WO2020051802A1

WO2020051802A1 - Retractable sheath

Info

Publication number: WO2020051802A1
Application number: PCT/CN2018/105241
Authority: WO
Inventors: Jieni GUO; Jing Tang; Yang Peng; Chunlang Hong
Original assignee: Covidien Lp
Priority date: 2018-09-12
Filing date: 2018-09-12
Publication date: 2020-03-19

Abstract

In some examples, a sheath may define a lumen and include a proximal sheath portion and a distal sheath portion. The distal sheath portion defines a first proximal end and a second proximal end proximal to the first proximal end, and is configured to rotate relative to the proximal sheath portion between a first rotational orientation and a second rotational orientation. When the distal sheath portion is in the first rotational orientation, the first proximal end is separated from the proximal sheath portion by a first distance, and when the distal sheath portion is in the second rotational orientation, the first proximal end is separated from the proximal sheath portion by a second distance. The second distance is less than the first distance such that the distal sheath portion can be retracted relative to the proximal sheath portion.

Description

RETRACTABLE SHEATH

TECHNICAL FIELD

The present disclosure relates to medical sheaths, and more specifically retractable medical sheaths.

BACKGROUND

Some medical devices include a retractable sheath. For example, a catheter may include a retractable sheath covering a treatment device, such as one or more heating elements configured to ablate tissue of a patient, a stent or stented device configured to be delivered in cardiovasculature of a patient, or the like. As another example, a catheter including a retractable sheath may be configured to deliver a therapeutic agent or another substance to a patient. In these examples, the sheath is configured to be retracted in a proximal direction (towards a user) to uncover and expose the treatment device, therapeutic agent delivery element or opening, or other treatment portion, or to detach a treatment device in order to enable implantation of the treatment element.

SUMMARY

The disclosure describes articles, systems, and techniques relating to retractable sheaths. The retractable sheaths described herein include at least two separate portions configured to be rotated relative to each other about a longitudinal axis of the respective sheath to proximally retract a distal portion of the respective sheath. The sheath defines a first total length in a first rotational configuration, in which the at least two separate portions have a first relative rotational position, and a second total length less than the first total length in a second rotational configuration, in which the at least two separate portions have a second relative rotational position.

In some examples, the at least two separate portions of the retractable sheath include a distal sheath portion and a proximal sheath portion. The distal sheath portion is shaped such that it includes a proximal stepped end comprising a first proximal end and a second proximal end proximal to the first proximal end. The proximal sheath portion is shaped such that it includes a distal stepped end comprising a first distal end and a second distal end distal to the first distal end. In some examples, the sheath is in the first rotational configuration when the first proximal end and the first distal end are aligned (e.g., adjacent and/or abutting each other) , and the sheath is in the second rotational configuration when the distal sheath portion and the proximal sheath portion are rotated relative to each other such that the first proximal end and the second distal end are aligned (e.g., adjacent and/or abutting each other) . Thus, rotating at least one of the proximal sheath portion and/or the distal sheath portion, for example 180°, relative to each other to place the sheath in the second rotational configuration enables the proximal retraction of the distal sheath portion to effectively reduce the total length of the sheath.

In some examples, a catheter comprises a sheath defining a lumen, the sheath comprising: a proximal sheath portion; and a distal sheath portion configured to rotate relative to the proximal sheath portion between a first rotational orientation and a second rotational orientation, the distal sheath portion defining a first proximal end and a second proximal end proximal to the first proximal end. When the distal sheath portion is in the first rotational orientation, the first proximal end is separated from the proximal sheath portion by a first distance, and when the distal sheath portion is in the second rotational orientation, the first proximal end is separated from the proximal sheath portion by a second distance, the second distance being less than the first distance.

In some examples, an ablation catheter comprises an inner member comprising a heating element; and a sheath defining a lumen configured to receive the inner member. The sheath comprises a proximal sheath portion and a distal sheath portion configured to rotate relative to the proximal sheath portion between a first rotational orientation and a second rotational orientation. When the distal sheath portion is in the second rotational orientation, the sheath has a first length, and when the distal sheath portion is in the second rotational orientation, the sheath has a second length shorter than the first length.

In some examples, a method comprises inserting a catheter into a hollow anatomical structure of a patient while a distal sheath portion of a sheath of the catheter is in a first rotational orientation relative to a proximal sheath portion; and rotating the distal sheath portion of the sheath relative to the proximal sheath portion of the sheath from the first rotational orientation to a second rotational orientation. The distal sheath portion defines a first proximal end and a second proximal end proximal to the first proximal end. When the distal sheath portion is in the first rotational orientation, the first proximal end is separated from the distal sheath portion by a first distance, and when the distal sheath portion is in the second rotational orientation, the first proximal end is separated from the distal sheath portion by a second distance.

In some examples, a kit comprises a circular compression bandage; and a catheter comprising: a sheath defining a lumen. The sheath comprises a proximal sheath portion; and a distal sheath portion configured to rotate relative to the proximal sheath portion between a first rotational orientation and a second rotational orientation. The distal sheath portion defines a first proximal end and a second proximal end proximal to the first proximal end. When the distal sheath portion is in the first rotational orientation, the first proximal end is separated from the proximal sheath portion by a first distance, and when the distal sheath portion is in the second rotational orientation, the first proximal end is separated from the proximal sheath portion by a second distance, the second distance being less than the first distance.

The details of one or more examples of the disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the disclosure will be apparent from the description and drawings, and from the claims.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1A and 1B are conceptual side elevation views of an example retractable sheath that includes at least two portions: a proximal sheath portion and a distal sheath portion.

FIG. 1C is a cross-sectional view of the distal sheath portion of the sheath of FIG. 1A taken along line C-C in FIG. 1A in a direction orthogonal to a longitudinal axis of the sheath.

FIG. 1D is another cross-sectional view of the distal sheath portion of the sheath of FIG. 1A taken along line D-D in FIG. 1A in a direction orthogonal to the longitudinal axis.

FIG. 1E is a cross-sectional view of the sheath of FIG. 1B taken along line E-E in FIG. 1A in a direction orthogonal to the longitudinal axis.

FIGS. 2A and 2B are conceptual side elevation views of an outer member positioned over the retractable sheath shown in FIGS. 1A and 1B.

FIGS. 3A and 3B are conceptual side elevation views of an example catheter including the sheath of FIGS. 1A and 1B and an inner member including a treatment portion.

FIG. 3C is a cross-sectional view of the catheter of FIG. 3A taken along line C-C in FIG. 3A in a direction orthogonal to a longitudinal axis.

FIG. 3D is another cross-sectional view of the catheter of FIG. 3A taken along line D-D in FIG. 3A in a direction orthogonal to the longitudinal axis.

FIG. 3E is a cross-sectional view of the catheter of FIG. 3B taken along line E-E in FIG. 3B in a direction orthogonal to the longitudinal axis.

FIG. 4 is a flow diagram illustrating an example technique of using the catheter of FIGS. 3A–3E to perform a medical procedure including ablation of a hollow anatomical structure of a patient.

FIGS. 5A–5D are conceptual diagrams illustrating stages of the example technique of FIG. 4 for ablation of the hollow anatomical structure of the patient.

DETAILED DESCRIPTION

A medical device, such as a catheter, may include a retractable sheath. For example, some catheters include an inner member and a retractable sheath configured to cover at least part of the inner member. The sheath may cover at least part of the inner member during delivery of the catheter to a target site within a body of a patient, during storage of the catheter, or both, and may be retracted in a proximal direction, away from a distal end of the inner member, when exposure of at least part of the covered part of the inner member is desired. For example, the sheath may cover a treatment portion of the catheter, which may be separate from the inner member or may be part of the inner member. Example treatment portions include treatment devices such as one or more heating elements configured to ablate tissue of a patient, a stent, a stented device such as a self-expandable heart valve device, a detachable coil for embolization or other medical device, a therapeutic agent delivery element, an electrode configured to deliver electrical energy to a tissue site in a patient, or an opening in the inner member configured to deliver and/or implant a therapeutic agent or medical device.

When the sheath is positioned over the inner member (or at least a part thereof) , the sheath may enable easier delivery of the catheter to a target site in a patient, such as by keeping a treatment device in a lower profile configuration, by the presence of a hydrophilic coating or surface modification treatment on an inner wall of the sheath, and/or by providing a lubricious outer member over the treatment portion of the catheter. In addition, the sheath may help protect the inner member or a treatment device during delivery of the catheter to the target site. For example, a treatment device may be delicate, sharp, coated with a therapeutic agent or another substance, expandable, or the like, and a retractable sheath help protect the treatment device from the external environment. In other examples, a retractable sheath as described herein may be used for a variety of other reasons.

The retractable sheaths described herein are configured to cover a treatment portion of a catheter and are configured to enable a user to change a total length of the sheath, e.g., to retract the sheath proximally to expose a treatment portion of the catheter. The total length of the sheath is measured along a longitudinal axis of the sheath from a proximal-most end of the sheath to a distal-most end of the sheath. In some examples, a longitudinal portion of the retractable sheath can assume at least two rotational orientations relative to another longitudinal portion of the retractable sheath; in a first rotational orientation, the retractable sheath is in a first rotational configuration and has a first total length, and in a second rotational orientation, the retractable sheath is in a second rotational configuration and has a second total length. In this way, a portion of the retractable sheath may be rotated or at least two portions of the retractable sheath may be rotated relative to each other to modify a total length of the sheath and retract the sheath to expose a treatment portion of the catheter. In other examples, the portion of the retractable sheath may be rotated to modify a total length of the sheath for other medical procedures requiring different catheter lengths, for example, the delivery of a self-expandable stent or self-expandable stented device such as a self-expandable heart valve device or a detachable coil.

The retractable sheaths described herein do not require a separate mechanical system for retraction and instead a user may manually translate one sheath portion longitudinally relative to the other sheath portion, e.g., after rotating the sheath portions relative to each other to enable the effective retraction of the distal sheath portion. For example, a user may rotate one or both the proximal and distal sheath portions and thereafter bring the distal sheath portion closer to the proximal sheath portion to shorten the total sheath length, such as by moving (in a longitudinal direction) the distal sheath portion towards the proximal sheath portion and/or by moving the proximal sheath portion towards the distal sheath portion. A user may not need to significantly move a handle of the catheter (e.g., in a direction away from a patient) in order to retract the sheath. Thus, the retractable catheter described herein may be simpler than some other catheters including retractable sheaths, and may enable a clinician to better control exposing the distal end of treatment portion of the catheter, even during retraction, compared to other catheters.

In addition, in some cases, the retractable sheaths described herein may be less complicated to use, easier to control the exposed length of a treatment portion of a catheter, easier to manufacture, or less likely to be inadvertently retracted in comparison to some other catheters including retractable sheaths. For example, the retractable sheaths described herein do not require the use of a pull wire, a pin and pull mechanism, or another mechanism separate from the sheath to retract the sheath. While pull wires and other mechanical systems for retracting a sheath relative to another component of a catheter or relative to a body of a patient are useful, these separate mechanical systems may be more complicated to use, more expensive to manufacture, more difficult to manufacture, more time-consuming to manufacture, or more subject to technical difficulties (e.g., twisting of the pull wire) , in comparison to the retractable sheaths described herein.

The retractable sheaths described herein include at least one portion configured to be rotated about its longitudinal axis to proximally retract a distal portion of the retractable sheath, which may help prevent inadvertent retraction of the sheath in comparison to a sheath that is retracted by moving (e.g., translating) the sheath proximally without another motion (e.g., rotation about its longitudinal axis) . In addition, the retractable sheath of the disclosure may enable a clinician to better control a proximal end of a catheter including the retractable sheath, as the retractable sheath described herein may enable a handle of the catheter to remain in a desired position to control the catheter, even during proximal retraction of a distal portion of the sheath.

FIGS. 1A and 1B are conceptual side elevation views of an example retractable sheath 10 that includes at least two portions: a proximal sheath portion 14 and a distal sheath portion 16. The proximal sheath portion 14 and the distal sheath portion 16 are configured to be rotated relative to each other in order to enable a distal-most end 17 of the distal sheath portion 16 to be moved closer to the proximal sheath portion 14 (by moving the distal sheath portion 16 and/or the proximal sheath portion 14) and thereby effectively change a total length of the sheath 10 and effectively retract the distal sheath portion 16 of the sheath 10. FIG. 1A illustrates the sheath 10 in a first rotational configuration, in which the distal sheath portion 16 is in a first rotational orientation and in which the sheath 10 has a first total length L ₁. FIG. 1B illustrates the sheath 10 in a second rotational configuration, in which the distal sheath portion 16 in a second rotational orientation and in which the sheath 10 has a second total length L ₂ that is less than the first total length L ₁. Thus, when the distal sheath portion 16 is in the second rotational orientation, the sheath 10 can assume a retracted configuration. The total lengths L ₁, L ₂ are measured along a longitudinal axis K of the sheath 10 from the distal-most end 17 of the sheath 10 to a proximal-most end 19 of the sheath 10. The longitudinal axis K is shown to be parallel to the x-axis direction in FIGS. 1A and 1B (orthogonal x-y axes are shown in FIGS. 1A and 1B, as well as other figures, for ease of description only) .

A “rotational configuration” of the sheath 10 is a configuration of the sheath 10 defined by the relative rotational orientations of the proximal and

distal sheath portions

14, 16 as well as the distance between the proximal sheath portion 14 and a distal-most end 17 of the sheath 10. For example, in a first rotational configuration of the sheath 10, the distal sheath portion 16 may be in a first rotational orientation relative to the proximal sheath portion 14. In a second rotational configuration of the sheath 10, the distal sheath portion 16 may be in a second rotational orientation relative to the proximal sheath portion 14 different than the first rotational orientation. As an example, a relative orientation of the proximal sheath portion 14 and the distal sheath portion 16 when the sheath 10 is in the second rotational orientation may be 180°different than when the sheath 10 is in the first rotational orientation.

In the example shown in FIGS. 1A and 1B, the sheath 10 is configured to be retracted by rotating the proximal sheath portion 14 and the distal sheath portion 16 relative to each other about longitudinal axis K, whether it is by rotating only one of the

sheath portions

14 or 16, or by rotating both of the

sheath portions

14, 16. For ease and brevity of description, rotation of the distal sheath portion 16 relative to the proximal sheath portion 14 is primarily referred to throughout the description as a way to change the rotational configuration of the sheath 10 to change a total length of the sheath 10 and retract the distal sheath portion 16 of the sheath 10. However, in other examples, both the proximal sheath portion 14 and the distal sheath portion 16 can be rotated (about longitudinal axis K) relative to each other to change the rotational configuration of the sheath 10 and change a total length of the sheath 10, or only the proximal sheath portion 14 can be rotated (about longitudinal axis K) relative to the distal sheath portion 16 to change the rotational configuration of the sheath 10 and change a total length of the sheath 10.

In order for the sheath 10 to be retracted, the proximal sheath portion 14 and/or the distal sheath portion 16 defines ends (also referred to as end portions in some examples) that are not longitudinally aligned in the x-axis direction, e.g., are different distances from an opposing end of the respective proximal sheath portion 14 or distal sheath portion 16. For example, the distal sheath portion 16 may define a proximal stepped end including a first proximal end 18A and a second proximal end 18B that is proximal to the first proximal end 18A (e.g., along a longitudinal axis K of the catheter 12) . In the example shown in FIGS. 1A and 1B, the first proximal end 18A is a first distance from the distal end 17 of the distal sheath portion 16 and the second proximal end 18B is a second distance from the distal end 17, where the second distance is greater than the first distance.

Similarly, in some examples, the proximal sheath portion 14 may define a distal stepped end including a first distal end 20A and a second distal end 20B (also referred to as end portions in some examples) distal to the first distal end 20A (e.g., along longitudinal axis K) . The first distal end 20A is a first distance from the proximal end 19 of the proximal sheath portion 14 and the second distal end 20B is a second distance from the proximal end 19, where the second distance is greater than the first distance.

FIG. 1C is a cross-sectional view of the distal sheath portion 16 of the sheath 10 taken along line C-C in FIG. 1A in a direction orthogonal to the longitudinal axis K of the sheath 10 and looking towards the proximal end 19 of the sheath 10. FIG. 1C illustrates a cross-section of the distal sheath portion 16 near the first proximal end 18A when the distal sheath portion 16 is in a first rotational orientation. As shown in FIG. 1C, the distal sheath portion 16 at or near the first proximal end 18A includes both the first proximal end 18A and the portion of the distal sheath portion 16 forming the second proximal end 18B. In other words, along line C-C in FIG. 1A, the distal sheath portion 16 subtends 100%of a total outer perimeter (e.g., an outer circumference) of the sheath 10 (e.g., there are no circumferential gaps in the distal sheath portion 16) .

FIG. 1D is a cross-sectional view of the distal sheath portion 16 taken along line D-D in FIG. 1A in a direction orthogonal to the longitudinal axis K of the sheath 10 and looking towards the proximal end 19 of the sheath 10. FIG. 1D illustrates a cross-section of the distal sheath portion 16 near the second proximal end 18B when the distal sheath portion 16 is in the first rotational orientation. As shown in FIG. 1D, the distal sheath portion 16 at or near the second proximal end 18B only includes the portion of the distal sheath portion 16 forming the second proximal end 18B and does not include the part of the distal sheath portion 16 forming the first proximal end 18A because the second proximal end 18B is proximal to the first proximal end 18A. Thus, the portion of the distal sheath portion 16 that includes the second proximal end 18B subtends less than 100%of a total outer perimeter of the sheath 10 (e.g., 10%to about 90%, such as about 25%to about 75%or about 50%of the outer perimeter) .

The proximal sheath portion 14 shown in FIG. 1D includes the first distal end 20A. As seen in FIG. 1D, in some examples, the first distal end 20A may also subtend less than 100%of a total outer perimeter of the sheath 10 (e.g., 10%to about 90%, such as about 25%to about 75%or about 50%of the outer perimeter) .

Each

end

18A, 18B, 20A, or 20B may subtend any suitable percentage of an outer perimeter (e.g., a circumference) of the respective distal sheath portion 16 or proximal sheath portion 14. For example, in some cases, the first proximal end 18A and the second proximal end 18B may each subtend about 10%to about 90%, such as about 25%to about 75%or about 50%of the outer perimeter of the distal sheath portion 16. In some examples, the first and second proximal ends 18A, 18B together subtend 100%of the total outer perimeter of the sheath 10, while in other examples, the first and second proximal ends 18A, 18B together subtend less than 100%of the total outer perimeter of the sheath 10. In other examples, the first proximal end 18A and the second proximal end 18B may subtend a different percentage of the outer perimeter of the distal sheath portion 16.

First and second distal ends 20A, 20B may similarly each subtend about 10%to about 90%, such as about 25%to about 75%or about 50%of the outer perimeter of the outer perimeter of the proximal sheath portion 14, or subtend another percentage of the outer perimeter of the proximal sheath portion 14. In some examples, the first and second distal ends 20A, 20B together subtend 100%of the total outer perimeter of the sheath 10, while in other examples, the first and second distal ends 20A, 20B together subtend less than 100%of the total outer perimeter of the sheath 10.

The percentages in which first and second proximal ends 18A, 18B subtend the outer perimeter of the distal sheath portion 16 and the percentages in which first and second distal ends 20A, 20B subtend the outer perimeter of the proximal sheath portion 14 may substantially correspond so that a total length of the sheath 10 can be modified by rotating the distal sheath portion 16 and the proximal sheath portion 14 relative to each other about the longitudinal axis K, e.g., by rotating the distal sheath portion 16 without rotating the proximal sheath portion 14, by rotating the proximal sheath portion 14 without rotating the distal sheath portion 16, or by rotating both the proximal and

distal sheath portions

14, 16 relative to each other.

In some examples, the second proximal end 18B may subtend a first percentage of the outer perimeter of the distal sheath portion 16 and the first distal end 20A may subtend a second percentage of the outer perimeter of the proximal sheath portion 14. The second percentage may be greater than or equal to the first percentage such that second proximal end 18B can fit within a gap 15 defined by the proximal sheath portion 14 when the distal sheath portion 16 is rotated about longitudinal axis K relative to the proximal sheath portion 14. In some cases, the percentage the second proximal end 18B subtends the outer perimeter of the distal sheath portion 16 may be the same or substantially the same as the percentage in which the first distal end 20A subtends the outer perimeter of the proximal sheath portion 14.

Similarly, in some examples, the percentage in which the first proximal end 18A subtends the outer perimeter of the distal sheath portion 16 may be the same or substantially the same as the percentage in which the second distal end 20B subtends the outer perimeter of the proximal sheath portion 14. In this way, the proximal and

distal sheath portions

14, 16 may form a pocket that defines the gap 15 of the sheath 10 when the sheath 10 is in the first rotational configuration and in which the distal sheath portion 16 (e.g., the second proximal end 18A) fits into when the sheath 10 is in the second rotational configuration. In other words, in the first rotational configuration, the sheath 10 may define the gap 15 between the first proximal end 18A, the first distal end 20A, and sides of the distal sheath portion 16 or the proximal sheath portion 14 that extend past the first proximal end 18A or the first distal end 20A, respectively.

In some examples, the distance (measured along the x-axis direction and along longitudinal axis K) by which the second proximal end 18B is proximal to the first proximal end 18A and the distance by which the second distal end 20B is distal to the first distal end 20A may also substantially correspond. For example, the distance by which the second proximal end 18B is proximal to the first proximal end 18A may be the same or substantially the same as the distance by which the second distal end 20B is distal to the first distal end 20A. In turn, in some examples, the sheath 10 may not define any longitudinal gaps between parts of the proximal and

distal sheath portions

14, 16 when the sheath 10 is in the second rotational configuration, as shown in FIG. 1B, or may define relatively smaller longitudinal gaps when the sheath 10 is in the second rotational configuration compared to the first rotational configuration. In other examples, the distance by which the second proximal end 18B is proximal to the first proximal end 18A and the distance by which the second distal end 20B is distal to the first distal end 20A may not substantially correspond. Thus, in some examples, the sheath 10 may include longitudinal gaps between parts of the proximal and

distal sheath portions

14, 16 in both the first and second rotational configurations.

The distal sheath portion 16 is configured to be rotated relative to the proximal sheath portion 14 in order to enable retraction of the distal sheath portion 16. Retraction of the distal sheath portion 16 may expose at least part of a treatment portion of an inner member (e.g., within a lumen 21 of the sheath 10) , change the total length of the sheath 10, or both. The distal sheath portion 16 is configured to rotate about longitudinal axis K relative to the proximal sheath portion 14 between a first rotational orientation (FIG. 1A) and a second rotational orientation (FIG. 1B) . As noted above, although the distal sheath portion 16 being rotated relative to the proximal sheath portion 14 to retract the distal sheath portion 16 is primarily described herein, in other examples, the proximal sheath portion 14 may be configured to be rotated about longitudinal axis K relative to the distal sheath portion 16 while the distal sheath portion 16 remains in a relatively steady rotational position, or both the proximal and

distal sheath portions

14, 16 may rotate relative to each other.

As shown in FIG. 1A, when the distal sheath portion 16 is in the first rotational orientation relative to the proximal sheath portion 14, the first proximal end 18A of the distal sheath portion 16 is a first distance D ₁ from the proximal sheath portion 14 (e.g., the first proximal end 18A does not contact the proximal sheath portion 14) . For example, the first proximal end 18A of the distal sheath portion 16 may be the first distance D ₁ from the first distal end 20A of the proximal sheath portion 14. In some examples, in the first rotational orientation, the second proximal end 18B may contact the proximal sheath portion 14 (e.g., the second distal end 20B) . Thus, because the second proximal end 18B is proximal to the first proximal end 18A and the second distal end 20B is distal to the first distal end 20A, there is the first distance D ₁ between the first proximal end 18A and the proximal sheath portion 14 (e.g., the first distal end 20A) when the distal sheath portion 16 is in the first rotational orientation. In some cases, the first distance D ₁ between the first proximal end 18A and the proximal sheath portion 14 (e.g., the first distal end 20A) defines a length in the longitudinal direction K of the gap 15 of the sheath 10. In other examples, the second proximal end 18B may not contact the proximal sheath portion 14 such that there is another longitudinal gap between the second proximal end 18B and the second distal end 20B when the sheath 10 is in the first rotational configuration.

In some examples, the first distance D ₁ is the amount by which the total length of the sheath 10 decreases and the amount by which the distal-most end 17 of the distal sheath portion 16 is proximally retracted when the distal sheath portion 16 is rotated relative to the proximal sheath portion 14 and subsequently pulled towards the proximal sheath portion 14 to place the sheath 10 in the second rotational configuration. The first distance D ₁ may have any suitable value, such as about 4 millimeters (mm) to about 180 mm. In some cases, the first distance D ₁ may depend on a length of a treatment portion of an inner member of a catheter that includes the sheath 10 and is selected such that when the distal sheath portion 16 of the sheath 10 is proximally retracted by the first distance D ₁, the treatment portion is uncovered by the sheath 10. For example, in examples in which a treatment portion includes a heating element, first distance D ₁ may correspond to a length of the heating element. For example, the first distance D ₁ may be about twice the length of the heating element. In other examples, first distance D ₁ may be a different length, or may correspond to a length of the treatment portion by a different factor (e.g., the same length, three times the length, or the like) . Examples of the inner member and the treatment portion will be described in more detail with respect to FIGS. 3A–3E.

In some examples, when the sheath 10 is in the first rotational configuration, the second proximal end 18B of the distal sheath portion 16 contacts (e.g., abuts) the second distal end 20B of the proximal sheath portion 14. Thus, in some such examples, when the distal sheath portion 16 is in the first rotational orientation, the sheath 10 may define the gap 15 between the first proximal end 18A and the first distal end 20A, but not between the second proximal end 18B and the second distal end 20B. In this way, at least some of the distal sheath portion 16 being in contact with the proximal sheath portion 14 may stabilize the sheath 10, which may improve handling of the sheath 10. For example, the sheath 10 including the second proximal end 18B abutting the second distal end 20B may have improved pushabililty in comparison to some sheaths in which the distal sheath portion 16 does not contact the proximal sheath portion 14 in the first rotational configuration. In other examples, the sheath 10 may define the gap 15 between the first proximal end 18A and the first distal end 20A and another gap between the second proximal end 18B and the second distal end 20B.

The distal sheath portion 16 may be rotated in any suitable amount about longitudinal axis K relative to the proximal sheath portion 14 to retract the distal sheath portion 16. For example, in some cases, such as in examples in which first and second proximal ends 18A, 18B each subtend about 50% (e.g., 50%or nearly 50%to the extent permitted by manufacturing tolerances) of the outer perimeter of the distal sheath portion 16 and first and second distal ends 20A, 20B also each subtend about 50%of the outer perimeter of the proximal sheath portion 14, the distal sheath portion 16 may be rotated about 180° relative to the proximal sheath portion 14 to retract the distal sheath portion 16. In other examples, the distal sheath portion 16 may be rotated any amount relative to the proximal sheath portion 14, such as, for example, an amount depending on the percentages in which proximal ends 18A, 18B and/or distal ends 20A, 20B subtend the outer perimeters of the distal sheath portion 16 or the proximal sheath portion 14, respectively.

In some examples, the distal sheath portion 16 may be rotated relative to the proximal sheath portion 14 and also moved in a proximal direction (e.g., along longitudinal axis K) to retract the distal sheath portion 16. Thus, in some examples, two types of motion (e.g., translation and rotation) may be used to retract the distal sheath portion 16. In this way, the distal sheath portion 16 may be less likely to be accidently retracted in comparison to some other retractable sheaths that are retracted by only translational movement, which may help prevent inadvertent exposure of a treatment portion of an inner member, unintended delivery of a therapeutic agent, unintended expansion of the treatment portion, or the like.

When the sheath 10 is in the second rotational configuration, shown in FIG. 1B, the first proximal end 18A of the distal sheath portion 16 substantially aligns about the longitudinal axis K with the second distal end 20B of the proximal sheath portion 14, and the second proximal end 18B of the distal sheath portion 16 substantially aligns with the first distal end 20A of the proximal sheath portion 14. In this way, the first proximal end 18A is a second distance D ₂ (which is less than the first distance D ₁) from the proximal sheath portion 14. In some examples, the second distance D ₂ may be zero such that the first proximal end 18A abuts the second distal end 20B when the sheath 10 in the second rotational configuration. Additionally, or alternatively, the second proximal end 18B may abut the first distal end 20A when the sheath is in the second rotational configuration and the distal-most end 17 of the distal sheath portion 16 is brought closer towards the proximal sheath portion 14. In other examples, the second distance D ₂ may be a different distance greater than zero and less than the first distance D ₁ such that the second proximal end 18B does not abut the first distal end 20A when the sheath 10 is in the second rotational configuration. For example, the second distance D ₂ may be about 0 mm to about 5 mm.

The first distance D ₁ is greater than the second distance D ₂, which enables a total length L ₁, L ₂ of the sheath 10 to be modified and the sheath 10 to be proximally retracted without requiring a mechanical retraction system (e.g., a thumbwheel) separate from the sheath 10 or without requiring the proximal-most end 19 of the sheath 10 to move relative to the patient (though a clinician may choose to move the proximal-most end 19) . When the distal sheath portion 16 is in the second rotational orientation, a second total length L ₂ of the sheath 10 is less than a first total length L ₁ of the sheath 10 when the distal sheath portion 16 is in the first rotational orientation. Thus, when the distal sheath portion 16 is in the second rotational orientation, the sheath 10 is effectively retracted, which may expose a treatment portion, for example, to enable expansion of the treatment portion, delivery of a therapeutic agent, exposure of a needle, a heating element, or another element, or the like.

FIG. 1E is a cross-sectional view of the sheath 10 taken along line E-E in FIG. 1B in a direction orthogonal to the longitudinal axis K and looking towards the proximal end 19 of the sheath 10. As shown in FIG. 1E, along line E-E in FIG. 1B, the sheath 10 includes the distal sheath portion 16 and the proximal sheath portion 14 such that there are no gaps in the sheath 10. For example, in the example of FIG. 1E, the sheath 10 does not include longitudinal gaps or circumferential gaps. As described above, in some examples, in the second rotational configuration of the sheath 10, the first proximal end 18A may abut the second distal end 20B and the second proximal end 18B may abut the first distal end 20A to fill the gap 15 that may be present when the sheath 10 is in the first rotational configuration and to retract the distal sheath portion 16.

The sheath 10 may define any total length L ₁, L ₂ suitable for the intended use of the sheath 10. For example, in some cases, such as examples in which the sheath 10 is used in an ablation procedure for treatment of varicose veins, the total length of the sheath 10 may be about 50 mm to about 1800 mm, such as about 50 mm to about 1200 mm. For example, the first total length L ₁ of the sheath 10 in the first rotational configuration may be about 54 mm to about 1800 mm, and the second total length L ₂ of the sheath 10 in the second rotational configuration may be about 50 mm to about 1300 mm. In other examples, the catheter 12 may have a different total length in one or both of the first rotational configuration or the second rotational configuration.

The sheath 10 may be made of any suitable material. In some examples, an inner wall of the sheath 10 may include a hydrophilic coating or surface modification treatment. In some examples, the sheath 10 may include a polymer, such as, for example, at least one of nylon, polyethylene, fluorinated ethylene propylene, polyether ether ketone, polyimide, polyvinylidene fluoride, polypropylene, or polytetrafluoroethylene. In other examples, the sheath 10 may include a different polymer or a different composition. In some examples, the sheath 10 may include more than one material. For example, in some examples, the distal sheath portion 16 may include a first material and the proximal sheath portion 14 may include a second material different than the first material. In other examples, the distal sheath portion 16 and the proximal sheath portion 14 may include the same material.

The sheath 10 may be configured to receive an inner member, such as an inner catheter or a guidewire. Thus, in some cases, the sheath 10 defines a lumen 21. In other examples, the lumen 21 may be used for other purposes than receiving an inner member. For example, the lumen 21 may be configured to transport a fluid, deliver a therapeutic agent, or the like. Moreover, in some examples, the lumen 21 may include more than one lumen. For example, the sheath 10 may define two lumens, one configured to receive an inner member and another configured to receive a guidewire. In any case, the sheath 10 and/or the lumen 21 of the sheath 10 may be configured in any suitable manner to fit particular needs (e.g., relating to a medical procedure in which the sheath 10 is used) .

In some examples, a dimension of the sheath 10 in a direction orthogonal to the longitudinal axis K, which may be a diameter in examples in which the sheath 10 has a circular cross-section, may depend on the intended use of a catheter including the sheath 10, whether an inner member is to be received in the lumen 21, a type of inner member or treatment portion, a target site within a body of a patient, an anatomy of the patient, or the like. In some examples, an outer diameter of the sheath 10 may be about 3 French (about 1 mm) to about 9 French (about 3 mm) , such as about 6 French (about 2 mm) to about 7 French (about 2.33 mm) . In other examples, the sheath 10 may have an alternative outer diameter. Additionally, or alternatively, the sheath 10 may have an inner diameter of about 2.5 French to about 8 French, such as about 2 French to about 6 French. In other examples, the sheath 10 may have a different inner diameter. The sheath 10 may have any suitable wall thickness, such as, but not limited to a wall thickness in a range of about 0.05 mm to about 0.18 mm.

In some examples in which the sheath 10 is configured to receive an inner member, the inner member may include a treatment portion, and sheath 10 may be configured to cover the treatment portion (e.g., when the sheath 10 is in the first rotational configuration) , and the distal sheath portion 16 may be retracted to expose the treatment portion (e.g., when the sheath 10 is in the second rotational configuration) . For example, in the first rotational configuration, the sheath 10 may have a first total length L ₁and may cover the treatment portion of a catheter, for example, to protect the treatment portion or hold the treatment portion in a specific configuration. Thus, in some examples, a catheter may include the sheath 10 and an inner member. The distal sheath portion 16 may be retracted when the sheath 10 is in the second rotational configuration by, for example, pulling the distal sheath portion 16 in a direction towards the proximal sheath portion 14 the distal sheath portion 16 in a direction towards the proximal sheath portion 14, by pushing the proximal sheath portion 14 towards the distal sheath portion 16, or any combination thereof.

In some examples, an outer member covers at least part of the sheath 10 and is mechanically connected to the sheath 10 to aid in rotation of one or both of the first and

second sheath portions

14, 16 about the longitudinal axis K. An example of an outer member 23 is shown in FIGS. 2A and 2B. In the example shown in FIGS. 2A and 2B, the outer member 23 covers only part of the sheath 10 and is mechanically connected to the sheath 10. FIG. 2A illustrates the sheath 10 in the first rotational configuration (corresponding to FIG. 1A) and FIG. 2B illustrates the sheath 10 in the second rotational configuration (corresponding to FIG. 2A) , while the sheath 10 is in the second rotational orientation and after the distal sheath portion 16 and the proximal sheath portion 14 and moved closer to each other (whether by moving one or both of the sheath portions 14, 16) .

The outer member 23 may cover any suitable length of the sheath 10. In some examples, when the sheath 10 is in the first rotational configuration, the outer member 23 fully covers at least a distal part of the proximal sheath portion 14 (e.g., only the distal part including the distal end 20B and, in some examples, the distal end 20A, or the entire proximal sheath portion 14) and at least part of the distal sheath portion 16 (e.g., only the proximal part including the proximal end 18B and, in some examples the proximal end 18A, or the entire distal sheath portion 16) . In the example shown in FIG. 2A, when the sheath 10 is in the first rotational configuration, the proximal end 19 of the sheath 10 is longitudinally aligned with a proximal end 23A of the outer member 23. In other examples, when the sheath 10 is in the first rotational configuration, the outer member 23 covers at least part of the distal sheath portion 16 and only part of the proximal sheath portion 14, e.g., leaving the proximal end 19 of the sheath 10 extending proximal to the proximal end 23A of the outer member 23.

Although a gap is shown between an outer surface of the sheath 10 and the inner surface of the outer member 23 in FIGS. 2A and 2B, in other examples, the inner surface of the outer member 23 contacts the outer surface of the sheath 10 when the outer member 23 is positioned around the sheath 10.

The outer member 23 may help keep the proximal sheath portion 14 and the distal sheath portion 16 fixed relative to each other during navigation of the sheath 10 to a target site within a patient, which may help improve navigability of the sheath 10 and, in some examples, help keep the sheath 10 in the first rotational configuration, when is inserted through vasculature or other tissue of a patient. For example, pushing or torqueing forces applied to the proximal sheath portion 14 may be translated to the distal sheath portion 16 when the

sheath portions

14, 16 are fixed to each other. The outer member 23 can be mechanically connected to the distal sheath portion 16 and not the proximal sheath portion 14, or to both the distal sheath portion 16 and the proximal sheath portion 14. The mechanical connection between the outer member 23 and the distal sheath portion 16 and/or the proximal sheath portion 14 may be permanent or may be temporary, and may be provided by any suitable mechanism, such as, but not limited to, adhesive, welding (e.g., ultrasonic welding) , a mechanical locking mechanism (e.g., a snap fit) , and the like.

In some cases, the distal sheath portion 16 is fully or partially introduced into the patient, such that a user may not be able to grasp the distal sheath portion 16 well enough to rotate it about the longitudinal axis K and/or to move it (e.g., towards the proximal sheath portion 14 to retract the distal-most end 17 of the distal sheath portion 16) . The outer member 23 provides a structure that a user may grasp in order to rotate the distal sheath portion 16 and/or move the distal sheath portion 16. In examples in which the outer member 23 is mechanically connected to both the proximal and

distal sheath portions

14, 16, the mechanical connection between the proximal sheath portion 14 and the outer member 23 may be weaker (e.g., at least in the rotational direction) than the mechanical connection between the distal sheath portion 16 and the outer member 23 such that when a user rotates the outer member 23 about the longitudinal axis K, the mechanical connection between the outer member 23 and the proximal sheath portion 14 breaks, but the integrity of the mechanical connection between the outer member 23 and the distal sheath portion 16 is maintained, such that a torqueing force applied to the outer member 23 is translated to the distal sheath portion 16 and enables the distal sheath portion 16 to rotate relative to the proximal sheath portion 14. In addition, because the integrity of the mechanical connection between the outer member 23 and the distal sheath portion 16 is maintained after the mechanical connection between the outer member 23 and the proximal sheath portion 14 is broken, movement of the outer member 23 along the longitudinal axis K is translated to the distal sheath portion 16, thereby enabling the distal sheath portion 16 to move along the longitudinal axis K relative to the proximal sheath portion 14.

As shown in FIG. 2B, in some examples, after the distal sheath portion 16 and the proximal sheath portion 14 are rotated relative to each other and moved relative to each other along the longitudinal axis K to bring the distal-most end 17 of the distal sheath portion 16 closer to the proximal-most end 19 of the sheath 10 (relative to the configuration shown in FIG. 2A) , the proximal-most end 19 of the sheath 10 may remain proximal to the proximal end 23A of the outer member 23. This may enable a user to continue to grasp the sheath 10 to manipulate the sheath 10 (e.g., rotate the sheath 10 about the longitudinal axis K, push or pull the sheath 10 by applying a pushing or pulling force to the proximal sheath portion 14, and the like) .

In other examples, however, the outer member 23 may have a different length, e.g., such that in the configuration shown in FIG. 2B, the proximal end 23A of the outer member 23 is aligned with or proximal to the proximal-most end 19 of the sheath 10. After the distal sheath portion 16 is in the second rotational orientation and the distal sheath portion 16 is retracted such that the sheath 10 is in the second rotational configuration, as shown in FIG. 2B, a user can detach the outer member 23 from the distal sheath portion 16 or may fix the outer member 23 to the proximal sheath portion 14 again to help keep the proximal sheath portion 14 and the distal sheath portion 16 fixed to each other during a medical procedure.

In some examples, the outer member 23 includes one or more features that help facilitate the gripping of the outer member 23 by a user’s hands or by a tool used by a user. For example, the outer member 23 can include tabs or a handle, or surface features (e.g., grooves, surface protrusions, and the like) that help facilitate the grasping of the outer sheath 23.

In addition, in some examples, the outer member 23 includes a marker 25, which can be visible to a user without the aid of medical imaging equipment or may be a radiopaque marker. The marker 25 can help a user identify the rotational orientation of the outer member 23 and, therefore, the distal sheath portion 16. Although the marker 25 is shown at a proximal end of the outer member 23, in other examples, the marker 25 can be positioned at any suitable location on the outer member 23. Further, the marker 25 can take any suitable form, such as, but not limited to, graphic, alphanumeric text, and the like.

The outer member 23 can be formed from any suitable material, such as, but not limited to, poly (tetrafluoroethylene) (PTFE) , high density polyethylene (HDPE) , or low density polyethylene (LDPE) . In some examples, the outer member 23 is transparent so the proximal sheath portion 14 and/or the distal sheath portion 16 are visible to a user through the outer member 23, e.g., so that a user can confirm the distal sheath portion 16 is in the second rotational orientation such that the distal sheath portion 16 can be retracted.

The distal sheath portion 16 may be retracted when the distal sheath portion 16 is in the second rotational orientation by, for example, pulling the distal sheath portion 16 in a direction towards the proximal sheath portion 14, by pulling the outer member 23, which is connected to the distal sheath portion 16, in a direction towards the proximal sheath portion 14, or by pushing the proximal sheath portion 14 towards the distal sheath portion 16, or any combination thereof.

FIGS. 3A and 3B are conceptual side elevation views of an example catheter 12 that includes the sheath 10 of FIGS. 1A and 1B and an inner member 22 including a treatment portion 24. FIG. 3C is a cross-sectional view of the catheter 12 taken along line C-C in FIG. 3A in a direction orthogonal to the longitudinal axis K and looking towards the proximal end of the catheter 12. FIG. 3D is a cross-sectional view of the catheter 12 taken along line D-D in FIG. 3A in a direction orthogonal to the longitudinal axis K and looking towards the proximal end of the catheter 12. FIG. 3E is a cross-sectional view of the catheter 12 of FIG. 3B taken along line E-E in FIG. 3B in a direction orthogonal to the longitudinal axis K and looking towards the proximal end of the catheter 12.

The catheter 12 may be used for a variety of medical procedures. For example, the catheter 12 may be used for an ablation procedure, to implant a stent or other medical device in a patient, tunnel a path through a patient’s anatomy, deliver a therapeutic agent, or the like. In some such examples, such as the example illustrated in FIGS. 3A and 3B, the inner member 22 is received in the lumen 21 of the sheath 10.

In the example of FIGS. 3A and 3B, the treatment portion 24 of the inner member 22 is positioned on a distal portion of the inner member 22. In other examples, however, the treatment portion 24 may be positioned anywhere relative to the inner member 22 and configured to be covered by the sheath 10. In some examples, the treatment portion 24 may include a heating element, a therapeutic agent-coated element, a stent, a needle, or another medical device, and may be delicate, sharp, coated with a therapeutic agent or another substance, expandable, or the like.

The sheath 10 is configured to cover the treatment portion 24, which may help prevent unintended delivery of a therapeutic agent, unintended expansion of the treatment portion 24, or the like. For example, when the distal sheath portion 16 is in the first rotational orientation, the distal sheath portion 16 may be configured to at least partially cover the treatment portion 24, and when the distal sheath portion 16 is in the second rotational orientation, the distal sheath portion 16 may expose (e.g., not cover) the treatment portion 24. As one example, the treatment portion 24 may include a balloon element, which may be delicate, and the balloon element may be delivered to a target site in a body of a patient while the sheath 10 is in the first rotational configuration to help protect the balloon element during navigation of the balloon element to the target site and to keep the balloon element in a relatively low profile state. When the catheter 12 is at the target site, the balloon may be exposed by rotating the distal sheath portion 16 relative to the proximal sheath portion 14 to the second rotational orientation to retract the distal sheath portion 16 and expose the balloon element.

In some examples in which the treatment portion 24 includes an expandable element, such as a stent or an expandable heating element, the sheath 10 may be configured to position the treatment portion 24 in different configurations. For example, the treatment portion 24 may be in a delivery configuration when the distal sheath portion 16 is in the first rotational orientation, and may be in an expanded configuration when the distal sheath portion 16 is in the second rotational orientation. The delivery configuration may be a lower profile configuration than the expanded configuration. In some of these examples, the treatment portion 24 may be configured to expand radially outward (e.g., radially outward from a central longitudinal axis K) by self-expansion or with the aid of a balloon or another expansion device when the distal sheath portion 16 is in the second rotational orientation. In this way, when the distal sheath portion 16 is in the first rotational orientation, the distal sheath portion 16 may at least partially cover the treatment portion 24 to keep the expandable element in a collapsed configuration (a relatively low profile configuration) , and the treatment portion 24 may be able to move into an expanded configuration when the distal sheath portion 16 is rotated relative to the proximal sheath portion 14 to retract the sheath 10.

In some examples, the catheter 12 may be used for an ablation procedure. For example, the catheter 12 may be used in an ablation procedure for treatment of varicose veins. In some such examples, the treatment portion 24 may include a heating element, which may be expandable (e.g., radially outward) in some examples. Expansion of the heating element may help the heating element achieve better contact with a hollow anatomical structure, such as a vein, or another target site within a body of a patient, which may improve the ablation of the vein or target site by the heating element. In the example shown in FIGS. 3A and 3B, treatment portion 24 includes an expandable heating element that comprises a plurality of expandable heating wires 28 surrounding a heating core 30. The plurality of expandable heating wires 28 may radially surround any circumferential portion of the heating core 30. For example, the plurality of heating wires 28 may define an arc length of about 360°, about 270°, about 180°, or about 90° around the heating core 30. In other examples, the plurality of heating wires 28 may define a different arc length around the heating core 30.

The plurality of heating wires 28 may include any number of heating wires. In some examples, the plurality of heating wires 28 may include 4 to 40 heating wires. In other examples, the plurality of heating wires 28 may include less than 4 or greater than 40 heating wires. In some examples, the number of heating wires of the plurality of heating wires 28 may depend on an intended use of the plurality of heating wires 28, the arc length around the heating core 30 that the plurality of heating wires defines, or the like. For example, a plurality of heating wires 28 that define a smaller arc length may include fewer heating wires than a plurality of heating wires 28 that define a larger arc length. In examples in which the plurality of heating wires 28 are used for an ablation procedure, such as to ablate a varicose vein, the plurality of heating wires 28 may define an arc length of about 360° around the heating core 30 so that the plurality of heating wires 28 can distribute heat around the inner wall of the vein being treated. In turn, the full circumferential coverage of the plurality of heating wires 28 may ablate the vein better than some heating elements that do not define arc lengths of about 360°.

In some examples, the plurality of heating wires 28 may form a single layer of heating wires around the heating core 30, as shown in FIGS. 3A and 3B. In some such examples, the plurality of heating wires 28 may include a fewer number of heating wires than examples in which the treatment portion 24 includes more than one layer of heating wires (e.g., heating wires stacked on top of each other around the heating core 30) . In other examples, the plurality of heating wires 28 may form multiple layers of heating wires around the heating core 30. The multiple layers of heating wires can, for example, increase a heating element surface area for a given treatment length.

The heating wires of the plurality of heating wires 28 may be made of any suitable material. In some examples, the plurality of heating wires 28 includes resistance wires. Such resistance wires may exhibit a relatively high resistivity and/or may be relatively resistant to oxidation at high temperatures. A relatively high resistivity may enable the resistance wire to convert energy, such as radio frequency (RF) energy, into heat, and the resistance to oxidation may help the plurality of heating wires 28 from breaking and/or burning out prematurely. In examples in which the plurality of heating wires 28 includes resistance wires, the plurality of heating wires 28 may include at least one of nichrome (a nickel-chromium alloy) , kanthal (a ferritic iron and chromium-aluminum alloy) , constantan (a copper–nickel alloy) , or a similar material. In other examples, the plurality of heating wires 28 may include a different material. Additionally, or alternatively, the plurality of heating wires 28 and/or the heating core 30 may include a coating, such as, for example, a heat and/or electric resistant coating. Such coatings may isolate each heating wire of the plurality of heating wires 28 and/or the heating core 30 from each other.

In some examples, the plurality of heating wires 28 may be round wires having circular cross-sections. In some such examples, each heating wire of the plurality of heating wires 28 may have a cross-sectional diameter of about 0.03 mm to about 0.50 mm. In other examples, the plurality of heating wires 28 may have a non-circular cross-section. For example, the plurality of heating wires 28 may be relatively flat, or may have an elliptical, a rectangular, a triangular, or another regular or irregular cross-sectional shape. In some examples, regardless of the shape of the cross-section of the plurality of heating wires 28, the plurality of heating wires 28 may have a cross-sectional dimension of about 0.03 mm to about 0.50 mm. In other examples, the cross-sectional dimension of each heating wire of the plurality of heating wires 28 may be less than about 0.03 mm or greater than about 0.50 mm.

As described above, the plurality of heating wires 28 may be expandable radially outward. In examples in which the plurality of heating wires 28 are used for an ablation medical procedure, such expandable heating wires 28 may make better contact with a hollow anatomical structure, such as vein, for ablation. In some examples, better contact with the hollow anatomic structure during ablation may provide better results of the medical procedure, reduce the need for follow-up procedures, reduce the time required for the ablation procedure, or the like. In some examples, a first cross-sectional dimension of the plurality of heating wires 28 (e.g., a diameter of the plurality of heating wires 28 around the heating core 30) may be about 2 French (about 0.66 mm) to about 8 French (about 2.66 mm) (e.g., as measured in the direction of the y-axis) when the distal sheath portion 16 is in the first rotational orientation (e.g., when the distal sheath portion 16 is at least partially covering the treatment portion 24) . When the distal sheath portion 16 is rotated relative to the proximal sheath portion 14 to expose the treatment portion 24, the plurality of heating wires 28 may expand radially outward to define a second cross-sectional dimension of about 4 French (1.33 mm) to about 30.3 French (about 10 mm) . In other examples, the plurality of heating wires 28 may have a different cross-sectional dimension.

The plurality of heating wires 28 may also be any suitable length, which is measured from a distal heating wire end 29 to a proximal heating wire end 31 (e.g., when the plurality of heating wires 28 are in a relatively straight configuration) . In some examples, the plurality of heating wires 28 may have a length of about 2 mm to about 100 mm. In other examples, the plurality of heating wires 28 may be a different length.

In some cases, a length of the treatment portion 24 may depend on the rotational orientation of the distal sheath portion 16. For example, the treatment portion 24 including the expandable heating element that includes the plurality of heating wires 28 may have a first length L ₃ when the distal sheath portion 16 is in the first rotational orientation and a second length L ₄ different than the first length L ₃ when the distal sheath portion 16 is in the second rotational orientation. For example, when the plurality of heating wires 28 are in the relatively low profile configuration (e.g., when the distal sheath portion 16 is in the first rotational orientation) , the treatment portion 24 may have a greater length L ₃ than when the plurality of heating wires 28 are in the expanded configuration (e.g., when the distal sheath portion 16 is in the second rotational orientation) .

In some examples, the catheter 12 includes an expansion mechanism configured to cause the plurality of heating wires 28 to expand when the distal sheath portion 16 is in the second rotational orientation. For example, an expansion mechanism may push or pull the plurality of heating wires 28 to cause them to expand. In the example of FIGS. 3A and 3B, the expansion mechanism includes a slip ring 32 and a spring 34. The slip ring 32 may be positioned proximal (e.g., along longitudinal axis K) to the plurality of heating wires 28, and the spring 34 may be positioned proximal to the slip ring 32. Moreover, in some examples, distal heating wire ends 29 of the plurality of heating wires 28 may be attached to a distal end of the heating core 30 and proximal heating wire ends 31 of the plurality of heating wires 28 may be attached to the slip ring 32 such that movement of the slip ring 32 results in movement of the proximal heating wire ends 31 of the plurality of heating wires 28, while the distal heating wire ends 29 of the plurality of heating wires 28 remain stationary.

When the distal sheath portion 16 is in the first rotational orientation, the plurality of heating wires 28 may be in the low profile configuration, and the spring 34 may be compressed as shown in FIG. 3A. When the distal sheath portion 16 is rotated to retract the distal sheath portion 16, the distal sheath portion 16 may no longer restrain the plurality of heating wires 28 in the low profile configuration. Without the restraint of the distal sheath portion 16, the spring 34 may be able to expand and exert a spring force against the slip ring 32 in a distal direction. In turn, the slip ring 32, and the plurality of heating wires 28 attached to the slip ring 32, may be pushed in a distal direction along the heating core 30 upon expansion of the spring 34 against the slip ring 32, which may expand the plurality of heating wires 28.

In some examples, the inner member 22 including the slip ring 32 and the spring 34 may expand the plurality of heating wires 28 upon retraction of the distal sheath portion 16 without requiring additional movements or steps by a clinician using the catheter 12. In this way, the inner member 22 including the slip ring 32 and the spring 34 may be simpler to use and/or enable a medical procedure to be performed more quickly in comparison to catheters that require a pull wire or another mechanical mechanism that is operated by a user. However, in other examples, such mechanical mechanisms or a different mechanism may be used to expand the plurality of heating wires 28, or the inner member 22 including the slip ring 32 and the spring 34 may be configured a different way. As one example, a pull wire may be used to expand the plurality of heating wires 28 after the distal sheath portion 16 is retracted. As another example, the plurality of heating wires 28 may be made of a shape memory material and may self-expand upon retraction of the distal sheath portion 16 (e.g., without the use of the slip ring 32, the spring 34, or another mechanism) . As yet another example, the inner member 22 may include the slip ring 32 and the spring 34 such that the spring 34 expands to push the slip ring 32 and the plurality of heating wires 28 in a proximal direction to expand the plurality of heating wires 28.

In some examples, the catheter 12 includes a sensor 36 configured to monitor a temperature of one or more heating wires 28, which may help a control device (not shown in FIGS. 3A and 3B) maintain a desired temperature of the heating wires 28. In some examples, the sensor 36 is located on the treatment portion 24, such as, for example, on the heating core 30. In other examples, the sensor 36 may be positioned elsewhere on catheter 12. In some cases, a device receives sensed data from the sensor 36 to control and/or adjust the temperature of the heating element. The sensor 36 may include any suitable temperature sensor, such as, but not limited to, a thermometer, thermocouple, thermistor, or another sensor configured to determine the temperature of the treatment portion 24.

In some examples, one or more electrical wires 44 may be used to connect the treatment portion 24 (e.g., the plurality of heating wires 28 and/or the heating core 30) to an energy generator configured to generate and deliver energy to the plurality of heating wires 28. For example, the plurality of heating wires 28 and/or the heating core 30 may be connected to a RF generator via one or more electrical wires 44. In some such examples, the inner member 22 may define an inner member lumen 38 (shown in FIGS. 3C–3E) , and one or more electrical wires 44 may be routed through the inner member lumen 38 from the treatment portion 24 to a handle 40. In some cases, routing electrical wires 44 through the inner member lumen 38 may help protect the electrical wires 44 and may neatly route electrical wires 44 from the handle 40 to the treatment portion 24. In some examples, inner member 22 may define more than lumen. For example, the inner member lumen 38 may include a lumen to route electrical wires 44 from the handle 40 to the treatment portion 24 and may include one or more additional lumens configured to transport fluids (e.g., a flushing lumen) , receive a guidewire, or the like.

In some cases, the sheath 10 and/or the inner member 22 may be connected to, extend within, or are routed through the handle 40. For example, the sheath 10 and/or the inner member 22 may extend within the handle 40 and may be in communication with one or

more ports

46, 48 of the handle 40.

Ports

46, 48 may provide access to the lumen 21 and/or the inner member lumen 38. For example, in the example of FIGS. 3A and 3B,

ports

46, 48 provide access to the inner member lumen 38. Port 46 may include a port that provides access to the inner member lumen 38 to facilitate advancing the catheter 12 along a guidewire, to facilitate transporting fluid through the inner member lumen 38, or the like, and port 48 may include a port that provides access to the inner member lumen 38 to route electrical wires 44 to the heating element of the treatment portion 24. In other examples, the handle 40 may include additional or

alternative ports

46, 48 in communication with the lumen 21 and/or the inner member lumen 38.

In some examples, the handle 40 may be configured to enable a clinician to control the heating element of the treatment portion 24. For example, the handle 40 may include an input device 42, such as a button, a switch, or the like, that enables the clinician to turn energy delivered to the heating element on and off. Additionally, or alternatively, input device 42 may enable the clinician to control an amount of energy delivered to the heating element, a type of energy delivered to the heating element, a parameter of the energy delivered to the heating element, or the like.

As described above, the electrical wires 44 may be used to deliver energy to the heating element of the treatment portion 24. Thus, electrical wires 44 may be electrically connected to the heating element (e.g., the plurality of heating wires 28 and/or the heating core 30) and may be electrically connected to an energy generator (not shown) . In some examples, the energy generator may include a RF generator. In some such examples, delivery of RF energy to the heating element generated by the RF generator may result in an ablation procedure easier to operate and/or requires less energy than some other ablation techniques, such as, for example, laser ablation. In other examples, the energy generator may be configured to generate a type of energy other than RF energy. For example, the energy generator may include an optical generator configured to generate optical energy, an electric resistance wire configured to heating energy, an ultrasound generator configured to generate ultrasonic energy, a microwave generator configured to generate microwave energy, or another type of energy generator. In some examples, the catheter 12 may be configured to be coupled to commercially available energy generators such that catheter 12 may be able to be used with existing equipment.

FIGS. 3C–3E are cross-sectional views of the catheter 12 taken along lines C-C, D-D, and E-E, respectively, in FIGS. 3A and 3B in a direction orthogonal to the longitudinal axis K. The part of the sheath 10 shown in FIGS. 3C–3E is similar to that shown in FIGS. 1C–1E. In addition, FIGS. 3C–3E illustrate the inner member 22 disposed within an inner lumen 21 of the sheath 10.

FIG. 4 is a flow diagram illustrating an example technique of using the catheter 12 of FIGS. 3A–3E to perform a medical procedure including ablation of a varicose vein of a patient. FIGS. 5A–5D are conceptual diagrams illustrating stages of the example technique of FIG. 4. In each of FIGS. 5A–5D, a leg of patient during the respective stages of the example technique of FIG. 4 are illustrated. In addition, each of FIGS. 5A–5D includes an enlarged view of an example hollow anatomical structure (HAS) , such as a varicose vein, of the leg of the patient with the catheter 12 inserted therein to perform the respective stage of the medical procedure. The technique of FIG. 4 will be described with respect to the catheter 12 of FIGS. 3A–3E and the stages illustrated in FIGS. 5A–5D for ease of description only; in other examples, other catheters or stages may be used with the technique of FIG. 4.

Properly functioning venous valves within the vasculature of a subject prevent the backflow of blood during circulation. For example, venous valves help to fight backflow of blood in the legs caused by gravity pulling the blood away from the heart and back towards the feet of a person when standing. However, when venous valves fail to work properly, blood can flow backwards within the veins and pool in, for example, the legs. Such pooling of blood can cause the veins to become distended, thereby causing the venous valves to fail further. This progressively worsening disorder can lead to varicose veins and chronic venous insufficiency, which can be painful and can lead to lower limb ulcerations. In some examples, the catheter 12 including the sheath 10 and the inner member 22 including the treatment portion 24 configured to ablate a hollow anatomical structure, such as a vein, of a patient may be used in a medical procedure for treatment of such varicose veins.

In the technique shown in FIG. 4, a clinician inserts the catheter 12 into a hollow anatomical structure (HAS) 60 of a patient (50) . In some cases, an introducer or another device may be used to insert the catheter 12 into the HAS 60. The HAS 60 may include a vein, such as a varicose vein in a leg 62 of the patient (e.g., as shown in FIGS. 5A–5D) . In other examples, however, the HAS 60 may include a vein in another portion of the patient’s body or a structure other than a vein. When the clinician inserts the catheter 12 into the HAS 60, the sheath 10 may be in a first rotational configuration in which the distal sheath portion 16 of the sheath 10 of the catheter 12 is in the first rotational orientation relative to the proximal sheath portion 14. In this way, the treatment portion 24 of the inner member 22 within the lumen 21 of the sheath 10 is at least partially covered by the distal sheath portion 16. For example, as described above, the treatment portion 24 may include the plurality of heating wires 28, and the plurality of heating wires 28 may be retained in a low profile configuration by the sheath 10 when the distal sheath portion 16 is at least partially covering the treatment portion 24 including the plurality of heating wires 28. In turn, the catheter 12 may be easier to deliver through the patient’s vasculature to a target site, such as the desired ablation site. FIG. 5A illustrates the catheter 12 within HAS 60 of the leg 62 of the patient.

In some examples, a clinician may elevate the leg 62 of the patient after inserting the catheter 12 into the HAS 60 (52) . For example, the clinician may elevate the leg 62 at an angle αrelative to a frontal plane of the patient (e.g., a plane that divides the body of the patient into ventral and dorsal portions) . In some cases, the clinician may elevate the leg 62 of the patient an angle α of at least about 45° relative to the frontal plane. Elevating the leg 62 of the patient at least about 45° relative to the frontal plane of the patient helps to evacuate blood from inside the HAS 60, which may reduce a lumen of the HAS 60 and/or lower a treatment energy required to ablate the HAS 60. FIG. 5B illustrates the leg 62 of the patient elevated about 45° relative to the frontal plane of the patient. In other examples, angle α may be a different angle, such as an angle between 30° to about 90°, such as 45° to 90°.

In addition, in some examples, a clinician may apply a circular compression bandage 64 to the leg 62 of the patient (54) . As shown in FIG. 5C, in some cases, the circular compression bandage 64 may be applied all the way around the patient’s leg 62. In other examples, the circular compression bandage 64 may be applied around a portion of the patient’s leg 64. Moreover, in other examples, the circular compression bandage 64 may additional or alternatively include an elastic stocking. In some examples, the circular compression bandage 64 may apply about 20 mmHg to about 50 mmHg of pressure to the leg 62 of the patient, such as about 10 mmHg to about 40 mmHg of venous pressure. In some examples, the pressures applied by compression bandage 64 has little to no effect on arterial blood flow; a pressure of 60 mmHg or more may be required to affect the arterial blood flow. In some examples, a kit may include the catheter 12 and the circular compression bandage 64. In this way, the kit may provide a clinician with the assembly described herein for performing the example technique of FIG. 4.

The circular compression bandage 64 is configured to apply a compression pressure to the HAS 60, which may further reduce any remaining blood in the HAS 60 and reduce a size of a lumen of the HAS 60. In this way, the use of the circular compression bandage 64 may enable the HAS 60 of the patient to be treated without the use of tumescent infiltration to reduce the lumen of the HAS 60 prior to inserting the catheter 12 into the HAS 60. In turn, the technique of FIG. 4 to ablate the HAS 60 may be faster, easier, require less equipment, reduce a risk of infection, reduce patient discomfort, or the like in comparison to treatments that include tumescent infiltration. In some examples, tumescent infiltration may also increase the risk of fully collapsing the HAS 60, which may then make it difficult or even impossible for the clinician to insert the catheter 12 into the HAS 60. Moreover, the use of the circular compression bandage 64 may enable the clinician to have use of both hands for the medical procedure rather than using one hand or both hands to manually apply pressure to the leg 62. In other example, a clinician may use the circular compression bandage 64 as well as tumescent infiltration and/or one or more hands to manually apply pressure to the leg 62.

The technique of FIG. 4 further includes the clinician rotating the distal sheath portion 16 of the sheath 10 relative to the proximal sheath portion 14 of the sheath 10 from the first rotational orientation to the second rotational orientation (56) . In some examples, the clinician may rotate the distal sheath portion 16 relative to the proximal sheath portion 14 of the sheath 10 from the first rotational orientation to the second rotational orientation while the catheter 12 is within the HAS 60 of the patient, which may expose the treatment portion 24 of the inner member 22 received in the lumen 21 of the sheath 10. In some such examples, exposure of the treatment portion 24 may cause the treatment portion 24 to expand radially outward. For example, as shown in FIG. 5D, the plurality of heating wires 28 may expand radially outward around the heating core 30 after the distal sheath portion 16 is retracted by being rotated relative to the proximal sheath portion 14, e.g., due to the force applied by the spring 34.

After exposing the treatment portion 24 of the catheter 12, the clinician may ablate a portion of the HAS 60 using the plurality of heating wires 28 of the treatment portion 24 when the distal sheath portion 16 is in the second rotational orientation (58) . In some examples, the catheter 12 may be configured to thermally ablate the HAS 60 using RF energy. For example, the catheter 12 may be coupled to an RF energy generator configured to generate RF energy. In some example, the catheter 12 coupled to an RF energy generator may apply a relatively lower temperature to the HAS 60, which may be increase patient comfort relative to higher temperature medical procedures, help reduce the amount of energy delivered to non-target tissue, or the like. Tumescence fluid may as act as a heat sink that helps absorb energy that is delivered to non- target tissue of the patient. Because the technique of FIG. 4 enables reduction in the size of HAS 60, e.g., due to the elevation of the patient’s leg 62 and the use of circular compression bandage 64, the technique may reduce the amount of energy used to ablate the HAS 60 of the patient and reduce the need for the heat sink provided by a tumescent fluid. In a similar manner, the catheter 12 that applies RF energy to the HAS 60 may not require the use of anesthesia due at least in part to the lower energy that may be needed to achieve ablation.

In some examples, the radial expansion of the plurality of heating wires 28 and the reduction of the lumen of the HAS 60 from the circular compression bandage 64 may enable the plurality of heating wires 28 to fully or substantially contact the interior of the HAS 60, which more effectively apply heat to the entire segment of the HAS 60 to denature collagen and collapse the segment of the HAS 60. In examples in which the plurality of heating wires 28 have an arc length of about 360° around the heating core 30, the increased contact of the expanded plurality of heating wires 28 and the compressed HAS 60 may prevent the treatment portion 24 from having to be rotated or otherwise moved to ablate the entirety of the desired segment of the HAS 60.

In some examples, a clinician may move the catheter 12, or at least the treatment portion 24, within the HAS 60 to ablate another segment of the HAS 60 after a first segment has been ablated. For example, the catheter 12 may be moved about the length L ₄ of the treatment portion 24, or about 20 mm to about 100 mm less than the length L ₄ of the treatment portion 24, in a proximal direction. In some examples, at least partially overlapping the first and second segments of the HAS 60 (e.g., when the catheter 12 is moved about 20 mm to about 100 mm less than the length L ₄ of the treatment portion 24) may provide better results of the ablation treatment. For example, it may be less likely to inadvertently not ablate a segment of the HAS 60 that was intended to be ablated. Any suitable number of segments may be ablated to treat the HAS 60 of the patient. In some examples, the number of segments that are ablated may be related to a condition, severity, location, or the like of the varicose vein or other HAS 60 being treated.

In some cases, the circular compression bandage 64 or another bandage or stocking may be left around the leg 62 of the patient for at least 3 days to help promote thrombosis formation of the treated HAS 60. Thrombosis formation may obstruct blood flow through the HAS 60, which may reduce the appearance of the varicose vein. In other examples, other techniques may be used to help promote thrombosis formation of the treated HAS 60.

In a first example, a catheter comprises a sheath defining a lumen, the sheath comprising: a proximal sheath portion; and a distal sheath portion configured to rotate relative to the proximal sheath portion between a first rotational orientation and a second rotational orientation, the distal sheath portion defining a first proximal end and a second proximal end proximal to the first proximal end. When the distal sheath portion is in the first rotational orientation, the first proximal end is separated from the proximal sheath portion by a first distance, and when the distal sheath portion is in the second rotational orientation, the first proximal end is separated from the proximal sheath portion by a second distance, the second distance being less than the first distance.

In a second example related to the first example, when the distal sheath portion is in the second rotational orientation, the sheath has a shorter length compared to when the distal sheath portion is in the first rotational orientation.

In a third example related to the first or second examples, when the distal sheath portion is in the first rotational orientation, the first proximal end is not in contact with the proximal sheath portion and the second proximal end is in contact with the proximal sheath portion.

In a fourth example related to any of the first through third examples, the second distance is zero.

In a fifth example related to any of the first through fourth examples, the catheter further comprises an inner member. The lumen is configured to receive the inner member, and when the distal sheath portion is in the first rotational orientation, the distal sheath portion is configured to at least partially cover a treatment portion of the inner member, and when the distal sheath portion is in the second rotational orientation, the distal sheath portion is configured to expose the treatment portion.

In a sixth example related to the fifth example, the treatment portion comprises an expandable element configured to expand radially outwards when the distal sheath portion is in the second rotational orientation.

In a seventh example related to the sixth example, the expandable element comprises a heating element including a plurality of expandable heating wires.

In an eighth example related to the seventh example, the inner member further comprises a slip ring proximal to the heating element, and a spring configured to push the slip ring in a distal direction to expand the plurality of heating wires of the heating element.

In an ninth example related to the seventh or eighth examples, the catheter further comprises a sensor configured to monitor a temperature of the heating element.

In a tenth example related to any of the seventh through ninth examples, when the distal sheath portion is in the first rotational orientation, a first cross-sectional dimension of the heating element is about 2 French to about 8 French, and when the distal sheath portion is in the second rotational orientation, a second cross-sectional dimension of the heating element is about 4 French to about 30.3 French.

In an eleventh example related to any of the seventh through tenth examples, the plurality of heating wires has 4 to 40 heating wires.

In a twelfth example related to any of the first through eleventh examples, the sheath comprises at least one of nylon, polyethylene, fluorinated ethylene propylene, polyether ether ketone, polyimide, polyvinylidene fluoride, polypropylene, or polytetrafluoroethylene.

In a thirteenth example related to any of the first through twelfth examples, the distal sheath portion is configured to rotate about a longitudinal axis of the sheath between the first rotational orientation and the second rotational orientation.

In a fourteenth example related to the thirteenth example, the distal sheath portion is configured to rotate about 180° about the longitudinal axis between the first rotational orientation and the second rotational orientation.

In a fifteenth example related to the thirteenth or fourteenth example, the distal sheath portion is configured to move in a proximal direction upon rotation of the distal sheath portion between the first rotational orientation and the second rotational orientation.

In a sixteenth example related to any of the first through fifteenth examples, the proximal sheath portion defines a first distal end and a second distal end distal to the first distal end, wherein when the distal sheath portion is in the first rotational orientation, the sheath defines a gap between the first proximal end and the first distal end, and when the distal sheath portion is in the second rotational orientation, the first proximal end of the distal sheath portion abuts the second distal end of the proximal sheath portion.

In a seventeenth example related to the sixteeth example, when the distal sheath portion is in the first rotational orientation, the second proximal end of the distal sheath portion abuts the second distal end of the proximal sheath portion, and when the distal sheath portion is in the second rotational orientation, the second proximal end of the distal sheath portion abuts the first distal end of the proximal sheath portion.

In an eighteenth example related to any of the first through seventeenth examples, the catheter further comprises an outer member configured to be positioned over at least part of the sheath, wherein the outer member is mechanically connected to the distal sheath portion such that rotation of the outer member is translated to the distal sheath portion.

In a nineteenth example related to the eighteenth example, the outer member is mechanically connected to the proximal sheath portion, wherein the mechanical connection between the outer member and the proximal sheath portion is weaker than the mechanical connection between the outer member and the distal sheath portion.

In a twentieth example, an ablation catheter comprises an inner member comprising a heating element; and a sheath defining a lumen configured to receive the inner member. The sheath comprises a proximal sheath portion and a distal sheath portion configured to rotate relative to the proximal sheath portion between a first rotational orientation and a second rotational orientation. When the distal sheath portion is in the second rotational orientation, the sheath has a first length, and when the distal sheath portion is in the second rotational orientation, the sheath has a second length shorter than the first length.

In a twenty-first example related to the twentieth example, the distal sheath portion defines a first proximal end and a second proximal end proximal to the first proximal end, and wherein when the distal sheath portion is in the first rotational orientation, the second proximal end is in contact with the proximal sheath portion.

In a twenty-second example related to the twentieth or twenty-first example, the distal sheath portion defines a first proximal end and a second proximal end proximal to the first proximal end, and wherein when the distal sheath portion is in the first rotational orientation, the first proximal end is separated from the proximal sheath portion by a first distance, and when the distal sheath portion is in the second rotational orientation, the first proximal end is separated from the proximal sheath portion by a second distance, the second distance being less than the first distance.

In a twenty-third example related to the twenty-second example, the second distance is zero.

In a twenty-fourth example related to any of the twentieth through twenty-third examples, when the distal sheath portion is in the first rotational orientation, the distal sheath portion is configured to at least partially cover the heating element of the inner member, and when the distal sheath portion is in the second rotational orientation, the distal sheath portion is configured to at least partially expose the heating element of the inner member.

In a twenty-fifth example related to any of the twentieth through twenty-fourth examples, wherein the distal sheath portion is configured to rotate about a longitudinal axis of the sheath between the first rotational orientation and the second rotational orientation.

In a twenty-sixth example related to the twenty-fifth example, the distal sheath portion is configured to move in a proximal direction upon rotation of the distal sheath portion between the first rotational orientation and the second rotational orientation.

In a twenty-seventh example related to any of the twentieth through twenty-sixth examples, the distal sheath portion defines a first proximal end and a second proximal end proximal to the first proximal end, and the proximal sheath portion defines a first distal end and a second distal end distal to the first distal end, wherein when the distal sheath portion is in the first rotational orientation, the sheath defines a gap between the first proximal end and the first distal end, and when the distal sheath portion is in the second rotational orientation, the first proximal end of the distal sheath portion abuts the second distal end of the proximal sheath portion.

In a twenty-eighth example related to the twenty-seventh example, the distal sheath portion is in the first rotational orientation, the second proximal end of the distal sheath portion abuts the second distal end of the proximal sheath portion, and when the distal sheath portion is in the second rotational orientation, the second proximal end of the distal sheath portion abuts the first distal end of the proximal sheath portion.

In a twenty-ninth example related to any of the twentieth through twenty-eighth examples, the inner member further comprises a slip ring proximal to the heating element and a spring configured to push the slip ring in a distal direction to expand the heating element radially outward.

In a thirtieth example related to any of the twentieth through twenty-ninth examples, the ablation catheter further comprises a sensor configured to monitor a temperature of the heating element.

In a thirty-first example related to any of the twentieth through thirtieth examples, the sheath comprises at least one of nylon, polyethylene, fluorinated ethylene propylene, polyether ether ketone, polyimide, polyvinylidene fluoride, polypropylene, or polytetrafluoroethylene.

In a thirty-second example related to any of the twentieth through thirty-first examples, when the distal sheath portion is in the first rotational orientation, a first cross-sectional dimension of the heating element is about 2 French to about 8 French, and when the distal sheath portion is in the second rotational orientation, a second cross-sectional dimension of the heating element is about 4 French to about 30.3 French.

In a thirty-third example related to any of the twentieth through thirty-second examples, the ablation catheter further comprises an outer member configured to be positioned over at least part of the sheath, wherein the outer member is mechanically connected to the distal sheath portion such that rotation of the outer member is translated to the distal sheath portion.

In a thirty-fourth example related to the thirty-third example, the outer member is mechanically connected to the proximal sheath portion, wherein the mechanical connection between the outer member and the proximal sheath portion is weaker than the mechanical connection between the outer member and the distal sheath portion.

In a thirty-fifth example, a method comprises inserting a catheter into a hollow anatomical structure of a patient while a distal sheath portion of a sheath of the catheter is in a first rotational orientation relative to a proximal sheath portion; and rotating the distal sheath portion of the sheath relative to the proximal sheath portion of the sheath from the first rotational orientation to a second rotational orientation. The distal sheath portion defines a first proximal end and a second proximal end proximal to the first proximal end. When the distal sheath portion is in the first rotational orientation, the first proximal end is separated from the distal sheath portion by a first distance, and when the distal sheath portion is in the second rotational orientation, the first proximal end is separated from the distal sheath portion by a second distance.

In a thirty-sixth example related to the thirty-fifth example, the hollow anatomical structure comprises a hollow anatomical structure in a leg of the patient, the method further comprising, after inserting the catheter into the hollow anatomical structure of the patient, elevating the leg of the patient.

In a thirty-seventh example related to the thirty-sixth example, elevating the leg of the patient comprises elevating the leg about 30° to 90°, such as about 45°, relative to a frontal plane of the patient.

In a thirty-eighth example related to any of the thirty-fifth through thirty-seventh examples, the method further comprises applying a circular compression bandage to the leg of the patient.

In a thirty-ninth example related to any of the thirty-fifth through thirty-eighth examples, rotating the distal sheath portion of the sheath of the catheter relative to the proximal sheath portion from the first rotational orientation to the second rotational orientation comprises rotating the distal sheath portion of the sheath of the catheter relative to the proximal sheath portion from the first rotational orientation to the second rotational orientation while the catheter is within the hollow anatomical structure of the patient.

In a fortieth example related to any of the thirty-fifth through thirty-eighth examples, rotating the distal sheath portion of the sheath relative to the proximal sheath portion from the first rotational orientation to the second rotational orientation exposes a treatment portion of an inner member received in a lumen of the sheath.

In a forty-first example related to the fortieth example, the treatment portion comprises an expandable heating element, and wherein rotating the distal sheath portion of the sheath of the catheter relative to the proximal sheath portion from the first rotational orientation to the second rotational orientation causes the expandable heating element to expand radially outward.

In a forty-second example related to the forty-first example, ablating at least a portion of the hollow anatomical structure of a patient using the expandable heating element when the distal sheath portion is in the second rotational orientation

In a forty-third example related to any of the thirty-fifth through forty-second examples, the hollow anatomical structure comprises a varicose vein.

In a forty-fourth example related to any of the thirty-fifth through forty-third examples, the catheter comprises any of the catheters of the first through thirty-fourth examples.

In a forty-fifth example, a kit comprises a circular compression bandage; and a catheter comprising: a sheath defining a lumen. The sheath comprises a proximal sheath portion; and a distal sheath portion configured to rotate relative to the proximal sheath portion between a first rotational orientation and a second rotational orientation. The distal sheath portion defines a first proximal end and a second proximal end proximal to the first proximal end. When the distal sheath portion is in the first rotational orientation, the first proximal end is separated from the proximal sheath portion by a first distance, and when the distal sheath portion is in the second rotational orientation, the first proximal end is separated from the proximal sheath portion by a second distance, the second distance being less than the first distance.

Various examples have been described. These and other examples are within the scope of the following claims.

Claims

A catheter comprising:

a sheath defining a lumen, the sheath comprising:

a proximal sheath portion; and

a distal sheath portion configured to rotate relative to the proximal sheath portion between a first rotational orientation and a second rotational orientation, the distal sheath portion defining a first proximal end and a second proximal end proximal to the first proximal end,

wherein when the distal sheath portion is in the first rotational orientation, the sheath is in a first rotational configuration in which the first proximal end is separated from the proximal sheath portion by a first distance, and

wherein when the distal sheath portion is in the second rotational orientation and the sheath is in a second rotational configuration, the first proximal end is separated from the proximal sheath portion by a second distance, the second distance being less than the first distance.
The catheter of claim 1, wherein when the distal sheath portion is in the second rotational orientation, the sheath has a shorter length compared to when the distal sheath portion is in the first rotational orientation.
The catheter of claim 1 or 2, wherein when the distal sheath portion is in the first rotational orientation, the first proximal end is not in contact with the proximal sheath portion and the second proximal end is in contact with the proximal sheath portion.
The catheter of any of claims 1–3, wherein the second distance is zero.
The catheter of any of claims 1–4, further comprising an inner member, wherein the lumen is configured to receive the inner member, and wherein when the distal sheath portion is in the first rotational orientation, the distal sheath portion is configured to at least partially cover a treatment portion of the inner member, and when the distal sheath portion is in the second rotational orientation, the distal sheath portion is configured to expose the treatment portion.
The catheter of claim 5, wherein the treatment portion comprises an expandable element configured to expand radially outwards when the distal sheath portion is in the second rotational orientation.
The catheter of claim 6, wherein the expandable element comprises a heating element including a plurality of expandable heating wires.
The catheter of claim 7, wherein the inner member further comprises:

a slip ring proximal to the heating element; and

a spring configured to push the slip ring in a distal direction to expand the plurality of heating wires of the heating element.
The catheter of claim 7 or 8, further comprising a sensor configured to monitor a temperature of the heating element.
The catheter of any of claims 1–13, wherein the distal sheath portion is configured to rotate about a longitudinal axis of the sheath between the first rotational orientation and the second rotational orientation.
The catheter of claim 10, wherein the distal sheath portion is configured to move in a proximal direction upon rotation of the distal sheath portion between the first rotational orientation and the second rotational orientation.
The catheter of any of claims 1–11, wherein the proximal sheath portion defines a first distal end and a second distal end distal to the first distal end, wherein when the distal sheath portion is in the first rotational orientation, the sheath defines a gap between the first proximal end and the first distal end, and when the distal sheath portion is in the second rotational orientation, the first proximal end of the distal sheath portion abuts the second distal end of the proximal sheath portion.
The catheter of any of claims 12, wherein when the distal sheath portion is in the first rotational orientation, the second proximal end of the distal sheath portion abuts the second distal end of the proximal sheath portion, and when the distal sheath portion is in the second rotational orientation, the second proximal end of the distal sheath portion abuts the first distal end of the proximal sheath portion.
The catheter of any of claims 1–14, further comprising an outer member configured to be positioned over at least part of the sheath, wherein the outer member is mechanically connected to the distal sheath portion such that rotation of the outer member is translated to the distal sheath portion.
The catheter of claim 14, wherein the outer member is mechanically connected to the proximal sheath portion, wherein the mechanical connection between the outer member and the proximal sheath portion is weaker than the mechanical connection between the outer member and the distal sheath portion.
An ablation catheter comprising:

an inner member comprising a heating element; and

a sheath defining a lumen configured to receive the inner member, the sheath comprising:

a proximal sheath portion; and

a distal sheath portion configured to rotate relative to the proximal sheath portion between a first rotational orientation and a second rotational orientation,

wherein when the distal sheath portion is in the first rotational orientation, the sheath is in a first rotational configuration and the sheath has a first length, and

wherein when the distal sheath portion is in the second rotational orientation and the sheath is in a second rotational configuration, the sheath has a second length shorter than the first length.
The ablation catheter of claim 16, wherein the distal sheath portion defines a first proximal end and a second proximal end proximal to the first proximal end, and wherein when the distal sheath portion is in the first rotational orientation, the second proximal end is in contact with the proximal sheath portion.
The ablation catheter of claim 16 or claim 17, wherein the distal sheath portion defines a first proximal end and a second proximal end proximal to the first proximal end, and wherein when the distal sheath portion is in the first rotational orientation, the first proximal end is separated from the proximal sheath portion by a first distance, and when the distal sheath portion is in the second rotational orientation, the first proximal end is separated from the proximal sheath portion by a second distance, the second distance being less than the first distance.
The ablation catheter of any of claims 16–18, wherein when the distal sheath portion is in the first rotational orientation, the distal sheath portion is configured to at least partially cover the heating element of the inner member, and when the distal sheath portion is in the second rotational orientation, the distal sheath portion is configured to at least partially expose the heating element of the inner member.
The ablation catheter of any of claims 16–19, wherein the distal sheath portion is configured to rotate about a longitudinal axis of the sheath between the first rotational orientation and the second rotational orientation.
The ablation catheter of any of claims 16–20, wherein the distal sheath portion defines a first proximal end and a second proximal end proximal to the first proximal end, and the proximal sheath portion defines a first distal end and a second distal end distal to the first distal end, wherein when the distal sheath portion is in the first rotational orientation, the sheath defines a gap between the first proximal end and the first distal end, and when the distal sheath portion is in the second rotational orientation, the first proximal end of the distal sheath portion abuts the second distal end of the proximal sheath portion.
The ablation catheter of any of claims 16–21, wherein the inner member further comprises:

a slip ring proximal to the heating element; and

a spring configured to push the slip ring in a distal direction to expand the heating element radially outward.
The ablation catheter of any of claims 16–22, further comprising a sensor configured to monitor a temperature of the heating element.
The ablation catheter of any of claims 16–23, further comprising an outer member configured to be positioned over at least part of the sheath, wherein the outer member is mechanically connected to the distal sheath portion such that rotation of the outer member is translated to the distal sheath portion.
A kit comprising:

a circular compression bandage; and

a catheter comprising:

a sheath defining a lumen, the sheath comprising:

a proximal sheath portion; and

a distal sheath portion configured to rotate relative to the proximal sheath portion between a first rotational orientation and a second rotational orientation, the distal sheath portion defining a first proximal end and a second proximal end proximal to the first proximal end,

wherein when the distal sheath portion is in the first rotational orientation, the sheath is in a first rotational configuration in which the first proximal end is separated from the proximal sheath portion by a first distance, and

wherein when the distal sheath portion is in the second rotational orientation and the sheath is in a second rotational configuration, the first proximal end is separated from the proximal sheath portion by a second distance, the second distance being less than the first distance.