Patent Publication Number: US-2015088072-A1

Title: Introducer sheath and methods of making

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. patent application Ser. No. 13/752,137, filed Jan. 28, 2013, which is a divisional of U.S. patent application Ser. No. 12/695,961, filed on Jan. 28, 2010, now U.S. Pat. No. 8,359,723, which is a continuation-in-part of U.S. patent application Ser. No. 11/427,306, filed Jun. 28, 2006, now abandoned, which claims the benefit of U.S. Provisional Patent Application Ser. No. 60/695,602, filed Jun. 30, 2005. This application is a continuation-in-part of U.S. patent application Ser. No. 12/695,975, filed Jan. 28, 2010, which is a continuation-in-part of U.S. patent application Ser. No. 11/427,306, filed Jun. 28, 2006, now abandoned, which claims the benefit of U.S. Provisional Patent Application Ser. No. 60/695,602, filed Jun. 30, 2005. This application is a continuation-in-part of U.S. patent application Ser. No. 13/892,106, filed May 10, 2013, which is a divisional of U.S. patent application Ser. No. 12/695,969, filed Jan. 28, 2010, now U.S. Pat. No. 8,440,122, which is a continuation-in-part of U.S. patent application Ser. No. 11/427,306, filed Jun. 28, 2006, now abandoned, which claims the benefit of U.S. Provisional Patent Application Ser. No. 60/695,602, filed Jun. 30, 2005. The entireties of which are each hereby incorporated by reference. This application relates to U.S. patent application Ser. No. 11/427,301, entitled “Modular Introducer and Exchange Sheath”, and filed Jun. 28, 2006, which claims the benefit of U.S. Provisional Patent Application Ser. No. 60/695,464, entitled “Modular Introducer Sheath”, and filed Jun. 30, 2005 and U.S. patent application Ser. No. 11/767,947, filed Jun. 25, 2007, and entitled “Expandable Introducer Sheath to Preserve Guidewire Access”, which is a continuation in part of U.S. patent application Ser. No. 11/427,308, filed Jun. 28, 2006, and entitled “Expandable Introducer Sheath.” The entireties of which are each hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. The Field of the Invention 
     The present invention relates generally to medical devices and methods. More specifically, embodiments of the invention relate to introducer sheaths and methods of making. 
     2. The Relevant Technology 
     A wide variety of sheaths have been developed for use in medical procedures. Sheaths are often used, for example, to access a vessel or artery to allow a surgical procedure to be performed. Sheaths are also used for medical procedures that utilize catheters such as, angioplasty or stenting. In practice, the introducer sheath is generally inserted into the patient&#39;s vasculature using the modified Seldinger technique. In the Seldinger technique, a needle is first inserted into the vessel and a guidewire then follows through the needle. Next, the needle is removed and a sheath/dilator combination is advanced over the guidewire. The dilator expands the puncture in the vessel to a size suitable to receive the distal end of an introducer sheath. After the distal end of the sheath is disposed within the vessel, the dilator and guidewire are removed, thereby allowing access to the vessel lumen or other body lumen via the inserted introducer sheath. 
     Conventionally, introducer sheaths are formed of three or more components that require assembly: a sheath portion, a hub, and a hemostasis valve disposed within the hub. A suitable example of such an assembly is shown in U.S. Pat. No. 5,807,350, which shows an introducer sheath having a construction similar to that described above, the entirety of which is hereby incorporated by reference. 
     Sheaths such as that described above are generally constructed of multiple pieces that must be assembled to form the sheath. Because the sheath is assembled from separate components, it is often difficult to align the lumen of the distal sheath portion with the lumen of the hub. As a result, additional time must be taken during manufacture to ensure alignment thereby leading to increased costs. 
     In some instances, the hub at the proximal end of the introducer sheath may be overmolded over the elongated sheath portion. While overmolding may produce a stronger sheath, there is the possibility of damaging a portion of the introducer sheath during the overmolding process. In addition to the cost of the overmolding process, the entire introducer sheath would then have to be discarded. There is a therefore a need for a new introducer sheath having lower manufacturing costs. 
     BRIEF SUMMARY OF THE INVENTION 
     These and other limitations may be overcome by embodiments of the present invention, which relates generally to medical devices and methods of use and in particular to introducer sheaths. Embodiments of the invention may provide several designs and methods of manufacture of an improved introducer sheath. 
     An embodiment of an introducer sheath is described. The introducer sheath includes an elongate tubular portion having a longitudinal axis. The elongate tubular portion is elastically deformable about the longitudinal axis. The introducer sheath includes a hub portion having proximal end and a distal end. The proximal end is substantially wider than the distal end and the distal end secured to the elongate tubular portion. The introducer sheath includes a valved cover elastically secured over the proximal end of the hub portion. The valved cover defines a non-planar outer surface in a relaxed state. The outer surface defines an aperture configured to receive a medical device. 
     In some embodiments, the hub portion and the elongate tubular portion are formed as a unitary member. The outer surface, in further embodiments, is substantially concave in the relaxed state. In still further embodiments, the aperture includes a sealing surface. The sealing surface, in yet further embodiments, is not generally parallel about a longitudinal axis through the aperture in the relaxed state. 
     In some embodiments, the sealing surface is configured to form a seal between the medical device and the hub in a deformed state. The aperture, in further embodiments, is tapered. In still further embodiments, the aperture has a diameter that increases with distance from the outer surface. 
     An embodiment of a method for making an introducer sheath assembly is described. The method includes forming a cap having a top portion and a sidewall portion defining a cavity. The top portion includes a valve secured thereto. A proximal end of a hub portion is inserted into the cavity. The hub portion includes an elongate tubular portion secured to a distal end thereof. 
     In some embodiments, inserting the proximal end of a hub portion into the cavity comprises elastically deforming the cap. Forming the cap, in further embodiments, includes forming the top portion and sidewall portion and removing a portion of the top portion to form the valve. 
     An upper surface of the top portion, in some embodiments, has a concave shape. In further embodiments, removing a portion of the top portion to form the valve includes elastically deforming the top portion to decrease a concavity thereof and removing a portion of the elastically deformed top portion to form the valve. 
     In some embodiments, the valve includes an aperture having a tapered shape when the top portion is in an undeformed state. The aperture, in further embodiments, narrows with distance from the hub portion. 
     The sidewall portion, in some embodiments, extends from a lower surface of the top portion. Elastically deforming the top portion to decrease a concavity thereof, in further embodiments, includes positioning an urging member within the cavity. In still further embodiments, the urging member comprises a planar upper surface engaging a lower surface of the top portion when the urging member is positioned within the cavity. 
     In some embodiments, one of an outer surface of the hub portion and an inner surface of the sidewall portion defines a circumferential groove and the other of the outer surface of the hub portion and the inner surface of the sidewall portion includes a circumferential lip. The circumferential groove, in further embodiments, is positioned to receive the circumferential lip when the hub portion is positioned within the cavity. In still further embodiments, the inner surface of the sidewall portion is cylindrical. 
     An embodiment of an assembly is described. The assembly includes an elongate tubular portion having a longitudinal axis. The elongate tubular portion is elastically deformable about the longitudinal axis. The assembly includes a hub portion having proximal end and a distal end. The proximal end is substantially wider than the distal end and the distal end is secured to the elongate tubular portion. The hub portion and elongate tubular portion define a lumen. The assembly includes a cap having a top portion and a sidewall portion defining a cavity sized to elastically receive a portion of the hub portion. The cap defines a valve in fluid communication with the lumen and is configured to receive a medical device. 
     In some embodiments, one of an outer surface of the hub portion and an inner surface of the sidewall portion defines a circumferential groove and the other of the outer surface of the hub portion and the inner surface of the sidewall portion comprises a circumferential lip. The circumferential groove, in further embodiments, is positioned to receive the circumferential lip when the hub portion is positioned within the cavity. An upper surface of the top portion, in still further embodiments, has a concave shape and the sidewall portion extends from a lower surface of the top portion. 
     In some embodiments, the elongate tubular portion may include a lumen that extends from a distal end toward a proximal end of the elongate tubular portion. The lumen may include a plurality of protrusions and/or a plurality of depressions. 
     In some embodiments, the elongate tubular portion may define a plurality of lumens. Each of the plurality of lumens, in further embodiments, may include a plurality of protrusions and/or a plurality of depressions within each lumen. In still further embodiments, the plurality of protrusions may define a first inner dimension within each lumen and/or the plurality of depressions may define a second inner dimension within each lumen. The first inner dimension may be smaller than the second inner dimension in each lumen. 
     The protrusions and/or depressions, in some embodiments, may extend from a proximal end to a distal end. In further embodiments, the protrusions and/or depressions may vary in angular orientation with respect to the longitudinal axis between a proximal end and a distal end. 
     In some embodiments, the plurality of protrusions and the plurality of depressions may extend longitudinally through the lumen. The tubular portion, in further embodiments, may include at least one weakened region and/or at least one stiffened region. 
     The protrusions and/or the depressions, in some embodiments, may define a friction reducing surface configured to contact an outer surface of a medical device. 
     A further embodiment of an introducer sheath is described. The introducer sheath may include a hub portion and/or an elongate tubular portion. The elongate tubular portion may extend from the hub portion. The elongate tubular portion may have a first lumen and/or a second lumen. The first lumen may include a plurality of first protrusions and/or a plurality of first depressions. The second lumen may include a plurality of second protrusions and/or a plurality of second depressions. 
     In some embodiments, the plurality of first protrusions and/or the plurality of first depressions may differ from the plurality of second protrusions and/or the plurality of second depressions. The plurality of protrusions and/or the plurality of depressions of the first inner surface, in further embodiments, are parallel from the proximal end toward the distal end. 
     A still further embodiment of an introducer sheath is described. The introducer sheath may include a hub portion and/or an elongate tubular portion. The elongate tubular portion may extend from the hub portion. The elongate tubular portion may have a lumen. The lumen including a plurality of protrusions and/or a plurality of depressions. The plurality of protrusions may define a first inner dimension. The plurality of depressions may define a second inner dimension. The first inner dimension may be smaller than the second inner dimension. 
     In some embodiments, the first inner dimension may be about fifty percent smaller than the second inner dimension. The first inner dimension may be from about thirty percent to about sixty percent smaller than the second inner dimension. The first inner dimension may be from about twenty percent to about seventy percent smaller than the second inner dimension. 
     A yet further embodiment of an introducer sheath is described. The introducer sheath may include a hub portion and/or an elongate tubular portion. The elongate tubular portion may extend from the hub portion. The elongate tubular portion may have a lumen. The lumen may include a plurality of protrusions and/or a plurality of depressions. The plurality of protrusions may define a first wall thickness. The plurality of depressions may define a second wall thickness. The first wall thickness may be larger than the second wall thickness. 
     In some embodiments, the first wall thickness is about fifty percent larger than the second wall thickness. The first wall thickness may be from about thirty percent to about sixty percent smaller than the second wall thickness. The first wall thickness may be from about twenty percent to about seventy percent smaller than the second wall thickness. In some embodiments, the tubular portion may include PTFE or FEP. 
     An embodiment of a method for performing a medical procedure is described. The method may include introducing a sheath into a lumen of a patient. The sheath may have a first unexpanded dimension and/or an irregular wall surface. A first medical device may be inserted into the lumen through the sheath to perform a medical procedure. The first medical device may have an outer dimension. At least a portion of a tubular member of the sheath may expand to a second expanded dimension to accommodate the outer dimension of the first medical device. 
     In some embodiments, a second medical device may be inserted through the sheath. Inserting a second medical device through the sheath may include introducing a vessel closure device through the sheath and/or closing the lumen of the patient with the vessel closure device. The sheath, in further embodiments, may include a tubular portion extending from the hub portion. The tubular portion may include at least one portion deformable to increase a cross sectional area of the tubular portion. In still further embodiments, the at least one portion may be splittable to increase a cross sectional area of the tubular portion. 
     The sheaths disclosed herein can be used with various medical devices. In one configuration, the sheath can be used in combination with a vessel closure device, such as those shown in U.S. Pat. No. 6,197,042 and pending U.S. patent application Ser. No. 10/638,115 filed Aug. 8, 2003 entitled “Clip Applier and Methods,” each of these assigned to a common owner and herein incorporated in their entireties by reference. 
     Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the invention. The features and advantages of the invention may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order that the manner in which the above-recited and other advantages and features of the invention are obtained, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
         FIG. 1A  is a plan view of an exemplary embodiment of an introducer sheath in accordance with the present invention; 
         FIG. 1B  illustrates a cross-sectional view of the sheath in  FIG. 1A  and illustrates a valve disposed in the sheath&#39;s hub and an alignment member; 
         FIG. 1C  is a cross-sectional view taken along line  1 C- 1 C of the sheath of  FIG. 1A  in accordance with the present invention; 
         FIG. 2A  illustrates a cross-sectional view of another sheath in accordance with the present invention; 
         FIG. 2B  is cross-sectional view of an alternative embodiment of the sheath of  FIG. 2A  illustrating the geometric features formed within wall of the sheath in accordance with the present invention; 
         FIG. 2C  is a cross-section view of a portion of an another alternative embodiment of the sheath of  FIG. 2A  in accordance with the present invention; 
         FIG. 3A  is a plan view of an alternative embodiment of a sheath in accordance with the present invention; 
         FIG. 3B  is a cross-sectional view of the sheath of  FIG. 3A  taken along line  3 A- 3 A in accordance with the present invention; 
         FIG. 3C  illustrates a cross-sectional view of an alternative embodiment of a sheath in accordance with the present invention; 
         FIGS. 4A-4E  illustrate cross-sectional views of an embodiment of a sheath in various stages of manufacture in accordance with the present invention; 
       FIGS.  4 C′ and  4 D′ illustrate cross-sectional views of the embodiment of a sheath shown in  FIGS. 4A-4E  in various stages of manufacture using an alternative embodiment of a forming device in accordance with the present invention; 
         FIGS. 5A-5C  illustrate cross-sectional views of another embodiment of a sheath in various stages of manufacture in accordance with the present invention; 
       FIG.  5 B′ illustrates a cross-sectional view of the embodiment of a sheath shown in  FIGS. 5A-5C  in various stages of manufacture using an alternative embodiment of a forming device in accordance with the present invention; 
         FIGS. 6A-6C  illustrate cross-sectional views of a further embodiment of a sheath in various stages of manufacture in accordance with the present invention; 
         FIGS. 7A-7C  illustrate a valved cover suitable for use with a sheath in accordance with an embodiment of the present invention; 
         FIGS. 8A through 8E  illustrate a method for manufacturing a valved cover in accordance with an embodiment of the present invention; 
         FIGS. 9A through 9C  illustrate an alternative method for manufacturing a valved cover in accordance with an embodiment of the present invention; 
         FIGS. 10A through 10C  illustrate another alternative method for manufacturing a valved cover in accordance with an embodiment of the present invention; and 
         FIGS. 11A and 11B  illustrate a method for using a valved cover in accordance with an embodiment of the present invention. 
         FIGS. 12A-16B  illustrate cross-sectional views of various embodiments of a sheath in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Due to the general nature of an elongate tubular member, the longer the member, the more column strength and/or other factors may be considered. Buckling and/or kinking during a procedure using an introducer sheath may hinder the procedure. The types of materials in some embodiments of introducer sheaths may also affect the column strength and/or kink resistance of the sheath. For example, kink occasions have been observed in some instances where a polytetrafluoroethylene (“PTFE”) introducer sheath is used for a prolonged procedure. 
     An irregular wall design may provide at least one of the following features. For example, an irregular wall design may provide increased column strength and/or kink resistance while maintaining an outer diameter sufficient to perform various medical procedures. In another example, an irregular wall design may minimize friction between the inner surface and/or outer surface of the introducer sheath and a medical device to be inserted into the introducer sheath and/or tissue near an insertion site, respectively. 
     An irregular wall design may include variations in wall thickness about a circumference (i.e. perimeter) of at least a portion of the introducer sheath. For instance, a plurality of protrusions and/or depressions about a portion of an inner surface and/or outer surface of an introducer sheath may be provided. For example, a typical introducer sheath may have a generally uniform inner diameter and/or outer diameter. While an introducer sheath with an irregular wall design may have at least some portions of the inner surface and/or outer surface that may be nonuniform. 
     An introducer sheath in accordance with the present invention is described herein as having portions or members, though it shall be understood that the introducer sheath as described herein may be formed as a unitary member such that the portions or members are portions or members of a unitary device. Embodiments of the introducer sheath are depicted in the drawings, which are not necessarily to scale and are not intended to limit the scope of the invention. It will be understood that the benefits of the present invention are not limited to application with an introducer sheath. Rather, other medical devices may be modified based upon the teaching contained herein such that they to can provide the identified functionality. 
     The introducer sheath may be formed, by way of example, using a co-extrusion process or an injection molding process or other method that results in a sheath formed as a unitary member. The process by which an introducer sheath is formed may include the use of one or more materials. The materials can be used simultaneously, or at different stages of the manufacturing process. 
     Typically, the materials used to form the introducer sheath are medical grade synthetics or plastics. Exemplary materials may include, but are not limited to, flexible PVC, polyurethane, silicone, liner low-density polyethylene (“LLDPE”), polyethylene, high density polyethylene, (“DHPE”), polyethylene-lined ethylvinyl acetate (“PE-EVA”), polypropylene, latex, thermoplastic rubber, and the like. In some embodiments, the materials are configured to have chemical resistance, crack resistance, no toxicity, Food and Drug Administration (“FDA”) compliance, non-electrically conductive, dimensional stability, and/or be sterilized by ethylene oxide, gamma radiation, autoclave, UV light, ozone, and the like. 
     In addition, the selection of materials for a particular sheath can depend on a variety of factors that include, but are not limited to, a particular stiffness and/or flexibility of the sheath or any portion of the sheath, including the desired column stiffness and strength to enable insertion of the sheath, a particular shear or split strength for the sheath or any portion of the sheath, the ability to resist kinking, and the like. For example, the material used for the tubular portion of the introducer sheath may be selected based on shear strength or how easily it can be split. Further, certain features of the sheath may be formed to enhance certain characteristics. For example, a strain relief portion may be formed to resist kinking while the elongated tubular portion may be formed to facilitate splitting. 
     When more than one material is used to form the sheath or to form specific portions of the introducer sheath, the materials may be selected, in addition to the factors identified herein, on a bond strength between the materials or on the elasticity of a particular material. The bond strength, for example, may have an impact on the splitability of the sheath or of a portion of the sheath. The bond strength may also affect the ability of the sheath to expand without splitting. 
     As described above, the materials of a sheath may be selected based on a splitting or shear property of the materials. One reason for this characteristic or property relates to use of the sheath in medical procedures. For example, when the sheath is used in conjunction with a medical device during a medical procedure, it may be desirable for the introducer sheath to split or shear during insertion or retrieval of the medical device. This may occur, for example, when a vessel is closed with a vessel closure device. The vessel closure device can be used to attach a clip that effectively seals or closes the entry to the body lumen. As the entry or access to the body lumen is closed, the vessel closure device can apply a force that causes the sheath to split. Embodiments of the invention thus contemplate embodiments of the sheath or of portions of the introducer sheath that facilitate splitting at the appropriate time. Further, embodiments of the sheath contemplate structural features that relate to the ease with which a sheath splits without otherwise impacting the use of the sheath. 
     In accordance with one embodiment of the present invention, an introducer sheath may include a hub member or hub portion having a proximal end and a distal end. The proximal end of the hub portion can be configured to receive a flexible valve member therein. The sheath further includes an elongated tubular portion generally extending from the distal portion of the hub member. The elongated tubular portion is generally centered with an axis of the hub member and the lumen of the tubular portion is aligned with a lumen of the hub portion because the sheath is formed as a single integrated unit in some embodiments. Alternatively, the lumen of the tubular portion can be aligned with a lumen of the hub portion, whether or not axially aligned. The aligning of the lumens can occur during manufacture, such as when the hub portion and the sheath are formed as a single integrated unit. 
     Referring now to  FIG. 1A , there is shown an exemplary embodiment of an introducer sheath  10 . The introducer sheath  10  can include a hub portion  20  having a proximal end  22  and a distal end  24 , and a tubular portion  30  having a proximal end  32  and a distal end  34 . The cross section of the hub portion  20  can be generally cylindrical in nature, although other configurations are contemplated. Exemplary configurations or shapes may include, by way of example, oval, polygonal, elliptical, or other cross-section that can be usable for a medical device that is insertable into a body lumen.  FIGS. 12A-16B  provide examples of various cross-sectional portions. 
     The elongate tubular portion  30  extends from the distal end  24  of the hub portion  20 . Because the sheath  10  can be formed as a unitary member, the proximal end  32  of the tubular portion  30  can be integrally formed with the distal end  24  of the hub portion  20 . Because the sheath  10  can be formed as a unitary member, the hub portion  20  effectively transitions to the tubular portion  30 . Because the transition between the hub portion  20  and the tubular portion  30  may introduce a natural flex point, embodiments of the invention can optionally include a strain relief portion  48 , which smoothly transitions the tubular portion  30  of the sheath  10  to the hub portion  20 . The strain relief portion  48  can be formed at the transition between the hub portion  20  and the tubular portion  30 . More particularly, the strain relief portion  48  can be disposed adjacent the distal end portion of the hub portion  20  and adjacent the proximal end  32  of the elongate tubular portion  30 . 
     The strain relief portion  48  can also be configured to provide additional support to at least the proximal end  32  of the elongate tubular portion  30  to prevent kinking at the transition zone of the proximal end  32  of the elongated portion  30  and the distal end  24  of the hub portion  20 . In one embodiment, the strain relief portion  48  can be formed by gradually increasing a thickness of tubular portion  30  as the tubular portion  30  of the sheath  10  transitions to the hub portion  20  of the sheath. Alternatively, the strain relief portion  48  can be formed using other structures or formations that provide, for example, support or kink resistance to the transition from the tubular portion  30  to the hub portion  20 . For instance, the strain relief portion  48  can include webs, extensions, or other internal or external structures to increase the strength and/or stiffness of the introducer sheath  10  at the hub portion/tubular portion transition. 
     With continued reference to  FIG. 1A , the distal end  34  of the tubular portion  30  can also include a tapered portion  36  that facilitates entry of the introducer sheath  10 , for example, into patient&#39;s vasculature or other body lumen. The tapered portion  36  may be formed after the initial forming process of the introducer sheath  10  or be formed as part of the initial forming process. For example, the tapered portion  36  may be formed as part of the extrusion or injection molding processes. Alternatively, the tapered portion  36  may be formed by heat forming, grinding, milling, laser treatment, etching, or other known methods that result in a thinner wall thickness. 
       FIG. 1B  further illustrates a cross-sectional view of the sheath  10  along the line  1 B. As shown, a lumen  28  extends from a proximal end  22  of the hub portion  20  to the distal end  34  of the tubular portion  30 . The lumen  28  can be generally uniform in cross-section over all or a portion of its length from the proximal end  22  of the hub portion  20  to the distal end  34  of the tubular portion  30 . In the illustrated configuration, the lumen  28  has a generally uniform cross-section along its length along the tubular portion  30 , while having a generally uniform cross-section portion and a changing cross-section portion along the length of the hub portion  20 . It will be understood, however, that other cross-sectional configurations are possible so long as they can accommodate a medical device or instrument inserted therein. For example at least one of the cross-sections illustrated in  FIGS. 12A-16B  may be implemented. 
     With continued reference to  FIG. 1B , the proximal end  22  of the hub portion  20 , within the lumen  28  and defined by the inner wall or surface  52  forming the lumen  28 , can also include a feature, such as a receiving feature  26 , therein, which is configured to receive a flexible valve member  50 . The valve member  50  may be inserted after the sheath  10  is formed. For instance, the receiving feature  26 , such as a groove or channel, can receive the valve member  50  and retain the same within the hub portion  20 . Optionally, a retaining cap (not shown) disposed adjacent to or within the proximal end of the hub portion  20  can aid the receiving feature  26  to retain the flexible valve member  50  within the hub portion  20 . Alternatively, the valve member  50  can be integrally formed with the hub portion  20  during the molding process of the sheath  10  and as such the hub portion  20  need not include the receiving feature  26 . 
     The cooperation between the receiving feature  26 , optional the retaining cap, and/or the valve member  50  result in a sealed hub portion  20 . Stated another way, the valve member  50  is self sealing once it is inserted or formed in the hub portion  20  to prevent fluid escaping from the body lumen. 
     The valve member  50  can be one of a variety of different seals, including optionally being self-sealing once it is inserted into the hub portion  20 . The valve member  50 , for example, may have an elastomeric body, such as silicone rubber or other material as described above, with at least one slit and/or other collapsible opening formed therein to allow selective insertion and removal of medical instruments, such as guidewires, catheters, and other such devices. The collapsible openings or other portions of the valve member  50  maintain a fluid tight seal with or against the medical instrument. Thus, blood or other bodily fluids are prevented from leaking out, and unwanted air is prevented from entering into the body. Examples of such flexible membranes or valve members, which can be utilized with the present invention, are shown in U.S. Pat. Nos. 4,798,594, 5,176,652, and 5,453,095 the entireties of which are herein incorporated by reference. 
     With continued reference to  FIG. 1B , illustrated is an optional port member  42  that may be formed on the outer surface or outer wall  44  of the hub portion  20 . The port member  42  may function as a fluid port for the sheath  10 . Thus, any fluid, such as saline or blood or medication for example, can be added or withdrawn through the port member  42 . The port member  42  may also be optionally or alternatively configured to align or position any device or instrument (e.g., a vessel closure device, a catheter) used in conjunction with the sheath  10 . The port member  42  may be shaped to interact with an alignment mechanism on a medical device and optionally create a fluid sealed connection. One exemplary type of port member is a member having a luer lock configuration. It will be understood that other types of port can performed the desired function. 
     Also formed on the outer surface or wall  44  of the hub portion  20  can be a retention recess or ring  46 , as shown in  FIG. 1A . The recess or ring  46  may be used to secure a cap (not shown) to the sheath  10 . The recess or ring  46  can have various configurations to perform the identified and desired function. For instance, although the walls forming the recess or ring  46  are illustrated as being generally parallel, the recess or ring  46  can have tapered wall, curved wall, combinations of generally parallel, tapered, or curved wall, or generally any other configuration that would allow a cap to be secured thereto or for the recess. 
     It is contemplated that the wall thickness along the length of the elongate tubular portion  30  can be varied to vary mechanical properties of the sheath (e.g., kink resistance, stiffness, flexibility and the like). Further, the thickness of the strain relief  40  (which can vary across the transition between the tubular portion  30  and the hub portion  20 ), the thickness of the hub portion  20 , the diameter of the lumen of the tubular portion  30  and of the lumen of the hub portion  20  can also be varied or specifically selected. 
     These dimensions of the sheath  10  are often controlled and determined during the manufacturing process. In an injection molding process, for example, the sheath  10  may be formed using a mold. The mold can be machined or configured based on the desired dimensions and configurations of the sheath  10  as described herein. After the mold (which may include more than one part) is formed, the injection molding process can begin by melting a suitable material, such as one described above, and then injecting the melted material into the mold, often under pressure. The mold used in the injection molding process is typically formed such that the molded introducer sheath can be removed after it has cooled and such that the resulting introducer sheath has the desired dimensions and characteristics described herein. As a result, the molded sheath  10  can be a unitary member and may not be assembled from separately formed parts. 
     Benefits of forming the introducer sheath  10  as a unitary member may include reduced costs, more accurate parts (i.e. dimension control) due to lack of assembly, as well as the ability to balance mechanical properties across the entire sheath  10 . For example, the thickness of the walls of the hub portion, the tubular portion, the strain relief, the tapered portion, and/or other portions can be controlled and varied as desired. 
     Referring now to  FIG. 1C , there is shown a cross-sectional view of the sheath  10  in accordance with the present invention along the line  1 C- 1 C of  FIG. 1A . In particular,  FIG. 2  illustrates a cross-sectional view of the elongate tubular portion  30  of the sheath  10 . The elongate tubular portion  30  can include an outer wall  60  and an inner wall  62  thereby defining a wall thickness. Additionally, the lumen  28  may extend along the length of the tubular portion  30 . The width or diameter of the lumen  28  can vary and may depend on the intended use of the sheath  10 . Because the hub portion  20  and the tubular portion  30  are integrally formed, the lumen  28  may be axially aligned along its length. Stated another way, the axis of the portion of the lumen  28  within the tubular portion  30  can be aligned with the axis of the portion of the lumen  28  within the hub portion  20 . 
     Generally, the outer wall, whether defined by the outer wall  60  of the tubular portion  30  or the outer wall  44  of the hub portion  20 , defines the outer surface or wall of the sheath  10 . Similarly, the inner wall, whether defined by the inner wall  62  of the tubular portion  30  or the inner wall  52  of the hub portion  20 , defines the inner surface or wall and lumen  28  of the sheath  10 . 
     As mentioned above, although the cross-sectional view of the tubular portion  30  is cylindrical in nature, other cross-sectional shapes (polygonal, oval, elliptical, rectangular, etc.) are within the scope of the invention. Further, the lumen  28  may also have an alternative cross-sectional shape other than circular. In one example, the cross-sectional shape of the tubular portion  30  and/or the lumen  28  can be determined by the mold used in an injection molding process. Further, the cross-sectional configuration of the lumen  28  need not be the same as that of the cross-section configuration of the tubular portion  30  as defined by the outer wall of the tubular portion  30 , and more generally the sheath  10 . 
     Referring now to  FIG. 2A  there is shown an exemplary embodiment of an alternative introducer sheath in accordance with the present invention. Much of the description related to the sheath  10  may also apply to the present embodiment of the sheath  110 , and vice versa. The alternative embodiment of the sheath will herein be described as having portions similar to that as described above. 
     As shown in  FIG. 2A , the sheath  110  can include a hub portion  120  having a proximal end  122  and a distal end  124 , and a tubular portion  130  having a proximal end  132  and a distal end  134 . Extending from the proximal end  122  to the distal end  134  is a lumen  128 . Generally, the configuration of the lumen  128  and the inner wall or surface forming the lumen  128  may be different from that described with respect to lumen  28  ( FIG. 1B ). A portion of the lumen  128  in the hub portion  120 , or the inner wall or surface  152  can have a stepped configuration. The stepped configuration can include a first portion  154  having a first inner diameter and a second portion  156  having a second diameter larger than the first diameter. This stepped configuration, or the transition between the first portion  154  and the second portion  156  provides or functions as a stop for an inserted valve member  150 . 
     The valve member  150  can be secure within the lumen  128  through a friction or interference fit with the inner surface or wall  152  of the hub portion  120 . Alternatively, or in addition to the friction or interference fit, the valve member  150  can be mounted within the lumen  128  through adhesives, thermal or chemical bond, mechanical coupling, such as, but not limited to, the use of a groove or recess in the inner surface or wall  152 , or other technique used to mount two components together. In one configuration, a retaining cap  170 , having a lumen  172  that can receive a medical device or instrument to be inserted through the valve member  150  and the lumen  128 , can secure the valve member  150 . The proximal end  174  of the retaining cap  170  can align with, overlap, or be recessed relative to the proximal end  122  depending upon the particular configuration of the end cap  170 . 
     Also formed on the outer surface or wall  152  of the hub portion  120  can be a retention recess or ring  127 , as shown in  FIG. 2A . The recess or ring  127  may be used to secure a cap (not shown) to the sheath  10 . The recess or ring  127  can have various configurations to perform the identified and desired function. For instance, although the walls forming the recess or ring  46  are illustrated as being generally parallel, the recess or ring  46  can have tapered wall, curved wall, combinations of generally parallel, tapered, or curved wall, or generally any other configuration that would allow a cap to be secured thereto or for the recess. 
     With reference to  FIGS. 2A and 2B , the elongated tubular portion  130  includes an outer surface or wall  160  and an inner surface or wall  162 . Formed in the inner wall  162  is at least one longitudinal groove  164 , and more generally a geometric pattern of grooves, channels, recesses, or other structures, that can extend along an axis parallel to axis extending through the center of the sheath, and centered within the lumen  128 . With one or more longitudinal grooves  164 , the longitudinal grooves  164  can be formed in various patterns and orientations to provide different characteristics to the tubular portion  130 . It is contemplated that additional styles and types of patterns may be utilized in accordance with the present invention. For example, one or more longitudinal grooves  164  may form a sinusoidal pattern disposed about the inner radius of the elongate tubular portion  130 . Alternatively, the one or more longitudinal grooves  164  may be configured to run along a different axis than one parallel to an axis extending along the center of the sheath  10 . For example, the one or more longitudinal grooves  164  may be formed as one or more spirals as illustrated in  FIG. 2C . The one or more longitudinal grooves  164  may also only extend partially along the length of the elongated portion  130 . In another embodiment, the one or more longitudinal grooves  164  may extend beyond the tubular portion  130  and into the hub portion  120  ( FIG. 1A ). In another example, the one or more longitudinal grooves  164  may not extend into the tapered portion of the tubular portion  130 . 
     Generally, it should be understood that the above described configuration of the at least one groove  164  should be considered exemplary and not limiting in any manner. It is contemplated that additional styles and types of patterns may be utilized in accordance with the present invention. For instance, one configuration of the longitudinal grooves  164  can provide increased column stiffness, while another configuration can provide kink resistance and/or resistance to torsional loads. Further, it should be understood that the inner wall  162  could have patterns or configurations of structures other than grooves to achieve desired configurations. For instance, and not by way of limitation, other dents, extensions, channels, recesses, or other structural formations can be created upon or in the inner wall  162 . 
     The formation of the geometric pattern of the plurality of grooves  164 , for example, can be formed by machining a corresponding feature in the mold and subsequently using the mold during compression molding, injection molding, blow molding, rotational molding, and/or molding or fabrication processes. As a result, the geometric pattern can be automatically formed during the manufacturing process and no additional steps or acts are required to form the geometric pattern on the inner wall  162 . 
     Referring now to  FIG. 3A  there is shown an exemplary embodiment of an alternative introducer sheath in accordance with the present invention. Much of the description related to sheath  10  and sheath  110  may also apply to the embodiment of the sheath  210 , and vice versa. The alternative embodiment of the sheath will herein be described as having portions similar to that as described above. 
     As shown in  FIG. 3A , the sheath  210  includes a hub portion  220  having a proximal end  222  and a distal end  224 . The sheath  210  further includes a composite elongate tubular portion  230  extending from the distal end  224  of the hub portion  220 . In this example, the elongated portion  230  may be generally tubular in construction and may include a proximal end  232  and a distal end  234 . As described above, the cross-sectional shape of both the elongated portion  230  and the hub portion  220  can be any shape, such as by way of example, circular, elliptical, square, polygonal, and the like. In this example, however, the tubular portion may be composite and can be formed from more than one material. 
     The sheath  210  may additionally include a feature formed within the hub portion  220  that may be configured to receive a flexible valve member (such as the valve member  50  in  FIG. 1B  or valve member  150  in  FIG. 2A ). The flexible valve member may be integrally formed into the hub portion during the molding process of the sheath  210  or may be held within the hub portion  220  using the techniques or methods described herein. Alternatively, the hub portion  220  of the sheath  210  can be molded to provide the elements needed to hold the valve member in place after insertion. The receiving feature  26  ( FIG. 1B ) or the stepped configuration illustrated in  FIG. 2A  are examples of features that can retain the valve member after insertion into the hub portion  220 . 
     Turning now to the tubular portion  230 , and with reference to  FIGS. 3A and 3B , at least one groove  280  may be disposed within at least a portion of the tubular portion  230 , with one being shown in the illustrated configuration. This groove  280  can receive an insert  282  to provide certain characteristics and properties to the tubular portion  230 . For instance, the insert  282  can provide structural stiffness or kink resistance to the tubular portion  230  and/or the introducer sheath  210 . The groove  280  can extend from (i) the outer surface or wall  260  to the inner surface or wall  262 , (ii) the outer surface or wall  260  toward the inner surface or wall  262 , or (iii) the inner surface or wall  262  toward the outer surface or wall  260 . 
     As shown in  FIGS. 3A and 3B , the groove  280  and/or the insert  282  can extend from the tubular portion  230  to the hub portion  220 . Generally, the groove  280  and/or the insert  282  can extend from a portion of the tubular portion  230  to a portion of the hub portion  220 . Alternatively, the groove  280  and/or the insert  282  may be formed only in the tubular portion  230 , only in the hub portion  220 , or in a portion of the hub portion  220  or the tubular portion  230 . In other embodiments, one or more grooves  280  and/or inserts  282  can be formed in the sheath  210 . Although reference is made to a groove, herein other geometric patterns or configurations of channels, recess, holes, or other structures formed in the sheath can be used. Further, a line or other geometric pattern scored or formed in the sheath, with or without the inclusion of the insert can function in a similar manner to the groove and insert as described herein. 
     With continued reference to  FIGS. 3A and 3B , the insert  282  can be formed in the groove  280  in a variety of manners. In one configuration, the groove  280  can be formed as part of the initial molding process. For instance, the sheath  210  can undergo a first injection molding process where the hub portion  220  and elongated portion  230  are formed as a single unitary unit, with the groove  280  being formed at that time. The mold used to form the sheath  210  may then be adapted, such as by removing the portion of the mold that was responsible for the groove  280 , and a second injection molding process may then be performed to inject a second material into the groove  280  to form the insert  282 . The insert  282  may effectively bond to the material defining the groove  280  resulting in the sheath, the sheath being a unitary member. One example of a molding technique that can be used to perform the above-described process is an over-molding injection molding process. 
     It is also contemplated that the first and second injection molding processes can be conducted simultaneously or within a time period of each other, for instance by way of an over-molding injection molding process or a 2-shot injection molding process. In one configuration, a mold can be manufactured and placed into an injection molding machine, wherein the first molding process can form the sheath including the groove  280  shown in  FIG. 3A  and a second molding process would form the completed sheath by filling the groove  280  with a second material to form the insert  282 , resulting in the configuration of  FIG. 3B . Thus, the tubular portion  230  can be a composite. The process times can be controlled depending upon the materials to be molded and the desired mechanical properties. 
     With reference to  FIG. 3B , a cross-sectional view of the elongated portion  230  taken about line  3 B- 3 B of  FIG. 3A  is illustrated. The cross-sectional view of  FIG. 3B  illustrates the tubular portion  230  after the groove  280  has been formed and filled with a second material, which forms the insert  282 . As shown in  FIG. 3B , the elongate tubular portion  230  has an outer wall  260  and an inner wall  262  thereby defining a lumen  228  as well as a wall thickness. The insert  282  is shown disposed in groove  280  thereby forming a continuous generally tubular cross-section. In one configuration, the inner wall or surface  262  of the elongated portion  230  typically remains smooth after the second material is injected into the groove  280  to form the insert  282 . Alternatively, the inner surface  262  of the elongated portion  230  can have one or more variations, at least one of which can be defined by the insert  282  within the groove  280 . For instance, during the process of applying or depositing the second material the mold defining the boundaries for the second material  282  can include the desired pattern of the portion of the inner wall or surface  262  associated with the insert  282 . 
     As previously described above, the second material, as well as the first material, may be chosen based upon desired mechanical properties for the sheath  210 . For example, it may be desirable to produce an elongated portion  230  that is easily splittable along a portion of the interface between the first and second materials or through the second material in response to an adequate applied force. In this case, the bond between the first material and the second material can be adjusted through the manufacturing process. As previously stated, the first and second materials may be selected according to the bond between the first material and the second material and on the splitability of the first and/or second materials. For example, the thickness of the first material at the interface with the second material can be less than the thickness of the first material at other locations. This, combined with a second material that fills the groove  280  to form the insert  282  and may have less strength than the first material, may provide a sheath that has particular properties. For example, the tubular portion  230  may be more likely to split along the groove  280  or along any other geometric pattern formed on the inner wall of the tubular portion  230 , whether or not filled with a second material or the insert  282 . In instances where the geometric pattern such as the groove  280  is filled with a second material to form the insert  282 , a bond may be formed automatically during the molding process. Alternatively, thermal bonding, chemical bonding, or other known techniques can be used to facilitate bonding between the similar or dissimilar medical grade materials forming the insert  282  and the remainder of the sheath  210 . 
     As illustrated above, mechanical properties of the tubular portion may be adjusted by forming the elongate tubular portion  230  as a composite member. For example, if it is desirable to produce a sheath that is splittable during use, the second material and the insert  282  may be weaker than the first material, thereby forming a joint wherein the sheath may be easily split by an applied force. Alternatively, the second material or insert  282  can be utilized to stiffen or weaken the overall tubular portion  230 . This can be used to prevent kinking, and the like. Alternatively, the second material or insert  282  can be used to stiffen or weaken the overall tubular portion  230  and assist in splitting the sheath during use. For example, the second material or insert  282  may provide stiffness and cause the tubular portion  230  to split at the groove or other geometric pattern in response to an applied force, such as the withdrawal of a medical device like a vessel closure device. 
     Although the alternative embodiment has been described with respect to specific geometries as well as construction methods this should not be considered limiting in any manner. For example, it is contemplated that the groove  280  may be formed having many different geometric shapes and patterns as well as lengths. Additionally, the groove may include a geometric feature formed along the length thereof, wherein the second material or insert  282  would fill into this feature, thereby interlocking the two materials together. 
       FIG. 3C , for example, illustrates another configuration of the interface between a first material and a second material or between the groove and an insert. In particular, the groove  280  includes sub-grooves  284  that extend outwardly from the main portion of the groove  280 . These sub-grooves  284  can receive or be filled with the second material that forms the insert  282  during the injection molding process and provide a mechanical connection or coupling between the two materials and between the groove  280  and the insert  282 . As such, the sub-grooves  284 , together with the insert  282  or second material deposited therein, may function as interlocking features that may mechanically tie the portions of the tubular portion  230  together. By so doing, the two portions of the tubular portion  230  can be mounted or coupled together through both the bonding of the two materials and the mechanical coupling of the interlocking features formed in the groove  280  and the insert  282 . 
     It will be understood that in another configuration, the insert  282  can be formed separately from the remainder of the sheath  210 . The insert  282  can then be mounted or coupled to the groove  280  during subsequent processing. For instance, the insert  282  can be mounted or coupled to the groove  280  using adhesives, thermal or chemical bonding, and/or other techniques to mount or couple similar or dissimilar medical grade materials. Further, the insert  282  can mount or couple using mechanical structures, such as but not limited to, the interlocking features, with or without the use of adhesives, thermal or chemical bonding, and/or other techniques to mount or couple similar or dissimilar medical grade materials. 
     Because the sheath can be formed by an injection molding process using molten or melted material, the shape of the sub-grooves  284 , or other mechanical structures that facilitate mechanical coupling between two components, can vary and accommodate any desired purpose. In some instances, the formation or filling of the groove  280  with the second material to form the insert  282  may cause the first material to melt, thereby causing the two materials to bond. For example, the shape of the feature  284  may include extensions that prevent the first material from separating from the second material without tearing or shearing. This can strengthen the bond, in one example, between the first and second materials. Further, the interlocking feature may ensure that the tubular portion shears at the groove  280  owing to the strength or lack thereof of the second material. 
     The at least one interlocking features illustrated in  FIG. 3C  can extend from a proximal end  232  to a distal end  234  of the tubular portion  230  and/or the introducer sheath  210 . It will be understood, however, that the at least one interlocking feature can extend only part way from the distal end toward the proximal end, from the proximal end to the distal end, or at any location along the length of the tubular portion  130  and/or the sheath  210 . 
     In addition to the use of a second material to fill the groove  280  or other geometric pattern, it is further contemplated that more than two materials may be utilized to form the introducer sheath in accordance with the present invention or that other portions of the sheath may be formed from a second material. For example, a first material may be utilized to form the hub portion and one or more materials (which may include the first material) may be utilized to form the elongated portion of the sheath. Again, the selection of materials may depend on the end use of the sheath, properties of medical devices used with the sheath, and the like or any combination thereof. Although the present invention has been shown and described in accordance with specific embodiments these should not be considered limiting in any manner. For example, multiple materials may be utilized to form a unitary sheath in accordance with the present invention, wherein multiple injection molding processes are performed simultaneously or in stages to form the unitary sheath in accordance with the present invention. 
     Referring generally to  FIGS. 4A-4E , there is shown a system  300  for manufacturing a sheath  310  during various stages of manufacture. The introducer sheath  310  of this embodiment may be at least partially functionally similar to that of the introducer sheaths,  10 ,  110 ,  210  previously described above and shown in  FIGS. 1A-3C  in most respects, wherein certain features will not be described in relation to this embodiment wherein those components may function in the manner as described above and are hereby incorporated into this alternative embodiment described below. Like structures and/or components are given like reference numerals. 
     The introducer sheath  310  may include a hub portion  320 , which includes a proximal end  322  and a distal end  324 , and/or a tubular portion  330 , which includes a proximal end  332  and a distal end (not shown). The cross section of the hub portion  320  can be generally cylindrical in nature, although other configurations are contemplated. The hub portion  320  may include a valve portion  350 . As shown in  FIG. 4A , the valve portion  350  may be a portion of a surface on the distal end  324  of the hub portion  320 . The valve portion  350  may include a distal surface  351 . 
     Although not illustrated in  FIGS. 4A-4E , the sheath  310  may include an optional port member, such as the optional port member  42  shown in  FIG. 1B , that may be formed on the outer surface or outer wall  344  of the hub portion  320 . The sheath  310  may further include a retention recess or ring, such as the retention recess or ring  46  shown in  FIG. 1A . 
     Referring specifically to  FIG. 4A , the system  300  for manufacturing a sheath  310  may include a first forming device  386  and/or an external forming device  388 . The first forming device  386  may include a concave proximal end  387 . The external forming device  388  may include a convex distal end  389 . For instance, the proximal end  387  of the first forming device  386  and/or the distal end  389  of the external forming device  388  may be curved, as shown in  FIG. 4A , or may come in other convex shapes such as an inverted “V” shape and/or other shapes that are substantially non-parallel toward the distal end  324  of the hub portion  320 . 
     In an injection molding process, for example, the sheath  310  may be formed using core pin as the first forming device  386  and a mold as the external forming device  388 . The first forming device  386  and/or the external forming device  388  can be machined or configured based on the desired dimensions and configurations of the sheath  310  as described herein. 
     After the first forming device  386  and/or the external forming device  388 , which may include multiple parts, are formed (i.e. milled, lathed, etc.), the injection molding process may begin by melting a suitable material, such as one described above, and then injecting the melted material using the first forming device  386  and/or the external forming device  388 , often under pressure. The external forming device  388  may be formed such that the molded introducer sheath  310  can be removed after it has cooled and such that the resulting introducer sheath  310  has the desired dimensions and characteristics described herein. As a result, the molded sheath  310  can be a unitary member and may not require assembly from separately formed parts. 
     As shown in  FIG. 4A , the valve portion  350  may be formed in a concave shape. As shown in  FIG. 4B , the valve portion  350  may have a concave shape in a relaxed state after the sheath  310  is formed and the first forming device  386  and/or the external forming device  388  are removed. The first forming device  386  may be removed through the lumen  328 . For example, the sheath  310  may be sufficiently elastic to allow the first forming device  386  to be removed through the lumen  328 . 
     A second forming device  392  may be inserted into the hub portion  320 , as shown in  FIG. 4C . The second forming device  392  may be inserted through the tubular portion  330 . The second forming device  392  may include a proximal end  393  that is substantially planar. The second forming device  392  may deform the valve portion  350  from the concave shape in the relaxed state, as shown in  FIG. 4B , toward a substantially planar shape in a deformed state, as shown in  FIG. 4C . For example, the proximal end  393  of the second forming device  392  may abut at least a portion of the distal surface  351  of the valve member  350  to deform the valve member  350 . In other embodiments, the proximal end  393  of the second forming device  392  may vary in shape. For instance, the proximal end  393  may be convex, square, and/or otherwise shaped. The proximal end  393  of the second forming device  392  may have a surface area that is substantially the same size as the distal surface  351  of the valve portion  350 , as shown in  FIG. 4C . 
     As shown in FIG.  4 C′, an alternative embodiment of a second forming device  392 ′ may be inserted into the hub portion  320 . The second forming device  392 ′ may be inserted through the tubular portion  330 . The second forming device  392 ′ may deform the valve portion  350  from the concave shape in the relaxed state, as shown in  FIG. 4B , toward a substantially planar shape in a deformed state, as shown in FIG.  4 C′. The proximal end  393 ′ of the second forming device  392 ′ may have a surface area that is substantially smaller than the distal surface  351  of the valve portion  350 . For example, the proximal end  393 ′ of the second forming device  392 ′ may have a surface area that is approximately the same size as the aperture  398  to be formed. In another example, the proximal end of the second forming device  392 ′ may have a surface area that is approximately the same size as an area of the lumen  328  of the tubular portion  330 . As shown in FIG.  4 D′, a blade  394  may have a dimension that is approximately the same as a dimension of the second forming device  392 ′. Other sizes and/or shapes of the second forming device  392 ′ may be used. 
     As shown in  FIG. 4D , an aperture  398  may be formed. The aperture  398  may be formed while the valve portion  350  is in the deformed state. Typically, the aperture  398  may be formed after the sheath  310  has cooled. However, it may be desirable to form the aperture  398  before and/or during the cooling process. 
     The aperture  398  may be formed using a blade  394 . The blade  394  may include a twist drill bit, a boring bit, and/or other blades. The blade  394  may remove material through at least a portion of the distal surface  351  of the valve portion  350 . The blade  394  may contact the second forming device  392  during forming of the aperture  398 . 
     The blade  394  may have a hardness that is lower than the hardness of the second forming device  392  and/or higher than the hardness of the valve portion  350 . Having a hardness that is lower than the second forming device  392  may limit damage to the second forming device  392 . However, other hardnesses may be selected for the blade  394 , the second forming device  392 , and/or the valve portion  350 . 
     The blade  394  may form a substantially cylindrical aperture  398 . Alternatively, the blade  394  may produce other shapes of apertures  398 . Typically, the aperture  398  may be formed through a central portion of the distal surface  351  of the valve portion  350 . For example, a longitudinal axis of the aperture  398  may be aligned with a longitudinal axis of the hub portion  320  and/or tubular portion  330 . 
     The aperture  398  of the valve portion  350  may provide a sealed hub portion  320 . Stated another way, the aperture  398  of the valve portion  350  may be self-sealing to prevent fluid escaping from the body lumen. To facilitate sealing, the aperture  398  may include a sealing surface  399 . The sealing surface  399  may be configured to form a seal between a medical device and the hub portion  320 . The sealing surface  399 , in the deformed state, may be generally parallel to the longitudinal axis of the hub portion  320  and/or tubular portion  330  (i.e. the sealing surface  399  may be substantially cylindrical). 
     As shown in  FIG. 4E , the valve portion  350  may still be generally concave in the relaxed state after the aperture  398  is formed. The sealing surface  399 , in the relaxed state, may be generally nonparallel to the longitudinal axis of the hub portion  320  and/or tubular portion  330  (i.e. the sealing surface  399  may be substantially conic). 
     When in use, a medical device may be inserted through the aperture  398  while the valve portion  350  is in the relaxed state. An outer surface of the medical device may contact at least a portion of the sealing surface  399  (i.e. a proximal edge and/or other portion). When the medical device has been inserted approximately a desired distance, the medical device may be retracted. Retracting the medical device may transition the valve portion  350  from the relaxed state toward the deformed state. For example, the outer surface of the medical device may engage the sealing surface  399  such that the valve portion  350  may transition toward the deformed state. 
     Benefits of forming an aperture  398  in the hub portion  320  of introducer sheath  310  may include reduced costs (i.e. assembly costs for a separate flexible valve member), more accurate parts (i.e. dimension control) due to lack of assembly, as well as the ability to balance mechanical properties across the entire sheath  310 . 
     Referring generally to  FIGS. 5A-5C , there is shown a system  400  for manufacturing a sheath  410  during various stages of manufacture. The introducer sheath  410  of this alternative embodiment may be at least partially functionally similar to that of the introducer sheaths,  10 ,  110 ,  210 ,  310  previously described above and shown in  FIGS. 1A-4E  in most respects, wherein certain features will not be described in relation to this embodiment wherein those components may function in the manner as described above and are hereby incorporated into this alternative embodiment described below. 
     For example, although not illustrated in  FIGS. 5A-5C , the sheath  410  may include an optional port member, such as the optional port member  42  shown in  FIG. 1B , that may be formed on the outer surface or outer wall  444  of the hub portion  420 . In another example, the sheath  410  may further include a retention recess or ring, such as the retention recess or ring  46  shown in  FIG. 1A . Like structures and/or components are given like reference numerals. 
     The introducer sheath  410  may include a hub portion  420 , which includes a proximal end  422  and a distal end  424 , and/or a tubular portion  430 , which includes a proximal end  432  and a distal end  434 . The cross section of the hub portion  420  can be generally cylindrical in nature, although other configurations are contemplated. The hub portion  420  may include a valve portion  450 . As shown in  FIG. 5A , the valve portion  450  may be a portion of a surface on the distal end  424  of the hub portion  420 . The valve portion  450  may include a distal surface  451 . 
     Referring specifically to  FIG. 5A , the system  400  for manufacturing a sheath  410  may include a forming device  486  and/or an external forming device  488 . The forming device  486  may include a substantially planar proximal end  487 . The forming device  486  may further be flared toward the proximal end  487 . The external forming device  488  may include a substantially planar distal end  489 . The external forming device  488  may further be flared internally toward the distal end  489 . In an injection molding process, for example, the sheath  410  may be formed using core pin as the forming device  486  and a mold as the external forming device  488 . The forming device  486  and/or the external forming device  488  can be machined or configured based on the desired dimensions and configurations of the sheath  410  as described herein. 
     After the forming device  486  and/or the external forming device  488 , which may include multiple parts, are formed (i.e. milled, lathed, etc.), the injection molding process may begin by melting a suitable material, such as one described above, and then injecting the melted material using the forming device  486  and/or the external forming device  488 , often under pressure. 
     As shown in  FIG. 5A , the valve portion  450  may be formed in a substantially planar shape. The sheath  410  may be formed in a deformed rather than a relaxed state. For example, the geometry of the forming device  486  and/or external forming device  488  may determine whether the sheath  410  is formed in a relaxed or a deformed state. In the present example, the sheath  410  may be formed in a deformed state because the forming device  486  and/or external forming device  488  are flared toward their proximal end  487  and/or distal end  489 , respectively. The flaring may generate internal stresses within the sheath  410  to deflect the valve portion  450  toward a substantially concave shape in a relaxed state. 
     As shown in  FIG. 5B , an aperture  498  may be formed. The aperture  498  may be formed while the valve portion  450  is in the deformed state. The aperture  498  may be formed using a blade  494  that may remove material through at least a portion of the distal surface  451  of the valve portion  450 . The blade  494  may contact the forming device  486  during forming of the aperture  498 . The blade  494  may have a hardness that is lower than the hardness of the forming device  486  and/or higher than the hardness of the valve portion  450 . 
     The blade  494  may form a substantially cylindrical aperture  498 . Alternatively, the blade  494  may produce other shapes of apertures  498 . Typically, the aperture  498  may be formed through a central portion of the distal surface  451  of the valve portion  450 . For example, a longitudinal axis of the aperture  498  may be aligned with a longitudinal axis of the hub portion  420  and/or tubular portion  430 . 
     The aperture  498  of the valve portion  450  may provide a sealed hub portion  420 . Stated another way, the aperture  498  of the valve portion  450  may be self-sealing to prevent fluid escaping from the body lumen. To facilitate sealing, the aperture  498  may include a sealing surface  499 . The sealing surface  499  may be configured to form a seal between a medical device and the hub portion  420 . The sealing surface  499 , in the deformed state, may be generally parallel to the longitudinal axis of the hub portion  420  and/or tubular portion  430  (i.e. the sealing surface  499  may be substantially cylindrical). 
     As shown in FIG.  5 B′, an alternative embodiment of a forming device  486 ′ may be used to form the sheath  410 . The forming device  486 ′ may be a combination of the forming device  486  and external forming device  488  of the embodiment shown in  FIG. 5A . However, in this alternative embodiment, an aperture forming member  490 ′ may be added to the forming device  486 ′ to form the aperture  498  in the valve portion  450  of the sheath  410 . The aperture forming member  490 ′ may eliminate the need for a blade  494  to form the aperture  498 . 
     An aperture forming member  490 ′ may be used in other embodiments. For example, an aperture forming member  490 ′ may be used with the system  400  for manufacturing a sheath  410 . In the system  400 , the aperture forming member  490 ′ may be shaped to generally match the shape of the aperture  498  in the relaxed shape. The use of an aperture forming member  490 ′ in the system  300  may eliminate the need for a second forming device  392  and/or a blade  394 . 
     In the present example, the aperture forming member  490 ′ may be substantially cylindrically shaped to form a substantially cylindrical shaped aperture  498 . However, other shapes may be used. 
     As shown in  FIG. 5C , the valve portion  450  may still be generally concave in the relaxed state after the aperture  498  is formed (i.e. by the blade  494  or by the aperture forming member  490 ′). The sealing surface  499 , in the relaxed state, may be generally nonparallel to the longitudinal axis of the hub portion  420  and/or tubular portion  430  (i.e. the sealing surface  499  may be substantially conic). The valve portion  450  may have a concave shape in a relaxed state after the sheath  410  is formed and the forming device  486  and/or the external forming device  488  or the forming device  486 ′ with an aperture forming member  490  are removed. 
     Referring generally to  FIGS. 6A-6C , there is shown a system  500  for manufacturing a sheath  510  during various stages of manufacture. The introducer sheath  510  of this alternative embodiment may be at least partially functionally similar to that of the introducer sheaths,  10 ,  110 ,  210 ,  310  previously described above and shown in  FIGS. 1A-5C  in most respects, wherein certain features will not be described in relation to this embodiment wherein those components may function in the manner as described above and are hereby incorporated into this alternative embodiment described below. 
     For example, although not illustrated in  FIGS. 6A-6C , the sheath  510  may include an optional port member, such as the optional port member  42  shown in  FIG. 1B , that may be formed on the outer surface or outer wall  544  of the hub portion  520 . In another example, the sheath  510  may further include a retention recess or ring, such as the retention recess or ring  46  shown in  FIG. 1A . Like structures and/or components are given like reference numerals. 
     The introducer sheath  510  may include a hub portion  520 , which includes a proximal end  522  and a distal end  524 , and/or a tubular portion  530 , which includes a proximal end  532  and a distal end  534 . The cross section of the hub portion  520  can be generally cylindrical in nature, although other configurations are contemplated. The hub portion  520  may include a valve portion  550 . As shown in  FIG. 6A , the valve portion  550  may be a portion of a surface on the distal end  524  of the hub portion  520 . The valve portion  550  may include a distal surface  551 . 
     Referring specifically to  FIG. 6A , the system  500  for manufacturing a sheath  510  may include a forming device  586  and/or an external forming device  588 . The forming device  586  may include a substantially planar proximal end  587 . The forming device  586  may further include a substantially cylindrical shape toward the proximal end  587 . The external forming device  588  may include a substantially planar distal end  589 . The external forming device  588  may further include a substantially cylindrical internal shape toward the distal end  589 . In an injection molding process, for example, the sheath  510  may be formed using core pin as the forming device  586  and a mold as the external forming device  588 . The forming device  586  and/or the external forming device  588  can be machined or configured based on the desired dimensions and configurations of the sheath  510  as described herein. 
     After the forming device  586  and/or the external forming device  588 , which may include multiple parts, are formed (i.e. milled, lathed, etc.), the injection molding process may begin by melting a suitable material, such as one described above, and then injecting the melted material using the forming device  586  and/or the external forming device  588 , often under pressure. 
     As shown in  FIG. 6A , the valve portion  550  may be formed in a substantially planar shape. Because the forming device  586 , in the present example, may be unflared (i.e. substantially cylindrical) toward the proximal end  587  and/or have a substantially planar proximal end  587 , the valve portion  550  may remain substantially planar in the relaxed state. A manufacturing process may be used to facilitate transitioning the valve portion  550  toward a substantially concave shape in the relaxed state. In one example, an interim stress differential may be created in and/or around the valve portion  550 . The interim stress differential may be created before the formed sheath  510  has substantially cooled. The interim stress differential may be created by, for example the temperatures of the molds near the valve portion  550 , the thickness along the valve portion  550 , other aspects of the mold and/or valve portion may be varied, or combinations thereof. 
     As shown in  FIG. 6B , an aperture  598  may be formed. The aperture  598  may be formed before, during, or after a manufacturing processes is used to facilitate transitioning the valve portion  550  toward a substantially concave shape in the relaxed state. The aperture  598  may be formed using a blade  594  that may remove material through at least a portion of the distal surface  551  of the valve portion  550 . The blade  594  may contact the forming device  586  during forming of the aperture  598 . 
     The blade  594  may form a substantially cylindrical aperture  598 . Alternatively, the blade  594  may produce other shapes of apertures  598 . 
     The aperture  598  of the valve portion  550  may provide a sealed hub portion  520 . Stated another way, the aperture  598  of the valve portion  550  may be self sealing to prevent fluid escaping from the body lumen. To facilitate sealing, the aperture  598  may include a sealing surface  599 . The sealing surface  599  may be configured to form a seal between a medical device and the hub portion  520 . The sealing surface  599 , in the deformed state, may be generally parallel to the longitudinal axis of the hub portion  520  and/or tubular portion  530  (i.e. the sealing surface  599  may be substantially cylindrical). 
     An alternative embodiment of a forming device (not shown), similar to the forming device shown in FIG.  5 B′ may be used to form the sheath  510 . The forming device may be a combination of the forming device  586  and external forming device  588  of the embodiment shown in  FIG. 6A . For example, the forming device may include a substantially planar exterior proximal end and/or interior distal end, similar to the forming device  486 ′ shown in FIG.  5 B′. The forming device may further include a substantially cylindrical shape toward the exterior proximal end and/or the interior distal end rather than being flared toward the exterior proximal end  487  and/or interior distal end  489  of the forming device  486 ′ shown in FIG.  5 B′. 
     As shown in  FIG. 6C , the valve portion  550  may still be generally concave in the relaxed state after the aperture  598  is formed (i.e. by the blade  594  or by an aperture forming member). 
     Although the present examples describe manufacturing the sheaths  310 ,  410 ,  510  as unitary members, the hub portions  320 ,  420 ,  520  may be manufactured separately from the tubular portions  330 ,  430 ,  530 . For example, the hub portion  320 ,  420 ,  520  may be manufactured separately as generally described above and then joined with a tubular portion  330 ,  430 ,  530 . Furthermore, although the present example describes an injection molding process, other forming processes may be used to from the hub portion  320 ,  420 ,  520  and/or tubular portion  330 ,  430 ,  530 . For instance, it is contemplated that a lost wax process and/or other suitable process may be used to form the tubular portion  330 ,  430 ,  530  and/or hub portion  320 ,  420 ,  520  having a substantially concave valve portion  350 ,  450 ,  550  in a relaxed state. 
     Referring to  FIGS. 7A through 7C , in an alternative embodiment an introducer sheath, such as is illustrated in  FIGS. 1A through 3C  may be adapted to receive a valved cover  700 . The cover  700  may be sized, for example to cover a portion of the hub  20  proximate the proximal end  22  of the introducer sheath of  FIGS. 1A through 1C . The cover  700  may likewise be positioned over a portion of the proximal end  122  of the hub  120  of  FIGS. 2A through 2C  or the proximal end  222  of the hub  220  of the introducer sheath of  FIGS. 3A through 3C . In embodiments where the valved cover  700  is used the flexible valve member  50  and corresponding receiving feature  26  may be omitted. Alternatively, one or both of the valve member  50  and receiving feature  26  may be retained in order to provide a redundant seal or to provide the option of positioning a seal member  50  in the receiving feature  26  if desired. Likewise, with respect to  FIGS. 2A through 2C , the seal member  150  may be omitted or retained where a valved cover  700  is used. 
     Referring specifically to  FIGS. 7A and 7B , the valved cover  700  may include an upper portion sized to cover the proximal end  22 ,  122 ,  222  of the hub portion  20 ,  120 ,  220 . The upper portion  702  may include an outer surface  704  that is exposed when the valved cover  700  is secured to the hub portion  20 ,  120 ,  220 . The outer surface  704  preferably has an inverted or concave shape. For example, the outer surface  704  may have a spherical or conical shape. A sidewall portion  706  may secure to the upper portion  702 . For example, the sidewall portion  706  may extend around a perimeter of the upper portion  702  such that the upper portion and sidewall portion  706  define a cavity sized to receive the proximal end  22 ,  122 ,  222  of the hub portion  20 ,  120 ,  220 . Alternatively, the cavity may be sized to receive the proximal end  22 ,  122 ,  222  of the hub portion  20 ,  120 ,  220  only after elastic deformation thereof. In the illustrated embodiment, the sidewall portion  706  defines a cylindrical inner surface  710 . However, the inner surface  710  may be shaped to conform to whatever shape is had near the proximal end  22 ,  122 ,  222  of the hub portion  20 ,  120 ,  220 . 
     A retaining member  712  may project inwardly from the inner surface  710  and engage the hub portion  20 ,  120 ,  220  to resist removal thereof. In the illustrated embodiment, the retaining member  712  is embodied as a lip extending circumferentially around the inner surface  710 . The lip or retaining member  712  may be sized to fit within the retention recess, or ring,  46  in the embodiments of  FIGS. 1A through 1C  or within the retention recess, or ring,  127  in the embodiments of  FIGS. 2A through 3C . In an alternative embodiment, the lip or retaining member  712  may be replaced by a circumferential groove formed in the inner surface  810  of the sidewall  706  and sized to receive a ridge extending circumferentially around the hub portion  20 ,  120 ,  220  near the proximal end  22 ,  122 ,  222 . 
     The valve cover  700  may be formed of an elastic material, such as an elastic, biocompatible polymer. The sidewall  706  and retaining member  712  preferably deforms sufficiently to allow the retaining member  712  to be passed over the proximal end  22 ,  122 ,  222  of the hub portion  20 ,  120 ,  220  and into engagement with the retention recess, or ring,  46 . 
     A valve  714  may be formed in the top portion  702 . The valve  714  may be sized to receive a catheter or other slender instrument for threading through the introducer sheath into the vasculature of a patient. In the illustrated embodiment, the valve  714  is embodied as an aperture  716  extending through the top portion  702 . Alternatively, the valve  714  may be a valving structure secured within the aperture  716  such as by means of overmolding, adhesive, or the like. The aperture  716  may be tapered when the top portion  702  is not deformed by an external force, such as an aperture  716  having a conical shape. The aperture  716  may be tapered such that the diameter  720  of the aperture  716  increases with distance from the upper surface  704  of the top portion. 
     Referring to  FIGS. 8A through 8E , the valve  700  may be formed in the top portion  702  according to the method illustrated. As shown in  FIG. 8A , the sidewall  706  and top portion  702  may be formed, such as by a molding process. As is apparent in  FIG. 8A , the mold  800  includes mold portions  800   a ,  800   b  combinable to form a cavity  802  that may be filled with a liquid polymer that becomes solid through a cooling or curing process. The cavity  802  may include surfaces  804   a ,  804   b  positioned on either side of the top portion  702  of the molded valved cover  700 . The surfaces  804   a ,  804   b  may be shaped such that the upper surface  704  has an inverted or concave shape following the molding process as shown by the valved cover  700  shown in  FIG. 8B . For example, the surfaces  804   a ,  804   b  may have a spherical shape. Alternatively, the surfaces  804   a ,  804   b  may have a conical shape such that the upper surface  704  has a conical shape. 
     Referring to  FIG. 8C , the concavity of the upper surface  704  may then be reduced by deforming the top portion  702  prior to forming the valve  714 . In the illustrated embodiment, reduction of the concavity of the upper surface  704  is accomplished by inserting a mandrel  806  within the cavity defined by the sidewall  706  and top portion  702 . The mandrel  806  may have an upper surface  808  that is flat or has a radius of curvature greater than an undeformed radius of curvature of the lower surface  810  of the top portion  702 , such that as the mandrel  806  is urged against the lower surface  810 , the concavity of the upper surface  704  is reduced. 
     Referring to  FIG. 8D , the aperture  716  for the valve  714  may then be formed in the top portion  702 , such as by means of cutting tool  812 , such as a rotating drill, punch, actuated blade, or the like. The mandrel  806  may then be removed to yield a valved cover  700  such as is illustrated in  FIGS. 7A and 7B . Referring to FIGS.  8 C′ and  8 D′, in some embodiments, the mandrel  806  may be embodied by a rod  814  pressed against the lower surface  808  during the cutting step illustrated in FIG.  8 D′. For example, the rod  814  may have an upper surface  814  that is has an area substantially smaller than the area of the lower surface  810  of the top portion  702 . For example, the rod  814  may have an area that is slightly greater or smaller (e.g. ±5 to 10%) that of the aperture  716 . 
     Upon removal of the mandrel  806  or rod  814 , the top portion  702  may elastically return to its undeformed shape, causing the aperture  716  to become tapered due to the return of the top portion  702  to a concave shape. 
     Referring to  FIGS. 9A through 9C , the valve  700  may be formed in the top portion  702  according to the method illustrated. As shown in  FIG. 9A , the sidewall  706  and top portion  702  may be formed, such as by a molding process. As is apparent in  FIG. 8A , the mold  900  includes mold portions  900   a ,  900   b  combinable to form a cavity  902  that may be filled with a liquid polymer that becomes solid through a cooling or curing process. The cavity  902  may include surfaces  904   a ,  904   b  positioned on either side of the top portion  702  of the molded valved cover  700 . In the illustrated embodiment, the surfaces  804   a ,  804   b  are planar. The mold portions  900   a ,  900   b  may be shaped such that the sidewall  706  are tapered or converge with distance from the top portion  702 . 
     Referring to  FIG. 9B , the aperture  716  for the valve  714  may then be formed in the top portion  702 , such as by means of cutting tool  906 , such as a rotating drill, punch, actuated blade, or the like. A mandrel  908  may be inserted within the cavity defined by the top portion  702  and sidewall  706  and urged against the top portion  702  for support during cutting of the aperture  716  and may then be removed to yield a valved cover  700  such as is shown in  FIG. 9C . Referring to FIG.  9 B′, alternatively, the mold  900  may define a projection  910  secured to one of the mold portions  900   a ,  900   b  and extending through the top portion  702  during molding such that following the molding step of FIG.  9 B′, the aperture  716  is already formed. 
     Following formation of the valved cover  700  and the aperture  716 , the upper surface  704  may assume an inverted or concave shape due to residual stresses within elastomeric polymer forming the valved cover  700 . For example, in the illustrated embodiment, the upper surface  704  assumes a conical shape. As the upper surface  704  assumes an inverted or concave shape, deformation of the top portion  702  may also cause the aperture  716  to assume a tapered shape such that the diameter of the aperture  716  increases with distance from the upper surface  704 . In a like manner the tapering of the sidewall  706  with distance from the top portion  702  may be reduced due to narrowing of the top portion  702  due to residual stresses within the top portion. 
     Referring to  FIG. 10A , in an alternative method of manufacturing a valved cover  700  a mold  1000  may be used including mold portions  1000   a  and  1000   b  forming a cavity  1002  constraining the sidewall  706  to be substantially perpendicular to the top portion  702 . As in the embodiments described hereinabove, the cavity  1002  may be filled with a liquid polymer that is allowed to harden due to cooling or curing to form a valved cover  700 . Referring to  FIG. 10B , the aperture  716  for the valve  714  of the valved cover  700  may be formed by means of a cutting tool  1004 , such as a drill, punch, articulated blade, or the like. A mandrel  1006  may be positioned within the cavity defined by the top portion  702  and sidewall  706  and resist deformation of the top portion  702  during the cutting step. The mandrel  1006  may then be removed to yield a valved cover  700  such as is shown in  FIG. 10C . 
     Referring to  FIG. 10C , as with the embodiment of  FIGS. 9A through 9C , cutting of the aperture  716  may result in deformation of the top portion  702  due to residual stresses within the valved cover  700 . Deformation of the top portion  702  may result in the upper surface  704  becoming concave, such as the conical shape illustrated in  FIG. 10C . Deformation of the top portion  702  may also result in the aperture  716  becoming tapered such that the diameter of the aperture  716  increases with distance from the upper surface  704 . 
     The residual stresses may include an interim stress differential created before the formed valved cover  700  has substantially cooled. The interim stress differential may be created by, for example the temperatures of the molds near the valve portion  550 , the thickness along the valve portion, other aspects of the mold and/or valve portion may be varied, or combinations thereof. 
     Referring to  FIGS. 11A and 11B , a valved cover  700  having a concave or inverted upper surface  704  may be used to promote sealing with a catheter  1100  inserted through the valved cover  700  and through the hub  20  and tubular portion  30  of an introducer sheath bearing the valved cover  700 . In one method of use, the catheter  1100  is inserted in a distal direction  1102  through the aperture  716  of the valve  714  and through the hub  20  and tubular portion  30 , as shown in  FIG. 11A . The catheter  1100  may then be drawn back slightly in proximal direction  1104  such that the concavity or inversion of the upper surface  704  is reduced. Urging the catheter  1100  slightly in the proximal direction  1104  may promote sealing by urging the walls of the aperture  716  against the catheter  1100  due to the tapered configuration of the aperture  716 . 
     Referring generally to  FIGS. 12A and 12B , there is shown a portion of an introducer sheath  1210 .  FIG. 12A  illustrates an exemplary cross-section (for example, about line  1 C- 1 C of  FIG. 1A , line  2 B- 2 B of  FIG. 2A , or line  3 B- 3 B of  FIG. 3A ) of at least a portion of a single lumen introducer sheath  1210 . It will be understood that an irregular wall design may be incorporated into a single lumen and/or multiple lumen introducer sheath. The exemplary cross-section of the introducer sheath  1210  of this embodiment may be at least partially incorporated into at least one of the introducer sheaths,  10 ,  110 ,  210  previously described above and shown in  FIGS. 1A-3C  or of the introducer sheaths  1310 ,  1410 ,  1510 ,  1610  described herein and shown in  FIGS. 13A-16B . As shown in  FIG. 12B , the cross-section of  FIG. 12A  may extend along at least a portion of the length of the introducer sheath  1210 . 
     Although the present embodiment is described with respect to a cutaway cross-section of the introducer sheath  1210 , the cross-section may be uniform and/or nonuniform along a length of the introducer sheath, may be uniformly and/or nonuniformly axially oriented with respect to a longitudinal axis, may be otherwise oriented, or combinations thereof. 
     The irregular wall surface may be formed as described herein. For example, the introducer sheath  1210  may be formed by injection molding and/or other processes. 
     The introducer sheath  1210  may include an outer surface  1260  and an inner surface  1262 . The outer surface  1260  and/or inner surface  1262  may include a plurality of protrusions  1266  and/or depressions  1268  with a substantially uniform outer surface  1262 . In other embodiments, the outer surface  1260  and/or the inner surface  1262  may include a plurality of protrusions  1266  and/or depressions  1268 . 
     The plurality of protrusions  1266  and/or depressions  1268  may be generally uniformly distributed about the inner circumference of the inner surface  1262 . In other embodiments, the plurality of protrusions  1266  and/or depressions  1268  may be at least partially randomly distributed about the inner or outer circumference of the inner and/or outer surface  1262 . 
     The outer wall and the inner wall of a typical elongate tubular member may define a wall thickness and an inner dimension, such as an inner diameter. In the present embodiment, the outer surface  1260  and the inner surface  1262  may define a plurality of wall thicknesses. For example, the outer surface  1260  and the inner surface  1262  may define a first wall thickness  1264   a  between the outer surface  1260  and the inner surface  1262  about a protrusion  1266 . In another example, the outer surface  1260  and the inner surface  1262  may define a second wall thickness  1264   b  between the outer surface  1260  and the inner surface  1262  about a depression  1268 . 
     The irregular wall design may define a plurality of inner and/or outer dimensions. For example, an inner dimension  1262   a , which happens to be the smallest inner diameter, may be formed through a longitudinal axis between the apexes of two protrusions  1266 . In another example, another inner dimension  1262   b , which happens to be the largest inner diameter, may be formed through a longitudinal axis between the apexes of two depressions  1268 . An outer dimension  1260   a  may also be defined. 
     The irregular wall design formed by the protrusions  1266  and depressions  1268 , in the present embodiment, may minimize friction between the inner surface  1262  of the introducer sheath  1210  and a medical device, such as a closure device delivery apparatus (not shown), to be inserted into the introducer sheath  1210 . 
     Referring generally to  FIGS. 13A and 13B , there is shown a portion of an introducer sheath  1310 .  FIG. 13A  illustrates an exemplary cross-section (for example, about line  1 C- 1 C of  FIG. 1A , line  2 B- 2 B of  FIG. 2A , or line  3 B- 3 B of  FIG. 3A ) of at least a portion of a single lumen introducer sheath  1310 . The cross-section of the introducer sheath  1310  of this embodiment may be at least partially functionally similar to that of the cross-sections of the introducer sheaths,  10 ,  110 ,  210 ,  1210 ,  1410 ,  1510 ,  1610  described herein, wherein certain features will not be described in relation to this embodiment wherein those components may function in the manner as described above and are hereby incorporated into this alternative embodiment described below. Like structures and/or components are given like reference numerals. As shown in  FIG. 13B , the cross-section of  FIG. 13A  may extend along at least a portion of the length of the introducer sheath  1310  at a non-parallel angle to the longitudinal axis of the sheath  1310 . 
     Although the present embodiment is described with respect to a cutaway cross-section of the introducer sheath  1310 , the cross-section may be uniform and/or nonuniformly along a length of the introducer sheath, may be uniformly and/or nonuniformly axially oriented with respect to a longitudinal axis, may be otherwise oriented, or combinations thereof. 
     The irregular wall surface may be formed as described herein. For example, the introducer sheath  1310  may be formed by injection molding and/or other processes. 
     The introducer sheath  1310  may include an outer surface  1360  and an inner surface  1362 . The inner surface  1362 , in the present embodiment, may generally take the form of a polygonal shape, such as an octagon. Other shapes, such as a triangle, square, ellipsoid, or other shape may be used. The apexes of the inner surface  1362  may define depressions  1368  while the midpoint of the lines between each adjacent pair of apexes may define protrusions  1366 . The outer surface  1360 , as shown in  FIG. 13A , may be substantially uniform. The plurality of protrusions  1366  and/or depressions  1368  are shown in  FIG. 13A  as generally uniformly distributed about the inner circumference of the inner surface  1362 . 
     The outer surface  1360  and the inner surface  1362  may define a plurality of wall thicknesses. For example, the outer surface  1360  and the inner surface  1362  may define a first wall thickness  1364   a  between the outer surface  1360  and the inner surface  1362  about a protrusion  1366  (i.e. at a midpoint of a line between two adjacent apexes). In another example, the outer surface  1360  and the inner surface  1362  may define a second wall thickness  1364   b  between the outer surface  1360  and the inner surface  1362  about a depression  1368  (i.e. at an apex). 
     The irregular wall design may define a plurality of inner and/or outer dimensions. For example, an inner dimension  1362   a , which happens to be the smallest inner diameter, may be formed through a longitudinal axis between the apexes of two protrusions  1366 . In another example, another inner dimension  1362   b , which happens to be the largest inner diameter, may be formed through a longitudinal axis between the apexes of two depressions  1368 . An outer dimension  1360   a  may also be defined. 
     The irregular wall design formed by the protrusions  1366  and depressions  1368 , in the present embodiment, may minimize friction between the inner surface  1362  of the introducer sheath  1310  and a medical device, such as a closure device delivery apparatus (not shown), to be inserted into the introducer sheath  1310 . 
     Referring to  FIG. 14 , there is shown a portion of an introducer sheath  1410  illustrating an exemplary cross-section (for example, about line  1 C- 1 C of  FIG. 1A , line  2 B- 2 B of  FIG. 2A , or line  3 B- 3 B of  FIG. 3A ) of at least a portion of a single lumen introducer sheath  1410 . The cross-section of the introducer sheath  1410  of this embodiment may be at least partially functionally similar to that of the cross-sections of the introducer sheaths,  10 ,  110 ,  210 ,  1210 ,  1310 ,  1510 ,  1610  described herein, wherein certain features will not be described in relation to this embodiment wherein those components may function in the manner as described above and are hereby incorporated into this alternative embodiment described below. Like structures and/or components are given like reference numerals. The cross-section of  FIG. 14  may extend along at least a portion of the length of the introducer sheath  1410 , such as is shown in  FIGS. 12B  and/or  13 B and/or may vary in axial alignment with the longitudinal axis. 
     Although the present embodiment is described with respect to a cutaway cross-section of the introducer sheath  1410 , the cross-section may be uniform and/or nonuniformly along a length of the introducer sheath, may be uniformly and/or nonuniformly axially oriented with respect to a longitudinal axis, may be otherwise oriented, or combinations thereof. 
     The irregular wall surface may be formed as described herein. For example, the introducer sheath  1410  may be formed by injection molding and/or other processes. 
     The introducer sheath  1410  may include an outer surface  1460  and an inner surface  1462 . The inner surface  1462 , in the present embodiment, may generally take the form of an octagonal shape with rounded concave portions at each apex. Other shapes, such as a triangle, square, ellipsoid, or other shape, may be used. The apexes of the concave portions of the inner surface  1462  may define depressions  1468  while the midpoint of the lines between each adjacent pair of apexes may define protrusions  1466 . The outer surface  1460 , as shown in  FIG. 14 , may be substantially uniform. The plurality of protrusions  1466  and/or depressions  1468  are shown in  FIG. 14  as generally uniformly distributed about the inner circumference of the inner surface  1462 . 
     The outer surface  1460  and the inner surface  1462  may define a plurality of wall thicknesses. For example, the outer surface  1460  and the inner surface  1462  may define a first wall thickness  1464   a  between the outer surface  1460  and the inner surface  1462  about a protrusion  1466  (i.e. at a midpoint of a line between two adjacent apexes). In another example, the outer surface  1460  and the inner surface  1462  may define a second wall thickness  1464   b  between the outer surface  1460  and the inner surface  1462  about a depression  1468  (i.e. at an apex of the concave portion). 
     The irregular wall design may define a plurality of inner and/or outer dimensions. For example, an inner dimension  1462   a , which happens to be the smallest inner diameter, may be formed through a longitudinal axis between the apexes of two protrusions  1466 . In another example, another inner dimension  1462   b , which happens to be the largest inner diameter, may be formed through a longitudinal axis between the apexes of two depressions  1468 . An outer dimension  1460   a  may also be defined. 
     The irregular wall design formed by the protrusions  1466  and depressions  1468 , in the present embodiment, may minimize friction between the inner surface  1462  of the introducer sheath  1410  and a medical device, such as a closure device delivery apparatus (not shown), to be inserted into the introducer sheath  1410 . 
       FIG. 15  shows a portion of an introducer sheath  1510  illustrating an exemplary cross-section (for example, about line  1 C- 1 C of  FIG. 1A , line  2 B- 2 B of  FIG. 2A , or line  3 B- 3 B of  FIG. 3A ) of at least a portion of a single lumen introducer sheath  1510 . The cross-section of the introducer sheath  1510  of this embodiment may be at least partially functionally similar to that of the cross-sections of the introducer sheaths,  10 ,  110 ,  210 ,  1210 ,  1310 ,  1410 ,  1610  described herein, wherein certain features will not be described in relation to this embodiment wherein those components may function in the manner as described above and are hereby incorporated into this alternative embodiment described below. Like structures and/or components are given like reference numerals. The cross-section of  FIG. 15  may extend along at least a portion of the length of the introducer sheath  1510 , such as is shown in  FIGS. 12B  and/or  13 B and/or may vary in axial alignment with the longitudinal axis. 
     Although the present embodiment is described with respect to a cutaway cross-section of the introducer sheath  1510 , the cross-section may be uniform and/or nonuniform along a length of the introducer sheath, may be uniformly and/or nonuniformly axially oriented with respect to a longitudinal axis, may be otherwise oriented, or combinations thereof. 
     The irregular wall surface may be formed as described herein. For example, the introducer sheath  1510  may be formed by injection molding and/or other processes. 
     The introducer sheath  1510  may include an outer surface  1560  and an inner surface  1562 . The inner surface  1562 , in the present embodiment, may generally take the form of an Reuleaux triangle. Other shapes, such as a triangle, square, ellipsoid, or other shape may be used. The apexes of the triangle of the inner surface  1562  may define depressions  1568  while the midpoint of the curves between each adjacent pair of apexes may define protrusions  1566 . The outer surface  1560 , as shown in  FIG. 15 , may be substantially uniform. The plurality of protrusions  1566  and/or depressions  1568  are shown in  FIG. 15  as generally uniformly distributed about the inner circumference of the inner surface  1562 . 
     The outer surface  1560  and the inner surface  1562  may define a plurality of wall thicknesses. For example, the outer surface  1560  and the inner surface  1562  may define a first wall thickness  1564   a  between the outer surface  1560  and the inner surface  1562  about a protrusion  1566  (i.e. at a midpoint of the curve between two adjacent apexes). In another example, the outer surface  1560  and the inner surface  1562  may define a second wall thickness  1564   b  between the outer surface  1560  and the inner surface  1562  about a depression  1568  (i.e. at an apex). 
     The irregular wall design may define a plurality of inner and/or outer dimensions. For example, an inner dimension  1562   a  may be formed through a longitudinal axis between an apex of a protrusion  1566  and an apex of a depression  1568 . An outer dimension  1560   a  may also be defined. 
     The irregular wall design formed by the protrusions  1566  and depressions  1568 , in the present embodiment, may minimize friction between the inner surface  1562  of the introducer sheath  1510  and a medical device, such as a closure device delivery apparatus (not shown), to be inserted into the introducer sheath  1510 . 
     Referring generally to  FIGS. 16A and 16B ,  FIG. 16A  shows a portion of an introducer sheath  1610  illustrating an exemplary cross-section (for example, about line  1 C- 1 C of  FIG. 1A , line  2 B- 2 B of  FIG. 2A , or line  3 B- 3 B of  FIG. 3A ) of at least a portion of a plural lumen introducer sheath  1610 . The cross-section of the introducer sheath  1610  of this embodiment may be at least partially functionally similar to that of the cross-sections of the introducer sheaths,  10 ,  110 ,  210 ,  1210 ,  1310 ,  1410 ,  1510  described herein, wherein certain features will not be described in relation to this embodiment wherein those components may function in the manner as described above and are hereby incorporated into this alternative embodiment described below. Like structures and/or components are given like reference numerals. As shown in  FIG. 16B , the cross-section of  FIG. 16A  may extend along at least a portion of the length of the introducer sheath  1610 . 
     Although the present embodiment is described with respect to a cutaway cross-section of the introducer sheath  1610 , the cross-section may be uniform and/or nonuniformly along a length of the introducer sheath, may be uniformly and/or nonuniformly axially oriented with respect to a longitudinal axis, may be otherwise oriented, or combinations thereof. 
     The irregular wall surface may be formed as described herein. For example, the introducer sheath  1610  may be formed by injection molding and/or other processes. 
     The introducer sheath  1610  may include an outer surface  1660  and a plurality of inner surfaces  1662 ,  1662 ′. The inner surfaces  1662 ,  1662 ′ may include a plurality of protrusions  1666 ,  1666 ′ and/or depressions  1668 ,  1668 ′ with a substantially uniform outer surface  1662 . Although the outer surface  1660 , as shown in  FIGS. 16A and 16B , is shown without a substantially circular cross section, the outer surface  1660  may be generally smooth and/or radiused. A smooth and/or radiused outer surface  1660  may facilitate conforming to an atheriotomy or other insertion site. In other embodiments, the inner surfaces  1662 ,  1662 ′ may include a plurality of protrusions  1666 ,  1666 ′ and/or depressions  1668 ,  1668 ′ and/or may be free of protrusions  1666 , 1666 ′ and/or depressions  1668 , 1668 ′. 
     The protrusions and/or depressions in this or other embodiments may trace a linear and/or non-linear path along the length of the sheath. For example, the protrusions and/or depressions may follow a linear path along the longitudinal axis of the sheath for a portion of the sheath and then follow a non-linear or other path for another portion of the sheath. 
     The irregular wall design formed by the protrusions  1666 ,  1666 ′ and depressions in the present embodiment, may minimize friction between the inner surface  1662  of the introducer sheath  1610  and a medical device, such as a closure device delivery apparatus (not shown), to be inserted into the introducer sheath  1610  and/or between the outer surface  1660  of the introducer sheath  1610  and tissue which the sheath  1610  may contact, such tissue near an opening in a body lumen (not shown), through which the introducer sheath  1610  may be inserted. 
     The first inner surface  1662 , in the present embodiment, may generally take the form of an interior gear, similar to the shape shown in  FIG. 12A . Other shapes, such as a triangle, square, ellipsoid, or other shape may be used. The outer surface  1660 , as shown in  FIG. 16A , may be substantially uniform. The plurality of protrusions  1666  and/or depressions  1668  in the first interior surface  1632  are shown in  FIG. 16A  as generally uniformly distributed about the inner circumference of the first inner surface  1662 . 
     The second inner surface  1662 ′, in the present embodiment, may generally take the form of an octagonal shape with rounded concave portions at each apex. Other shapes, such as a triangle, square, ellipsoid, or other shape may be used. The apexes of the concave portions of the second inner surface  1662 ′ may define depressions  1668 ′ while the midpoint of the lines between each adjacent pair of apexes may define protrusions  1666 ′. The plurality of protrusions  1666 ′ and/or depressions  1668 ′ are shown in  FIG. 16A  as generally uniformly distributed about the inner circumference of the first inner surface  1662 ′. 
     The outer surface  1660  and the inner surfaces  1662 ,  1662 ′ may define a plurality of wall thicknesses. For example, the outer surface  860  and the first inner surface  1662  may define a first wall thickness  1664   a  between the outer surface  1660  and the inner surface  1662  about a protrusion  1666  and/or the outer surface  1660  and the second inner surface  1662 ′ may define a first wall thickness  1664   a ′ between the outer surface  1660  and the second inner surface  1662 ′ about a protrusion  1666 ′. In another example, the outer surface  1660  and the first inner surface  1662  may define a second wall thickness  1664   b  between the outer surface  1660  and the first inner surface  1662  about a depression  1668  and/or the outer surface  1660  and the second inner surface  1662 ′ may define a second wall thickness  1664   b ′ between the outer surface  1660  and the second inner surface  1662 ′ about a depression  1668 ′. 
     The irregular wall design may define a plurality of inner and/or outer dimensions. For example, a first inner dimension  1662   a  of the first inner surface  1662 , which happens to be the smallest inner diameter within the first inner surface  1662 , may be formed through a longitudinal axis between two protrusions  1666  and/or a first inner dimension  1662   a ′ of the second inner surface  1662 ′, which happens to be the smallest inner diameter within the second inner surface  1662 ′, may be formed through a longitudinal axis between two protrusions  1666 ′. In another example, a second inner dimension  1662   b  of the first inner surface  1662 , which happens to be the largest inner diameter of the first inner surface  1662 , may be formed through a longitudinal axis between two depressions  1668  and/or a second inner dimension  1662   b ′ of the second inner surface  1662 ′, which happens to be the largest inner diameter of the second inner surface  1662 ′, may be formed through a longitudinal axis between two depressions  1668 ′. An outer dimension  1660   a  may also be defined. 
     The irregular wall design formed by the protrusions  1666 ,  1666 ′ and depressions  1668 ,  1668 ′, in the present embodiment, may minimize friction between the inner surfaces  1662 ,  1662 ′ of the introducer sheath  1610  and a medical device, such as a closure device delivery apparatus (not shown), to be inserted into the introducer sheath  1610 . 
     The irregular wall design may facilitate splitting of one or more of the inner surfaces  1662 ,  1662 ′ and/or the outer surface  1660 . For example as a part of a forming process, such as injection molding, a slit and/or other weakening of the wall of one or more of the inner surfaces  1662 ,  1662 ′ and/or the outer surface  1660 , such as between the two lumens, may facilitate splitting of the introducer sheath  1610 . 
     The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.