Elastic catheter

Abstract

We provide a retractable catheter for selectively moving components of medical device systems. [Solution] An exemplary retractable catheter may include a proximal hub adjacent to the proximal end of the catheter, a drive cable, and a retractable portion extending from the proximal end adjacent to the proximal hub to the distal end. This retractable portion may include an intermediate sheath having a proximal end connected to the proximal hub and extending distally to the distal end, an outer sheath positioned on the intermediate sheath and having a proximal end and a distal end, an inner sheath positioned inside the intermediate sheath and having a proximal end and a distal end, and a sealing member positioned between the intermediate sheath and the outer surface of the inner sheath. The intermediate sheath may be configured to be longitudinally offset relative to the inner sheath and the outer sheath.

Description

Technical Field

[0001] The present disclosure relates to medical imaging and systems and methods for medical imaging. More specifically, the present disclosure relates to systems and methods for vascular imaging that include a telescoping portion.

Background Art

[0002] A wide variety of medical imaging systems and methods have been developed for medical use, for example, for use in imaging the anatomical structure of blood vessels. Some of these systems and methods include intravascular imaging modalities. These systems and methods include various configurations and may be implemented or used according to any one of a variety of methods. Known vascular imaging systems and methods each have specific advantages and disadvantages. Therefore, there is a current need to provide alternative systems and methods for imaging and evaluating blood vessels.

Summary of the Invention

[0003] The present disclosure provides an alternative telescoping catheter. In a first example, the telescoping catheter may include a proximal hub adjacent to the proximal end of the telescoping catheter, a drive cable, and a telescoping portion extending from the proximal end adjacent to the proximal hub to the distal end. The telescoping portion may include an intermediate sheath having a proximal end coupled to the proximal hub and extending distally to a distal end, an outer sheath disposed over the intermediate sheath and having a proximal end and a distal end, an inner sheath disposed within the intermediate sheath and having a proximal end and a distal end, and a seal member disposed between the outer surface of the intermediate sheath and the inner sheath. The intermediate sheath may be configured to be longitudinally offset relative to the inner and outer sheaths.

[0004] Instead of or in addition to any of the above examples, in another example, the seal member may be configured to form a fluid-tight seal between the inner sheath and the intermediate sheath. In an alternative or additional example, the intermediate sheath may have a constant outer diameter from its proximal end to its distal end.

[0005] In an alternative or additional example, the sealing member may include an O-ring. In an alternative or additional example, the relationship between the outer sheath and the inner sheath may be fixed.

[0006] In an alternative or additional example to any of the above examples, the intermediate sheath may define a lumen that substantially surrounds the inner sheath when the intermediate sheath is configured to advance distally, and surrounds a portion of the drive cable when the intermediate sheath is configured to be displaced proximal.

[0007] In an alternative or additional example, the telescopic catheter may further comprise an outer cover positioned over the drive cable. In an alternative or additional example, the outer cover may comprise a first layer and a second layer.

[0008] In an alternative or additional example, the telescopic catheter may further comprise a housing coupled to the proximal end of the outer sheath. In an alternative or additional example, the telescopic catheter may further comprise a retaining sleeve fixed to the outer surface of the intermediate sheath.

[0009] In an alternative or additional example, the retractable catheter may further include a retaining plug extending distally from the sealing member. In an alternative or additional example to any of the above examples, the proximal strain relief may be coupled to the proximal hub and configured to mechanically engage with the proximal portion of the housing to restrict the proximal movement of the intermediate sheath.

[0010] In an alternative or additional example to any of the above examples, the retaining sleeve may be configured to mechanically engage with a portion of the housing to restrict the proximal movement of the intermediate sheath.

[0011] In an alternative or additional example, the outer diameter of the retaining plug may be the same as the outer diameter of the intermediate sheath. In an alternative or additional example, the retaining sleeve may be positioned on or in contact with the distal end region of the intermediate sheath, on the sealing member, and on the proximal end region of the retaining plug.

[0012] In another example, the retractable catheter may comprise a drive cable and a retractable portion extending longitudinally along the retractable catheter and having a distal end. The retractable portion may comprise an inner sheath coupled to the distal end of the retractable portion and defining a first lumen for housing the drive cable, and an outer sheath coupled to the distal end of the retractable portion and defining a second lumen, wherein the relationship between the outer and inner sheaths may be fixed, and the outer sheath substantially surrounds the inner sheath, an intermediate sheath having a proximal end and extending distally to the distal end, and a sealing member positioned adjacent to the distal end of the intermediate sheath and configured to provide a fluid-sealing seal between the intermediate sheath and the inner sheath. The intermediate sheath may be configured to slide between the inner and outer sheaths to extend and retract the retractable catheter.

[0013] In an alternative or additional example, the intermediate sheath may define a third lumen that substantially surrounds the inner sheath when the intermediate sheath is configured to advance distally, and surrounds a portion of the drive cable when the intermediate sheath is configured to be displaced proximal.

[0014] In an alternative or additional example, the telescopic catheter may further comprise a retaining sleeve fixed to the outer surface of the intermediate sheath. In an alternative or additional example, the retractable catheter may further include a retaining plug extending distally from the sealing member.

[0015] In an alternative or additional example, the intermediate sheath may have a constant outer diameter from its proximal end to its distal end. In an alternative or additional example, the outer diameter of the retaining plug may be the same as the outer diameter of the intermediate sheath.

[0016] In an alternative or additional example, the retaining sleeve may be positioned on or in contact with the distal end region of the intermediate sheath, on the sealing member, and on the proximal end region of the retaining plug.

[0017] In an alternative or additional example, the sealing member may include an O-ring. In an alternative or additional example, the telescopic catheter may further comprise an outer cover positioned over the drive cable.

[0018] In an alternative or additional example, the outer cover may comprise a first layer and a second layer. In another example, the retractable catheter may comprise a proximal hub adjacent to the proximal end of the retractable catheter, a drive cable, and a retractable portion extending from the proximal end adjacent to the proximal hub to the distal end. This retractable portion may comprise a distal hub positioned adjacent to the distal end of the retractable portion, an intermediate sheath assembly, an outer sheath positioned on the intermediate sheath having a proximal end and a distal end securely coupled to the distal hub, and an inner sheath positioned inside the intermediate sheath having a proximal end and a distal end securely coupled to the distal hub. The intermediate sheath assembly may comprise an intermediate sheath having a proximal end coupled to the proximal hub and extending distally to the distal end, a retaining plug having a proximal end and a distal end and extending collinearly with the intermediate sheath, a sealing member positioned between the distal end of the intermediate sheath and the proximal end of the retaining plug, and a retaining sleeve positioned on and in contact with the distal end region of the intermediate sheath, on the sealing member and on the proximal end region of the retaining plug. The intermediate sheath assembly may be configured to be offset longitudinally from the inner and outer sheaths.

[0019] In an alternative or additional example to any of the above examples, the retaining sleeve may be configured to mechanically engage with a portion of the housing coupled to the proximal end of the outer sheath, thereby restricting the proximal movement of the intermediate sheath.

[0020] In an alternative or additional example, the intermediate sheath assembly may define a third lumen that substantially surrounds the inner sheath when the telescopic catheter is fully retracted and surrounds a portion of the drive cable when the telescopic catheter is fully extended.

[0021] The above summaries of some embodiments are not intended to describe each embodiment of the disclosure or all practices of this disclosure. The following drawings and detailed descriptions illustrate these embodiments more specifically. [Brief explanation of the drawing]

[0022] This disclosure may be more fully understood in consideration of the following detailed description in combination with the accompanying drawings. [Figure 1] FIG. 1 is a side view of an exemplary medical device. [Figure 2] FIG. 2 is a side view of another exemplary medical device. [Figure 3] FIG. 3 is a perspective view of the medical device of FIG. 2 in a stored configuration. [Figure 4] FIG. 4 is a perspective view of the medical device of FIG. 2 in an extended configuration. [Figure 5] FIG. 5 is a cross-sectional view of a portion of the medical device of FIG. 2 taken along line 5-5 of FIG. 3. [Figure 6] FIG. 6 is a cross-sectional view of a portion of the medical device of FIG. 2 taken along line 6-6 of FIG. 3. [Figure 7] FIG. 7 is a cross-sectional view of a portion of the medical device of FIG. 2 taken along line 7-7 of FIG. 4.

[0023] This disclosure readily accepts various changes and alternative forms, and specific examples thereof are illustratively shown in the drawings and described in detail. However, it should be understood that the intention is not to limit the invention to the specific embodiments described. On the contrary, it is intended to cover all modifications, equivalents, and alternatives within the spirit and scope of this disclosure.

Mode for Carrying Out the Invention

[0024] For the terms defined below, these definitions apply unless different definitions are provided anywhere within the claims or this specification. All numerical values in this specification are assumed to be modified by the term "about" whether explicitly shown or not. The term "about" generally refers to a numerical range that a person skilled in the art might consider equivalent to the recited value (e.g., having the same function or the same result). In many instances, the term "about" may include numbers rounded to the nearest significant digit.

[0025] Numerical ranges with multiple endpoints include all numbers within that range (for example, 1-5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5). When used herein and in the appended claims, the singular forms "a," "an," and "the" include plural subjects unless the context explicitly indicates otherwise. When used herein and in the appended claims, the term "or" is generally adopted to mean "and / or" unless the context explicitly indicates otherwise.

[0026] In this specification, references to “one embodiment,” “several embodiments,” and “other embodiments” indicate that the described embodiment may include one or more specific features, structures, or properties. However, such descriptions do not necessarily mean that all embodiments include that particular feature, structure, or property. In addition, when a particular feature, structure, or property is described in combination with one embodiment, such feature, structure, or property may be used in combination with other embodiments, whether explicitly described or not, unless the opposite is explicitly stated.

[0027] The following detailed description should be read with reference to the drawings, where similar elements in different drawings are numbered the same. The drawings are not necessarily to scale and illustrate exemplary embodiments; they are not intended to limit the scope of the invention.

[0028] In medical technology, catheters are frequently used to diagnose and treat various abnormalities in a patient's body (e.g., but not limited to, blocked or occluded blood vessels). Catheters are introduced into a patient's blood vessels, for example, by making an incision in the patient's body over a blood vessel or by inserting the catheter into the patient's blood vessel. A catheter operator, such as an internist, then carefully moves the catheter through the patient's blood vessel until it is positioned appropriately to diagnose or treat the abnormal site. Because the careful movement of a catheter within a patient's body can sometimes be a difficult task (requiring a high degree of care and time to change the catheter's position), a type of catheter known as a retractable catheter is frequently used to perform such diagnoses and treatments. A retractable catheter with reduced force during retraction and suppressed foam formation is disclosed herein.

[0029] Figure 1 is a side view of an exemplary medical device 10. In at least some examples, the medical device 10 takes the form of an imaging medical device. For example, the medical device 10 may be an intravascular ultrasound (IVUS) device that can be used to image blood vessels. The structure / morphology of the medical device 10 varies considerably. In some examples, the medical device 10 may include an elongated shaft 12 having a proximal end region 14 and a distal end region 16. A proximal hub or connector 18 may be coupled to the proximal end region 14, or otherwise positioned adjacent to the proximal end region 14. A tip member 20 may be coupled to the distal end region 16, or otherwise positioned adjacent to the distal end region 16. The tip member 20 may comprise a guidewire exit port 32, a non-invasive distal end 34, one or more radiopaque markers 36, and / or other features of a guidewire lumen 30. In some embodiments, the tip member 20 may extend at an angle not parallel to the proximal end region 14 of the elongated shaft 12. The imaging assembly 22 may be positioned inside the lumen of the shaft 12. Typically, the imaging assembly may be used to capture / generate images of blood vessels. In some embodiments, the medical device may include devices and / or features similar to those disclosed in U.S. Patent Application Publication 2012 / 0059241 and U.S. Patent Application Publication 2017 / 0164925 (their entire disclosures are incorporated herein by reference). In at least some examples, the medical device 10 may be similar to, and may include similar features to, the OPTICROSS® imaging catheter commercialized by BOSTON SCIENTIFIC®, Marlborough, Massachusetts.

[0030] The imaging assembly 22 may include a drive cable or shaft 24, a housing 26, and an imaging member or transducer 28 coupled to the drive cable 24 and / or housing 26. In at least some examples, the transducer 28 includes an ultrasonic transducer. Other transducers are also possible. The transducer 28 may be rotatable and / or axially translatable with respect to the shaft 12. For example, the drive cable 24 may be rotated and / or translated in order to rotate and / or translate the transducer 28 (and housing 26).

[0031] Although not explicitly shown in Figure 1, the medical device 10 may include an extendable portion, which is configured to allow the medical device operator to move the drive shaft 24, which includes the imaging assembly 22, proximal and distally within the catheter without having to move the entire catheter within the patient's body. This allows the catheter operator to easily change the position of the imaging assembly or other medical devices within the patient's body. For example, the extendable portion may be operated to change the position of the imaging assembly 22 within an elongated shaft 12. A medical device that reduces the extensional force required to operate the extendable portion is disclosed herein.

[0032] Furthermore, when using the medical device 10, it may be desirable to prepare and / or clean the shaft 12. To clean the medical device 10, a fluid may be injected onto or into a cleaning port located on the hub 18. The fluid may be discharged from the medical device through a discharge hole (not shown) adjacent to the distal end of the housing 26. In some examples, the cleaning process may lead to bubble formation inside the shaft 12. Since bubbles can reflect / interfere with signals from the transducer 28 (e.g., ultrasound signals), thereby impairing the image, it is desirable to clean the medical device 10 in a manner that suppresses bubble formation and / or removes / destroys any bubbles that have formed. Although the cleaning process is usually effective in removing bubbles, some bubbles may still remain inside the shaft 12. A medical device designed to help suppress bubble formation inside that medical device is disclosed herein.

[0033] Figure 2 illustrates a side view of another exemplary medical device, such as, but not limited to, a retractable catheter 100. The catheter 100 extends from a proximal end region 102 to a distal end region 104. A proximal hub 106 may be attached adjacent to the proximal end region 102. This proximal hub 106 may include a check valve and a flushing port 108. Fluid may be injected through the flushing port 108 to flush the catheter 100. The catheter 100 extends from a proximal end region 113 to a distal end region 115 and may further include a retractable portion 110 positioned between the proximal end region 102 and the distal end region 104 of the catheter 100. An elongated shaft 112 extends distally from the distal end region 115 of the retractable portion 110. The elongated shaft 112 may include a tip member 114 adjacent to the distal end region 104 of the catheter 100. The tip member 114 may be similar in form and function to the tip member 20 described with respect to Figure 1. For example, the tip member 114 may have a guidewire lumen with a guidewire exit port, a non-invasive distal end, one or more radiopaque markers, and / or other features.

[0034] The imaging assembly 116 (see, for example, Figure 3) may be movably positioned inside the lumen of the elongated shaft 112. The imaging assembly 116 may include a drive cable or shaft 120, a housing 122, and an imaging member or transducer 118 coupled to the drive cable 120 and / or housing 122. The imaging assembly 116 may include, or be replaced by, other medical devices, such as, for example, a cutting head or other devices. The specific device selected as the drive cable 120 may be selected based on the desired function for the catheter 100. The drive cable 120 may extend proximal from the imaging member 118 through the telescopic portion 110 to the proximal hub 106. The proximal hub 106 may include a configuration to which the drive cable 120 is adapted to connect to a power supply and / or other electrical couplings. In some cases, the proximal end of the drive cable 120 may be attached to the proximal hub 106. Although not explicitly stated, the drive cable 120 may have a single-layer outer cover or sheath, or a double-layer outer cover or sheath, as desired. If provided in this manner, the outer cover may extend to the entire length of the drive cable 120 or to a length shorter than the entire length of the drive cable 120.

[0035] The telescopic section 110 may comprise a first sheath, i.e., an intermediate sheath 124, a second sheath, i.e., an outer sheath 126, and a third sheath, i.e., an inner sheath 128. Typically, the outer sheath 126 is positioned above the intermediate sheath 124, which in turn may be positioned above the inner sheath 128. The intermediate sheath 124 may be axially and / or rotatably offset from the outer sheath 126 and the inner sheath 128, so that movement of the proximal hub 106 can be converted into movement of the intermediate sheath 124 and the drive cable 120. The distal hub 138 may be positioned adjacent to the distal end region 115 of the telescopic section 110. The distal hub 138 may comprise a distal strain relief 139 configured to connect to the elongated shaft 112. Furthermore, the distal ends of the outer sheath 126 and the inner sheath 128 may be securely fixed to the distal hub 138, respectively.

[0036] The intermediate sheath 124 extends distally from a proximal end region 130, which is coupled to the proximal strain relief 132, to a distal end 134 that extends into the outer sheath 126. The intermediate sheath 124 may, but is not required, have a constant diameter from the proximal end region 130 to the distal end 134. The proximal strain relief 132 is coupled to the proximal hub 106. The intermediate sheath 124 is movable relative to the inner sheath 128 and the outer sheath 126, such that the distal end 134 of the intermediate sheath 124 is movable between the distal hub 138 and the housing 142. The intermediate sheath 124 defines a lumen 136 extending from the proximal end region 130 to its distal end 134 (see, for example, Figures 5-7). The lumen 136 may receive and / or house a portion of the drive shaft 120 and / or a portion of the inner sheath 128.

[0037] The outer sheath 126 extends distally from a proximal end region 140 coupled to a housing or container 142 to a distal end 144 attached to a distal hub 138 (see, for example, Figure 5). The outer sheath 126 defines a lumen 146 extending from the proximal end region 140 to the distal end 144 (see, for example, Figures 5-7). The lumen 146 may receive or house a portion of the inner sheath 128 and / or a portion of the intermediate sheath 124.

[0038] The inner sheath 128 extends distally from its proximal end region to its distal end 148, which is attached to the distal hub 138 (see, for example, Figure 5). The inner sheath 128 defines a lumen 150 that extends from its proximal end region to its distal end 148 (see, for example, Figures 5 to 7). The lumen 150 may receive or house a portion of the drive shaft 120. For example, the inner sheath 128 may be configured to support the drive shaft 120 when the intermediate sheath 124 is displaced proximal (see, for example, Figure 4). In some embodiments, the proximal end region of the inner sheath 128 may be located adjacent to the proximal end region 140 of the outer sheath 126. In other embodiments, the proximal end region of the inner sheath 128 may be distal to the proximal end region 140 of the outer sheath 126.

[0039] Figure 3 illustrates a perspective view of the telescopic catheter of Figure 2 when the proximal hub 106 and intermediate sheath 124 (and thus the drive shaft 120) are in their most distal position. At this time, the catheter 100 is at its shortest length, so this configuration can be considered a fully retracted configuration. In Figure 3, the elongated shaft 112 is not shown in order to more clearly illustrate the structure of the imaging assembly 116. In the embodiment of Figure 3, the intermediate sheath 124 is advanced distally into the lumen 146 of the outer sheath 126. The distal movement of the intermediate sheath 124 can be limited by a mechanical stopper created between the proximal strain relief 132 and the housing 142. When the proximal hub 106 and intermediate sheath 124 are in their most distal position, most of the lumen length of the lumen 136 of the intermediate sheath 124 may surround the inner sheath 128.

[0040] Figure 4 illustrates a perspective view of the proximal portion of the telescopic catheter of Figure 2, where the proximal hub 106 and intermediate sheath 124 (and consequently the drive shaft 120) are near their nearest position. At this time, the catheter 100 is at its maximum length, so this configuration can be considered as fully extended. In the embodiment of Figure 4, the intermediate sheath 124 is displaced proximal within the lumen 146 of the outer sheath 126. The proximal movement of the intermediate sheath 124 can be limited by a mechanical stopper created between a fitting feature on the distal end region of the intermediate sheath 124 and the housing 142. When the proximal hub 106 and intermediate sheath 124 are in their nearest position, most of the lumen length of the lumen 136 of the intermediate sheath 124 may surround the drive cable 120.

[0041] Figures 3 and 4 illustrate an appropriate degree of movement of the telescopic portion 110, but the proximal hub 106 and intermediate sheath 124 may be positioned at any location in between. Since the drive cable 120 is coupled to the proximal hub 106, proximal and distal movement is converted to the drive cable 120 and imaging assembly 116, thereby allowing the imaging assembly to be moved without moving the entire catheter 100. It is also conceivable that rotational movement of the proximal hub 106 is converted to the drive shaft 120 and imaging assembly 116, thereby allowing the imaging assembly 116 to rotate within the elongated shaft 112.

[0042] Figure 5 is a cross-sectional view of the distal end region 115 of the telescopic section 110 when the proximal hub 106 and intermediate sheath 124 are in their distal configuration, broken along line 5-5 in Figure 3. The drive shaft 120, inner sheath 128, intermediate sheath 124, and outer sheath 126 are coaxially mounted. In this configuration, the distal end 134 of the intermediate sheath 124 is adjacent to or near the distal end 144 of the outer sheath 126 and the distal end 148 of the inner sheath 128. The telescopic section 110 further includes a sealing member 152 positioned between the intermediate sheath 124 and the outer surface of the inner sheath 128, on the proximal side of the distal end 134 of the intermediate sheath 124. The sealing member 152 may be a flexible and / or deformable component configured to provide a fluid-sealing seal between the intermediate sheath 124 and the inner sheath 128. In some cases, the sealing member 152 may be a silicone O-ring. However, other shapes and / or materials of the sealing member are possible. When the retractable catheter 100 is cleaned, the sealing member 152 may be sized and shaped to restrict the flow path. For example, when fluid is introduced through the port 108, the fluid may fill the lumen 136 of the intermediate sheath 124 and the lumen 150 of the inner sheath 128. However, the sealing member 152 provides a simpler flow path by preventing the fluid from escaping the lumen 136 of the intermediate sheath 124 and thereby preventing the fluid from entering the lumen 146 of the outer sheath 126. Furthermore, the fluid can pass distally through the lumen 150 of the inner sheath 128, through the distal hub 138, and to the elongated shaft 112. Placing the sealing member 152 between the intermediate sheath 124 and the inner sheath 128 can suppress the retraction and extension forces of the catheter 100.

[0043] In some embodiments, the intermediate sheath 124 may be part of an intermediate sheath assembly 154. The intermediate sheath assembly 154 may comprise the intermediate sheath 124, a retaining plug 156, a retaining sleeve 158, and a sealing member 152. The retaining plug 156 may extend collinearly with the intermediate sheath 124. For example, the retaining plug 156 may have an inner diameter approximately the same size as the inner diameter of the intermediate sheath 124 and an outer diameter approximately the same size as the outer diameter of the intermediate sheath 124, but this is not required. In some embodiments, the sealing member 152 may be positioned between the distal end 134 of the intermediate sheath 124 and the proximal end 160 of the retaining plug 156. However, this is not required. The sealing member 152 may be positioned and / or configured as desired. For example, the sealing member 152 may be configured to extend between the inner surface of the intermediate sheath 124 and / or the retaining plug 156 and the outer surface of the inner sheath 128. The intermediate sheath 124 and retaining plug 156 may be formed as separate parts and may be substantially mounted together. In other embodiments, the intermediate sheath 124 and retaining plug 156 may be formed as a single structure. For example, the intermediate sheath 124 and retaining plug 156 may be formed as a single part on the sealing member 152, or they may be formed to have a small cavity configured to receive the sealing member 152. These are merely some examples.

[0044] The retaining sleeve 158 may be positioned on the outer surface of the intermediate sheath 124, on the retaining plug 156, and / or on the sealing member 152, and may extend from the proximal end 164 to the distal end 166. The proximal end 164 of the retaining sleeve 158 may be positioned proximal to the distal end 134 of the intermediate sheath 124, while the distal end 166 of the retaining sleeve 158 may be positioned distal to the proximal end 160 of the retaining plug 156, such that the retaining sleeve 158 extends over the distal end region of the intermediate sheath 124, over the sealing member 152, and over the proximal end region of the retaining plug 156. The retaining sleeve 158 may be heat-shrinkable, molded, or fixed to the intermediate sheath 124, the sealing member 152, and the retaining plug 156. In some embodiments, the retaining sleeve 158 may fix the intermediate sheath 124, the sealing member 152, and the retaining plug 156 to each other. In addition, the intermediate sheath 124, the sealing member 152, and the retaining plug 156 may be fixed using adhesive, or they may be formed as a single unit through a mold or overmolding. The retaining sleeve 158 may have an inner diameter that is approximately the same as the outer diameter of the intermediate sheath 124 and / or the retaining plug 156, and an outer diameter that is smaller than the inner diameter of the outer sheath 126, so that the retaining sleeve 158 does not frictionally engage with the inner surface of the outer sheath 126.

[0045] Figure 6 is a cross-sectional view of the proximal end region 113 of the expandable portion 110 when the proximal hub 106 and intermediate sheath 124 are in their most distal configuration, broken along line 6-6 in Figure 3. The proximal end region 140 of the outer sheath 126 is fixed inside the lumen 168 of the housing 142. The proximal end region 170 of the inner sheath 128 is not attached to any other components. In some embodiments, the housing 142 may be provided with anchor seal plugs 172 located at or near their proximal ends 174. The proximal end 176 of the anchor seal plugs 172 may be configured to provide a mechanical stopper to the proximal strain relief 132 in order to restrict further distal movement of the proximal hub 106 and intermediate sheath 124. For example, when the proximal hub 106 and intermediate sheath 124 are in the most distal configuration, the distal end of the proximal strain relief 132 contacts the proximal end 176 of the anchor seal plug 172.

[0046] As described above, the drive cable 120 may be provided with an outer cover or sheath. The outer cover may be formed from a first layer 121 and a second layer 123. However, in some embodiments, fewer than two layers (e.g., one layer or no layers) may be provided as desired, or more than two layers (e.g., three or more layers) may be provided.

[0047] Figure 7 is a cross-sectional view of the intermediate region of the expandable portion 110, broken along line 7-7 in Figure 4, when the proximal hub 106 and intermediate sheath 124 are near the nearest configuration. In Figures 4 and 7, the proximal hub 106 and intermediate sheath 124 are actuated proximal 182 from the configuration illustrated in Figures 3, 5, and 6. In the exemplary embodiment, the proximal hub 106 and intermediate sheath 124 are shifted proximal until the proximal end 134 of the intermediate sheath 124 is positioned inside the housing 142. The housing 142 may include an annular projection 178 extending radially inward from the inner surface of the housing 142. The annular projection may define a distal wall 180. It is conceivable that this projection 178 may define an opening having a diameter approximately equal to the outer diameter of the intermediate sheath 124. Since the retaining sleeve 158 has a larger outer diameter than the intermediate sheath 124, the movement 182 that further shifts the proximal hub 106 and the intermediate sheath 124 proximal causes the proximal end 164 of the retaining sleeve 158 to be adjacent to the distal wall 180 of the protrusion 178. This mechanical engagement restricts the proximal movement 182 of the proximal hub 106 and the intermediate sheath 124 and also prevents the intermediate sheath 124 from disengaging from the inner sheath 128 and the outer sheath 126.

[0048] It should be understood that this disclosure is illustrative in many respects. Modifications may be made to details, particularly in terms of shape, size, and step sequence, without exceeding the scope of this disclosure. This may include, to an appropriate degree, the use of some of the features of one exemplary embodiment used in other embodiments. The scope of the invention is, of course, defined in the language in which the appended claims are expressed. This disclosure includes the following components. [Note 1] A retractable catheter comprising: a proximal hub adjacent to the proximal end of the retractable catheter; a drive cable; and a retractable portion extending from the proximal end adjacent to the proximal hub to the distal end, wherein the retractable portion comprises: an intermediate sheath having a proximal end connected to the proximal hub and extending distally to the distal end; an outer sheath disposed on the intermediate sheath and having a proximal end and a distal end; an inner sheath disposed inside the intermediate sheath and having a proximal end and a distal end; a sealing member disposed between the intermediate sheath and the outer surface of the inner sheath; and the intermediate sheath being configured to be longitudinally offset relative to the inner sheath and the outer sheath, wherein the retractable catheter is configured such that a fluid introduced through a lavage port fills the lumen of the intermediate sheath and the lumen of the inner sheath. [Note 2] The expandable catheter according to Note 1, wherein the sealing member is configured to form a fluid-seal seal between the inner sheath and the intermediate sheath. [Note 3] The expandable catheter according to Note 1 or Note 2, wherein the intermediate sheath has a constant outer diameter from its proximal end to its distal end. [Note 4] The expandable catheter according to Note 1 or Note 2, wherein the sealing member is equipped with an O-ring. [Note 5] The outer sheath and the inner sheath are fixed in relation to each other, as described in Note 1 or Note 2, for the retractable catheter. [Note 6] The telescopic catheter according to Note 1 or Note 2, wherein the intermediate sheath defines a lumen that substantially surrounds the inner sheath when the intermediate sheath is advanced distally, and surrounds a portion of the drive cable when the intermediate sheath is displaced proximally. [Note 7] The telescopic catheter according to Note 1 or Note 2, further comprising an outer cover positioned on the drive cable. [Note 8] The expandable catheter according to Note 7, wherein the outer cover comprises a first layer and a second layer. [Note 9] The telescopic catheter according to Note 1 or Note 2, further comprising a housing coupled to the proximal end of the outer sheath. [Note 10] The expandable catheter according to Note 9, further comprising a retaining sleeve fixed to the outer surface of the intermediate sheath. [Note 11] The expandable catheter according to Note 10, further comprising a retaining plug extending distally from the sealing member. [Note 12] The telescopic catheter according to Note 9, wherein the proximal strain relief is coupled to the proximal hub and is configured to mechanically engage with the proximal portion of the housing to restrict the proximal movement of the intermediate sheath. [Note 13] The retractable catheter according to Note 10, wherein the retaining sleeve is configured to mechanically engage with a portion of the housing to restrict the proximal movement of the intermediate sheath. [Note 14] The expandable catheter as described in Note 11, wherein the outer diameter of the retaining plug is the same as the outer diameter of the intermediate sheath. [Note 15] The expandable catheter according to Note 11, wherein the retaining sleeve is positioned on and in contact with the distal end region of the intermediate sheath, the sealing member, and the proximal end region of the retaining plug. [Note 16] The expandable catheter according to Note 1 or 2, wherein the sealing member is adjacent to the distal end of the intermediate sheath.

Claims

[Claim 1] The invention described in the specification and drawings.

Images