Expandable Catheter

Abstract

A telescoping catheter for selectively moving components of a medical device system is disclosed. An exemplary telescoping catheter may include a proximal hub adjacent a proximal end of the catheter, a drive cable, and a telescoping section extending from a proximal end adjacent the proximal hub to a distal end. The telescoping section 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, the outer sheath having a proximal end and a distal end, an inner sheath disposed within the intermediate sheath, the inner sheath having a proximal end and a distal end, and a seal member disposed between the intermediate sheath and an outer surface of the inner sheath. The intermediate sheath may be configured to be longitudinally displaceable relative to the inner sheath and the outer sheath.

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to medical imaging and to systems and methods for medical imaging. More particularly, the present disclosure relates to systems and methods for vascular imaging that include telescoping portions. [Background technology]

[0002] A wide variety of medical imaging systems and methods have been developed for medical use, for example, for use in imaging vascular anatomy. Some of these systems and methods include intravascular imaging modalities. These systems and methods include a variety of configurations and may be performed or used according to any one of a variety of methods. Each of the known vascular imaging systems and methods has certain advantages and disadvantages. Thus, there is an ongoing need to provide alternative systems and methods for imaging and evaluating blood vessels. Summary of the Invention

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

[0004] Alternatively or additionally 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. Alternatively or additionally to any of the above examples, in another example, the intermediate sheath may have a constant outer diameter from its proximal end to its distal end.

[0005] Alternatively or additionally to any of the above examples, in another example, the sealing member may comprise an O-ring. Alternatively or additionally to any of the above examples, in another example, the outer sheath and the inner sheath may be fixed in relationship to each other.

[0006] Alternatively or in addition to any of the above examples, in another example, the intermediate sheath may define a lumen configured to substantially surround the inner sheath when the intermediate sheath is in a distally advanced configuration and to surround a portion of the drive cable when the intermediate sheath is in a proximally displaced configuration.

[0007] Alternatively or additionally to any of the above examples, in another example, the expansion catheter may further comprise an outer covering disposed over the drive cable. Alternatively or in addition to any of the above examples, in another example, the outer cover may comprise a first layer and a second layer.

[0008] Alternatively or additionally to any of the above examples, in another example, the expandable catheter may further comprise a housing coupled to the proximal end of the outer sheath. Alternatively or additionally to any of the above examples, in another example, the expandable catheter may further comprise a retaining sleeve secured to an outer surface of the intermediate sheath.

[0009] Alternatively or additionally to any of the above examples, in another example, the expandable catheter may further comprise a retaining plug extending distally from the seal member. Alternatively or in addition to any of the above examples, in another example, a proximal strain relief may be coupled to the proximal hub and configured to mechanically engage a proximal portion of the housing to limit proximal movement of the intermediate sheath.

[0010] Alternatively or in addition to any of the above examples, in another example, the retaining sleeve may be configured to mechanically engage a portion of the housing to limit proximal movement of the intermediate sheath.

[0011] Alternatively or additionally to any of the above examples, in another example, the outer diameter of the retaining plug may be the same as the outer diameter of the intermediate sheath. Alternatively or in addition to any of the above examples, in another example, the retaining sleeve may be disposed over and contact the distal end region of the intermediate sheath, over the sealing member, and over the proximal end region of the retaining plug.

[0012] In another example, a telescopic catheter may include a drive cable and a telescopic section extending longitudinally along the telescopic catheter and having a distal end. The telescopic section may include an inner sheath coupled to the distal end of the telescopic section and defining a first lumen for housing the drive cable, and an outer sheath coupled to the distal end of the telescopic section and defining a second lumen, the outer and inner sheaths may be fixed in relationship to one another, and the outer sheath substantially surrounds the inner sheath, an intermediate sheath having a proximal end and extending distally to a distal end, and a seal member disposed adjacent the distal end of the intermediate sheath and configured to provide a fluid-tight seal between the intermediate sheath and the inner sheath. The intermediate sheath may be configured to slide between the inner and outer sheaths to telescopically telescope the telescopic catheter.

[0013] Alternatively or in addition to any of the above examples, in another example, the intermediate sheath may define a third lumen configured to substantially surround the inner sheath when the intermediate sheath is in a distally advanced configuration and to surround a portion of the drive cable when the intermediate sheath is in a proximally displaced configuration.

[0014] Alternatively or additionally to any of the above examples, in another example, the expandable catheter may further comprise a retaining sleeve secured to an outer surface of the intermediate sheath. Alternatively or additionally to any of the above examples, in another example, the expandable catheter may further comprise a retaining plug extending distally from the seal member.

[0015] Alternatively or additionally to any of the above examples, in another example, the intermediate sheath may have a constant outer diameter from its proximal end to its distal end. Alternatively or additionally to any of the above examples, in another example, the outer diameter of the retaining plug may be the same as the outer diameter of the intermediate sheath.

[0016] Alternatively or in addition to any of the above examples, in another example, the retaining sleeve may be disposed over and contact the distal end region of the intermediate sheath, over the sealing member, and over the proximal end region of the retaining plug.

[0017] Alternatively or additionally to any of the above examples, in another example, the sealing member may comprise an O-ring. Alternatively or additionally to any of the above examples, in another example, the expansion catheter may further include an outer covering disposed over the drive cable.

[0018] Alternatively or in addition to any of the above examples, in another example, the outer cover may comprise a first layer and a second layer. In another example, a telescopic catheter may include a proximal hub adjacent a proximal end of the telescopic catheter, a drive cable and a telescopic section extending from a proximal end adjacent the proximal hub to a distal end. The telescopic section may include a distal hub disposed adjacent a distal end of the telescopic section, a mid-sheath assembly, an outer sheath disposed over the mid-sheath, the outer sheath having a proximal end and a distal end fixedly coupled to the distal hub, and an inner sheath disposed within the mid-sheath, the inner sheath having a proximal end and a distal end fixedly coupled to the distal hub. The mid-sheath assembly may include a mid-sheath having a proximal end coupled to the proximal hub and extending distally to a distal end, a retaining plug having a proximal end and a distal end extending collinearly with the mid-sheath, a sealing member disposed between the distal end of the mid-sheath and the proximal end of the retaining plug, and a retaining sleeve disposed over and in contact with the distal end region of the mid-sheath, over the sealing member, and over the proximal end region of the retaining plug. The intermediate sheath assembly may be configured to be longitudinally offset relative to the inner sheath and the outer sheath.

[0019] Alternatively or in addition to any of the above examples, in another example, the retaining sleeve may be configured to mechanically engage a portion of a housing coupled to a proximal end of the outer sheath to limit proximal movement of the intermediate sheath.

[0020] Alternatively or in addition to any of the above examples, in another example, the intermediate sheath assembly may define a third lumen configured to substantially surround the inner sheath when the telescopic catheter is in a fully retracted configuration and to surround a portion of the drive cable when the telescopic catheter is in a fully extended configuration.

[0021] The above summary of some embodiments is not intended to describe each disclosed embodiment or every implementation of the present disclosure. The following figures and detailed description more particularly exemplify these embodiments. [Brief description of the drawings]

[0022] The present disclosure may be more fully understood from consideration of the following detailed description in conjunction with the accompanying drawings. [Figure 1] FIG. 1 is a side view of an exemplary medical device. [Diagram 2] FIG. 2 is a side view of another exemplary medical device. [Diagram 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 expanded configuration. [Diagram 5] 5 is a cross-sectional view of a portion of the medical device of FIG. 2 taken along line 5-5 of FIG. [Figure 6] 6 is a cross-sectional view of a portion of the medical device of FIG. 2 taken along line 6-6 of FIG. [Figure 7] 7 is a cross-sectional view of a portion of the medical device of FIG. 2 taken along line 7-7 of FIG.

[0023] The disclosure is susceptible to various modifications and alternative forms, specific examples of which have been shown by way of example in the drawings and have been described in detail. It is to be understood, however, that it is not intended to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] For the following defined terms, these definitions shall be applied unless a different definition is given in the claims or anywhere in this specification. All numerical values ​​herein, whether explicitly stated or not, are assumed to be modified by the term "about." The term "about" generally refers to a range of numerical values ​​that one of ordinary skill in the art would consider equivalent to the recited value (e.g., having the same function or result). In many instances, the term "about" may include numbers that are rounded to the nearest significant figure.

[0025] The recitation of numerical ranges with multiple endpoints includes all numbers within that range (eg, 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5). As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term "or" is generally employed in its sense including "and / or" unless the content clearly dictates otherwise.

[0026] It should be noted that references herein to "one embodiment," "some embodiments," "other embodiments," etc., indicate that the described embodiment may include one or more of a particular feature, structure, or characteristic. However, such a description does not necessarily mean that all embodiments include that particular feature, structure, or characteristic. In addition, when a particular feature, structure, or characteristic is described in combination with one embodiment, such feature, structure, or characteristic may also be used in combination with other embodiments, whether or not explicitly stated, unless expressly stated to the contrary.

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

[0028] In the medical arts, catheters are frequently used to diagnose and treat various abnormalities within a patient's body, such as, but not limited to, clogged or blocked blood vessels. A catheter is introduced into a patient's blood vessel, for example, by making an incision in the patient's body over the blood vessel and inserting the catheter into the patient's blood vessel. A catheter operator, such as a physician, then carefully moves the catheter through the patient's blood vessel until the catheter is appropriately positioned to diagnose or treat the abnormality. Because carefully moving 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 stretchable catheter is frequently used to perform such diagnoses and treatments. Disclosed herein is a stretchable catheter that has reduced stretching movement forces and reduced bubble formation.

[0029] FIG. 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, such as may be used to image blood vessels. The medical device 10 may have a variety of configurations / forms. In some examples, the medical device 10 may include an elongate shaft 12 having a proximal end region 14 and a distal end region 16. A proximal hub or connector 18 may be coupled to or otherwise disposed adjacent the proximal end region 14. A tip member 20 may be coupled to or otherwise disposed adjacent the distal end region 16. The tip member 20 may include a guidewire lumen 30 having a guidewire exit port 32, an atraumatic distal end 34, one or more radiopaque markers 36, and / or other features. In some embodiments, the tip member 20 may extend at a non-parallel angle to the proximal end region 14 of the elongate shaft 12. The imaging assembly 22 may be disposed within the lumen of the shaft 12. In general, 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 Nos. 2012 / 0059241 and 2017 / 0164925, the disclosures of which are incorporated herein by reference in their entireties. In at least some examples, the medical device 10 may be similar to and include features similar to the OPTICROSS® imaging catheter available from 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 ultrasound transducer. Other transducers are contemplated. The transducer 28 may be rotatable and / or axially translatable relative to the shaft 12. For example, the drive cable 24 may be rotated and / or translated to rotate and / or translate the transducer 28 (and housing 26).

[0031] 1, the medical device 10 may include a telescoping portion configured to allow an operator of the medical device to move the drive shaft 24 carrying the imaging assembly 22 proximally and distally within the catheter without having to move the entire catheter within the patient. This allows the operator of the catheter to easily reposition the imaging assembly or other medical device within the patient. For example, the telescoping portion may be actuated to reposition the imaging assembly 22 within the elongate shaft 12. Disclosed herein are medical devices that reduce the telescoping movement force required when actuating the telescoping portion.

[0032] Additionally, when using the medical device 10, it may be desirable to prime and / or clean the shaft 12. To clean the medical device 10, fluid may be injected into a cleaning port on or at the hub 18. The fluid may be drained from the medical device at a drain hole (not shown) adjacent the distal end of the housing 26. In some instances, the cleaning process may lead to bubble formation within the shaft 12. Because bubbles can reflect / interfere with signals (e.g., ultrasound signals) from the transducer 28, thereby impairing images, it is desirable to clean the medical device 10 in a manner that inhibits bubble formation and / or removes / destroys any bubbles that do form. While cleaning processes are typically effective at removing bubbles, some bubbles may still remain within the shaft 12. Disclosed herein are medical devices that are designed to help inhibit bubble formation within the medical device.

[0033] 2 illustrates a side view of another exemplary medical device, such as, but not limited to, a telescopic 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 the proximal end region 102. The 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 may further include a telescopic portion 110 extending from a proximal end region 113 to a distal end region 115 and disposed between the proximal end region 102 and the distal end region 104 of the catheter 100. An elongate shaft 112 extends distally from the distal end region 115 of the telescopic portion 110. The elongate shaft 112 may include a tip member 114 adjacent the distal end region 104 of the catheter 100. Tip member 114 may be similar in form and function to tip member 20 described with respect to Figure 1. For example, tip member 114 may include a guidewire lumen having a guidewire exit port, an atraumatic distal end, one or more radiopaque markers, and / or other features.

[0034] An imaging assembly 116 (see, e.g., FIG. 3 ) may be movably disposed within the lumen of the elongate 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 the housing 122. It is contemplated that the imaging assembly 116 may include or be replaced with another medical device, such as, for example, but not limited to, a cutting head or other device. The particular device selected for the drive cable 120 may be selected based on the desired functionality for the catheter 100. The drive cable 120 may extend proximally from the imaging member 118 through the telescoping portion 110 to the proximal hub 106. The proximal hub 106 may include features adapted to connect the drive cable 120 to a power source and / or other electrical coupling. In some cases, the proximal end of the drive cable 120 may be attached to the proximal hub 106. Although not explicitly shown, drive cable 120 may be provided with a single layer outer covering or coating, or a dual layer outer covering or coating, as desired. If so provided, the outer covering may extend the entire length of drive cable 120 or less than the entire length of drive cable 120.

[0035] The telescoping portion 110 may include a first or middle sheath 124, a second or outer sheath 126, and a third or inner sheath 128. Typically, the outer sheath 126 may be disposed over the middle sheath 124, which may be disposed over the inner sheath 128. The middle sheath 124 may be axially and / or rotationally offset relative to the outer sheath 126 and the inner sheath 128, such that movement of the proximal hub 106 may translate to movement of the middle sheath 124 and the drive cable 120. A distal hub 138 may be disposed adjacent the distal end region 115 of the telescoping portion 110. The distal hub 138 may include a distal strain relief 139 configured to couple to the elongate shaft 112. Additionally, a distal end of the outer sheath 126 and a distal end of the inner sheath 128 may each be fixedly secured to the distal hub 138.

[0036] The intermediate sheath 124 extends distally from a proximal end region 130 coupled to a proximal strain relief 132 to a distal end 134 extending within the outer sheath 126. The intermediate sheath 124 may have a constant diameter from the proximal end region 130 to the distal end 134, but this is not required. 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 a distal hub 138 and a housing 142. The intermediate sheath 124 defines a lumen 136 extending from the proximal end region 130 to its distal end 134 (see, e.g., FIGS. 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 receptacle 142 to a distal end 144 attached to a distal hub 138 (see, e.g., FIG. 5). The outer sheath 126 defines a lumen 146 extending from the proximal end region 140 to the distal end 144 (see, e.g., FIGs. 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 a proximal end region to a distal end 148 attached to the distal hub 138 (see, e.g., FIG. 5). The inner sheath 128 defines a lumen 150 extending from the proximal end region to its distal end 148 (see, e.g., FIGS. 5-7). 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 in a proximally displaced configuration (see, e.g., FIG. 4). In some embodiments, the proximal end region of the inner sheath 128 may be disposed 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] FIG. 3 illustrates a perspective view of the telescopic catheter of FIG. 2 when the proximal hub 106 and the intermediate sheath 124 (and thus the drive shaft 120) are in their distal-most configuration. Since the catheter 100 is at its shortest length at this time, this configuration can be considered a fully retracted configuration. In FIG. 3, the elongate shaft 112 is not shown to more clearly show the structure of the imaging assembly 116. In the embodiment of FIG. 3, the intermediate sheath 124 is advanced distally within the lumen 146 of the outer sheath 126. Distal movement of the intermediate sheath 124 may be limited by a mechanical stop created between the proximal strain relief 132 and the housing 142. When the proximal hub 106 and the intermediate sheath 124 are in their distal-most configuration, the majority of the lumen length of the lumen 136 of the intermediate sheath 124 may surround the inner sheath 128.

[0040] FIG. 4 illustrates a perspective view of the proximal portion of the telescopic catheter of FIG. 2 with the proximal hub 106 and the intermediate sheath 124 (and thus the drive shaft 120) near their proximal-most positions. Since the catheter 100 is at its maximum length at this time, this configuration can be considered a fully extended configuration. In the embodiment of FIG. 4, the intermediate sheath 124 is displaced proximally within the lumen 146 of the outer sheath 126. Proximal movement of the intermediate sheath 124 can be limited by a mechanical stop created between a mating 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 proximal-most positions, the majority of the lumen length of the lumen 136 of the intermediate sheath 124 can surround the drive cable 120.

[0041] 3 and 4 illustrate an appropriate degree of movement of the telescoping portion 110, the proximal hub 106 and intermediate sheath 124 may be located anywhere therebetween. Because the drive cable 120 is coupled to the proximal hub 106, proximal and distal movement is translated relative to the drive cable 120 and imaging assembly 116, thereby allowing movement of the imaging assembly without moving the entire catheter 100. It is further contemplated that rotational movement of the proximal hub 106 is also translated relative to the drive cable 120 and imaging assembly 116, thereby allowing rotation of the imaging assembly 116 within the elongate shaft 112.

[0042] 5 is a cross-sectional view of the distal end region 115 of the telescoping portion 110 when the proximal hub 106 and the intermediate sheath 124 are in their distal-most configurations taken along line 5-5 of FIG. 3. The drive shaft 120, the inner sheath 128, the intermediate sheath 124, and the outer sheath 126 are coaxially disposed. 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 telescoping portion 110 further comprises a seal member 152 proximal to the distal end 134 of the intermediate sheath 124 and disposed between the outer surface of the intermediate sheath 124 and the inner sheath 128. The seal member 152 may be a flexible and / or deformable component configured to provide a fluid-tight seal between the intermediate sheath 124 and the inner sheath 128. In some cases, the seal member 152 may be a silicone O-ring. However, other shapes and / or materials of the seal member are contemplated. The seal member 152 may be sized and shaped to restrict the flow path when the telescopic catheter 100 is flushed. For example, when fluid is introduced through the port 108, the fluid may fill the lumen 136 of the middle sheath 124 and the lumen 150 of the inner sheath 128. However, the seal member 152 provides a simpler flow path by preventing the fluid from exiting the lumen 136 of the middle sheath 124, thereby preventing the fluid from entering the lumen 146 of the outer sheath 126. Additionally, the fluid may pass through the lumen 150 of the inner sheath 128, through the distal hub 138, and distally to the elongate shaft 112. Positioning the seal member 152 between the middle sheath 124 and the inner sheath 128 may limit the telescopic movement 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 include the intermediate sheath 124, a retaining plug 156, a retaining sleeve 158, and a sealing member 152. The retaining plug 156 may extend co-linearly with the intermediate sheath 124. For example, the retaining plug 156 may have an inner diameter sized to be comparable to the inner diameter of the intermediate sheath 124 and an outer diameter sized to be comparable to the outer diameter of the intermediate sheath 124, but this is not required. In some embodiments, the sealing member 152 may be disposed 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 disposed in other locations and / or configurations, as desired. For example, the sealing member 152 may be configured to extend between an inner surface of the intermediate sheath 124 and / or the retaining plug 156 and an outer surface of the inner sheath 128. It is contemplated that the intermediate sheath 124 and the retaining plug 156 may be formed as separate pieces or may be substantially attached. In other embodiments, the intermediate sheath 124 and the retaining plug 156 may be formed as a unitary structure. For example, the intermediate sheath 124 and the retaining plug 156 may be molded as a single piece over the seal member 152 or may be molded with a cavity configured to receive the seal member 152. These are merely a few examples.

[0044] The retaining sleeve 158 may be disposed on an outer surface of the mid-sheath 124, on the retaining plug 156, and / or on the seal member 152 and may extend from a proximal end 164 to a distal end 166. The proximal end 164 of the retaining sleeve 158 may be disposed proximal to the distal end 134 of the mid-sheath 124, while the distal end 166 of the retaining sleeve 158 may be disposed 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 mid-sheath 124, over the seal member 152, and over the proximal end region of the retaining plug 156. It is contemplated that the retaining sleeve 158 may be heat shrunk, molded, or bonded to the mid-sheath 124, the seal member 152, and the retaining plug 156. In some embodiments, the retaining sleeve 158 may secure the mid-sheath 124, the seal member 152, and the retaining plug 156 to one another. Additionally or alternatively, the mid sheath 124, the seal member 152, and the retaining plug 156 may be secured together using an adhesive or may be formed as a unitary structure through molding or overmolding. The retaining sleeve 158 may have an inner diameter that is approximately the same as the outer diameter of the mid sheath 124 and / or the retaining plug 156, and an outer diameter that is smaller than the inner diameter of the outer sheath 126, such that the retaining sleeve 158 does not frictionally engage the inner surface of the outer sheath 126.

[0045] 6 is a cross-sectional view of the proximal end region 113 of the telescoping portion 110 when the proximal hub 106 and intermediate sheath 124 are in their distal-most configurations, taken along line 6-6 in FIG. 3. The proximal end region 140 of the outer sheath 126 is fixed within the lumen 168 of the housing 142. The proximal end region 170 of the inner sheath 128 is free to be attached to other components. In some embodiments, the housings 142 may include an anchor seal plug 172 located at or near their proximal ends 174. The proximal ends 176 of the anchor seal plugs 172 may be configured to provide a mechanical stop to the proximal strain relief 132 to limit 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 their distal-most configuration, the distal end of the proximal strain relief 132 contacts the proximal end 176 of the anchor seal plug 172 .

[0046] As discussed above, drive cable 120 may include an outer covering or coating. The outer covering may be formed from a first layer 121 and a second layer 123. However, in some embodiments, less than two layers (e.g., one layer or no layers) may be provided, or more than two layers (e.g., three or more layers) may be provided, as desired.

[0047] FIG. 7 is a cross-sectional view of the intermediate region of the telescoping portion 110 taken along line 7-7 in FIG. 4 when the proximal hub 106 and the intermediate sheath 124 are near their most proximal configuration. In FIGS. 4 and 7, the proximal hub 106 and the intermediate sheath 124 have been actuated in a proximal direction 182 from the configuration illustrated in FIGS. 3, 5, and 6. In the illustrated embodiment, the proximal hub 106 and the intermediate sheath 124 have been displaced proximally until the proximal end 134 of the intermediate sheath 124 is disposed within the housing 142. The housing 142 may include an annular protrusion 178 extending radially inward from an inner surface of the housing 142. The annular protrusion may define a distal wall 180. It is contemplated that the protrusion 178 may define an opening having a diameter approximately the same as the outer diameter of the intermediate sheath 124. Because the retaining sleeve 158 has a larger outer diameter than the mid-sheath 124, further proximal displacement 182 of the proximal hub 106 and mid-sheath 124 will cause the proximal end 164 of the retaining sleeve 158 to abut the distal wall 180 of the projection 178. This mechanical engagement limits proximal displacement 182 of the proximal hub 106 and mid-sheath 124 and also prevents the mid-sheath 124 from disengaging from the inner sheath 128 and outer sheath 126.

[0048] It will be understood that this disclosure is, in many respects, only illustrative. Changes may be made in details, particularly in matters of shape, size and arrangement of steps, without exceeding the scope of the disclosure. This may include using, to an appropriate extent, some of the features of one illustrative embodiment used in other embodiments. The scope of the invention will, of course, be defined in the language in which the appended claims are expressed.

Claims

1. 1. A stretchable catheter comprising: a proximal hub adjacent a proximal end of the telescopic catheter; A drive cable; a telescoping portion extending from a proximal end adjacent the proximal hub to a distal end; The catheter includes: 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, the outer sheath having a proximal end and a distal end; an inner sheath disposed within the intermediate sheath, the inner sheath having a proximal end and a distal end; a seal member disposed between the intermediate sheath and an outer surface of the inner sheath; the intermediate sheath is configured to be longitudinally offset relative to the inner sheath and the outer sheath; The elastic portion is provided with Expandable catheter.

2. The telescopic catheter of claim 1 , wherein the sealing member is configured to form a fluid-tight seal between the inner sheath and the intermediate sheath.

3. 3. The telescopic catheter of claim 1, wherein the intermediate sheath has a constant outer diameter from its proximal end to its distal end.

4. The catheter of any one of claims 1 to 3, wherein the sealing member comprises an O-ring.

5. The telescopic catheter according to any one of claims 1 to 4, wherein the outer sheath and the inner sheath are fixed in relationship to each other.

6. 6. The telescopic catheter of claim 1, wherein the intermediate sheath defines a lumen configured to substantially surround the inner sheath when the intermediate sheath is in a distally advanced configuration and to surround a portion of the drive cable when the intermediate sheath is in a proximally displaced configuration.

7. The telescopic catheter of any one of claims 1 to 6, further comprising an outer cover disposed over the drive cable.

8. The catheter of claim 7 , wherein the outer cover comprises a first layer and a second layer.

9. The telescopic catheter of any one of claims 1 to 8, further comprising a housing coupled to the proximal end of the outer sheath.

10. The telescopic catheter according to any one of claims 1 to 9, further comprising a retaining sleeve secured to an outer surface of the intermediate sheath.

11. The telescopic catheter of any one of claims 1 to 10, further comprising a retaining plug extending distally from the seal member.

12. The telescopic catheter of claim 9 , wherein a proximal strain relief is coupled to the proximal hub and configured to mechanically engage a proximal portion of the housing to limit proximal movement of the intermediate sheath.

13. The telescopic catheter of claim 10 , wherein the retaining sleeve is configured to mechanically engage a portion of the housing to limit proximal movement of the intermediate sheath.

14. The telescopic catheter of claim 11 , wherein the outer diameter of the retaining plug is the same as the outer diameter of the intermediate sheath.

15. 12. The telescopic catheter of claim 11, wherein the retaining sleeve is disposed over and contacts a distal end region of the intermediate sheath, over the sealing member, and over a proximal end region of the retaining plug.

Images