Patent Publication Number: US-11648375-B2

Title: System and method for delivering a catheter

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a Divisional of U.S. patent application Ser. No. 15/407,728 filed Jan. 17, 2017, the contents of which are incorporated herein by reference in their entirety. 
    
    
     FIELD 
     This disclosure relates to medical instruments, and more particularly, guidewire and catheter delivery systems. 
     BACKGROUND 
     Catheters can be pliable tubular structures that enter vasculature of a patient. Catheters can be used for a variety of purposes and applications. For example, they can be introduced into a particular area of interest within a vasculature and then act as a guide for introducing other peripheral, central venous, or arterial devices therein through its lumen. Such devices can include single or multi-lumen catheters, clot capturing devices, balloon catheters, and the like. 
     During certain procedures, a guidewire is typically introduced first separate from the catheter. Catheters and guidewires can range in size and diameter, depending on a particular procedure and area of interest in the vasculature. In a clinical setting, tracking of catheters over a guidewire can lead to complications since step movement between the larger catheter and smaller guidewire can lead to injuries to the vessel wall. 
     Additionally, previous approaches have permitted the guidewire to move within the catheter during delivery even upon the slightest pressure from the guidewire to the catheter. In turn, this risks injury to the patient. In typical guidewire-catheter systems, the guidewire is normally loose within the lumen of the catheter during delivery of the catheter and therefore susceptible to what is understood as step movement. However, because catheters can range in size depending on the therapeutic mechanisms they may deliver, larger outer diameters of the catheter unfortunately result in larger step movements between the guidewire that prevent safe delivery within the vasculature. This step movement can unnecessarily risk injuring the vessel wall or otherwise resulting in ineffective treatment. 
     Previous approaches, including those described in U.S. Pat. No. 7,731,707, have failed to resolve the issues related to step movement between the catheter and guidewire. For example, the &#39;707 patent is directed towards creating a space in the vasculature itself as opposed to delivering a surface that extends beyond the outer diameter of the catheter for resolving step movement between a guidewire and catheter. Additionally, the &#39;707 patent fails to teach or reasonably suggest any element that resolves step movement between catheter, guidewire, and vessel wall. 
     Another disclosure is also seen in U.S. Pat. Pub. 2007/0021685, wherein a catheter balloon is used with a catheter. During peripheral vasculature or coronary procedures, it can be desirous for a catheter balloon to be stationary relative to the guidewire. However, in practice, because the balloon does tend to move, the &#39;685 publication sought to resolve this movement by implementing a break inside of the balloon and by pulling on the wire at the end. In so doing, the lumen of the catheter in the &#39;685 publication is caused to expand into a locked state. This is strictly done to avoid longitudinal movement of the balloon within the lumen, when the balloon inflates, since the balloon is then trapped in the &#39;685 publication by the wire inside the balloon. Unfortunately, expansion and activation is only caused in the &#39;685 publication by manually pulling on or applying tension to the wire. Additionally, in procedures that involve catheter balloons and guidewires, the guidewire must be at the location of interest first and then the balloon is tracked over the wire. 
     Accordingly, in the process of tracking the guidewire, a self-expanding balloon would never actually be outside the catheter or address step movement between catheter and guidewire since doing so would run counter to the specific order of operations in procedures that mirror the &#39;685 publication. For example, if the balloon in the &#39;685 publication did expand outside the catheter, it would be difficult to track to the catheter or to the vasculature without risking injury to the vessel walls. 
     Therefore, there remains a need for new devices to safely and effectively advance catheters to locations of interest when used with guidewires to resolve these and other problems of the art. 
     SUMMARY 
     In some aspects, the present disclosure relates to a catheter delivery system. The system can include a guidewire. A catheter with a lumen is also included, the catheter having a distal end and a proximal end. A self-expanding sheath may also be slidably disposed in the lumen, the self-expanding sheath having a distal end and a proximal end. The self-expanding sheath can be capable of moving from a collapsed state within the catheter to an expanded state outside the catheter during deployment with an outer diameter greater than an inner diameter of the catheter. In certain embodiments, the outer diameter of the sheath in the expanded stated may be approximately equal to or slightly larger than the outer diameter of the catheter. The self-expanding sheath and the catheter can be advanceable in tandem over the guidewire. In this respect, as the distal end of the self-expanding sheath is moved distally relative to the catheter, the self-expanding sheath expands to the expanded state. 
     In the collapsed state, the outer diameter of the self-expanding sheath can be substantially snug with the inner diameter of the catheter. The distal end of the self-expanding sheath can also included a convoluted tip. The tip may be tapered with the distal end including an inner diameter substantially snug with the guidewire. In certain embodiments, the guidewire and/or the inner diameter of the sheath can include a lubricant. The outer diameter of the sheath and/or the inner diameter of the catheter can also or separately include a lubricant. The self-expanding sheath can have a radiopaque band proximal to the distal end. 
     The self-expanding sheath may include a plurality of slits, wherein as the self-expanding sheath is moved distally away from the distal end of the catheter, the slits can cause the outer diameter of the sheath to expand so it is greater than the inner diameter of the catheter. Also, moving to the expanded state can cause the self-expanding sheath to impart an outward force to the vessel wall. In this respect, the catheter can be released from the vessel wall. The slits can be etched longitudinally and disposed between proximal and distal ends of the self-expanding sheath. The slits can also be spiral etches or curved etches disposed between proximal and distal ends of the self-expanding sheath. The slits of each embodiment can enhance flexibility of the self-expanding sheath where otherwise adding a sheath would risk rendering the catheter too rigid for use in the tortuous vessels. 
     In some embodiments, the self-expanding sheath may be movable so that its distal end is capable of being distal of the distal end of the distal end of the catheter. Moving the distal end of the self-expanding sheath a predetermined distance away from the distal end of the catheter can cause the outer diameter of the self-expanding sheath to be greater than the outer diameter of the catheter. 
     In other embodiments, a self-expanding sheath is disclosed for use with a catheter and a guidewire. The sheath can include an outer surface slidably disposable in a lumen of the catheter. An expandable element may also be disposed on a distal end of the self-expanding sheath, the expandable element capable of moving from a collapsed state within the lumen to an expanded state outside the lumen during deployment. An outer diameter of the expandable element can be greater than an outer diameter of the catheter. The self-expanding sheath may be capable of being advanced in tandem with the catheter over the guidewire such that as the distal end of the self-expanding sheath is moved distally relative to the catheter, the self-expanding sheath can deploy or move to the expanded state. The expandable element can include a plurality of slits etched between distal and proximal ends of the sheath. As the self-expanding sheath is moved distally away from the distal end of the catheter, the slits cause the outer diameter of the sheath to be greater than the inner diameter of the catheter. In the expanded state, the slits can cause the sheath to form a “pear-like” shape. 
     In other embodiments, a method is disclosed for delivering a catheter to a location of interest in the vasculature. The method can include selectively positioning a guidewire at the location, positioning a self-expanding sheath within a lumen of the catheter, advancing the catheter and the self-expanding sheath in tandem over the guidewire, and distally moving a distal end of the self-expanding sheath out from the lumen of the catheter thereby causing the self-expanding sheath to move from a collapsed state within the catheter to an expanded state outside the catheter. 
     The method can also include having an outer surface of the self-expanding sheath contact the distal end of the lumen as the sheath is deployed so that the sheath separates the catheter from the vessel walls. In certain embodiments, the method can also include forming a plurality of slits on the self-expanding sheath between its proximal and distal ends, and the slits causing the self-expanding sheath to expand to the expanded stated with an outer diameter greater than the outer diameter of the catheter. The method may also include extending the distal end of the sheath beyond a distal end of the catheter thereby smoothening a transition between the catheter and the guidewire during delivery. The method can also include removing the self-expanding sheath from the catheter and the guidewire once the catheter and self-expanding sheath have been delivered to the location of interest forming a void between the guidewire and the catheter. Finally, the method can include the self-expanding sheath imparting an outward expansion force to the vessel wall as the self-expanding sheath moves to the expanded state. 
     Other aspects and features of the present disclosure will become apparent to those of ordinary skill in the art, upon reviewing the following detailed description in conjunction with the accompanying figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Reference will now be made to the accompanying drawings, which are not necessarily drawn to scale. 
         FIG.  1    is a partial perspective view of an example embodiment of the catheter system disclosed herein, wherein the sheath is being deployed from the catheter. 
         FIG.  2    is a partial side plan view of the system shown in  FIG.  1   . 
         FIG.  3    is a partial perspective view of the catheter and guidewire of  FIGS.  1 - 2    without the sheath. 
         FIG.  4    is a partial side plan view of the catheter and guidewire of  FIGS.  1 - 2    without the sheath. 
         FIG.  5    is a partial perspective view of a sheath in a collapsed state. 
         FIG.  6    is a side plan perspective view of a sheath in a collapsed state. 
         FIG.  7    is a partial perspective view the catheter system disclosed herein, wherein the sheath is deployed from the catheter in an expanded state. 
         FIG.  8    is a partial side plan view of the system shown in  FIG.  7   . 
         FIG.  9    is a partial perspective view of a sheath in an expanded state. 
         FIG.  10    is a side plan perspective view of the sheath in  FIG.  9   . 
         FIG.  11    is a partial perspective view of another exemplary sheath in an expanded state. 
         FIG.  12    is a side plan perspective view of the sheath in  FIG.  11   . 
         FIG.  13    is a side plan view of an example embodiment of the catheter system disclosed herein in combination with an exemplary delivery system, wherein the sheath and catheter are compressed. 
         FIG.  14    is a side plan view of an example embodiment of the catheter system disclosed herein in combination with an exemplary delivery system, wherein the sheath and catheter are in an expanded state. 
         FIG.  15    is a flow diagram for a method of delivering a catheter to a location of interest in the vasculature. 
         FIG.  16    is a flow diagram for a method of manufacturing a self-expanding sheath. 
     
    
    
     DETAILED DESCRIPTION 
     Although example embodiments of the disclosed technology are explained in detail herein, it is to be understood that other embodiments are contemplated. Accordingly, it is not intended that the disclosed technology be limited in its scope to the details of construction and arrangement of components set forth in the following description or illustrated in the drawings. The disclosed technology is capable of other embodiments and of being practiced or carried out in various ways. 
     It must also be noted that, as used in the specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. By “comprising” or “containing” or “including” it is meant that at least the named compound, element, particle, or method step is present in the composition or article or method, but does not exclude the presence of other compounds, materials, particles, method steps, even if the other such compounds, material, particles, method steps have the same function as what is named. 
     In describing example embodiments, terminology will be resorted to for the sake of clarity. It is intended that each term contemplates its broadest meaning as understood by those skilled in the art and includes all technical equivalents that operate in a similar manner to accomplish a similar purpose. It is also to be understood that the mention of one or more steps of a method does not preclude the presence of additional method steps or intervening method steps between those steps expressly identified. Steps of a method may be performed in a different order than those described herein without departing from the scope of the disclosed technology. Similarly, it is also to be understood that the mention of one or more components in a device or system does not preclude the presence of additional components or intervening components between those components expressly identified. 
     As discussed herein, vasculature of a “subject” or “patient” may be vasculature of a human or any animal. It should be appreciated that an animal may be a variety of any applicable type, including, but not limited thereto, mammal, veterinarian animal, livestock animal or pet type animal, etc. As an example, the animal may be a laboratory animal specifically selected to have certain characteristics similar to a human (e.g., rat, dog, pig, monkey, or the like). It should be appreciated that the subject may be any applicable human patient, for example. 
     As discussed herein, “operator” may include a doctor, surgeon, or any other individual or delivery instrumentation associated with delivery of a braided stent body to the vasculature of a subject. 
     The method and systems disclosed herein are directed towards minimizing or eliminating the step between a catheter and corresponding guidewire and to form a backward step. A guidewire can be selectively positioned at a location of interest in the vasculature. A self-expanding sheath may be assembled with a catheter by being slidably inserted therein, wherein the catheter and self-expanding sheath can then be advanced in tandem over a guidewire. The self-expanding sheath may not completely hug or contact the guidewire. While the sheath can be collapsed within the catheter, the sheath may be self-expanding so that an outer surface of the sheath can be larger than the outer surface of the catheter during deployment. In this respect, once the sheath and catheter have been positioned at the location of interest in the vasculature, the sheath can be moved distal so that it extends beyond the outer diameter (OD) of the catheter. As the sheath is deployed, it expands so that the sheath operates to separate the catheter from the vessel walls during use. 
     The herein disclosed system and method that incorporates the self-expanding sheath, catheter, and guidewire may be delivered to the location of interest without any corresponding therapeutic mechanisms (e.g. a balloon, coil, adhesive, or the like). Instead, the system and method disclosed herein is a safe, efficient, and cost-effective solution for delivering a catheter in tandem with a sheath disposed therein, wherein the sheath can be moved distally out from the inner lumen of the catheter so that the guidewire can safely deliver therapeutic mechanisms to the location of interest. In particular regard to procedures in the neurovasculature, vessels are typically tortuous through which catheters can be difficult to advance. By using the self-expanding sheath of this disclosure, the catheter can be safely traversed within the vasculature, tortuous or not, since the step movement is minimized between the catheter and guidewire. 
     Turning to  FIGS.  1 - 2   , one embodiment of the self-expanding sheath  10  is depicted assembled with the catheter  20  and guidewire  30  extended therethrough. The sheath  10  includes a proximal end  18  near the operator, and a distal end  19  disposed away from the operator. At a distal end  26  of the catheter  20  where the guidewire  30  can be caused to be deployed, the sheath  10  may be in contact at its outer surface with the inner surface of the catheter  20  at its distal end  26  as the sheath  10  expands during deployment. This is particularly advantageous in the art as catheter flexibility is necessary for tracking and maintaining patient safety during use. While adding a sheath to a guidewire-catheter system would normally surrender flexibility of the catheter when the sheath is stowed therein, the self-expanding, flexible sheath  10  described herein permits the sheath and catheter to be collectively flexible and trackable during use over the guidewire  30  within the vasculature. 
     The sheath  10  and the catheter  20  may be advanced in tandem over the guidewire  30  simultaneously to the location of interest (as opposed to tracking a self-expanding balloon first and then the catheter). After catheter  20  and self-expanding sheath  10  are advanced to the location of interest, the sheath  10  can then be advanced distally away from the catheter  20  a predetermine distance so that it self-expands a predetermined amount OD at the distal end of the catheter  20  that is greater than the OD of the catheter. In turn, any step movement between the guidewire  30  and catheter  20  is all but eliminated when the catheter  20  is being advanced thereover to the location of interest. The sheath  10  described herein can be used over the guidewire  30  so as to minimize the step between OD of the guidewire  30  and ID of the catheter  20  to facilitate safe insertion of a venous device into vasculature of a patient. 
     The snug fit between sheath  10 , catheter  20 , and guidewire  30  ensures that the guidewire  30  does not otherwise injure the patient. Specifically, system and methods of this disclosure are directed towards different procedures altogether without catheter balloons. In the system and methods of this disclosure, catheter  20  may be any biocompatible material known, including a polymeric material such as polyethylene, polypropylene, polystyrene, polyester, polyurethane, polyamide, peboxes, and the like. For example, the catheter  20  can be formed from a rubber or a plastic such as fluorinated ethylene-propethylene (FEP), polyethylene (PE), or the like. Catheter  20  can be elongate and/or tubular with an inner lumen  25  that extends longitudinally through catheter  20 . Catheter  20  can have an OD  22  and an ID  24  defined by lumen  25 . 
     The self-expanding sheath  10  may have an inner lumen  12 , wherein the sheath  10  can have an OD  6  and an ID  8 . Sheath  10  may be may be any biocompatible material known, including a polymeric material such as polyethylene, polypropylene, polystyrene, polyester, polyurethane, polyamide, peboxes, and the like. Sheath  10  may be capable of extending internally along catheter  20 . A distal end  19  of sheath  10  may extend beyond a distal end  24  of catheter  20  thereby avoiding a blunt transition between catheter  20  and guidewire  30 . It is understood that sheath  10  may be movable within catheter  20 , fixed in place, or movable between a plurality of predetermined positions. 
     The OD  6  of sheath  10  can be disposed inside catheter  20  before or while catheter is disposed in the vasculature of the patient. The OD  6  of the sheath  10  may be configured to fit snugly within the catheter  20  so as to minimize the step or distance between the sheath  10  and catheter  20 . In some embodiments, the OD  6  of sheath  10  may be substantially similar to the ID  22  of catheter  20 . Sheath  10  may also be partially or substantially covered with a lubricant coating or be constructed from a material that induces movement between sheath  10  and catheter  20 . 
     Sheath  10  may also include a radio opaque portion  40 . Portion  40  may be one or more bands or selected areas of sheath  10  constructed from a radio opaque material. Portion  40  can be disposed about sheath  10  to facilitate the fluoroscopic observation thereof during a procedure. Another radiopaque marker can be provided on catheter  20  to fluoroscopically determine the location of guidewire  30  and/or catheter  20 . Guidewire  30  may be any guidewire as is known in the art, including being elongated, constructed of any relatively rigid material including metals. Guidewire  30  may be any shape and may have a constant stiffness or flex. 
     Sheath  10  may be formed from one material or from a blend of materials selectively positioned for operable for positioning within catheter  20  when disposed in the vasculature of a patient. In certain embodiments, sheath  10  can be formed from a material that becomes softer with warmer temperatures but is substantially rigid outside the patient. Typical materials can include polyurethane, polytetrafluorethylene (PTFE), FEP, or PE. 
     Once the catheter  20  and self-expanding sheath  10  have been delivered to the location of interest, the self-expanding sheath  10  may be removed from the catheter and the patient thereby leaving a space between the guidewire and catheter to carry out the required procedure and deliver therapeutic mechanisms thereto. This can be more clearly seen in  FIGS.  3  and  4   , wherein a partial perspective view of system  1  is shown whereby sheath  10  has been removed leaving only guidewire  30  and catheter  20 . This space that is defined between the guidewire  30  and ID  24  of catheter  20  can accommodate various therapeutic mechanisms that may be desired for delivery to the location of interest for the relevant procedure. Thus, in one example, the self-expanding sheath  10  cannot and does not provide or deliver any therapeutic mechanisms to the patient. It can be solely used to deliver the catheter  20  along the guidewire  30  to the location of interest. 
     A convoluted tip  16  can be located at the distal end  19  of sheath  10 . In  FIGS.  1 - 2   , tip  16  can be seen as tapering from OD  6  to a smaller diameter at its distal end  19  about guidewire  30 . This is more clearly seen in  FIGS.  5 - 6    which show sheath  10  alone, unassembled with catheter  20  and guidewire  30 . Specifically,  FIG.  5    depicts a partial perspective view of sheath  10  and  FIG.  6    depicts a partial side plan view of sheath  10 . Tip  16  is disposed adjacent sidewalls  14  which may be substantially non-convoluted or tubular along the ID  22  of catheter  20 . Sidewalls  14  can be circular or tubular but sheath  10  is not so limited and may be any shape, including oblong shapes, depending on the corresponding catheter  20 . Sidewalls  14  include one or more slits  17  or cutouts. The one or more slits  17  can extend partially or completely through sidewalls  14  and may weaken the structural integrity of sheath  10 . In this regard, flexibility of sheath  10  is enhanced. Slits  17  can extend partially and/or completely axially along the OD  6  and ID  8  of sheath  10 . Tip  16  can include an opening  15  operable to slide over guidewire  30 . Step movement is substantially limited, if not eliminated, as between opening  15  of the distal end  19  of sheath  10  and guidewire  30  since the ID of opening  15  of sheath  10  is slightly larger than the OD of the guidewire  30 . In certain embodiments, a gap of about 0.0002″-0.001″ can exist between guidewire  30  and the ID of the opening of the sheath  10  thereby permitting the guidewire  30  to move independently of the sheath  10 . 
     Slits  17  may be self-expanding and etched longitudinally between distal and proximal ends of the sheath  10 . The slits  17  may be integrally formed with the sheath  10 . The sheath  10  may also be constructed from a single, unitary material. In certain embodiments, the sheath  10  with its one or more slits  17  may impart a predetermined outward force to the vessel wall as it expands when being slid distally out of the catheter  20  during use. In certain embodiments, the slits  17  may be formed with the sheath  10  so that the sheath  10  in a deployed, expanded state takes a “pear-like” shape. However, sheath  10  is not so limited and the sheath  10  may take any shape as needed or required in an expanded state that can expand the vasculature to move catheter  20  from contacting the vessel walls. Longitudinal slits  17  are particularly advantageous from a manufacturing and design perspective since they minimize complexity without sacrificing the self-expanding nature of the sheath when used in a system with a catheter and guidewire. 
     In  FIGS.  7 - 8   , system  1  is depicted with sheath  10  having been moved distally away from catheter into the expanded state.  FIG.  7    in particular depicts a perspective view of sheath  10  in an expanded state and assembled with guidewire  30  and catheter  20 .  FIG.  8    depicts a side plan view of the system  1  shown in  FIG.  7   . Sheath  10  may be operable to move between a compressed state within the catheter  20  and a deployed state outside of the catheter  20 . OD  6 ′ of the sheath  10  in the deployed state may be a predetermined ratio greater than the OD  22  of the catheter  20 . However, in the deployed state, the sheath  10  does not exhibit outward pressure such as, for example, a catheter balloon that imparts pressures to vessel walls of the vasculature. 
     Turning to  FIGS.  9 - 10   , sheath  10 ′ is depicted alone in an expanded state unassembled with catheter  20  and guidewire  30 . Specifically,  FIG.  9    depicts a partial perspective view of sheath  10 ′ and  FIG.  10    depicts a partial side plan view of sheath  10 ′. Sidewalls  14  expand as slits  17  are moved distally away from catheter  20  thereby causing its OD  6  to expand to expanded OD  6 ′. In the expanded state, as shown, sheath  10 ′ may take a “pear-like”, elliptical shape with its central portion having an OD substantially greater than the OD associated with distal end  19  and/or portion  40 . However, sheath  10 ′ is not so limited and sheath  10 ′ may take any shape or assume any OD that is at least greater than OD  22  of catheter  20  so that sheath  10 ′ is capable of imparting an outward force to the vessel walls during deployment from catheter  20 . 
     Turning to  FIGS.  11 - 12   , another sheath  110 ′ is depicted alone in an expanded state unassembled with catheter  20  and guidewire  30 . Specifically,  FIG.  11    depicts a partial perspective view of sheath  110 ′ and  FIG.  12    depicts a partial side plan view of sheath  110 ′. Instead of being longitudinally etched, slits  117  may be spiral or curved slits etched into sidewalls  114  of sheath  110 ′. As a result, sidewalls  114  expand as slits  117  are moved distally away from catheter  20  thereby causing its OD  6  to expand to expanded OD  6 ′. In the expanded state, as shown, sheath  110 ′ may take a “pear-like”, elliptical shape with its central portion having an OD substantially greater than the OD associated with distal end  119  and/or portion  40 . However, sheath  110  is not so limited and sheath  110 ′ may take any shape or assume any OD that is at least greater than OD  22  of catheter  20  so that sheath  110 ′ is capable of imparting an outward force to the vessel walls during deployment from catheter  20 . 
     Turning to  FIGS.  13  and  14    are side plan views of an example catheter system  1  in combination with an exemplary delivery system, wherein the sheath  10  and catheter  20  in  FIG.  13    are compressed but in the process of being deployed.  FIG.  14    shows the sheath  10  and catheter  20  in an expanded state following deployment from the delivery system. 
     Turning to  FIG.  15    is a method  200  of delivering catheter  20  to a location of interest in the vasculature. The method can include ( 201 ) selectively positioning guidewire  30  at the location, ( 202 ) positioning sheath  10  within a lumen of the catheter  20 , ( 203 ) advancing the catheter  20  and the self-expanding sheath  10  in tandem over the guidewire  30 , and ( 204 ) distally moving distal end  19  of the self-expanding sheath  10  out from the lumen of the catheter  20  thereby causing the self-expanding sheath  10  to move from a collapsed state within the catheter  20  to an expanded state outside the catheter  20 . The method can also include ( 205 ) removing the self-expanding sheath  10  from the catheter  20  and the guidewire  30  once the catheter  20  and self-expanding sheath  10  have been delivered to the location of interest forming a void between the guidewire  30  and the catheter  20 . The method can also include ( 206 ) advancing a therapeutic mechanism through the catheter  20  and over the guidewire  30 . 
     Turning to  FIG.  16   , a method  300  is disclosed for manufacturing sheath  10 ,  110  for use in a system  1  with guidewire  30  and catheter  20 . The method may include step  301  wherein sheath  10 ,  110  is formed with OD  6 ,  106  and a predetermined wall thickness. Then, in step  302  one or more slits  17 ,  117  can be etched through the walls of the sheath  10 ,  110 . In step  303 , sheath  10 ,  110  may be heat fit to a predetermined shape, inner and/or outer diameter for insertion in the catheter  20 . Sheath  10 ,  110  may have a predetermined resiliency and/or flexibility. During use, sheath  10 ,  110  and catheter  20  may be advanced in tandem over guidewire  30  to a location of interest in the vasculature, wherein sheath  10 ,  110  can be moved distally passed distal end  26  of catheter  20  thereby causing sheath  10 ,  110  to move from a first OD  6 ,  106  and second, greater OD  6 ′,  106 ′ that is larger than OD  22  of catheter  20 . 
     The systems and methods of this disclosure also contemplate a catheter system  500  that may be a kit that includes catheter  20  and one or more of sheaths  10 ,  110 . Each sheath  10 ,  110  can be separately, selectively inserted within catheter  20 . Each sheath  10 ,  110  can range in terms of diameter and/or any of the previously disclosed shapes. A kit may include a plurality of sheathes (e.g.  10  sheathes) that are separately sized so that a given sheath can be selected and positioned as required for different sized guidewires. 
     The specific configurations, choice of materials and the size and shape of various elements can be varied according to particular design specifications or constraints requiring a system or method constructed according to the principles of the disclosed technology. Such changes are intended to be embraced within the scope of the disclosed technology. The presently disclosed embodiments, therefore, are considered in all respects to be illustrative and not restrictive. It will therefore be apparent from the foregoing that while particular forms of the disclosure have been illustrated and described, various modifications can be made without departing from the spirit and scope of the disclosure and all changes that come within the meaning and range of equivalents thereof are intended to be embraced therein.