WO2010036541A1

WO2010036541A1 - Catheter system having variable stiffness

Info

Publication number: WO2010036541A1
Application number: PCT/US2009/057075
Authority: WO
Inventors: Charles L. Mcintosh; James C. Elsesser; Aaron Weeks
Original assignee: Cook Incorporated
Priority date: 2008-09-24
Filing date: 2009-09-16
Publication date: 2010-04-01

Abstract

A catheter system a method and a kit for cannulating an occlusion in a body lumen are provided. The catheter system includes an elongate sheath having a proximal portion, a distal portion, a first lumen extending at least partially through the elongate sheath and a second lumen extending at least partially through the sheath. The sheath further includes an opening at the distal portion of the sheath, the opening is connected to the first lumen and positioned proximal to a distal end of the second lumen. The system also includes a stiffening elongate member slidably and removably positionable within the second lumen and distally extendable within the second lumen so that a distal end of the stiffening elongate member is positional distal to the opening. The stiffening member has a first stiffness.

Description

CATHETER SYSTEM HAVING VARIABLE STIFFNESS

RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 61/099,795, filed September 24, 2008, which is incorporated herein in its entirety.

TECHNICAL FIELD

[0002] This invention generally relates to medical devices, and more particularly to a catheter system for crossing occlusions in body lumens.

BACKGROUND

[0003] Chronic total occlusions (CTOs) in the vasculature, including coronary and peripheral arteries and veins, present a challenge in interventional therapy. Preferably, CTOs may be treated using percutaneous treatment, such as percutaneous transluminal coronary angioplasty (PTCA) for the treatment of coronary arteries. During a PTCA procedure, a wireguide is typically introduced through the femoral artery via a small incision made in the groin. The wireguide is advanced to the occlusion site and frequently, with partial occlusions, the wireguide may be pushed through the occlusion. A treatment device is then advanced over the wireguide to the occlusion to provide treatment such as increasing the lumen diameter at the occlusion site. For example, a balloon catheter may be advanced over the wireguide to the site, either for treatment with the balloon alone or for placement of a stent. The occlusion may be approached using a wireguide in both the antegrade and retrograde directions. Occlusions in other body lumens may also be treated using percutaneous transluminal angioplasty (PTA), such as the ducts of the gallbladder, the prostate gland, vas deferens, trachea, bronchus and liver.

[0004] Traditionally, the initial crossing of the occlusion utilizes various wireguides with unique tip configurations and/or degrees of stiffness. Often, CTOs require very stiff wireguides advanced with significant force to penetrate the occlusions. One problem with advancing a wireguide through the CTO is that the wireguide can perforate the vessel wall, requiring more invasive surgery, such as coronary bypass surgery to repair the perforation.

[0005] What is needed in the art is a device and method for crossing CTOs and minimizing the risk of vessel perforation.

SUMMARY OF THE INVENTION

[0006] Accordingly, it is an object of the present invention to provide a catheter system and method having features that resolve or improve on the above- described drawbacks.

[0007] The foregoing object is obtained by providing a catheter system for cannulating an occlusion in a body lumen. The catheter system includes an elongate sheath having a proximal portion, a distal portion, a first lumen extending at least partially through the elongate sheath and a second lumen extending at least partially through the sheath. The sheath further includes an opening at the distal portion of the sheath, the opening is connected to the first lumen and positioned proximal to a distal end of the second lumen. The system also includes a stiffening elongate member slidably and removably positionable within the second lumen and distally extendable within the second lumen so that a distal end of the stiffening elongate member is positional distal to the opening. The stiffening member has a first stiffness.

[0008] In another aspect, the catheter system includes an elongate sheath having a proximal portion, a distal portion, a lumen extending at least partially through the elongate sheath and configured to receive the stiffening elongate member, and a distal tip. The catheter system further includes a stiffening elongate member slidably and removably positionable within the lumen, the stiffening elongate member being slidable within the lumen and is extendable to the distal portion of the sheath, but cannot extend past the distal tip. [0009] In another aspect, a method of cannulating an occlusion in a body lumen using a catheter system of the present invention is provided. The method includes inserting an elongate sheath into a body lumen. The elongate sheath includes a proximal portion, a distal portion, a longitudinally extending central axis, a lumen extending at least partially through the elongate sheath and configured to receive a stiffening elongate member. The method further includes advancing the sheath to the occlusion, inserting a first stiffening elongate member having a first stiffness into the lumen, advancing the first stiffening elongate member distally to a distal end portion of the sheath and advancing the sheath having the first stiffening elongate member therein at least partially into the occlusion. The method also includes exchanging the first stiffening elongate member with a second stiffening elongate member having a stiffness different than the first stiffness and advancing the sheath distally through the occlusion. [0010] In yet another aspect, a kit including a catheter system is provided. The catheter system includes an elongate sheath having a proximal portion a distal portion, a longitudinally extending central axis, a lumen extending at least partially through the elongate sheath, and an opening at the distal portion of the sheath. The catheter system of the kit further includes a plurality of stiffening elongate members configured for insertion into the lumen of the elongate sheath, each of the plurality of stiffening elongate members having a different stiffness. The catheter system also includes an advancing elongate member sized and shaped to distally advance through the opening at the distal portion of the sheath. The kit also includes a package configured to enclose the catheter system therein.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG. 1 is a side view of a catheter system of the present invention; [0012] FIG. 2A is a partial view of a distal portion of an embodiment of a stiffening elongate member for use with the catheter system shown in FIG. 1 ; [0013] FIG. 2B is a partial view of a distal portion of an embodiment of a stiffening elongate member for use with the catheter system shown in FIG. 1 having a different stiffness than the embodiment shown in FIG. 2A; [0014] FIG. 2C is a partial view of a distal portion of an embodiment of a stiffening elongate member for use with the catheter system shown in FIG. 1 having a different stiffness than the embodiment shown in FIGS. 2 A and 2B; [0015] FIG. 2D is a partial view of a distal portion of an embodiment of a stiffening elongate member for use with the catheter system shown in FIG. 1 ;

[0016] FIG. 3A is a partial, sectional view of the distal portion of the catheter system shown in FIG. 1 having a stiffening elongate member;

[0017] FIG. 3B is a partial, sectional view of the distal portion of the catheter system shown in FIG. 1 showing an another embodiment of a stiffening elongate member;

[0018] FIG. 4 is a partial, sectional view of the distal portion of the catheter system shown in FIG. 3 having an advancing elongate member with a different distal outer minimum diameter;

[0019] FIG. 5 A is a partial perspective view of a distal end portion of an of an embodiment of the present invention;

[0020] FIG. 5B is a partial perspective view of an alternate distal end portion of the embodiment shown in FIG. 5 A;

[0021] FIG. 6A is a partial sectional view of the distal portion of an alternative embodiment of catheter system of the present invention;

[0022] FIG. 6B is a partial sectional view of the distal portion of the catheter system shown in FIG. 6A having an advancing elongate member with a different distal outer minimum diameter;

[0023] FIG. 7 is a partial section view of an embodiment of a catheter system according to the present invention;

[0024] FIG. 8A is a partial view of a stiffening elongate member;

[0025] FIG. 8B is a partial view of a catheter system having the stiffening elongate member shown in FIG. 8A therein;

[0026] FIG. 9A is a partial sectional view of an embodiment of a catheter system according to the present invention;

[0027] FIG. 9B is a partial sectional view of an embodiment of a catheter system according to the present invention showing an advancing elongate member extending from a side port; [0028] FIG. 1OA is a partial sectional view of the distal portion of an alternative embodiment of catheter system of the present invention having two lumens;

[0029] FIG. 1OB is a partial, sectional view of the distal portion of the catheter system shown in FIG. 1 OA having an advancing elongate member with a different distal outer minimum diameter in one of the lumens;

[0030] FIG. 1 1 is a partial, sectional view of the distal portion of an alternative embodiment of catheter system of the present invention having two lumens; and

[0031] FIG. 12A-12E depict a method of using the catheter system of the present invention.

DETAILED DESCRIPTION

[0032] The invention is described with reference to the drawings in which like elements are referred to by like numerals. The relationship and functioning of the various elements of this invention are better understood by the following detailed description. However, the embodiments of this invention are not limited to the embodiments illustrated in the drawings. It should be understood that the drawings are not to scale, and in certain instances details have been omitted which are not necessary for an understanding of the present invention, such as conventional fabrication and assembly.

[0033] As used in the specification, the terms proximal and distal should be understood as being in the terms of a physician using the catheter system. Hence the term "distal" means the portion of the catheter system which is farthest from the physician and the term "proximal" means the portion of the catheter system which is nearest to the physician.

[0034] FIG. 1 illustrates a catheter system 10 in accordance with an embodiment of the present invention. The catheter system 10 includes a proximal portion 20 and a distal portion 30. The proximal portion 20 includes a handle 32 that may include an injection port 34 and a proximal opening 36. An outer sheath 38 is operably connected to the handle 32 and extends distally from the handle 32 to a distal end portion 42 of the sheath 38. The distal end portion 42 further includes an opening 40 that is connected to a lumen 48 extending at least partially through the sheath 38. The catheter system 10 further includes an elongate member 44 that may be slidably received within the lumen 48 within at least a portion of the elongate sheath 38. The distal end portion 42 of the sheath 38 may have any shape that facilitates entry into a body lumen having an occlusion therein. For example, the distal end portion 42 may be rounded or curvilinear. The distal end portion 42 of the sheath 38 may also be tapered and/ or asymmetric as will be described in more detail below. The distal end portion 42 may also include a channel portion 49 extending distally along the sheath 38 from the opening 40 that is sized and shaped to accommodate an advancing elongate member 46 through the opening 40. An exemplary channel portion is shown in FIGS. 5 A and 5B. The sheath 38 is configured for lateral movement in relation to a longitudinal axis A of the sheath 38 that can be repetitive side to side movement to help cross the occlusion with the sheath 38, also known as "dottering" the occlusion. In some embodiments, the sheath 38 or a portion thereof may be coated with a lubricious coating to facilitate passage of the sheath 38 through the body lumens and through the occlusions. The coating will be discussed in more detail below.

[0035] A stiffening elongate member 44 may be received within the lumen 48 of the sheath 38 to provide additional stiffness to the sheath 38 and to facilitate the lateral movement of the sheath 38 to cross the occlusion. The elongate member 44 may be provided in a plurality of sizes, shapes and stiffnesses. For example, a plurality of stiffening elongate members 44a-44d as shown in FIG. 2A-2D may be provided for use with the elongate sheath 38. The stiffening elongate members 44a-44d each have a different stiffness and can be used to optimize the passage of the sheath 38 through the occlusion as will be explained in more detail below. In the embodiment illustrated in FIGS. 2A-2C, the different stiffness is provided by varying the diameter of the portion of the stiffening elongate member 44a-44c proximal of the distal end 54. As shown in FIGS. 2A-2C, the stiffening elongate member 44a having the narrowest diameter shaft is the least stiff elongate member. The stiffness increases from elongate member 44a to elongate member 44b to elongate member 44c as the diameter increases, with the elongate member 44c having the greatest diameter and the greatest stiffness. [0036] The different stiffness may also be provided by varying the materials, the density, providing coils and the like as will be understood by one skilled in the art. The stiffening elongate members 44 may be interchanged during the occlusion crossing while the sheath 38 remains within the patient. The stiffening elongate member 44 may be positioned within the lumen so that a distal end 54 of the elongate member 44 abuts an interior wall 65 of the distal end portion 42 of the sheath 38. The distal end 54 of the elongate member may be positioned anywhere along the lumen 48 so as to provided the stiffness and allow flexibility needed for the distal portion of the sheath 38 to cross the occlusion.

[0037] As shown in FIGS. 1 and 4, the sheath 38 includes the opening 40 at a distal end portion 42 with the opening 40 positioned centrally along the longitudinal axis A. The opening 40 may connect to a single lumen 48 in the sheath 38. Alternatively, additional lumens may be present. As shown in FIGS. 3 A and 3B, the stiffening elongate member 44 is sized so that the stiffening elongate member 44 has a diameter 52 at the distal end 54 that is larger than a diameter 56 of the opening 40. In addition, the opening 40 has a minimum diameter that is less than a maximum diameter of the lumen 48. The distal end 54 may include an expanded region 62 at the distal end 54 that has a larger diameter than a shaft 64 of the elongate member as shown in FIGS. 2A-2C and 3 A. For example, the distal end 54 may include a ball tip having the increased diameter 52. Alternatively, the distal end 54 of the stiffening elongate member 44d may have about the same diameter 52 as the shaft 64 where the diameter 52 of the entire elongate member 44 is larger than the diameter 56 of the opening 40 as shown in FIGS. 2D and 3B.

[0038] The stiffening elongate member 44 may be received in a distal portion 66 of the lumen 48 so that the distal end 54 of the elongate member 44 abuts against the wall 65 of the distal end portion 42 of the sheath 38. The distal end 54 of the elongate member 44 may be sized and shaped so that fluid may still flow through the opening 42 of the sheath 38 when the distal end 54 is pressed against the wall 65 for advancing the sheath 38 through the occlusion. As shown in FIG. 4, a second, narrower diameter advancing elongate member 46 may be received within the lumen 48 of the sheath 38 when the elongate member 44 has been removed. The advancing elongate member 46 has a diameter 57 that is smaller than the diameter 56 of the opening 40 so that the advancing elongate member 46 is advanced distally through the opening 40 and into the patient. For example, the advancing elongate member 46 may be a wire guide known to one skilled in the art. The sheath 38 may be proximally withdrawn from the advancing elongate member 46 and removed from the patient, leaving the advancing elongate member 46 in position through the occlusion.

[0039] FIGS. 5 A and 5B illustrate an embodiment of the present invention having the lumen 48 with the opening 40 located proximal to a distal tip 66 on the distal end portion 42 of the sheath 38. The opening 40 is sized and shaped for the advancing elongate member 46 to advance distally through the opening 40 and into the body lumen. As shown in FIG. 5A, the lumen 48 is configured to receive the stiffening elongate member 44 therein, but the stiffening elongate member 44 does not pass through the opening 40. As shown in FIG. 5B, the sheath 38 includes the opening 40 of the lumen 48 located proximal to the distal tip 66. The sheath 38 may also include a second lumen 49 that extends distal to the opening 40 and has a closed end 63 near the distal tip 66 of the distal end portion 42. Stiffening elongate members 44 may be inserted into the lumen 49 and abut the wall 65 of the lumen 49 at the distal end portion 42 to help advance the sheath 38 through the occlusion. Variable stiffness elongate members 44 may be interchanged in the lumen 49 to facilitate advancement of the sheath 38 through the occlusion as describe in detail below. The advancing elongate member 46 is sized and shaped to advance distally through the opening 40 as described above. [0040] As shown in FIG. 6 A, an opening 140 in a sheath 138 may be offset from the longitudinal axis A. Similar to the sheath 38 discussed above, the sheath 138 includes a lumen 148 that is configured to receive an elongate member 44 therein. The elongate member 44 may include an enlarged distal end 62 as shown in FIGS. 2A-2C or a uniformly sized elongate member 44 having the distal end 54 connected to the shaft 64 having the same diameter 152. The diameter 52 of the distal end 54 of the elongate member 44 may be larger than a diameter 157 of the opening 140. Varying stiffness elongate members 44 may be exchanged within the lumen 148 of the sheath 138.

[0041] The distal end 142 of the sheath 138 may have any shape tip that is configured to facilitate passage of the distal end 142 through the occlusion. For example, the distal end 142 may have a conically shaped tip 168 as shown in FIG. 6A. The tip 168 may include an apex 169 that coincides with the longitudinal axis A of the sheath 138. In some embodiments, the tip 168 may include an apex that is offset from the longitudinal axis A (not shown). Similar to the distal tip 54 of the elongate member 44 and the inner wall 65 of the sheath 38, a fluid flow modification may be included on the elongate member 44 and/or the sheath 138. [0042] The opening 140 of the sheath 138 may be sized and shaped to allow the second, narrower diameter elongate member 46 to extend into the lumen 148 after the elongate member 44 has been proximally removed from the lumen 148. As shown in FIG. 6B, the advancing elongate member 46 may have a diameter 57 that is smaller than a diameter 156 of the opening 40 so that the advancing elongate member 46 may be advanced distally through the opening 140 and into the patient. As discussed above, the advancing elongate member 46 may be a wire guide known to one skilled in the art. An inner wall 165 may include an angled portion 170 that is curved to deflect the advancing elongate member 46 toward the opening 140 as the advancing elongate member 46 is distally advanced within the lumen 148 of the sheath 138. The sheath 138 may be proximally withdrawn from the advancing elongate member 46 and removed from the patient, leaving the advancing elongate member 46 in position through the occlusion. [0043] FIG. 7 illustrates a catheter system 100 in accordance with an embodiment of the present invention. The catheter system 100 includes an elongate sheath 102 having a proximal portion 120 and a distal portion 130. The proximal portion 120 of the sheath 102 includes a handle 134. A distal end portion 122 of the sheath 102 may be rounded, curvilinear, tapered and/or asymmetric. The distal end 122 may also include a thickened tip 124 at a distal end of a channel 128. The channel 128 extends through at least a portion of the sheath 102 to the thickened tip 124. As shown in FIG. 7, the distal end of the sheath 102 is closed. The distal portion 130 may include a marker portion 132 formed from a radiopaque polymer or one or more bands of radiopaque material or an echogenic material. A stiffening elongate member 44 may be received within the channel 128 to provide additional stiffness to the sheath 128 to facilitate advancement of the sheath 128 though the occlusion. As described above and with reference to FIGS. 2A-2D, a plurality of stiffening elongate members 44a- 44d may be provided for use with the elongate sheath 102. In some embodiments, the catheter system 100 may be provided as a microcatheter system having a size of 2.5 to 3 Fr, although additional sizes may also be used. [0044] As shown in FIG. 8A, a stiffening elongate member 44e having a curved distal end 131 may be provided for use with the catheter system 100. As shown in FIG. 8B, the stiffening member 44e is inserted into the channel 128 of the sheath 102. The elongate member 44e provides a curved distal portion 130 of the sheath 102.

[0045] As shown in FIGS. 9A and 9B, the catheter system 100 may include a side port 136 and a closed distal end 122 in the sheath 102. The port 136 may be connected to a lumen 126 extending adjacent to at least a portion of the channel 128. As shown in FIG. 9A, the port 136 is positioned proximal to the distal end 122 and proximal to the marker region 132, such as an echogenic region. The channel 128 extends distally of the sheath 102 in relation to the port 136. As shown in FIG. 9B, a curved tip advancing elongate member 146 may be extended though the lumen 126 and out of the port 136. The sheath 102 may be advanced through the occlusion past the port 136 so that the advancing elongate member may be extended out of the port 136 distal to the occlusion and the sheath 102 removed. Use of an exemplary catheter system will be explained in more detail below.

[0046] The stiffening elongate member 44 and advancing elongate member 46 may be used with conventional over-the-wire (OTW) catheters as well as with rapid exchange catheters (RX). An exemplary rapid exchange catheter system is shown in FIGS. 1 OA and 1 OB. The catheter system shown in FIG. 1 OA illustrates a sheath 238 having a first lumen 248 and a second lumen 249. A distal end portion 242 includes a first lumen opening 240 connected to the first lumen 248 and a second lumen opening 241 connected to the second lumen 249. The first lumen 248 also includes a first side port 252 and the second lumen 249 includes a second side port 253. Similar to the embodiments described above, the first lumen 248 that is configured to receive an elongate member 44 therein. The elongate member 44 may include an enlarged distal end 62 as shown in FIGS. 2A-2C or a uniformly sized elongate member 44 having the distal end 54 connected to the shaft 64 having the same diameter 52. The diameter 52 of the distal end 54 of the elongate member 44 is larger than a diameter 257 of the opening 240. Varying stiffness elongate members 44 may be exchanged within the lumen 248 of the sheath 238 through the first side port 252. The second lumen 249 is configured to receive an advancing elongate member 46 therein through the second side port 253. The second advancing member 46 is dimensioned to pass distally through the second opening 241.

[0047] The opening 240 of the sheath 238 is sized and shaped to allow the advancing elongate member 46 to extend distally through the first opening 240 from the lumen 248 after the elongate member 44 has been proximally removed from the lumen 248. The advancing elongate member 46 in the first lumen 248 and/or the advancing elongate member 46 in the second lumen 249 may be extended through the openings 240, 241 when the sheath 238 has passed the occlusion.

[0048] The catheter system shown in FIG. 11 illustrates a sheath 338 having a first lumen 348 and a second lumen 349. A distal end portion 342 includes a first lumen closed end 343 connected to the first lumen 348 that prevents the first lumen 348 from extending through the distal end portion 342 of the sheath 338. A lumen opening 341 is connected to the second lumen 349. Similar to the embodiments described above, the first lumen 348 that is configured to receive a stiffening elongate member 44 therein (not shown). The elongate may include an enlarged distal end 62 as shown in FIGS. 2A-2C or a uniformly sized elongate member 44 having the distal end 54 connected to the shaft 64 having the same diameter 52. The closed end 343 of the lumen 349 prevents the elongate member 44 from extending distal to the distal end portion 342. The distal end portion 342 may include a reinforced portion to prevent accidental distal extension of the elongate member 44 through the sheath 338. The closed end 343 of the lumen 348 may provide additional strength to help facilitate crossing of the occlusion. In some embodiments, the closed end 343 is distal to the opening 341 of the lumen 349. Varying stiffness elongate members 44 may be exchanged within the lumen 348 of the sheath 338 as described above. The lumen 349 is configured to receive an advancing elongate member 46 therein. The second advancing member 46 is dimensioned to pass distally through the opening 341.

[0049] The advancing elongate member 46 in the lumen 349 may be extended distally through the opening 341 when the sheath 338 has passed the occlusion. [0050] The sheath 38 may be made from a material that allows the sheath to be sufficiently flexible yet having adequate columnar strength to navigate the patient's vascular system. In some embodiments, the outer sheath is made primarily of a polymer such as polytetrafluorothylene (PTFE). Additional possible materials include, but are not limited to the following, polyethylene ether ketone (PEEK), fluorinated ethylene propylene (FEP), perfluoroalkoxy polymer resin (PFA), polyamide, polyurethane, high density or low density polyethylene, and nylon including multi-layer or single layer structures and may also include reinforcement wires, braid wires, coils, coil springs and or filaments. A non- limiting exemplary type of sheath that may be used with the present invention is the "Flexor^®" Sheath. (Cook Incorporated, of Bloomington, Indiana) Examples of the Flexor^® sheath devices, materials, and methods of manufacturing them are found in United States Patent Nos. 5,700,253 and 5,380,304, the contents of which are incorporated herein by reference. In some embodiments, the sheath 38 may be formed from a lubricious material such as PTFE and the like for easy slidability of the elongate member 44 within the sheath 38 and for slidability of the sheath within the vasculature and through the occlusion. An inner surface 39 of the sheath 38 may also be treated with materials to make the inner surface 39 more lubricious. An exterior surface 41 of the sheath 38 may also be coated or impregnated with other compounds and materials to achieve the desired properties, such as increased lubricity. Exemplary coatings or additives include, but are not limited to, parylene, glass fillers, silicone hydrogel polymers and hydrophilic coatings. A hydrophilic coating such as SLIP-COAT™ (Sterilization Technical Services, Inc., Rush, N. Y.) can be used as a coating material as well as other lubricious coatings or coating materials. Exemplary sizes for the catheter may be about 2.5 Fr to about 10 Fr. Other sizes are possible. The sheath may also include a radiapaque portion that may be bonded to the distal end of the sheath or radiopaque bands on the distal end of the sheath for visualization of the location of the distal end of the catheter system. An echogenic portion may be provided on the distal end of the sheath in addition to or as an alternative to the radiopaque marker. By way of non-limiting example, the echogenic region may be provided as dimples, grooves or ridges randomly positioned on the surface of the sheath, or in more regular patterns, for example in geometric shapes and patterns such as concentric circles, or as lines running substantially parallel or perpendicular to an axis of the device e.g. in a circumferential arrangement to give bands or corsets, or in a helical arrangement as will be understood by one skilled in the art. [0051] The elongate member may be formed from any material that is biocompatible and that is suitable for insertion within the lumen of the sheath. The elongate member is preferably formed from a metal or metal alloy, or from a polymer or other composition having sufficient rigidity to provide the desired stiffness to the sheath for crossing the occlusion or for navigating the body passageway to the site of the occlusion. By way of non-limiting example, the elongate member may be formed from materials such as stainless steel, nitinol, and relatively stiff polymers such as PTFE, high density polyethylene (HDPE) and PEEK. The elongate member may also include reinforcement wires, braid wires, coils, coil springs and or filaments. The elongate member 44 may be provided in a plurality of stiffnesses depending on the nature of the occlusion and one elongate member may be exchanged for another elongate member having a differing stiffness. The elongate member may also have variably stiffness along the length of the individual elongate member. When the elongate member itself has a variable stiffness, the transition between the differing stiffness regions will be gradual to avoid kinking of the elongate member or the sheath. Non-limiting examples of the varying stiffness of elongate members that may be used with the present invention include elongate members or distal portions there of having flexural rigidity of about 3g to about 2Og, preferably about 4g to about 12g. The flexural rigidity of the elongate member or portion thereof will allow manual torquing of the sheath to facilitate crossing of the occlusion. The elongate member 44 is sized to fit within the lumen 48 of the sheath 38 and can vary depending on the size of the sheath, the rigidity of the elongate member and the size of the opening of the sheath.

[0052] The second, narrower diameter elongate member may be formed from the same materials as the elongate member discussed about. The advancing, elongate member may be any type of device known in the art suitable for entering tortuous passageways in the body, such as a wire guide. In some embodiments, the advancing elongate member may be about 0.018 to about 0.035 inches in diameter (coated or uncoated) and about 205 cm in length for a device that allows exchange at the distal end portion of the sheath in an RX catheter and up to about 1000 cm in length for an OTW catheter. Other diameters and lengths may be used as these sizes are presented only for illustrative purposes. [0053] The catheter system 10 may be provided as a kit. By way of non- limiting example, the catheter system 10 may be provided with the sheath 38, at least two stiffening elongate members 44 having differing stiffnesses and the advancing elongate member 46. Additional stiffening elongate members 44 may also be provided with the kit to provide a range of stiffnesses. The kit may be provided in a sterile package for delivery to the endoscopist. [0054] Operation of the catheter system 10 of the present invention is illustrated in FIGS. 12A-12E. The operation described herein is by way of nonlimiting example. Other methods of operation may also be used with the catheter system 10. [0055] An occlusion 210 in a portion of a body lumen 212 is shown in FIG. 12 A. The catheter system 10 may be advanced through body passageways to the body lumen 212 and to the site of the occlusion 210 using the sheath 38. The endoscopist may first attempt to advance the sheath 38 alone through the occlusion 210 (not shown). Preferably, at least the distal end portion 42 of the sheath 38 includes a lubricious coating to facilitate passage of the sheath 38 through the occlusion 210. If the attempt with the sheath 38 alone is unsuccessful to cross the occlusion 210, the elongate member 44 may be positioned in the lumen 48 of the sheath 38. The first stiffening elongate member 44 used to attempt to cross the occlusion 210 may be the least stiff elongate member 44a (see FIG. 2A). Each of the elongate members 44 will have sufficient flexibility to navigate through the body passageways to the site of the occlusion 210 within the sheath 38. At the site of the occlusion 210, stiffening elongate members 44 having increasing stiffness may be exchanged with the previously attempted, less stiff, elongate member 44 until the occlusion 210 has been successfully crossed with the sheath 38. Stiffening members may also be used beginning with a stiffer elongate member and decreasing the stiffness with the subsequent stiffening member. The catheter system 10 having a stiffening elongate member 44a with a first stiffness within the lumen 48 of the sheath 38 is shown advancing into the occlusion 210 in FIG. 12B. The distal end 54 of the elongate member 44 a is advanced into the lumen 48 to the distal end 65 of the sheath 38 and the catheter system 10 is advanced distally through the occlusion 210 by pushing the elongate member 44a within the sheath 10 in a distal direction indicated by arrow 215. Arrows 216 shown in FIG. 12B indicate the direction of the manual torque that may also be applied in a lateral direction to facilitate advancement of the catheter system 10 though the occlusion 210.

[0056] If the first stiffness elongate member 44a is not sufficient to cross the occlusion 210, a second elongate member 44b may be exchanged with the elongate member 44a shown in FIG. 12B to further advance the catheter system 10 through the occlusion 210. The elongate member 44b is shown with the catheter 10 advancing distally through the occlusion 210. The elongate member 44b provides a different stiffness than the elongate member 44a. The stiffness of the elongate member 44b may be greater than or less than the stiffness provided by the elongate member 44a. The catheter system 10 with the elongate member 44b therein may also be used to apply manual torque in a lateral direction to facilitate advancement of the catheter system 10 through the occlusion 210 as indicted by the arrows 216. FIG. 12D illustrates the catheter system 10 advanced past the occlusion 210. In addition, the elongate member 44b shown in FIG. 12C has been withdrawn and the narrower diameter elongate member 46 is shown advanced through the opening 40 of the sheath 38 and past the occlusion 210. The sheath 38 of the catheter system 10 may be withdrawn proximally through the occlusion 210 indicated by arrow 217, leaving the advancing elongate member in the body lumen 212 and through the occlusion 210 as shown in FIG. 12E. The advancing elongate member may then be used as a wire guide to advance additional catheters and the like to the site of the occlusion for further treatment or diagnosis. For example, a conventional balloon catheter having a stent thereon may be delivered to the site to place a stent at the occlusion 210. Additional devices known to one of skill in the art may also be advanced over the advancing elongate member 46 to the site of the occlusion after the sheath 38 has been withdrawn.

[0057] In some methods of operation, each subsequent stiffening elongate member is stiffer than the previous stiffening elongate member 44. The stiffening elongate members may be exchanged for an increasingly stiffer elongate member 44 until the sheath 38 is able to cross the occlusion 210. For some occlusions 210, the sheath 38 alone may be sufficient to cross the occlusion. For other occlusions 210, one, two, three or more stiffening elongate members may be exchanged within the sheath 38 to cross the occlusion 210.

[0058] The above figures and disclosure are intended to be illustrative and not exhaustive. This description will suggest many variations and alternatives to one of ordinary skill in the art. All such variations and alternatives are intended to be encompassed within the scope of the attached claims. Those familiar with the art may recognize other equivalents to the specific embodiments described herein which equivalents are also intended to be encompassed by the attached claims. Application of the principles of the invention to any bodily lumens or vessels within the body of a patient, including areas within the digestive tract such as the pancreatic system, the digestive tract location and vascular systems, by way of non-limiting examples, are within the ordinary skill in the art and are intended to be encompassed within the scope of the attached claims.

Claims

1. A catheter system configured for facilitating cannulation of an occlusion of a body lumen, the system comprising: an elongate sheath comprising: a proximal portion; a distal portion; a first lumen extending at least partially through the elongate sheath; a second lumen extending at least partially through the sheath; and an opening at the distal portion of the sheath, the opening connected to the first lumen and positioned proximal to a distal end of the second lumen; and a stiffening elongate member slidably and removably positionable within the second lumen and distally extendable within the second lumen so that a distal end of the stiffening elongate member is positionable distal to the opening, the stiffening elongate member having a first stiffness.

2. The catheter system of claim 1, wherein at least a portion of the sheath comprises a marker region.

3. The catheter system of claim 1, comprising a plurality of stiffening elongate members, each of the plurality of stiffening elongate members having a different stiffness, the plurality of stiffening elongate members exchangeably positionable within the lumen.

4. The catheter system of claim 1, further comprising an advancing elongate member, the advancing elongate member having a diameter that is less than the diameter of the opening so that the advancing elongate member is advanceable through the opening.

5. The catheter system of claim 1, wherein the distal end portion comprises a curvilinear tip.

6. The catheter system of claim 1, wherein the opening is offset from a longitudinal central axis.

7. The catheter system of claim 6, further comprising a tapered tip having an apex aligned with the longitudinal central axis.

8. The catheter system of claim 1, wherein the stiffening elongate member comprises a shaft connected to a distal end portion of the stiffening member wherein a diameter of the shaft is less than a diameter of the distal end portion of the stiffening elongate member.

9. The catheter system of claim 1 , wherein the stiffening elongate member comprises a flexural rigidity between about 3g and about 2Og.

10. A catheter system configured for facilitating cannulation of an occlusion of a body lumen, the system comprising: an elongate sheath comprising: a proximal portion; a distal portion; a lumen extending at least partially through the elongate sheath; and a distal tip; and a stiffening elongate member slidably and removably positionable within the lumen, the stiffening elongate member being slidable within the lumen and extendable to the distal portion of the sheath, but cannot extend past the distal tip.

11. The catheter system of claim 10, wherein the elongate sheath further comprises an opening at the distal portion of the sheath, the opening connected to the lumen and having an opening diameter that is less than a maximum diameter of the lumen and the stiffening elongate member having a distal end portion diameter greater than the diameter of the opening.

12. The catheter system of claim 10, wherein the lumen comprises a closed end at the distal tip.

13. The catheter system of claim 10, comprising a plurality of stiffening elongate members, each of the plurality of stiffening elongate members having a different stiffness, the plurality of stiffening elongate members exchangeably positionable within the lumen.

14. The catheter system of claim 10, further comprising an advancing elongate member, exchangeable with the stiffening elongate member for positioning within the lumen, the advancing elongate member having a diameter that is less than the diameter of the opening so that the advancing elongate member is dismally advanceable through the opening.

15. The catheter system of claim 10, comprising a single lumen extending at least partially through the elongate sheath.

16. The catheter system of claim 10, wherein the lumen comprises an angled lumen interior at the distal end portion configured to deflect an advancing elongate member to the opening.

17. The catheter system of claim 10, wherein the stiffening elongate member comprises a flexural rigidity between about 3g and about 2Og.

18. A method of cannulating an occlusion in a body lumen, the method comprising: inserting an elongate sheath into a body lumen having an occlusion therein, the elongate sheath comprising a proximal portion, a distal portion, a longitudinally extending central axis, and a lumen extending at least partially through the elongate sheath and configured to receive a stiffening elongate member; advancing the sheath to the occlusion; inserting a first stiffening elongate member having a first stiffness into the lumen and advancing the first elongate member distally to a distal end portion within the sheath; advancing the sheath having the first stiffening elongate member therein at least partially into the occlusion; exchanging the first stiffening elongate member with a second stiffening elongate member having a second stiffness different than the first stiffness; and advancing the sheath distally and through the occlusion.

19. The method of claim 18 further comprising inserting an advancing elongate member into the sheath and advancing the advancing elongate member through an opening at the distal portion of the sheath and into the body lumen.

20. The method of claim 19, further comprising proximally withdrawing the sheath from the body lumen while maintaining the position of the advancing elongate member across the occlusion.

21. The method of claim 19, further comprising advancing a treatment device over the advancing elongate member to the occlusion.

22. A kit comprising: a catheter system, the catheter system comprising; an elongate sheath comprising a proximal portion, a distal portion, a longitudinally extending central axis, a lumen extending at least partially through the elongate sheath, and an opening at the distal portion of the sheath; a plurality of stiffening elongate members configured for insertion into the lumen of the elongate sheath, each of the plurality of stiffing elongate members having a different stiffness; and an advancing elongate member sized and shaped to distally advance through the opening at the distal portion of the sheath; and a package configured to enclose the catheter system therein.

23. The kit of claim 22, wherein the elongate sheath comprises at least two lumens, at least one lumen having the opening at the distal end portion of the sheath, the opening of the at least one lumen sized and shaped for allowing passage of the advancing member therethrough.