Abstract:
The present disclosure relates to catheters for delivering medical devices to a human patient&#39;s vasculature. A catheter comprises a sock which covers the medical device at the end of the catheter, and an introducer sheath which is reduced in diameter. This reduced diameter introducer sheath minimizes the crossing of the catheter.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Application No. 61/473,503, entitled “ENDOPROSTHESIS DELIVERY SYSTEM” filed Apr. 8, 2011, which is hereby incorporated by reference in its entirety. 
     
    
     FIELD 
       [0002]    The present disclosure relates generally to catheters, and more specifically, to a system for delivering an endoprosthesis to a treatment region in the vasculature of a patient. 
       BACKGROUND 
       [0003]    Current methods for providing medical treatment to human vasculature involve the use of catheters. In many cases, catheters are used to deliver endoprostheses, such as, for example, stents and stent grafts (self-expanding or otherwise), bifurcated stents and stent grafts, drug-eluting stents, and vascular filters, such as inferior vena cava filters, as well as endoluminal imaging devices. 
         [0004]    Frequently catheters enter the body through an orifice or incision. Catheters are typically inserted through main arteries, such as the femoral or brachial artery, and then navigated through the vasculature to the region requiring treatment. Once the tip of the catheter is in the treatment region, it may deploy a medical device. In many cases, the device is a self-expanding endoprosthesis. In other configurations, a balloon may be used to expand the endoprosthesis to its operational size. 
         [0005]    One significant problem with current endoprosthesis delivery systems is the size of the incision required to accommodate the system. This incision may be referred to as the crossing of the catheter. Large crossings may cause increased patient discomfort, longer recovery times, and potential scarring. Thus, a need exists for endoprosthesis delivery systems that can safely and effectively deliver endoprostheses to the treatment region within the vasculature through a relatively small crossing. Those skilled in the art will recognize numerous advantages of such embodiments over the prior art, for example, reducing the size of the crossing necessary to deliver endoprostheses. 
       SUMMARY 
       [0006]    An endoprosthesis delivery device of the present disclosure comprises a catheter, which further comprises an endoprosthesis, a catheter shaft, an introducer sheath, a sock, and a sock securing element. The introducer sheath has an outer diameter equal to or less than the outer diameter of the endoprosthesis in a compressed and/or collapsed configuration. The sock extends from the trailing end of the introducer sheath to the leading end, exits the introducer sheath, and continues over the endoprosthesis. 
         [0007]    Another endoprosthesis delivery device of the present disclosure comprises a catheter having a trailing and leading end, a stent located at the leading end of the catheter, an introducer sheath, a leading tip, a sock, a sock retaining segment, a sock securing suture, and a sock removal mechanism located at the trailing end of the catheter. The introducer sheath has an outer diameter less than or equal to the outer diameter of the stent in its collapsed and/or compressed configuration. The sock extends from the sock removal mechanism, through the introducer sheath and beyond its leading end, continuing over the stent and sock retaining segment. The sock retaining segment and sock securing suture work together to maintain the position of the sock along the catheter before the stent is delivered to the treatment area. 
         [0008]    A method of delivering an endoprosthesis to a treatment region within a human patient comprises inserting an endoprosthesis delivery system into the body of the patient, the endoprosthesis delivery system comprising an endoprosthesis, a catheter shaft, an introducer sheath having an inner diameter equal to or less than the endoprosthesis, a sock extending from the leading end of the introducer sheath over the endoprosthesis and a sock positioning element, guiding the leading end of the catheter shaft to the region to be treated, retracting the sock, deploying the endoprosthesis, and retracting the catheter shaft from the body. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The accompanying drawings are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure, and together with the description, serve to explain the principles of the disclosure, wherein; 
           [0010]      FIG. 1  illustrates a side view of a catheter in accordance with the present disclosure; 
           [0011]      FIGS. 2A and 2B  illustrate axial cross sectional views of a catheter in accordance with the present disclosure; 
           [0012]      FIGS. 3A ,  3 B, and  3 C illustrate longitudinal cross-sectional views of catheters in accordance with the present disclosure; 
           [0013]      FIG. 4  illustrates a cross sectional view of a segment of a catheter in accordance with the present disclosure; 
           [0014]      FIG. 5  illustrates a side view of a catheter in accordance with the present disclosure; and 
           [0015]      FIG. 6  illustrates a cross section of a catheter in accordance with the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    Persons skilled in the art will readily appreciate that various aspects of the present disclosure can be realized by any number of methods and systems configured to perform the intended functions. Stated differently, other methods and systems can be incorporated herein to perform the intended functions. It should also be noted that the accompanying drawing figures referred to herein are not all drawn to scale, but may be exaggerated to illustrate various aspects of the present disclosure, and in that regard, the drawing figures should not be construed as limiting. Finally, although the present disclosure can be described in connection with various principles and beliefs, the present disclosure should not be bound by theory. 
         [0017]    An endoprosthesis delivery system of the present disclosure comprises a catheter shaft, introducer sheath, endoprosthesis, and sock. In such an embodiment, the catheter shaft is housed within the introducer sheath, and the endoprosthesis is situated at the leading end of the catheter shaft, outside of the introducer sheath. The sock, which surrounds the catheter shaft within the introducer sheath, exits the leading end of the introducer sheath and covers the endoprosthesis. In various embodiments, the outer diameter of the introducer sheath is less than or equal to the outer diameter of the endoprosthesis in its collapsed and/or compressed configuration. 
         [0018]    In the present disclosure, the term “leading” is used to describe a position inside the body of a patient that is farthest from the entry point of the device into the body. For example, the leading end of a catheter refers to the end, inside the vasculature of the body, which is farthest from the entry point of the catheter. The term “trailing” is used to describe a position closest to the entry point of a device into the body of a patient. For example, the trailing end of a catheter refers to the portion of the catheter outside of the body of a patient. 
         [0019]    Turning now to such embodiments, and with reference to  FIG. 1 , catheter  100  is an endoprosthesis delivery system. Catheter  100  includes an introducer sheath  104 , an endoprosthesis  101  and a leading tip  103 . In various embodiments, endoprosthesis  101  is positioned between introducer sheath  104  and leading tip  103 . In various embodiments, endoprosthesis  101  can be an expandable stent or stent graft. In an aspect of these embodiments, endoprosthesis  101  is a self-expanding stent or stent graft. In various embodiments, before catheter  100  is inserted into the body of a patient, endoprosthesis  101  is in a collapsed and/or compressed state. 
         [0020]    In various embodiments, the inner diameter of introducer sheath  104  is less than or equal to the outer diameter of endoprosthesis  101  in a collapsed and/or compressed state. In these embodiments, because the outer diameter of endoprosthesis  101  is larger than the inner diameter of introducer sheath  104 , endoprosthesis  101  cannot be deployed from within introducer sheath  104 . In an aspect of these embodiments, the outer diameter of introducer sheath  104  may also be less than or equal to the outer diameter of endoprosthesis  101  in a collapsed and/or compressed state. In embodiments in which the outer diameter of introducer sheath  104  is equal to the outer diameter of endoprosthesis  101 , introducer sheath  104  and endoprosthesis  101  form an integrated tube of constant diameter from the entry point of introducer sheath  104  to the leading end of endoprosthesis  101 . 
         [0021]    With reference to  FIG. 2A , catheter  200  is an endoprosthesis delivery device. In various embodiments, catheter  200  comprises a catheter shaft  202 , introducer sheath  204  and sock  205 . In these embodiments, introducer sheath  204  is inserted into the vasculature. Catheter shaft  202  and sock  205  pass through introducer sheath  204  and are navigated towards the treatment area in the vasculature. 
         [0022]    With reference to  FIG. 2B , catheter  200  further comprises an endoprosthesis  201 . In various embodiments, endoprosthesis  201  is situated at the leading end of catheter shaft  202 . Endoprosthesis  201  may comprise, for example, a stent. In an aspect of these embodiments, endoprosthesis comprises a self-expanding stent or stent graft in a compressed and/or collapsed configuration. However, any endoprosthesis which may be delivered by a catheter to a treatment region is within the scope of the present disclosure. 
         [0023]    In various embodiments, catheter  200  further comprises a sock  205 . In these configurations, sock  205  has an inner diameter greater than or equal to that of catheter shaft  202  and less than the inner diameter of introducer sheath  204 . Sock  205  surrounds catheter shaft  202 , passes through introducer sheath  204 , and extends outward from the leading end of introducer sheath  204 . Sock  205  then surrounds the exterior of endoprosthesis  201 . In various embodiments, sock  205  has an inner diameter greater than or equal to that of endoprosthesis  201  and greater than or equal to that of introducer sheath  204 . 
         [0024]    In various embodiments, sock  205  protects endoprosthesis  201  as the device is delivered to the treatment region. For example, sock  205  may prevent endoprosthesis  201  from becoming contaminated as the catheter  200  is navigated to the treatment region. In various embodiments, sock  205  covers both endoprosthesis  201  and a deployment sheath (not shown). In these configurations, the deployment sheath surrounds endoprosthesis  201  and retains it in a collapsed and/or compressed configuration. In embodiments which do not utilize a deployment sheath, sock  205  may provide both protection against contamination and retention of endoprosthesis  201  in a collapsed and/or compressed configuration. 
         [0025]    Sock  205  may comprise, for example, a biologically compatible material, such as a polymer. In an aspect of these embodiments, sock  205  comprises ePTFE. However, any material which allows sock  205  and endoprosthesis  201  to traverse a vasculature without causing adverse biological impact is within the scope of the present disclosure, such as, for example, nylons, polycarbonates, polyethylenes, polypropylenes, polytetrafluoroethylenes, polyvinyl chlorides, polyurethanes, polysiloxanes, and other biocompatible materials. 
         [0026]    In various embodiments, the inner diameter of introducer sheath  204  is less than or equal to the outer diameter of endoprosthesis  201  in a collapsed and/or compressed state. In an aspect of these embodiments, the outer diameter of introducer sheath  204  is less than or equal to the outer diameter of endoprosthesis  201 . 
         [0027]    In various embodiments, catheter shaft  202  of catheter  200  comprises a guidewire. However, any flexible shaft which provides support for catheter  200  is within the scope of the present disclosure. The term “flexible shaft” includes any longitudinally extending structure with or without a lumen therethrough. Thus, flexible shafts include but are not limited to tubes with lumens, solid rods, hollow or solid wires (e.g., guidewires), hollow or solid stylets, metal tubes (e.g., hypotubes), polymer tubes, pull cords or tethers, fibers, filaments, electrical conductors, radiopaque elements, radioactive elements and radiographic elements. Flexible shafts can be of any material and can have any cross-sectional shape including but not limited to profiles that are circular, oval, triangular, square, polygon shaped or randomly shaped. 
         [0028]    Because introducer sheath  204  provides the medical device being delivered access to the vasculature, it is important that introducer sheath  204  comprise a material that is biologically compatible material. In various embodiments, introducer sheath  204  comprises a polymer, such as, for example, Pebax. However, any material which allows introducer sheath to traverse a vasculature without causing adverse biological impact is within the scope of the present disclosure, such as, for example, ePTFE, nylons, polycarbonates, polyethylenes, polypropylenes, polytetrafluoroethylenes, polyvinyl chlorides, polyurethanes, polysiloxanes, and other biocompatible materials. 
         [0029]    With reference to  FIGS. 3A and 3B , catheter  200  is the endoprosthesis delivery system of  FIGS. 2A and 2B . In various embodiments, catheter  200  further comprises a leading tip  203 . Leading tip  203  may be connected to the leading end of catheter shaft  202 . In various embodiments, leading tip  203  comprises a tip capable of piercing a thrombus. In various embodiments, leading tip  203  may comprise a material that is radiopaque and/or comprises a marker. Leading tip  203  can comprise, for example, a biologically compatible material, such as a polymer. However, any material which allows leading tip to navigate a vasculature without causing adverse biological impact is within the scope of the present disclosure. 
         [0030]    In various embodiments, endoprosthesis  201  is positioned between the leading end of introducer sheath  204  and leading tip  203 . This configuration allows leading tip  203  to remove or traverse potential blockages or thrombus in the vasculature and provides access to the treatment area by endoprosthesis  201 . 
         [0031]    With initial reference to  FIG. 3C , catheter  200  comprises a leading tip  203 . In various embodiments, leading tip  203  comprises a cavity. In an aspect of these embodiments, the leading end of sock  205  enters and is retained within a conically-shaped cavity of leading tip  203 . 
         [0032]    Catheter  200  further comprises a sock retaining segment  207 . In various embodiments, sock retaining segment  207  is positioned between endoprosthesis  201  and leading tip  203 . Sock retaining segment  207  can, for example, include a cavity into which the leading end of sock  205  enters. In these embodiments, sock retaining segment  207  may retain the position of sock  205  by preventing sock  205  from changing position as catheter  200  traverses the vasculature. 
         [0033]    In various embodiments, sock  205  extends from the leading end of the introducer sheath  204 , over endoprosthesis  201 , over sock retaining segment  207 , and finally enters the cavity of sock retaining segment  207  and/or leading tip  203 . Leading tip  203  can, for example, include an indented lip, which allows sock retaining segment  207  to interface with leading tip  203  and creates a smooth transition between the end of the sock  205  and the surface of leading tip  203 . 
         [0034]    With reference to  FIG. 4 , catheter  400  is an endoprosthesis delivery system. Various embodiments of catheter  400  comprise a sock  405  and sock securing element  406 . Sock securing element  406  can comprise, for example, a suture which reduces the diameter of sock  405  at or near its leading end over the reduced diameter, or within the cavity, of sock retaining segment  207 . This prevents sock  405  from moving from the desired position as the device is inserted into the patient and navigated through the vasculature. 
         [0035]    In various embodiments, catheter  400  further comprises a pull string  410 . Pull string  410  may be attached to sock securing element  406 . In various embodiments, pull string  410  may be actuated by, for example, providing tension to pull string  410 . In these embodiments, when pull string  410  is actuated, sock securing element  406  releases from sock  405 . In an aspect of these embodiments, sock securing element  406  can comprise a suture that releases and restores sock  405  to its initial inner diameter. This allows sock  405  to be removed from catheter  400 . 
         [0036]    In various embodiments, catheter  400  further comprises a sock removal mechanism  409 . In these embodiments, sock removal mechanism  409  may be connected to sock  405 . When sock removal mechanism  409  is actuated, sock  405  is removed from catheter  400 . Sock  405  can extend from the inside of an introducer sheath (not shown) to cover an endoprosthesis (not shown). As sock  405  is removed, the endoprosthesis becomes exposed and may be deployed in the treatment area. 
         [0037]    In various embodiments, sock removal mechanism  409  is connected to both sock  405  and pull string  410 . In these embodiments, pull string  410  further comprises a section of additional length, such that pull string  410  is not in tension. Sock  405  also further comprises a section of additional length. The section of additional length of pull string  410 , can, for example, be shorter than the section of additional length of sock  405 . In these configurations, when tension is applied to sock removal mechanism  409 , pull string  410  becomes taught before sock  405 . This allows for pull string  410  to release sock securing element  406 , which expands the diameter of sock  405 , and allows sock  405  to then be removed from the body. 
         [0038]    In an embodiment, the endoprosthesis is a self-expanding stent or stent graft, and actuation of sock removal mechanism  409  allows the endoprosthesis to expand and deploy to the treatment area. In other embodiments, the actuation of sock removal mechanism  409  allows for final placement of the endoprosthesis in the vasculature, and other means may be used, such as, for example, an expanding balloon, to deploy the endoprosthesis. 
         [0039]    With reference now to  FIGS. 5 and 6 , catheter  500  is an endoprosthesis delivery device. Catheter  500  comprises a handle  512 , through which catheter shaft  502  is controlled. Catheter shaft  502  passes through a valve  511  and into introducer sheath  504 . Sock  505  passes through introducer sheath  504  and surrounds catheter shaft  502 . Sock  505  exits the introducer sheath  504  at its leading end. 
         [0040]    Endoprosthesis  501  is positioned on catheter shaft  502  at the leading end of the introducer sheath  504  prior to insertion of catheter  500  into the body. Though not shown in the drawing, sock  505 , after exiting introducer sheath  504 , surrounds endoprosthesis  501 . A sock retaining segment  507  is positioned adjacent to endoprosthesis  501 . At the leading end of catheter shaft  502 , and adjacent to sock retaining segment  507 , is a leading tip  503 . A sock removal mechanism  509  is connected to sock  505  and situated on handle  512 . 
         [0041]    With initial reference to  FIG. 6 , a cross sectional view of catheter  500  is presented. Catheter  500  comprises a slitting blade  513 . In various embodiments, when sock removal mechanism  509  is actuated, slitting blade  513  cuts sock  505 , which allows it to be removed from catheter shaft  502 . In other embodiments, sock  205  can be configured so that it can be removed without the use of slitting blade  513 , such as, for example, by using a perforated film, a longitudinally-oriented film, and/or a film of varying thickness, such that sock  205  can be relatively easily torn or deconstructed at a particular location. However, any means of facilitating the removal of sock  505  from catheter shaft  502  is within the scope of the present disclosure. 
         [0042]    Thus, the endoprosthesis delivery system of the present disclosure provides an effective, low crossing system capable of delivering endoprostheses to a vasculature. 
         [0043]    It will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the spirit or scope of the disclosure. Thus, it is intended that the present disclosure cover the modifications and variations of this disclosure provided they come within the scope of the appended claims and their equivalents. 
         [0044]    Likewise, numerous characteristics and advantages have been set forth in the preceding description, including various alternatives together with details of the structure and function of the devices and/or methods. The disclosure is intended as illustrative only and as such is not intended to be exhaustive. It will be evident to those skilled in the art that various modifications can be made, especially in matters of structure, materials, elements, components, shape, size and arrangement of parts including combinations within the principles of the disclosure, to the full extent indicated by the broad, general meaning of the terms in which the appended claims are expressed. To the extent that these various modifications do not depart from the spirit and scope of the appended claims, they are intended to be encompassed therein.