US20230218866A1

Movatterモバイル変換

Info

Publication number: US20230218866A1
Application number: US17/574,797
Authority: US
Inventors: Edgar D. Guzman
Original assignee: Orlando Health Inc
Current assignee: Orlando Health Inc
Priority date: 2022-01-13
Filing date: 2022-01-13
Publication date: 2023-07-13
Also published as: WO2023137273A1; US11529497B1

Abstract

A catheter may include an elongated tube enclosing at least one catheter lumen, and a centering device coupled to a distal end of the elongated tube, wherein the centering device includes a plurality of legs. Each leg of the plurality of legs may include a first end fixed to an outer surface of the elongated tube. Each leg of the plurality of legs may include an outward bias such that a central portion of each leg of the plurality of legs is spaced radially outward from the elongated tube when the centering device is in an expanded state.

Description

TECHNICAL FIELD

The present disclosure is generally related to a centering device for a catheter. More particularly, the present disclosure describes a device secured to a distal end of a vascular catheter that prevents an elongated tube’s distal end from contacting a vessel wall.

BACKGROUND

Catheters medical devices that are often used to administer or collect fluids located within interior spaces of a patient body. For example, a catheter may be used in a vascular space for administering a medication and/or collecting blood, sometimes simultaneously. One particular application of a catheter is hemodialysis, where blood is removed from a vessel, cleaned with a dialyzer, and then re-administered through a separate port/opening. While such procedures have been used with success, vascular catheters utilizing suction often misbehave, as they tend to lean against vessel walls. The vessel walls may block or otherwise prevent access to the ports/openings leading to the catheter lumen. The embodiments described in this document address this issue.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments discussed herein may be better understood with reference to the following drawings and description. The components in the figures are not necessarily to scale. Moreover, in the figures, like-referenced numerals designate corresponding parts throughout the different views.

FIG.1 is an illustration showing a side view of a catheter having a centering device in an expanded state in accordance with certain aspects of the present disclosure.

FIG.2 is an illustration showing a front view of the catheter having the expanded centering device fromFIG.1.

FIG.3 is an illustration showing a section view about section 3-3 ofFIG.1.

FIG.4 is an illustration showing a section view about section 4-4 ofFIG.1.

FIG.5 is an illustration showing a section view about section 5-5 ofFIG.1.

FIG.6 is an illustration showing a side view of a catheter similar to the catheter fromFIG.1, wherein the centering device is in a collapsed delivery state in accordance with certain aspects of the present disclosure.

FIG.7 is an illustration showing a side view of the catheter fromFIG.6, where a sheath has moved proximally to release a set of centering device legs in accordance with certain aspects of the present disclosure.

FIG.7A is an illustration showing an enlarged view of portion 7A identified inFIG.7.

FIG.8 is an illustration showing an additional embodiment of a catheter where a set of legs of a centering device extend distally beyond an elongated tube of the catheter in accordance with certain aspects of the present disclosure.

FIG.9 is an illustration showing the catheter ofFIG.8 in an expanded, deployed state in accordance with certain aspects of the present disclosure.

FIGS.10 and11 are illustrations showing the catheter fromFIG.8 during operation within a body vessel, whereFIG.10 shows the catheter in a delivery state and whereFIG.11 shows the catheter in an expanded deployed state in accordance with certain aspects of the present disclosure.

FIG.12 is an illustration showing the catheter ofFIGS.8-11 during a medical procedure involving suction and administration of a fluid in accordance with certain aspects of the present disclosure.

FIG.13 is an illustration showing an additional embodiment of a catheter with a centering device, the centering device having legs with two ends attached to the underlying elongated tube in accordance with certain aspects of the present disclosure.

FIG.14 is an illustration showing an additional embodiment of a catheter with a centering device, the centering device having legs that are formed from a material different than a material of the underlying elongated tube in accordance with certain aspects of the present disclosure

FIG.14A is an illustration showing an enlarged view about 14A identified inFIG.14.

DETAILED DESCRIPTION

Various aspects are described below with reference to the drawings in which like elements generally are identified by like numerals. The relationship and functioning of the various elements of the aspects may be better understood by reference to the following detailed description. However, aspects are not limited to those illustrated in the drawings or explicitly described below. It also should be understood that the drawings are not necessarily to scale, and in certain instances details may have been omitted that are not necessary for an understanding of aspects disclosed herein, such as conventional fabrication and assembly.

The terms “distal” and “proximal” are used herein in the common usage sense where they refer respectively to a tool/patient-end of a device or related object and the opposite end (e.g., typically the handle/doctor-end of the device or related object).

As discussed in the background above, existing vascular catheters, particularly when utilizing suction, may become blocked if the lumen opening is obstructed by a vessel wall. The embodiments herein provide acatheter102 that addresses this issue. In particular, as shown inFIGS.1-7, thecatheter102 includes anelongated tube104, which may have at least one lumen therein (as discussed in more detail below). At least partially surrounding the elongated tube is acentering device106. In exemplary embodiments, thecentering device106 is located at or near thedistal end140 of theelongated tube104. Generally, the entering device is advantageous for preventing the distal end of the elongated tube, and particularlyopenings132,134 (leading to one or more lumens), from approaching and contacting a vessel wall.

FIGS.1-2 depict thecentering device106 in an expanded state, which may be the state typically assumed when thecatheter102 is placed within a vessel and a medical procedure is underway. As shown, thecentering device106 may include a plurality oflegs108 that generally fan radially outward from anouter surface116 of theelongated tube104. While eachleg108 may be substantially the same in structure and function (as shown), it is contemplated that certain legs may differ from others, which may be advantageous where different legs are intended to provide different, direction-oriented spacing. Eachleg108 may include afirst end110 fixed to anouter surface116 of theelongated tube104 and asecond end112 that is spaced radially away/outward from theouter surface116. For example, in certain applications, and when fully expanded, thelegs108 may open to form a cavity having a diameter of between about 20 mm and about 25 mm, which matches the diameter of the superior vena cava in a human patient. The outer diameter of theelongated tube104 may be significantly less, e.g., about 4 mm in certain embodiments (e.g., at least 50% less than the diameter of the expanded legs, and perhaps 75% (or more) less). To assume and retain this configuration, thelegs108 may be formed of a flexible and resilient material that has an outward bias or spring-like tendency. Without limitation, carbothane may be used, which is a form of polyurethane. I am not sure this material can be used for the centering legs.

Each of thelegs108 may also include acentral portion114 that extends from thefirst end110 to thesecond end112. Thecentral portions114 may be elongated strips of material that form the primary structure of thelegs108. In certain embodiments, thecentral portions114 may be specifically shaped such that thecentral portion114 has a particular outer dimension and/or outer profile shape for engaging the inner wall of a body lumen. For example, in the depicted embodiment, thecentral portions114 of thelegs108 include an optionalconcave profile portion120 adjacent to thefirst ends110, which may be advantageous for ensuring thecentral portion114 quickly reaches a sufficiently large diameter as it extends distally. Thelegs108 may also include a set of optionalconvex profile portions122 extending from theconcave profile portions120 to thesecond ends112, which may be advantageous for providing smoothness to the outer profile to prevent snagging, cutting, etc. of body tissue engaging thelegs108. Acrimp124 or other junction structure may be located between eachconcave profile portion120 andconvex profile portion122. In other embodiments, thelegs108 may have a different shape and/or orientation for providing a different profile shape of thecentering device106.

Thelegs108 of thecentering device106 may be formed with any suitable structure or method. In one non-limiting exemplary example, thelegs108 may be formed by displacing a portion of theouter surface116 of the elongated tube104 (e.g., via slicing or peeling) but leaving the displaced material attached at an end. In other words, referring toFIG.7A, thelegs108 may be cut from theouter surface116 of theelongated tube104 itself. After formation, thelegs108 may correspond with a set of depressions or channels beneath eachleg108. This method of formation and resulting structure is advantageous for several reasons. First, the resulting structure results in thelegs108 being integral with the elongated tube, meaning that the material of theouter surface116 and thelegs108 is uniform, and no separate attachment means is needed. Thus, theleg108 may be secured without the use of an adhesive or other attachment mechanism, thereby enhancing the durability of theleg108 to reduce the risk of disengagement within a patient’s body while also reducing manufacturing cost relative to other embodiments. Second, since eachleg108 may have acorresponding depression126 sized substantially the same as itsrespective leg108, the outer profile of the centeringdevice106 may be substantially compact, uniform, and consistent with the tube’souter surface116 when thelegs108 are in the retracted/collapsed, delivery state. For example, as shown inFIG.6, the outer-facing surface of theelongated tube104 andlegs108 may snugly fit and generally match the inner-facing surface of thesheath138.

In some implementations, the second ends112 of thelegs108 may have a blunted shape or another suitable shape such that they do not cut or otherwise cause injury to body tissue upon contact. For example, the second ends112 may be rounded/curved, chamfered, tapered, conical, slope, smoothed, or otherwise structured without sharp edges that may come into contact with body tissue. Advantageously, a medical professional may move the device within the patient, including distally and proximally, without undue concern over causing injury. Notably, when thelegs108 are formed via material displacement from the elongated tube104 (as discussed below), blunting of the second ends112 of the legs may be accomplished after general leg formation. It is further contemplated that other edges of the legs108 (and/or other components) may be smoothed/blunted to remove sharp edges and burrs during the manufacturing process.

Theelongated tube104 may include a more than one lumen, such as afirst lumen128 and asecond lumen130 divided by a barrier. In certain embodiments (e.g., those where one lumen is used for injection and another for suction, as discussed below), thefirst lumen128 may be fluidly isolated from thesecond lumen130 within theelongated tube104, such as by using abifurcating barrier136 or another suitable structure. Thefirst opening132 may be configured to provide access to thefirst lumen128, and thesecond opening134 may be configured to provide access to thesecond lumen130. More or fewer than two lumens may be included, and each lumen may be associated with more than one opening in other embodiments.

Thefirst opening132 and/or thesecond opening134 may face opposite one another (e.g., as best shown inFIG.3). Advantageously, this orientation may prevent or reduce the likelihood of a phenomenon known as recirculation, which occurs when blood that has just been dialyzed and re-inserted into the vessel immediately re-enters the inflow opening.

FIGS.6-7 show thecatheter102 when in the compact delivery state and the expanded deployed state, respectively. As shown inFIG.6, asheath138 is placed at least partially over thelegs108 and prevents outward movement of thelegs108 such that they remain adjacent to theelongated tube104. The overall outer diameter of the device is much smaller when the sheath restricts thelegs108, and in this embodiment is equal to anouter diameter142 of thesheath138. Advantageously, the device may be placed into and moved through a patient body when in this configuration, allowing the device to quickly and easily reach a target location while fitting through tight spaces, rounding turns, etc. When thedistal end140 of the device is properly located, thesheath138 may be slide proximally relative to the centeringdevice106 such that it may selectively uncover thelegs108. In summary, when thelegs108 are covered (FIG.6), they may be prevented from fanning outward, but when thesheath138 slides proximally into its position ofFIG.7, the internal bias of thelegs108 may cause the centeringdevice106 to assume its expanded state without further manipulation from thesheath138. In other embodiments, thesheath138 may peel away or otherwise be removed, for example. Notably, thelegs108 have sufficient flexibility such that they can be removed from the body without needed to be re-engaged by thesheath138 without concern over damaging the body, which is advantageous in certain embodiments for limiting the need for control wires or other features that extend from thesheath138 to a handle of the device.

As shown inFIG.6, when in the compact delivery state, thelegs108 may terminate adjacent to anendcap144 or other distal end portion of thecatheter102. This structure may be the result of thelegs108 being formed from displaced material of the elongated tube, where the cutting/peeling process (as mentioned above) begins near the terminus of theelongated tube104 to substantially maximize the length of thelegs108. One extended radially outward as shown inFIG.7, the second ends112 of the legs may retract distally due to their fanning outward. Thus, once in the expanded state, the second ends112 of thelegs108 may be located proximally relative to thedistal end140 of theelongated tube104. At least one of the

openings

132,134 may therefore be located distally relative to the second ends112 of thelegs108 such that thelegs108 are not radially coextensive with the

openings

132,134. Notably, the

openings

132,134 extend through theendcap144 in the depicted embodiment, but this is not necessarily the case. In alternative implementations, the

openings

132,134 may extend through the sidewalls of theelongated tube104. When theendcap144 is included, it may alternatively lack any openings, and in some embodiments it may include a curved, tapered, or otherwise blunt surface for ease of movement of the elongated tube through the body during deployment.

FIGS.8-9 show an alternative arrangement. As shown, thelegs108 extend further distally relative to thedistal terminus146 of theelongated tube104. In this embodiment, thelegs108 are radially coextensive with the

openings

132,134 and also the distal terminus of theelongated tube104. Advantageously, the protection of the

openings

132,134 by thelegs108 may be enhanced since the

openings

132,134 are within a “cage” structure formed by thelegs108. To form this embodiment, the portion of the elongated tube that extends beyond the first ends110 of thelegs108 may be shortened (e.g., via cutting), for example.

FIGS.10-11 show an illustration of thecatheter102 fromFIGS.8-9 when inserted into a patient body. As shown inFIG.10, the distal end of the device may be placed into the body and moved into an appropriate position, such as within a patient’s vessel. When ready, the physician or other medical professional may retract thesheath138 such that thelegs108 are released and fan outward. When required based on the sizing of thebody lumen150, thelegs108 may contact and press against the outer wall(s)152 of thebody lumen150, thereby ensuring thedistal end140 of the elongated tube104 (and particularly theopenings132,134) remain spaced from thewalls152. Flexibility of thelegs108 may provide softness/cushioning such that thelegs108 retain space between the openings and the vessel walls without damaging the vessel walls.

FIG.12 shows thecatheter102 during a medical procedure, such as during hemodialysis. Other procedures are alternatively contemplated. In this particular procedure, thefirst opening132 may lead to a first opening that is exposed to a vacuum, which results in blood inflow. After dialysis, this same blood may be reintroduced through thesecond opening134. Since thefirst opening132 and thesecond opening134 face opposite directions, unwanted hemodialysis recirculation may be very unlikely, particularly since the openings remain free from obstructions due to operation of the centeringdevice106. This embodiment has advantageous over embodiments requiring openings to be located at the catheter tip, for example, since such embodiments may lack the ability for side openings due to vessel wall obstructions discussed above.

FIG.13 shows an alternative embodiment of a centeringdevice106. The primary difference between this embodiment and those above is that the second ends112 of thelegs108 are secured to theelongated tube104, thereby providing two points of attachment between thelegs108 and theelongated tube104. This embodiment may be advantageous where enhanced stability of thelegs108 is required, where thelegs108 provide support for another device (e.g., a balloon or other inflation device), etc. To form this embodiment, at least end of thelegs108 may be secured via a separate securement structure, such as with the use of an adhesive, a mechanical clamp or fastener, a tie, or the like. Alternatively, it is contemplated that thelegs108 may be stretched or otherwise elongated along their longitudinal axes such that they are capable of buckling outward relative to the underlyingelongated tube104. Notably, theopening132 may be located proximally of the second ends112, but other locations are also contemplated.

FIGS.14 and14A show another alternative embodiment, which is similar to the embodiment ofFIG.9 but with one primary exception: thelegs108 are not integral with theelongated tube104, but are instead attached to theelongated tube104 in another way at ajunction160. For example, thelegs108 may be secured to the elongated tube with an adhesive, a mechanical clamp or fastener, a tie, or the like. While the prior embodiments may be advantageous in certain circumstances, the present embodiment may be advantageous where a particular material is desirable for thelegs108 that is not easily accommodated by the elongated tube (or vice versa). For example, in certain embodiments, theelongated tube104 may be formed of a polymer material while thelegs108 may be formed of a shape memory metal (e.g., Nitinol), which may enhance the ability for precise operation of thelegs108 when in a patient body.

While various embodiments have been described, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible. Accordingly, the embodiments described herein are examples, not the only possible embodiments and implementations.

Having described various aspects of the subject matter above, additional disclosure is provided below that may be consistent with the claims originally filed with this disclosure. In describing this additional subject matter, reference may be made to the previously described figures. Any of the following aspects may be combined, where compatible.

A 1^st aspect includes a catheter. The catheter may include an elongated tube enclosing at least one catheter lumen, and a centering device coupled to a distal end of the elongated tube, wherein the centering device includes a plurality of legs. Each leg of the plurality of legs may include a first end fixed to an outer surface of the elongated tube. Each leg of the plurality of legs may include an outward bias such that a central portion of each leg of the plurality of legs is spaced radially outward from the elongated tube when the centering device is in an expanded state.

In a 2^nd aspect, the catheter of aspect 1 may be implemented such that each leg of the plurality of legs includes a second end located distally of the first end, wherein the central portion extends from the first end to the second end, and wherein the second end is spaced radially outward from the elongated tube when the centering device is in the expanded state.

In a 3^rd aspect, the catheter of aspect 2 may be implemented such that at least one leg of the plurality of legs includes a concave profile portion and a convex profile portion, the concave profile portion extending distally from the first end, and the convex profile portion extending proximally from the second end.

In a 4^th aspect, the catheter of aspect 2 may be implemented such that the second end of each leg of the plurality of legs includes a blunt outer surface.

In a 5^th aspect, the catheter of aspect 1 may be implemented such that the legs of the plurality of legs are integral with the outer surface of the elongated tube such that a material forming the outer surface is uniform with the material forming the legs.

In a 6^th aspect, the catheter of aspect 1 may be implemented such that the elongated tube includes a first opening configured to provide access to a first catheter lumen, wherein the first opening is located distally of terminal distal end of at least one leg of the plurality of legs when the centering device is in the expanded state.

In a 7^th aspect, the catheter of aspect 1 may be implemented such that the elongated tube includes a first opening configured to provide access to a first catheter lumen, wherein the first opening is at least partially surrounded by the legs of the centering device such that the legs are configured to prevent engagement between the first opening and a target body surface.

In an 8^th aspect, the catheter of aspect 1 may be implemented such that the elongated tube includes a first opening configured to provide access to a first catheter lumen, wherein the elongated tube includes a second opening configured to provide access to a second catheter lumen, and wherein the first catheter lumen is fluidly isolated from the second catheter lumen within the elongated tube.

In a 9^th aspect, the catheter of aspect 8 may be implemented such that the first opening extends through a wall of the elongated tube and faces a first direction, wherein the second opening extends through a wall of the elongated tube and faces a second direction, and wherein the first direction is substantially opposite the second direction.

In a 10^th aspect, the catheter of aspect 1 may include a sheath configured for preventing outward movement of the legs of the centering device when the centering device is in a delivery state.

In an 11^th aspect, the catheter of aspect 1 may include an endcap forming a distal terminus of the elongated tube, wherein the endcap lacks an opening to an inner lumen within the catheter.

In a 12^th aspect, the catheter of aspect 1 may be implemented such that the elongated tube includes a plurality of depressions corresponding to the plurality of legs such that the legs are received by the depressions when the centering device is in the delivery state.

A 13^th aspect includes a catheter. The catheter may include an elongated tube enclosing at least one catheter lumen; a first opening located at a distal end of the elongated tube, the first opening being configured to provide access to a first lumen, the first lumen extending through the elongated tube; a second opening located at the distal end of the elongated tube, the second opening being configured to provide access to a second lumen, the second lumen extending through the elongated tube and being fluidly isolated relative to the first lumen within the elongated tube; and a centering device coupled to the distal end of the elongated tube, wherein the centering device is moveable between a delivery state and an expanded state, and wherein the centering device includes a bias towards the expanded state.

In a 14^th aspect, the catheter of aspect 13 may be implemented such that the centering device includes a plurality of legs, wherein each leg of the plurality of legs includes a distal end that is spaced radially outward from the elongated tube when the centering device is in the expanded state.

In a 15^th aspect, the catheter of aspect 14 may be implemented such that the distal end of each leg of the plurality of legs includes a blunt outer surface.

In a 16^th aspect, the catheter of aspect 14 may be implemented such that the legs of the plurality of legs are integral with an outer surface of the elongated tube such that a material forming the outer surface is uniform with the material forming the legs.

In a 17^th aspect, the catheter of aspect 13 may include an endcap forming a distal terminus of the elongated tube, wherein the endcap lacks an opening to an inner lumen within the catheter.

An 18^th aspect includes a method. The method may include forming a catheter having an elongated tube and a centering device, wherein the centering device is coupled to a distal end of the elongated tube, wherein the centering device includes a plurality of legs, wherein each leg of the plurality of legs includes a first end fixed to an outer surface of the elongated tube, and wherein each leg of the plurality of legs includes an outward bias such that a central portion of each leg of the plurality of legs is spaced radially outward from the elongated tube when the centering device is in an expanded state.

In a 19^th aspect, the method of aspect 18 may be implemented such that forming the legs includes displacing a portion of the outer surface of the elongated tube, and wherein a central portion of each of the legs consists of the displaced portion of the outer surface of the elongated tube.

In a 20^th aspect, the method of aspect 19 may include attaching the legs to the outer surface of the elongated tube after forming the elongated tube and after forming the legs of the centering device.

Claims

We claim:

1. A catheter, comprising:

an elongated tube enclosing at least one catheter lumen; and

a centering device coupled to a distal end of the elongated tube, wherein the centering device includes a plurality of legs,

wherein each leg of the plurality of legs includes a first end fixed to an outer surface of the elongated tube, and

wherein each leg of the plurality of legs includes an outward bias such that a central portion of each leg of the plurality of legs is spaced radially outward from the elongated tube when the centering device is in an expanded state.

2. The catheter ofclaim 1, wherein each leg of the plurality of legs includes a second end located distally of the first end, wherein the central portion extends from the first end to the second end, and wherein the second end is spaced radially outward from the elongated tube when the centering device is in the expanded state.

3. The catheter ofclaim 2, wherein at least one leg of the plurality of legs includes a concave profile portion and a convex profile portion, the concave profile portion extending distally from the first end, and the convex profile portion extending proximally from the second end.

4. The catheter ofclaim 2, wherein the second end of each leg of the plurality of legs includes a blunt outer surface.

5. The catheter ofclaim 1, wherein the legs of the plurality of legs are integral with the outer surface of the elongated tube such that a material forming the outer surface is uniform with the material forming the legs.

6. The catheter ofclaim 1, wherein the elongated tube includes a first opening configured to provide access to a first catheter lumen, wherein the first opening is located distally of terminal distal end of at least one leg of the plurality of legs when the centering device is in the expanded state.

7. The catheter ofclaim 1, wherein the elongated tube includes a first opening configured to provide access to a first catheter lumen, wherein the first opening is at least partially surrounded by the legs of the centering device such that the legs are configured to prevent engagement between the first opening and a target body surface.

8. The catheter ofclaim 1, wherein the elongated tube includes a first opening configured to provide access to a first catheter lumen, wherein the elongated tube includes a second opening configured to provide access to a second catheter lumen, and wherein the first catheter lumen is fluidly isolated from the second catheter lumen within the elongated tube.

9. The catheter ofclaim 8, wherein the first opening extends through a wall of the elongated tube and faces a first direction, wherein the second opening extends through a wall of the elongated tube and faces a second direction, and wherein the first direction is substantially opposite the second direction.

10. The catheter ofclaim 1, further comprising a sheath configured for preventing outward movement of the legs of the centering device when the centering device is in a delivery state.

11. The catheter ofclaim 1, further comprising an endcap forming a distal terminus of the elongated tube, wherein the endcap lacks an opening to an inner lumen within the catheter.

12. The catheter ofclaim 1, wherein the elongated tube includes a plurality of depressions corresponding to the plurality of legs such that the legs are received by the depressions when the centering device is in the delivery state.

13. A catheter, comprising:

an elongated tube enclosing at least one catheter lumen;

a first opening located at a distal end of the elongated tube, the first opening being configured to provide access to a first lumen, the first lumen extending through the elongated tube;

a second opening located at the distal end of the elongated tube, the second opening being configured to provide access to a second lumen, the second lumen extending through the elongated tube and being fluidly isolated relative to the first lumen within the elongated tube; and

a centering device coupled to the distal end of the elongated tube, wherein the centering device is moveable between a delivery state and an expanded state, and wherein the centering device includes a bias towards the expanded state.

14. The catheter ofclaim 13, wherein the centering device includes a plurality of legs, wherein each leg of the plurality of legs includes a distal end that is spaced radially outward from the elongated tube when the centering device is in the expanded state.

15. The catheter ofclaim 14, wherein the distal end of each leg of the plurality of legs includes a blunt outer surface.

16. The catheter ofclaim 14, wherein the legs of the plurality of legs are integral with an outer surface of the elongated tube such that a material forming the outer surface is uniform with the material forming the legs.

17. The catheter ofclaim 13, further comprising an endcap forming a distal terminus of the elongated tube, wherein the endcap lacks an opening to an inner lumen within the catheter.

18. A method, comprising:

forming a catheter having an elongated tube and a centering device,

wherein the centering device is coupled to a distal end of the elongated tube,

wherein the centering device includes a plurality of legs,

19. The method ofclaim 18, wherein forming the legs includes displacing a portion of the outer surface of the elongated tube, and wherein a central portion of each of the legs consists of the displaced portion of the outer surface of the elongated tube.

20. The method ofclaim 19, further comprising attaching the legs to the outer surface of the elongated tube after forming the elongated tube and after forming the legs of the centering device.