewire might not be stiff enough, so that when pushed distally it buckles instead of penetrating the lesion. In another example, the guidewire might not buckle but still be unable to penetrate the lesion, so that when the catheter is advanced in a distal direction the guidewire moves proximally relative to the catheter body and retreats back into catheter lumen 210 and trap lumen 218. In these cases, the guidewire trap 216 can be used to secure the guidewire. Securing the guidewire with the guidewire trap helps the distal end of the guidewire to penetrate the lesion in at least two ways: it decreases the effective column length of the distal end so that the distal end will not buckle as easily, and it prevents retreat of the guidewire back into the- 8 - Docket No. 15695WOO1catheter body and the trap body. Put differently, the guidewire trap supports the guidewire and increase the tip load.

[0037] To activate guidewire trap 216, the trap is pushed distally (e.g., in a distal direction) relative to catheter body 202, so that it moves from the position shown in FIG. 2A to the position shown in FIG. 2B. When pushed distally, tapered section 222 engages with locking mechanism 214. Locking mechanism 214 in turn exerts an inward radial force on tapered section 222, closing the segments of the collet around guidewire 220 and thus trapping the guidewire (see FIGS. 3A-3D). The trapped guidewire 220 is supported to resist movement of the guidewire relative to the catheter body 202 and thus facilitate system crossing through the lesion.

[0038] FIGS. 3A-3D together illustrate an embodiment of a guidewire trap 216. As seen in FIG. 3 A, guidewire trap 216 has a proximal end 216p and a distal end 216d and is made up of proximal section 302 and a tapered section 222. A trap lumen 218 runs from substantially through the center of the guidewire trap proximal end 216p to distal end 216d. A body axis 304 runs along the center of trap lumen 210. When inserted in trap lumen 218, guidewire 220 runs substantially along body axis 304.

[0039] Proximal section 302 has a substantially annular cross-section with constant outside radius Rl. Tapered section 222, as previously noted, tapers in a distal direction — e.g., the radius of tapered section 222 decreases from radius R2 near the distal end to radius R3 at the distal end, where R2 > R3. In the illustrated embodiment R2 > Rl, but in other embodiment R2 can be substantially equal to Rl so that tapered section 222 does not form an arrowhead shape as shown in the figure. As a result of its taper, tapered section 222 has a tapered outer surface 306; in an embodiment where proximal section 302 and tapered section 222 have an annular cross-section, tapered outer surface 306 will, in three dimensions, form a conical or frustoconical surface. As discussed above for FIG. 2B, locking mechanism 214 in the catheter lumen engages tapered outer surface 306 to close the collet.- 9 - Docket No. 15695WOO1

[0040] FIG. 3B is a cross-section taken substantially at section line B-B in FIG. 3A showing that, in the illustrated embodiment of guidewire trap 216, proximal section 302 has a substantially annular cross-section with trap lumen 218 forming a central void of the annulus. Guidewire 220 is positioned in the trap lumen.

[0041] FIGS. 3C-3D are cross-sections taken substantially at section line C-C in FIG. 3 A, illustrating the construction of tapered section 222. Tapered section 222 has a generally annular cross-section, but in at least part of tapered section 222 the anulus is split into separate segments 308 that together form a collet. In the illustrated embodiment the collet is formed by four segments 308a-308d, but in other embodiments the collet can be formed with a different number of segments than shown. Trap lumen 218 is substantially at the center of segments 308a- 308d, and guidewire 220 can be positioned within trap lumen 218. FIG. 3C show the collet in an open position, where the collet segments 308 do not engage guidewire 220.

[0042] FIG. 3D shows tapered section 222 with the collet in a closed position in which segments 308 have moved radially inward toward body axis 304 to engage guidewire 220. As a result of tapered outer surface 306 engaging with locking mechanism 214 when guidewire trap 216 is pushed distally through the catheter lumen (see FIGS. 2A-2B), the locking mechanism applies a radially inward force F on collet segments 308a-308d. As a result of the radially inward force, the segments deflect radially inward to engage and retain guidewire 220.

[0043] FIGS. 4A-4D illustrate embodiments of locking mechanisms that can be used in catheter system 200. FIG. 4A is a side view of catheter system 200, illustrating that catheter body 202 includes a locking mechanism 214 positioned at or near distal end 202d of the catheter and projecting radially inward, from inner surface 206 toward catheter axis 212. FIGS. 4B-4D are cross-sections, taken substantially at section line B-B in FIG. 4A, of different embodiments of locking mechanisms.- 10 - Docket No. 15695WOO1

[0044] FIG. 4B illustrates an embodiment of a locking mechanism 400. Locking mechanism 400 includes a ring 402 that projects radially inward, toward catheter axis 212, from inner surface 206 of catheter body 202 and extends completely around a perimeter of inner surface 206, forming a complete annular ring along inner surface 206.

[0045] FIG. 4C illustrates another embodiment of a locking mechanism 425. Locking mechanism 425 includes a number of discrete bumps that projects radially inward, from inner surface 206 of catheter body 202 toward catheter axis 212. The illustrated embodiment has four bumps 426a-426d, but other embodiments can have more or less bumps than shown; in some embodiments, the number of bumps will equal the number of collet segments in tapered section 222 (see FIGS. 3A-3D), but that need not be the case in other embodiments. In the illustrated embodiment bumps 426a-426d are uniformly spaced around the perimeter (e.g., they have a regular angular spacing), but in other embodiments the angular spacing between bumps need not be regular. In the illustrated embodiment bumps 426 have a partially circular cross-section, but in other embodiments the bumps can have a different cross-section, such as a partial ellipse.

[0046] FIG. 4D illustrates another embodiment of a locking mechanism 450. Locking mechanism 450 is in most respects similar to locking mechanism 425. The primary difference between locking mechanisms 425 and 450 is that locking mechanism 450 replaces bumps 426a-426d with tabs 452a-452d that have a quadrilateral cross-section. In the illustrated embodiment bumps 452 have a substantially square cross-section, but in other embodiments the tabs can have a different quadrilateral cross-section, such as rectangular or trapezoidal, or can have a cross-section that is a non-quadrilateral polygon.

[0047] FIGS. 5A-5B illustrate other embodiments of locking mechanisms that can be used in catheter system 200. FIG. 5A illustrates an embodiment in which catheter body 202 is divided into a proximal section 502 and a distal section 504. Proximal section 502 has an inner- 11 - Docket No. 15695WOO1surface 206 with a substantially constant radius Rl, but distal section 504 has a tapered inner surface 506 that tapers in a distal direction — e.g., the radius of tapered inner surface 506 decreases from radius Rl near the proximal end of distal section 504 to radius R2 at distal end 202d, where Rl > R2. In this configuration, then, the inner surface of the catheter body has two sections: a first section having an un-tapered inner surface 206 and a second section having the tapered inner surface 506. The second section having the tapered inner surface 506 can then function as a locking mechanism for guidewire trap 216.

[0048] FIG. 5B illustrates an embodiment in which catheter body 202 is divided into a proximal section 552 and a distal section 554. In distal section 554, sidewall 208 is “necked” — that is, sidewall 208 has a radial contraction 556 that bows or contracts radially inward toward catheter axis 212. In this configuration, radial contraction 556 can function as a locking mechanism for guidewire trap 216.

[0049] FIG. 6 illustrates an embodiment of a method 600 for using a catheter with a guidewire trap, such as catheter system 200 (see FIGS. 2A-2B). The process starts at block 602. At block 603, the guidewire is inserted in the trap lumen and the guidewire, with the guidewire trap inside, is inserted in the catheter lumen. At block 604, catheter system 200 is inserted into a blood vessel and navigated through the blood vessel until it reaches a lesion. Upon reaching a lesion at block 604, the process can take two different paths.

[0050] In the first path, the process moves from block 604 to block 606, where the guidewire trap is pushed distally so that it engages the guidewire. Once the guidewire trap has been activated and the guidewire engaged, the process moves to block 608, where the guidewire is pushed through the lesion.

[0051] In the second path, the process moves from block 604 to block 610, where the surgeon can first evaluate the hardness or density of the lesion by trying to push the guidewire through the lesion without using the guidewire trap. At block 612 the process evaluates the- 12 - Docket No. 15695WOO1result of the test at block 610. If at block 612 the guidewire easily penetrates the lesion without being engaged by the guidewire trap, then the process moves to block 608, where the guidewire is pushed through the lesion. But if at block 612 the guidewire does not easily penetrate the lesion, the process moves to block 606, where the guidewire trap engages the guidewire, and then moves to block 608, where the guidewire is pushed through the lesion.

[0052] Whether the process arrives at block 608 by the first path or the second path, the process then moves to block 614, where the catheter is then pushed through the lesion, following the guidewire, until the catheter is substantially within the lesion. From block 614, the process moves on to block 616, where the surgeon performs the needed procedure. When the procedure at block 616 is complete, the process moves to block 618, where the catheter is withdrawn from the patient, and then moves on to block 620, where the process stops.

[0053] FIGS. 7A-7E together illustrate an embodiment of a bump catheter 700. FIG. 7A is a side view of the bump catheter and FIGS. 7B-7D are, respectively, cross-sectional views taken substantially along section lines B-B, C-C, and D-D in FIG. 7A. FIG. 7E is a cross- sectional view illustrating the angular relationship that can exist between bump groups.

[0054] Bump catheter 700 includes a catheter body 702. The catheter body is a flexible tube with a proximal end 702p, a distal end 702d, an outer surface 704 and an inner surface 706. In various embodiments, catheter body 702 can be made of a hard but flexible material such as a polyamide or polytetrafluoroethylene (PTFE). Embodiments of catheter body 702 need not have constant stiffness, but can instead have a stiffness profile — that is, the stiffness of the catheter body can vary with longitudinal position along the catheter body. The material between the outer and inner surfaces defines a sidewall 708 of the catheter, and inner surface706 forms the boundary of a lumen 710 within the catheter. Lumen 710 runs the entire length of the catheter from proximal end 702p to distal end 702d. A catheter axis 712 runs along the center of catheter body 702 and, if lumen 710 is centered in the catheter body, also along the- 13 - Docket No. 15695WOO1center of the lumen. In the illustrated embodiment the catheter is straight, so that axis 712 is also straight. But because the catheter is flexible and can be bent into shapes that are not straight, axis 712 also need not be straight. The lumen is sized to accommodate a guidewire 711, and the guidewire usually extends from outside proximal end 702p to outside distal end 702d.

[0055] Catheter body 702 includes a number of bump sets S. Each bump set S includes one or more bumps projecting radially from outer surface 704. The illustrated embodiment has three bump sets S: a first bump set SI, second bump set S2, and third bump set S3. But other embodiments of bump catheter 700 can have more or less bump sets than shown. In one embodiment the bumps are formed directly in or on the catheter body, so that the bumps and the catheter body form an integrated whole. But in other embodiments the bumps can be physically separate elements that are then attached to outer surface 704, for instance with an adhesive in one embodiment.

[0056] The bump sets are positioned at different longitudinal positions along catheter body 702: bump set SI is the most distal, bump set S3 is the most proximal, and bump set S2 is between bump sets SI and S3. In the illustrated embodiment, the longitudinal spacing (e.g., spacing along axis 712) between bump sets is uniform, so that longitudinal distance LI separating bump sets S 1 and S2 is substantially equal to longitudinal distance L2 separating bump sets S2 and S3. In one embodiment, distances LI and L2 can both be about 3cm, but in other embodiments the spacing can be different. And in still other embodiments the spacing between bump sets need not be uniform, so that LI L2.

[0057] Within each bump set, the individual bumps have a longitudinal dimension W (e.g., a dimension along axis 712) and a transverse or radial dimension R (e.g., a dimension normal to axis 712): bump set SI has a longitudinal dimension W1 and radial dimension Rl, S2 has longitudinal dimension W2 and radial dimension R2, and S3 has longitudinal dimension W3- 14 - Docket No. 15695WOO1and radial dimension R3. In the illustrated embodiment, the radial dimension increases with proximal distance from distal end 702d, so that R3 > R2 > R1. In one embodiment, for instance, R3 can be approximately twice R1 (R3 « 2 x Rl). But in other embodiments the radial dimensions R of the bumps can have different relative sizes. And, in still other embodiments, radial dimensions R need not increase with proximal distance from the distal end.

[0058] In the illustrated embodiment the bumps in every set, when viewed normally to axis 712, have a substantially triangular shape, as shown in FIG. 7A. In this embodiment, as a result of their triangular shape each bump has a double radial taper: moving in either the proximal or distal direction, each bump first reverse-tapers radially from radially narrow to radially wide, starting at a minimum radial dimension at outer surface 704 and reaching a maximum radial dimension at the apex. Each bump then tapers from radially wide back to radially narrow at outer surface 704. But in other embodiments the bumps can be configured differently: the bumps need not be triangular (see, e.g., FIGS. 8A-8E), not all bumps in a bump set need have the same shape, and the bumps in one bump set can have a different shape than bumps in other bump sets.

[0059] FIGS. 7B-7D illustrate embodiments of bump sets S1-S3. FIG. 7B is a cross-sectional view of bump set SI taken substantially along section line B-B in FIG. 7A, FIG. 7C is a cross-sectional view of bump set S2 taken substantially along section line C-C in FIG. 7A, and FIG. 7D is a cross-sectional view of bump set S3 taken substantially along section line D-D in FIG. 7A.

[0060] In the illustrated embodiments of bump sets S1-S3, every bump set has four individual bumps that are spaced along the perimeter of catheter body 702 at a regular angular spacing — that is, angles al-a4, p 1- p4, and yl-y4 are all 90 degrees. But in other embodiments the bump sets can be configured differently than shown. In one embodiment, each bump set can include more or less bumps than shown, resulting in different angular spacing than- 15 - Docket No. 15695WOO1shown (e.g., if bump set SI had three regularly-spaced bumps instead of four, then al-a3 would be 120 degrees and there would be no a4). In other embodiments the bumps in a given bump set can have an irregular angular spacing (e.g., in bump set SI angles al-a4 need not all have the same value), and in still other embodiments every bump set need not have the same number of bumps.

[0061] As shown in FIGS. 7B-7D, each bump set can include bumps of different sizes and different cross-sectional shapes. In the illustrated embodiment, the bumps in every bump set have the same dimensions and have a tapered cross-sectional shape, with curved apexes in sets S2 and S3. But in other embodiments the bumps can have different cross-sectional shapes than shown (see, e.g., FIGS. 9A-9C) and not every bump set, nor every bump within a bump set, need have the same cross-sectional shape. In other embodiments, the bumps can also have different radial dimensions and circumferential dimensions (e.g., the dimensions of the bumps along the circumference of outer surface 704) within each bump set or in different bump sets.

[0062] FIG. 7E illustrates an embodiment of angular offset between bump groups in a bump catheter such as bump catheter 700. As illustrated in FIGS. 7B-7D, the bumps in each bump set are angularly spaced from each other, but in some embodiments it can be desirable for the bump sets to be angularly offset from each other. As shown in FIG. 7E, bump set S2 is angularly offset from bump set SI by angle ([> and bump set S3 is angularly offset from bump set SI by angle 0, so that bump set S3 is angularly offset from bump set SI by angle 0 - c|). In an embodiment where all bump sets have the same number of bumps and the bumps are regularly angularly spaced, all bumps in every bump set will be aligned if c|) = 0 = 0. In other embodiments not all bump sets need be angularly offset from each other. For instance, in another embodiment bump sets S 1 and S3 can be aligned but bump set S2 can be offset, in which case 0 = 0 and ([> 0.- 16 - Docket No. 15695WOO1

[0063] FIGS. 8A-8E illustrate other embodiments of bump shapes that can be used in bump catheter 700 besides the substantially triangular shapes shown in FIG. 7A. FIG. 8A illustrates an embodiment of a semi-circular bump, but in other embodiments the bump can be formed by any segment of a circle. A segment is defined as the part of a circle enclosed between an arc of the circle and a straight line that intersects the arc; where the straight line coincides with the diameter of the circle, the segment is a semi-circle. FIG. 8B illustrates an embodiment of a semi-elliptical bump, but in other embodiments the bump can be formed by any segment of an ellipse. As in the embodiment of FIG. 8 A, in an elliptical embodiment a segment is a part of an ellipse enclosed between an arc of the ellipse and a straight line that intersects the arc; where the straight line coincides with the major axis or minor axis of the ellipse, the segment is a semi-ellipse.

[0064] FIGS. 8C-8E illustrate embodiments of quadrilateral bumps. FIG. 8C illustrates a rectangular bump, but in an embodiment of FIG. 8C where the bump has equal dimensions the bump will be a square (e.g., a square is a special case of a rectangle). FIG. 8D illustrates a trapezoidal bump which tapers radially (e.g., the dimension W of the bump at outer surface 704 is greater than the dimension at the tip of the bump). FIG. 8E illustrates a reverse-trapezoidal bump with an inverse radial taper (e.g., the dimension W of the bump at outer surface 704 is smaller than the dimension at the tip of the bump).

[0065] FIGS. 9A-9C illustrate embodiments of bump cross-sections that can be used in bump catheter 700. FIG. 9A illustrates an embodiment of a bump with constants width. FIG. 9B illustrates an embodiment of a tapered bump (see also FIGS. 7B-7D), and FIG. 9C illustrates an embodiment of a reverse-tapered bump.

[0066] FIGS. 10A-10D together illustrate an embodiment of an expandable bump catheter1000. FIG. 10A shows the bump catheter in its contracted state, FIGS. 10B-10C respectively- 17 - Docket No. 15695WOO1show cross-sections of the catheter at section lines B-B and C-C in FIG. 10A, and FIG. 10D shows the expandable bump catheter in its expanded state.

[0067] Bump catheter 1000 includes a catheter body 1002. The catheter body is a flexible tube that has a proximal end 1002p, a distal end 1002d, an outer surface 1004 and an inner surface 1006. In various embodiments, catheter body 1002 can be made of a hard but flexible material such as a polyamide or polytetrafluoroethylene (PTFE). Embodiments of catheter body 1002 need not have a uniform stiffness but can instead have a stiffness profile — that is, the stiffness of the catheter body can vary with longitudinal (proximal or distal) position along the catheter body.

[0068] The material between outer surface 1004 and inner surface 1006 defines a sidewall 1008 of the catheter, and inner surface 1006 forms the boundary of a primary lumen 1010 within the catheter. Primary lumen 1010 runs the entire length of the catheter from proximal end 1002p to distal end 1002d. A catheter axis 1012 runs along the center of catheter body and, if the primary lumen is centered in the catheter body, axis 1012 also runs along the center of the primary lumen. In the illustrated embodiment the catheter is straight, so that axis 1012 is also straight. But because the catheter body can be bent into different shapes, axis 712 need not always be straight. The primary lumen can accommodate a guidewire 1011, and the guidewire usually extends from outside proximal end 1002p to outside distal end 1002d (see, e.g., FIGS. 1A-1B).

[0069] Catheter body 1002 has three sections: a proximal section 1014, a distal section 1016, and an expanding section 1018 between the proximal and distal sections. Distal section 1016 is movable relative to proximal section 1014 along axis 1012 in both the proximal and distal directions. Expanding section 1018 includes a plurality of longitudinally-running slits 1020 that are formed in and completely penetrate sidewall 1008 — that is, the slits extend throughout the entire thickness of sidewall 1008 from outer surface 1004 to inner surface 1006.- 18 - Docket No. 15695WOO1Forming slits 1020 this way creates a plurality of sidewall columns 1022 in the interstices between slits. Each sidewall column 1022 is bounded by outer surface 1004, inner surface 1006, and adjacent slits 1020.

[0070] A pair of auxiliary lumens 1024 are formed in sidewall 1008 and run from proximal end 1002p to at least the boundary between expanding section 1018 and distal section 1016. The illustrated embodiment has two diametrically-opposed auxiliary lumens, but other embodiments can have more or less auxiliary lumens (including no auxiliary lumens; see, e.g., FIGS. 11A-11B). In other embodiments with auxiliary lumens, the auxiliary lumens need not be positioned within the sidewall (see, e.g., FIGS. 12A-12B) nor do they need to be regularly spaced around the circumference as shown.

[0071] A pair of pull wires 1026 runs through auxiliary lumens 1024, with one pull wire in each auxiliary lumen. The pull wires extend from outside proximal end 1002p through their corresponding auxiliary lumens to distal section 1016, where the pull wires are attached to distal section 1016. Other embodiments can use a different number of pull wires, and in embodiments without auxiliary lumens, the pull wires can run through the primary lumen (see, e.g., FIGS. 11A-11B). In one embodiment, pull wires 1026 can be athin single-strand wire or a thin braided cable, but in other embodiments the pull wires can be made of some other material.

[0072] FIGS. 10A and 10D together illustrate the operation of expandable bump catheter 1000: FIG. 10A shows the unexpanded bump catheter, and FIG. 10D shows the expanded catheter. In operation, bump catheter 1000 and guidewire 1011 are inserted into a blood vessel with the catheter in its unexpanded state and navigated to a point where it becomes necessary to get the catheter through a lesion (see, e.g., FIGS. 1A-1B). The guidewire can be used to penetrate the lesion, and bump catheter 1000 can also be radially expanded to help modify the lesion so that the catheter can go through it.- 19 - Docket No. 15695WOO1

[0073] To radially expand bump catheter 1000, pull wires 1026 are pulled proximally (e.g., in a proximal direction, as illustrated by the arrows in FIG. 10D) while holding proximal section 1014, so that the pull wires move relative to the proximal section. Because the pull wires move relative to proximal section 1014 but are attached to distal section 1016, distal section 1016 is pulled along axis 1012 toward proximal section 1014, applying a compression load on sidewall columns 1022. In response to the applied compression load, sidewall columns 1022 buckle and radially outward, decreasing the length of expanding section 1018 from original length A to a shorter length 8 and simultaneously increasing the radius of the catheter from its original radius r to a greater radius R. By buckling radially outward, sidewall columns 1022 thus increase the diameter of the catheter and can help the guidewire modify a lesion by pressing on the lesion. In some embodiments, the radial expansion of expanding section 1018 can be reversed — e.g., the expanding section can be restored to its unexpanded state by either releasing the pull wires or pushing them in a distal direction.

[0074] FIGS. 11A-1 IB together illustrate an alternative embodiment of the routing of pull wires 1026 through the catheter body in an expandable catheter such as expandable bump catheter 1000. FIG. 11A is a cross-section of the proximal section 1014, FIG. 1 IB a cross-section of the expanding section 1018. This embodiment does not include auxiliary lumens 1024, so that pull wires 1026 must be routed through primary lumen 1010 from proximal end 1002p to distal section 1016.

[0075] FIGS. 12A-12B together illustrate an alternative embodiment of the routing of pull wires 1026 in an expandable catheter such as expandable bump catheter 1000. FIG. 12A is a cross-section of the proximal section 1014, FIG. 12B a cross-section of the expanding section 1018. This embodiment includes external auxiliary lumens 1202 formed on the exterior of the catheter body on outer surface 1004 instead of in sidewall 1008. As in an embodiment auxiliary- 20 - Docket No. 15695WOO1lumens 1024 in the sidewalls, in this embodiment pull wires 1026 are routed from proximal end 1002p to distal section 1016 through external auxiliary lumens 1202.

[0076] FIG. 13 illustrates an embodiment of a method 1300 for using a bump catheter such as bump catheter 700 (see FIGS. 7A-7E). The process starts at block 1302. At block 1304, the bump catheter is inserted into a blood vessel and navigated through the blood vessel until it reaches a lesion. Upon reaching a lesion, at block 1306 the guidewire is pushed through the lesion until the lesion is penetrated. At block 1308, the bump catheter is then pushed through the lesion, following the guide wire, until at least some of the bump sets on the exterior of the bump catheter have engaged with, and modified, the lesion.

[0077] At block 1310, the modification of the lesion is checked to see if it was sufficiently modified by the bump catheter. If at block 1310 the lesion is sufficiently modified, the process moves on to block 1312, where the surgeon performs the needed procedure. When the procedure is complete, the process moves to block 1314, where the bump catheter is withdrawn from the patient, and then moves on to block 1316, where the process stops.

[0078] But if at block 1310 the lesion was not sufficiently modified by the bump catheter, then at block 1318 the bump catheter can be retracted through the lesion. From block 1318, the process moves to block 1320, where the bump catheter is pushed through the lesion again, and then returns to block 1310 to check whether the lesion has been sufficiently modified. This sequence of blocks 1310, 1318, and 1320 can be repeated until the lesion is satisfactorily modified.

[0079] FIG. 14 illustrates an embodiment of a method 1400 for using an expandable bump catheter such as expandable bump catheter 1000 (see FIGS. 10A-10D). The process starts at block 1402. At block 1404, the expandable bump catheter is inserted into a blood vessel and navigated through the blood vessel until it reaches a lesion. Upon reaching a lesion, at block 1406 the guidewire is pushed through the lesion until the lesion is penetrated. At block 1408,- 21 - Docket No. 15695WOO1the expandable bump catheter is then pushed through the lesion, following the guidewire, until expanding section 1018 is substantially within the lesion.

[0080] At block 1410 expanding section 1018 is expanded by pulling pull wires 1026 proximally, so that distal section 1016 is pulled toward proximal section 1014 and sidewall columns 1022 buckle outward. The outwardly-buckling sidewall columns 1022 form a bump that engages and modifies the lesion. At block 1412, the modification of the lesion is checked to see if it was sufficiently modified by the expansion of expanding section 1018. If at block 1412 the lesion is sufficiently modified, the process moves on to block 1414, where the surgeon performs the needed procedure. When the procedure at block 1414 is complete, the process moves to block 1416, where the expandable bump catheter is withdrawn from the patient, and then moves on to block 1418, where the process stops.

[0081] But if at block 1412 the lesion was not sufficiently modified by the expandable bump catheter, then at block 1413 the expandable bump catheter is reinserted into the lesion (if it was removed after block 1410) and expanding section 1018 is expanded again in the lesion. In one embodiment, each successive expansion of expanding section 1018 can increase the radius R of the expanding section (see FIG. 10D) more than the last, but in other embodiments that need not be the case. This sequence of blocks 1412 and 1413 can be repeated until the lesion is satisfactorily modified.

[0082] Embodiments of catheters for arterial lesion modification are described above. More particularly, such embodiments are described, either explicitly or implicitly. The following paragraphs summarize some of the described embodiments. More particularly, embodiments are described in the following enumerated example clauses.

[0083] Example 1. A catheter system comprising: a catheter including a catheter axis extending in a longitudinal direction, a sidewall having an inner surface bounding a catheter lumen, and a locking mechanism projecting from the inner surface toward the catheter axis in a- 22 - Docket No. 15695WOO1radial direction normal to the longitudinal direction; and a guidewire trap positioned in the catheter lumen, the guidewire trap comprising a trap body including a trap lumen extending in the longitudinal direction and adapted to receive a guidewire therein, and a collet formed at a trap distal end, wherein the collet includes a tapered outer surface that is adapted to engage with the locking mechanism in the catheter lumen; wherein when the guidewire trap is pushed in a distal direction through the catheter lumen the locking mechanism engages with the tapered outer surface to cause the collet to contract radially toward the catheter axis.

[0084] Example 2. The catheter system of example 1 further comprising a guidewire positioned in the trap lumen.

[0085] Example 3. The catheter system of example 2, wherein when the collet contracts radially it engages the guidewire and prevents longitudinal motion of the guidewire relative to the guidewire trap.

[0086] Example 4. The catheter system of example 1, wherein the locking mechanism comprises an annular ring projecting radially inward from the inner surface of the catheter lumen.

[0087] Example 5. The catheter system of example 1, wherein the locking mechanism comprises a plurality of bumps projecting radially inward from the inner surface of the catheter lumen.

[0088] Example 6. The catheter system of example 5, wherein the collet includes a plurality of segments, and wherein a number of the plurality of bumps matches a number of the plurality of segments.

[0089] Example 7. The catheter system of example 1, wherein the locking mechanism comprises a plurality of tabs projecting radially inward from the inner surface of the catheter lumen.- 23 - Docket No. 15695WOO1

[0090] Example 8. The catheter system of example 7, wherein the collet includes a plurality of segments, and wherein a number of the plurality of tabs matches a number of the plurality of segments.

[0091] Example 9. A kit, comprising: a guidewire; and a catheter system including: a catheter axis extending in a longitudinal direction, a sidewall having an inner surface bounding a catheter lumen, and a locking mechanism projecting from the inner surface toward the catheter axis in a radial direction normal to the longitudinal direction, and a guidewire trap positioned in the catheter lumen, the guidewire trap comprising a trap body including a trap lumen extending in the longitudinal direction and adapted to receive a guidewire therein, and a collet formed at a trap distal end, wherein the collet includes a tapered outer surface that is adapted to engage with the locking mechanism in the catheter lumen; wherein when the guidewire trap is pushed in a distal direction through the catheter lumen the locking mechanism engages with the tapered outer surface to cause the collet to contract radially toward the catheter axis.

[0092] Example 10. The kit of example 9, wherein if the guidewire is positioned in the trap lumen when the collet contracts radially it engages the guide wire and prevents longitudinal motion of the guidewire relative to the guide wire trap.

[0093] Example 11. The kit of example 9, wherein the locking mechanism comprises an annular ring projecting radially inward from the inner surface of the catheter lumen.

[0094] Example 12. The kit of example 9, wherein the locking mechanism comprises a plurality of bumps projecting radially inward from the inner surface of the catheter lumen.

[0095] Example 13. The kit of example 12, wherein the collet includes a plurality of segments, and wherein a number of the plurality of bumps matches a number of the plurality of segments.

[0096] Example 14. The kit of example 9, wherein the locking mechanism comprises a plurality of tabs projecting radially inward from the inner surface of the catheter lumen.- 24 - Docket No. 15695WOO1

[0097] Example 15. The kit of example 14, wherein the collet includes a plurality of segments, and wherein the number of tabs matches a number of the plurality of segments.

[0098] Example 16. A method, comprising: inserting a catheter system into a blood vessel and navigating the catheter system through the blood vessel to a lesion in the blood vessel, wherein the catheter system comprises a catheter having a catheter lumen, a guidewire trap positioned in the catheter lumen, the guidewire trap having a trap lumen, and a guidewire positioned in the trap lumen; activating the guidewire trap to engage the guidewire; and advancing the engaged guidewire trap and the guidewire through the lesion.

[0099] Example 17. The method of example 16, wherein engaging the guidewire shortens an effective column length of a distal end of the guidewire.

[0100] Example 18. The method of example 16, wherein engaging the guidewire prevents retreat of the guidewire into the trap lumen and the catheter lumen.

[0101] Example 19. The method of example 16, wherein the catheter includes a catheter axis extending in a longitudinal direction, a sidewall having an inner surface bounding a catheter lumen, and a locking mechanism projecting from the inner surface toward the catheter axis in a radial direction normal to the longitudinal direction, and wherein the guidewire trap includes a trap body adapted to be inserted into the catheter lumen, the trap body including the trap lumen extending in the longitudinal direction and adapted to receive the guidewire therein, and a collet formed at a trap distal end, wherein the collet includes a tapered outer surface that is adapted to engage with the locking mechanism in the catheter lumen, and wherein when the guidewire trap is pushed in a distal direction through the catheter lumen the locking mechanism activates to engage the tapered outer surface to cause the collet to contract radially toward the catheter axis.

[0102] Example 20. The method of example 19, wherein the locking mechanism comprises an annular ring projecting radially inward from the inner surface of the catheter lumen,- 25 - Docket No. 15695WOO1a plurality of bumps projecting radially inward from the inner surface of the catheter lumen, or a plurality of tabs projecting radially inward from the inner surface of the catheter lumen.

[0103] Example 21. A bump catheter, comprising: a catheter body having a catheter axis extending in a longitudinal direction, and a sidewall having an interior surface bounding a lumen; a first bump set including a first plurality of bumps formed on an exterior surface of the sidewall and projecting from the exterior surface in a radial direction normal to the longitudinal direction; and a second bump set including a second plurality of bumps formed on the exterior surface and projecting from the exterior surface in the radial direction, wherein the second bump set is positioned at a different longitudinal location than the first bump set.

[0104] Example 22. The bump catheter of example 21, wherein the first plurality ofbumps in the first bump set are regularly angularly spaced on the exterior surface.

[0105] Example 23. The bump catheter of example 21, wherein the second plurality of bumps in the second bump set are regularly angularly spaced on the exterior surface and are angularly offset from the first plurality ofbumps in the first bump set.

[0106] Example 24. The bump catheter of example 21, wherein the first bump set includes a same number ofbumps as the second bump set.

[0107] Example 25. The bump catheter of example 21, wherein the second plurality of bumps in the second bump set have a greater radial dimension than the first plurality ofbumps in the first bump set.

[0108] Example 26. The bump catheter of example 21, wherein the second bump set is positioned at a more proximal location than the first bump set.

[0109] Example 27. The bump catheter of example 21 further comprising a third bump set including a third plurality of bumps formed on the exterior surface and projecting from the exterior surface in the radial direction, wherein the third bump set is positioned at a different longitudinal location along the catheter body than the first bump set and the second bump set.- 26 - Docket No. 15695WOO1

[0110] Example 28. The bump catheter of example 27, wherein the first bump set, the second bump set, and the third bump set are regularly spaced in the longitudinal direction.

[0111] Example 29. The bump catheter of example 27, wherein the third plurality of bumps in the third bump set are equally angularly spaced on the exterior surface and are angularly offset from the second plurality of bumps in the second bump set.

[0112] Example 30. The bump catheter of example 27, wherein the third bump set is positioned at a more proximal location than the second bump set.

[0113] Example 31. The bump catheter of example 27, wherein the third plurality of bumps in the third bump set have a greater radial dimension than the first plurality of bumps in the first bump set and the second plurality of bumps in the second bump set.

[0114] Example 32. An expandable bump catheter, comprising: a catheter body including a catheter axis extending in a longitudinal direction, and a sidewall having an interior surface bounding a primary lumen, wherein the catheter body includes a proximal section, a distal section longitudinally movable relative to the proximal section along the catheter axis, and an expanding section between the proximal section and the distal section, the expanding section comprising a plurality of slits formed in the sidewall, wherein interstitial parts of the sidewall between slits form a plurality of sidewall columns; and a pair of pull wires positioned in the catheter body, wherein the pair of pull wires is movable relative to the proximal section and is attached to the distal section.

[0115] Example 33. The expandable bump catheter of example 32, wherein pulling the pair of pull wires in a proximal direction causes the distal section to move toward the proximal section, compressing the expanding section and causing the sidewall columns to buckle outward.

[0116] Example 34. The expandable bump catheter of example 32, wherein the pair of pull wires runs through the primary lumen in the proximal section.- 27 - Docket No. 15695WOO1

[0117] Example 35. The expandable bump catheter of example 32 further comprising a pair of auxiliary lumens formed in the sidewall of the proximal section, wherein each pull wire in the pair of pull wires runs through a corresponding auxiliary lumen.

[0118] Example 36. The expandable bump catheter of example 32 further comprising a guidewire positioned in the primary lumen.

[0119] Example 37. A method comprising: inserting a catheter into a blood vessel and navigating the catheter to a lesion in the blood vessel; and modifying the lesion by engaging the lesion with a bump on the catheter.

[0120] Example 38. The method of example 37, wherein the catheter is a bump catheter comprising: a catheter body having a catheter axis extending in a longitudinal direction, and a sidewall having an interior surface bounding a lumen; a first bump set including a first plurality of bumps, wherein the first plurality of bumps in the first bump set are formed on an exterior surface of the sidewall and project from the exterior surface in a radial direction normal to the longitudinal direction; and a second bump set including a second plurality of bumps, wherein the second plurality of bumps in the second bump set are formed on the exterior surface and project from the exterior surface in the radial direction, and wherein the second bump set is positioned at a different longitudinal location than the first bump set; wherein the first plurality of bumps in the first bump set and the second plurality of bumps in the second bump set engage the lesion.

[0121] Example 39. The method of example 38, wherein the bump catheter further comprises a third bump set including a third plurality of bumps, wherein the third plurality of bumps in the third bump set are formed on the exterior surface and project from the exterior surface in the radial direction, wherein the third bump set is positioned at a different longitudinal location along the catheter body than the first bump set and the second bump set, and wherein the- 28 - Docket No. 15695WOO1first plurality of bumps in the first bump set, the second plurality of bumps in the second bump set, and the third plurality of bumps in the third bump set engage the lesion.

[0122] Example 40. The method of example 37, wherein the catheter is an expandable bump catheter comprising: a catheter body including a catheter axis extending in a longitudinal direction, and a sidewall having an interior surface bounding a primary lumen, wherein the catheter body includes a proximal section, a distal section longitudinally movable relative to the proximal section along the catheter axis, an expanding section between the proximal section and the distal section, the expanding section comprising a plurality of slits formed in the sidewall, wherein interstitial parts of the sidewall between slits form a plurality of sidewall columns; and a pair of pull wires positioned in the catheter, wherein the pair of pull wires is movable relative to the proximal section and is attached to the distal section; wherein, when the pair of pull wires move relative to the proximal section, the sidewall columns buckle outward to form the second bump set that engages the lesion.

[0123] The above description of embodiments is not intended to be exhaustive or to limit the invention to the described forms. Specific embodiments of, and examples for, the invention are described herein for illustrative purposes, but various modifications are possible.- 29 - Docket No. 15695WOO1

Claims

CLAIMSWhat is claimed is:

1. A catheter system comprising: a catheter including a catheter axis extending in a longitudinal direction, a sidewall having an inner surface bounding a catheter lumen, and a locking mechanism projecting from the inner surface toward the catheter axis in a radial direction normal to the longitudinal direction; and a guidewire trap positioned in the catheter lumen, the guidewire trap comprising a trap body including a trap lumen extending in the longitudinal direction and adapted to receive a guidewire therein, and a collet formed at a trap distal end, wherein the collet includes a tapered outer surface that is adapted to engage with the locking mechanism in the catheter lumen; wherein when the guidewire trap is pushed in a distal direction through the catheter lumen, the locking mechanism engages with the tapered outer surface to cause the collet to contract radially toward the catheter axis.

2. The catheter system of claim 1, further comprising a guidewire positioned in the trap lumen.

3. The catheter system of claim 2, wherein when the collet contracts radially it engages the guide wire and prevents longitudinal motion of the guidewire relative to the guide wire trap.

4. The catheter system of claim 1, wherein the locking mechanism comprises an annular ring projecting radially inward from the inner surface of the catheter lumen.- 30 - Docket No. 15695WOO15. The catheter system of claim 1, wherein the locking mechanism comprises a plurality of bumps projecting radially inward from the inner surface of the catheter lumen.

6. The catheter system of claim 5, wherein the collet includes a plurality of segments, and wherein a number of the plurality of bumps matches a number of the plurality of segments.

7. The catheter system of claim 1, wherein the locking mechanism comprises a plurality of tabs projecting radially inward from the inner surface of the catheter lumen.

8. The catheter system of claim 7, wherein the collet includes a plurality of segments, and wherein a number of the plurality of tabs matches a number of the plurality of segments.

9. A kit, comprising: a guidewire; and a catheter system including: a catheter axis extending in a longitudinal direction, a sidewall having an inner surface bounding a catheter lumen, and a locking mechanism projecting from the inner surface toward the catheter axis in a radial direction normal to the longitudinal direction, and a guidewire trap positioned in the catheter lumen, the guidewire trap comprising a trap body including a trap lumen extending in the longitudinal direction and adapted to receive a guidewire therein, and a collet formed at a trap distal end, wherein the collet includes a tapered outer surface that is adapted to engage with the locking mechanism in the catheter lumen;- 31 - Docket No. 15695WOO1wherein when the guidewire trap is pushed in a distal direction through the catheter lumen, the locking mechanism engages with the tapered outer surface to cause the collet to contract radially toward the catheter axis.

10. The kit of claim 9, wherein if the guidewire is positioned in the trap lumen when the collet contracts radially it engages the guidewire and prevents longitudinal motion of the guidewire relative to the guidewire trap.

11. The kit of claim 9, wherein the locking mechanism comprises an annular ring projecting radially inward from the inner surface of the catheter lumen.

12. The kit of claim 9, wherein the locking mechanism comprises a plurality of bumps projecting radially inward from the inner surface of the catheter lumen.

13. The kit of claim 12, wherein the collet includes a plurality of segments, and wherein a number of the plurality of bumps matches a number of the plurality of segments.

14. The kit of claim 9, wherein the locking mechanism comprises a plurality of tabs projecting radially inward from the inner surface of the catheter lumen.

15. The kit of claim 14, wherein the collet includes a plurality of segments, and wherein the number of tabs matches a number of the plurality of segments.

16. A method, comprising:- 32 - Docket No. 15695WOO1inserting a catheter system into a blood vessel and navigating the catheter system through the blood vessel to a lesion in the blood vessel, wherein the catheter system comprises a catheter having a catheter lumen, a guidewire trap positioned in the catheter lumen, the guidewire trap having a trap lumen, and a guidewire positioned in the trap lumen; activating the guidewire trap to engage the guidewire; and advancing the engaged guidewire trap and the guidewire through the lesion.

17. The method of claim 16, wherein engaging the guidewire shortens an effective column length of a distal end of the guidewire.

18. The method of claim 16, wherein engaging the guidewire prevents retreat of the guidewire into the trap lumen and the catheter lumen.

19. The method of claim 16, wherein the catheter includes a catheter axis extending in a longitudinal direction, a sidewall having an inner surface bounding a catheter lumen, and a locking mechanism projecting from the inner surface toward the catheter axis in a radial direction normal to the longitudinal direction, and wherein the guidewire trap includes a trap body adapted to be inserted into the catheter lumen, the trap body including the trap lumen extending in the longitudinal direction and adapted to receive the guidewire therein, and a collet formed at a trap distal end, wherein the collet includes a tapered outer surface that is adapted to engage with the locking mechanism in the catheter lumen, and wherein when the guidewire trap is pushed in a distal direction through the catheter lumen, the locking mechanism activates to engage the tapered outer surface to cause the collet to contract radially toward the catheter axis.- 33 - Docket No. 15695WOO120. The method of claim 19, wherein the locking mechanism comprises an annular ring projecting radially inward from the inner surface of the catheter lumen, a plurality of bumps projecting radially inward from the inner surface of the catheter lumen, or a plurality of tabs projecting radially inward from the inner surface of the catheter lumen.

21. A bump catheter, comprising : a catheter body having a catheter axis extending in a longitudinal direction, and a sidewall having an interior surface bounding a lumen; a first bump set including a first plurality of bumps formed on an exterior surface of the sidewall and projecting from the exterior surface in a radial direction normal to the longitudinal direction; and a second bump set including a second plurality of bumps formed on the exterior surface and projecting from the exterior surface in the radial direction, wherein the second bump set is positioned at a different longitudinal location than the first bump set.

22. The bump catheter of claim 21, wherein the first plurality of bumps in the first bump set are regularly angularly spaced on the exterior surface.

23. The bump catheter of claim 21, wherein the second plurality of bumps in the second bump set are regularly angularly spaced on the exterior surface and are angularly offset from the first plurality of bumps in the first bump set.

24. The bump catheter of claim 21, wherein the first bump set includes a same number of bumps as the second bump set.- 34 - Docket No. 15695WOO125. The bump catheter of claim 21, wherein the second plurality of bumps in the second bump set have a greater radial dimension than the first plurality of bumps in the first bump set.

26. The bump catheter of claim 21, wherein the second bump set is positioned at a more proximal location than the first bump set.

27. The bump catheter of claim 21, further comprising a third bump set including a third plurality of bumps formed on the exterior surface and projecting from the exterior surface in the radial direction, wherein the third bump set is positioned at a different longitudinal location along the catheter body than the first bump set and the second bump set.

28. The bump catheter of claim 27, wherein the first bump set, the second bump set, and the third bump set are regularly spaced in the longitudinal direction.

29. The bump catheter of claim 27, wherein the third plurality of bumps in the third bump set are equally angularly spaced on the exterior surface and are angularly offset from the second plurality of bumps in the second bump set.

30. The bump catheter of claim 27, wherein the third bump set is positioned at a more proximal location than the second bump set.

31. The bump catheter of claim 27, wherein the third plurality of bumps in the third bump set have a greater radial dimension than the first plurality of bumps in the first bump set and the second plurality of bumps in the second bump set.- 35 - Docket No. 15695WOO132. An expandable bump catheter, comprising: a catheter body including a catheter axis extending in a longitudinal direction, and a sidewall having an interior surface bounding a primary lumen, wherein the catheter body includes a proximal section, a distal section longitudinally movable relative to the proximal section along the catheter axis, and an expanding section between the proximal section and the distal section, the expanding section comprising a plurality of slits formed in the sidewall, wherein interstitial parts of the sidewall between slits form a plurality of sidewall columns; and a pair of pull wires positioned in the catheter body, wherein the pair of pull wires is movable relative to the proximal section and is attached to the distal section.

33. The expandable bump catheter of claim 32, wherein pulling the pair of pull wires in a proximal direction causes the distal section to move toward the proximal section, compressing the expanding section and causing the sidewall columns to buckle outward.

34. The expandable bump catheter of claim 32, wherein the pair of pull wires runs through the primary lumen in the proximal section.

35. The expandable bump catheter of claim 32, further comprising a pair of auxiliary lumens formed in the sidewall of the proximal section, wherein each pull wire in the pair of pull wires runs through a corresponding auxiliary lumen.

36. The expandable bump catheter of claim 32, further comprising a guidewire positioned in the primary lumen.

37. A method comprising:- 36 - Docket No. 15695WOO1inserting a catheter into a blood vessel and navigating the catheter to a lesion in the blood vessel; and modifying the lesion by engaging the lesion with a bump on the catheter.

38. The method of claim 37, wherein the catheter is a bump catheter comprising: a catheter body having a catheter axis extending in a longitudinal direction, and a sidewall having an interior surface bounding a lumen; a first bump set including a first plurality of bumps, wherein the first plurality of bumps in the first bump set are formed on an exterior surface of the sidewall and project from the exterior surface in a radial direction normal to the longitudinal direction; and a second bump set including a second plurality of bumps, wherein the second plurality of bumps in the second bump set are formed on the exterior surface and project from the exterior surface in the radial direction, and wherein the second bump set is positioned at a different longitudinal location than the first bump set; wherein the first plurality of bumps in the first bump set and the second plurality of bumps in the second bump set engage the lesion.

39. The method of claim 38, wherein the bump catheter further comprises a third bump set including a third plurality of bumps, wherein the third plurality of bumps in the third bump set are formed on the exterior surface and project from the exterior surface in the radial direction, wherein the third bump set is positioned at a different longitudinal location along the catheter body than the first bump set and the second bump set, and wherein the first plurality of bumps in the first bump set, the second plurality of bumps in the second bump set, and the third plurality of bumps in the third bump set engage the lesion.- 37 - Docket No. 15695WOO140. The method of claim 37, wherein the catheter is an expandable bump catheter comprising: a catheter body including a catheter axis extending in a longitudinal direction, and a sidewall having an interior surface bounding a primary lumen, wherein the catheter body includes a proximal section, a distal section longitudinally movable relative to the proximal section along the catheter axis, an expanding section between the proximal section and the distal section, the expanding section comprising a plurality of slits formed in the sidewall, wherein interstitial parts of the sidewall between slits form a plurality of side wall columns; and a pair of pull wires positioned in the catheter, wherein the pair of pull wires is movable relative to the proximal section and is attached to the distal section; wherein, when the pair of pull wires move relative to the proximal section, the sidewall columns buckle outward to form the second bump set that engages the lesion.- 38 - Docket No. 15695WOO1

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