Patent Publication Number: US-2010130937-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. 11/427,306, entitled “Introducer Sheath,” filed Jun. 28, 2006, which claims the benefit of U.S. Provisional Patent Application Ser. No. 60/695,602, entitled “Introducer Sheath,” filed Jun. 30, 2005, each of the preceding are incorporated herein by reference in its entirety. 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; 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;” U.S. patent application Ser. No. ______ filed ______, and entitled “Introducer Sheath and Methods of Making,” (Attorney Docket No. 16497.13.1.1); U.S. patent application Ser. No. ______ filed ______, and entitled “Modular Introducer and Exchange Sheath,” (Attorney Docket No. 16497.13.1.3); U.S. patent application Ser. No. ______ filed ______, and entitled “Expandable Introducer Sheath to Preserve Guidewire Access,” (Attorney Docket No. 16497.14.1.1); and U.S. patent application Ser. No. ______ filed ______, and entitled “Expandable Introducer Sheaths and Methods for Manufacture and Use,” (Attorney Docket No. 16497.14.2), the disclosures of which are hereby incorporated by reference in their entireties. 
    
    
     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 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 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 are assigned to a common owner and herein incorporated by reference in their entireties. 
     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; and 
         FIG. 3C  illustrates a cross-sectional view of an alternative embodiment of a sheath in accordance with the present invention. 
         FIGS. 4A-8B  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 include 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, (“PTFE”), fluorinated ethylene propylene (“FEP”), other materials, or combinations thereof. In some embodiments, the materials are configured to have chemical resistance, crack resistance, no toxicity, Food and Drug Administration (“FDA”) compliance, non-electrical conductivity, dimensional stability, be sterilized by ethylene oxide, gamma radiation, autoclave, UV light, ozone, other configurations, or combinations thereof. 
     In addition, the selection of materials for a particular sheath can depend on a variety of factors that may 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 and/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 may include and/or be configured to receive a flexible valve member therein. The sheath may further include 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  may 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. 4A-8B  provide examples of various cross-sectional portions. 
     The elongate tubular portion  30  may extend 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  may effectively transition 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 may include a strain relief portion  48 , which may provide a more effective transition of the tubular portion  30  of the sheath  10  to the hub portion  20 . The strain relief portion  48  may be formed at the transition between the hub portion  20  and the tubular portion  30 . More particularly, the strain relief portion  48  may 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  may also be configured to provide additional support to at least the proximal end  32  of the elongate tubular portion  30  to reduce and/or 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  may 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  may 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  may include webs, extensions, other internal or external structures, or combinations thereof 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  may include a tapered portion  36  that may facilitate 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, other methods, or combinations thereof that may produce 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  may be generally uniform in cross-section over all or a portion of its length between the proximal end  22  of the hub portion  20  and 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. 4A-8B  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 , may include a feature, such as a receiving feature  26 , therein, which may be 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 . In another example, a retaining cap (not shown) may be disposed adjacent to or within the proximal end of the hub portion  20  may aid the receiving feature  26  to retain the flexible valve member  50  within the hub portion  20 . In a further example, the valve member  50  may 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  may provide a sealed hub portion  20 . Stated another way, the valve member  50  may be self sealing once inserted or formed in the hub portion  20  to limit fluid escaping from the body lumen. 
     The valve member  50  may be one of a variety of different seals, including 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  may provide a fluid tight seal with or against the medical instrument. Thus, leakage of blood other bodily fluids, and/or fluids such as unwanted air may be inhibited and/or prevented from entering 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 a 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, may be added and/or withdrawn through the port member  42 . The port member  42  may be 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 may include a member having a luer lock configuration. It will be understood that other types of ports can perform the desired function. 
     A retention recess or ring  46 , as shown in  FIG. 1A  may be formed on the outer surface or wall  44  of the hub portion  20 . The recess or ring  46  may be used to secure a cap (not shown) to the sheath  10 . The recess or ring  46  may 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  may have tapered wall, curved wall, combinations of generally parallel, tapered, or curved walls, 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/or 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, other portions, or combinations thereof can be controlled and/or 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  may vary and/or may depend on the intended use of the sheath  10 . Because the hub portion  20  and the tubular portion  30  may be 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 (such as those shown in  FIGS. 4A-8B ) are within the scope of the invention. Further, the lumen  28  may also have an alternative cross-sectional shape other than generally 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  may 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 may receive a medical device or instrument to be inserted through the valve member  150  and/or the lumen  128  may secure the valve member  150 . The proximal end  174  of the retaining cap  170  may align with, overlap, or be recessed relative to the proximal end  122  depending upon the particular configuration of the end cap  170 . 
     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  may be at least one longitudinal groove  164 , and more generally a geometric pattern of grooves, channels, recesses, depressions, or other structures, that may extend along an axis parallel to axis extending through the center of the sheath, and may be centered within the lumen  128 . With one or more longitudinal grooves  164 , the longitudinal grooves  164  can be formed in various patterns and/or 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 tubular 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, other molding and/or fabrication processes, or combinations thereof. As a result, the geometric pattern may be automatically formed during the manufacturing process and additional steps or acts may be unnecessary 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  may include a hub portion  220  having a proximal end  222  and a distal end  224 . The sheath  210  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 herein, 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  may 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 may 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 , protrusion, depression, or combinations thereof may be disposed within at least a portion of the tubular portion  230 , with one being shown in the illustrated configuration. This groove  280  may receive an insert  282  to provide certain characteristics and properties to the tubular portion  230 . For instance, the insert  282  may provide structural stiffness and/or kink resistance to the tubular portion  230  and/or the introducer sheath  210 . The groove  280  may extend between (i) the outer surface or wall  260  and the inner surface or wall  262 , (ii) the outer surface or wall  260  toward the inner surface or wall  262 , (iii) the inner surface or wall  262  toward the outer surface or wall  260 , or combinations thereof. 
     As shown in  FIGS. 3A and 3B , the groove  280  and/or the insert  282  may extend from the tubular portion  230  to the hub portion  220 . Generally, the groove  280  and/or the insert  282  may 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  and/or the tubular portion  230 . In other embodiments, one or more grooves  280  and/or inserts  282  may be formed in the sheath  210 . Although reference is made to a groove, herein other geometric patterns or configurations of channels, recess, holes, other structures, or combinations thereof formed in the sheath can be used. For example, irregular wall patterns, such as those shown in  FIGS. 4A-8B , may 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  may be formed in the groove  280  in a variety of manners. In one configuration, the groove  280  may be formed as part of the initial molding process. For instance, the sheath  210  may undergo a first injection molding process where the hub portion  220  and elongated portion  230  may be 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   a  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   a  to form the insert  282 . Alternatively, the inner surface  262  of the elongated portion  230  may have one or more variations, at least one of which may be defined by the insert  282  within the groove  280   a . For instance, during the process of applying or depositing the second material the mold defining the boundaries for the second material  282  may include the desired pattern of the portion of the inner wall or surface  262  associated with the insert  282 . 
     As described herein, 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 may split along a portion of the interface between the first and second materials or through the second material in response to an adequate applied force, including relatively small applied forces. 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   a  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   a  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   a  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 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/or 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 and/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 and/or insert  282  can be used to stiffen or weaken the overall tubular portion  230  and/or assist in splitting the sheath during use. For example, the second material and/or insert  282  may provide stiffness and/or cause the tubular portion  230  to split at the groove and/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, patterns, lengths, or combinations thereof. Additionally, the groove may include a geometric feature formed along the length thereof, wherein the second material and/or insert  282  may at least partially 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   b  may include sub-grooves  284  that may extend outwardly from the main portion of the groove  280   b . These sub-grooves  284  may receive and/or be filled with the second material that may form the insert  282  during the injection molding process and/or provide a mechanical connection and/or coupling between the two materials and/or between the groove  280   b  and/or the insert  282 . As such, the sub-grooves  284 , together with the insert  282  and/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  may be mounted and/or coupled together through both the bonding of the two materials and/or the mechanical coupling of the interlocking features formed in the groove  280   b  and/or the insert  282 . 
     It will be understood that in another configuration, the insert  282  may be formed separately from the remainder of the sheath  210 . The insert  282  may then be mounted and/or coupled to the groove  280   b  during subsequent processing. For instance, the insert  282  can be mounted and/or coupled to the groove  280   b  using adhesives, thermal or chemical bonding, other techniques, or combinations thereof to mount and/or couple similar and/or dissimilar medical grade materials. Further, the insert  282  may mount and/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  and/or other mechanical structures that facilitate mechanical coupling between two components may vary and/or accommodate many desired purposes. In some instances, the formation and/or filling of the groove  280   b  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 may limit the first material from separating from the second material without tearing or shearing. This may 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  may extend between a proximal end  232  and 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 may 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  and/or other geometric pattern, it is further contemplated that more than two materials may be utilized to form the introducer sheath and/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 and 4B , there is shown a portion of an introducer sheath  410 .  FIG. 4A  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  410 . 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  410  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  510 ,  610 ,  710 ,  810  described herein and shown in  FIGS. 5A-8B . As shown in  FIG. 4B , the cross-section of  FIG. 4A  may extend along at least a portion of the length of the introducer sheath  410 . 
     Although the present embodiment is described with respect to a cutaway cross-section of the introducer sheath  410 , 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  410  may be formed by injection molding and/or other processes. 
     The introducer sheath  410  may include an outer surface  460  and an inner surface  462 . The outer surface  460  and/or inner surface  462  may include a plurality of protrusions  466  and/or depressions  468  with a substantially uniform outer surface  462 . In other embodiments, the outer surface  460  and/or the inner surface  462  may include a plurality of protrusions  466  and/or depressions  468 . 
     The plurality of protrusions  466  and/or depressions  468  may be generally uniformly distributed about the inner circumference of the inner surface  462 . In other embodiments, the plurality of protrusions  466  and/or depressions  468  may be at least partially randomly distributed about the inner or outer circumference of the inner and/or outer surface  462 . 
     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  460  and the inner surface  462  may define a plurality of wall thicknesses. For example, the outer surface  460  and the inner surface  462  may define a first wall thickness  464   a  between the outer surface  460  and the inner surface  462  about a protrusion  466 . In another example, the outer surface  460  and the inner surface  462  may define a second wall thickness  464   b  between the outer surface  460  and the inner surface  462  about a depression  468 . 
     The irregular wall design may define a plurality of inner and/or outer dimensions. For example, an inner dimension  462   a , which happens to be the smallest inner diameter, may be formed through a longitudinal axis between the apexes of two protrusions  466 . In another example, another inner dimension  462   b , which happens to be the largest inner diameter, may be formed through a longitudinal axis between the apexes of two depressions  468 . An outer dimension  460   a  may also be defined. 
     The irregular wall design formed by the protrusions  466  and depressions  468 , in the present embodiment, may minimize friction between the inner surface  462  of the introducer sheath  410  and a medical device, such as a closure device delivery apparatus (not shown), to be inserted into the introducer sheath  410 . 
     Referring generally to  FIGS. 5A and 5B , there is shown a portion of an introducer sheath  510 .  FIG. 5A  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  510 . The cross-section of the introducer sheath  510  of this embodiment may be at least partially functionally similar to that of the cross-sections of the introducer sheaths,  10 ,  110 ,  210 ,  410 ,  610 ,  710 ,  810  described herein and shown in  FIGS. 1A-4B  and  6 - 8 B 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. As shown in  FIG. 5B , the cross-section of  FIG. 5A  may extend along at least a portion of the length of the introducer sheath  510  at a non-parallel angle to the longitudinal axis of the sheath  510 . 
     Although the present embodiment is described with respect to a cutaway cross-section of the introducer sheath  510 , 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  510  may be formed by injection molding and/or other processes. 
     The introducer sheath  510  may include an outer surface  560  and an inner surface  562 . The inner surface  562 , 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  562  may define depressions  568  while the midpoint of the lines between each adjacent pair of apexes may define protrusions  566 . The outer surface  560 , as shown in  FIG. 5A , may be substantially uniform. The plurality of protrusions  566  and/or depressions  568  are shown in  FIG. 5A  as generally uniformly distributed about the inner circumference of the inner surface  562 . 
     The outer surface  560  and the inner surface  562  may define a plurality of wall thicknesses. For example, the outer surface  560  and the inner surface  562  may define a first wall thickness  564   a  between the outer surface  560  and the inner surface  562  about a protrusion  566  (i.e. at a midpoint of a line between two adjacent apexes). In another example, the outer surface  560  and the inner surface  562  may define a second wall thickness  564   b  between the outer surface  560  and the inner surface  562  about a depression  568  (i.e. at an apex). 
     The irregular wall design may define a plurality of inner and/or outer dimensions. For example, an inner dimension  562   a , which happens to be the smallest inner diameter, may be formed through a longitudinal axis between the apexes of two protrusions  566 . In another example, another inner dimension  562   b , which happens to be the largest inner diameter, may be formed through a longitudinal axis between the apexes of two depressions  568 . An outer dimension  560   a  may also be defined. 
     The irregular wall design formed by the protrusions  566  and depressions  568 , in the present embodiment, may minimize friction between the inner surface  562  of the introducer sheath  510  and a medical device, such as a closure device delivery apparatus (not shown), to be inserted into the introducer sheath  510 . 
     Referring to  FIG. 6 , there is shown a portion of an introducer sheath  610  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  610 . The cross-section of the introducer sheath  610  of this embodiment may be at least partially functionally similar to that of the cross-sections of the introducer sheaths,  10 ,  110 ,  210 ,  410 ,  510 ,  710 ,  810  described herein and shown in  FIGS. 1A-5B  and  7 A- 8 B 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 cross-section of  FIG. 6  may extend along at least a portion of the length of the introducer sheath  610 , such as is shown in  FIGS. 4B  and/or  5 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  610 , 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  610  may be formed by injection molding and/or other processes. 
     The introducer sheath  610  may include an outer surface  660  and an inner surface  662 . The inner surface  662 , 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  662  may define depressions  668  while the midpoint of the lines between each adjacent pair of apexes may define protrusions  666 . The outer surface  660 , as shown in  FIG. 6 , may be substantially uniform. The plurality of protrusions  666  and/or depressions  668  are shown in  FIG. 6  as generally uniformly distributed about the inner circumference of the inner surface  662 . 
     The outer surface  660  and the inner surface  662  may define a plurality of wall thicknesses. For example, the outer surface  660  and the inner surface  662  may define a first wall thickness  664   a  between the outer surface  660  and the inner surface  662  about a protrusion  666  (i.e. at a midpoint of a line between two adjacent apexes). In another example, the outer surface  660  and the inner surface  662  may define a second wall thickness  664   b  between the outer surface  660  and the inner surface  662  about a depression  668  (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  662   a , which happens to be the smallest inner diameter, may be formed through a longitudinal axis between the apexes of two protrusions  666 . In another example, another inner dimension  662   b , which happens to be the largest inner diameter, may be formed through a longitudinal axis between the apexes of two depressions  668 . An outer dimension  660   a  may also be defined. 
     The irregular wall design formed by the protrusions  666  and depressions  668 , in the present embodiment, may minimize friction between the inner surface  662  of the introducer sheath  610  and a medical device, such as a closure device delivery apparatus (not shown), to be inserted into the introducer sheath  610 . 
       FIG. 7  shows a portion of an introducer sheath  710  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  710 . The cross-section of the introducer sheath  710  of this embodiment may be at least partially functionally similar to that of the cross-sections of the introducer sheaths,  10 ,  110 ,  210 ,  410 ,  510 ,  610 ,  810  described herein and shown in  FIGS. 1A-6  and  8 A- 8 B 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 cross-section of  FIG. 7  may extend along at least a portion of the length of the introducer sheath  710 , such as is shown in  FIGS. 4B  and/or  5 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  710 , 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  710  may be formed by injection molding and/or other processes. 
     The introducer sheath  710  may include an outer surface  760  and an inner surface  762 . The inner surface  762 , 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  762  may define depressions  768  while the midpoint of the curves between each adjacent pair of apexes may define protrusions  766 . The outer surface  760 , as shown in  FIG. 7 , may be substantially uniform. The plurality of protrusions  766  and/or depressions  768  are shown in  FIG. 7  as generally uniformly distributed about the inner circumference of the inner surface  762 . 
     The outer surface  760  and the inner surface  762  may define a plurality of wall thicknesses. For example, the outer surface  760  and the inner surface  762  may define a first wall thickness  764   a  between the outer surface  760  and the inner surface  762  about a protrusion  766  (i.e. at a midpoint of the curve between two adjacent apexes). In another example, the outer surface  760  and the inner surface  762  may define a second wall thickness  764   b  between the outer surface  760  and the inner surface  762  about a depression  768  (i.e. at an apex). 
     The irregular wall design may define a plurality of inner and/or outer dimensions. For example, an inner dimension  762   a  may be formed through a longitudinal axis between an apex of a protrusion  766  and an apex of a depression  768 . An outer dimension  760   a  may also be defined. 
     The irregular wall design formed by the protrusions  766  and depressions  768 , in the present embodiment, may minimize friction between the inner surface  762  of the introducer sheath  710  and a medical device, such as a closure device delivery apparatus (not shown), to be inserted into the introducer sheath  710 . 
     Referring generally to  FIGS. 8A and 8B ,  FIG. 8A  shows a portion of an introducer sheath  810  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  810 . The cross-section of the introducer sheath  810  of this embodiment may be at least partially functionally similar to that of the cross-sections of the introducer sheaths,  10 ,  110 ,  210 ,  410 ,  510 ,  610 ,  710  described herein and shown in  FIGS. 1A-7  and  9 A- 8 B 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. As shown in  FIG. 8B , the cross-section of  FIG. 8A  may extend along at least a portion of the length of the introducer sheath  810 . 
     Although the present embodiment is described with respect to a cutaway cross-section of the introducer sheath  810 , 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  810  may be formed by injection molding and/or other processes. 
     The introducer sheath  810  may include an outer surface  860  and a plurality of inner surfaces  862 ,  862 ′. The inner surfaces  862 ,  862 ′ may include a plurality of protrusions  866 ,  866 ′ and/or depressions  868 ,  868 ′ with a substantially uniform outer surface  862 . Although the outer surface  860 , as shown in  FIGS. 8A and 8B , is shown without a substantially circular cross section, the outer surface  860  may be generally smooth and/or radiused. A smooth and/or radiused outer surface  860  may facilitate conforming to an atheriotomy or other insertion site. In other embodiments, the inner surfaces  862 ,  862 ′ may include a plurality of protrusions  866 ,  866 ′ and/or depressions  868 ,  868 ′ and/or may be free of protrusions  866 ,  866 ′ and/or depressions  868 ,  868 ′. 
     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  866 ,  866 ′ and depressions  868 ,  868 ′, in the present embodiment, may minimize friction between the inner surface  862  of the introducer sheath  810  and a medical device, such as a closure device delivery apparatus (not shown), to be inserted into the introducer sheath  810  and/or between the outer surface  860  of the introducer sheath  810  and tissue which the sheath  810  may contact, such tissue near an opening in a body lumen (not shown), through which the introducer sheath  810  may be inserted. 
     The first inner surface  862 , in the present embodiment, may generally take the form of an interior gear, similar to the shape shown in  FIG. 4A . Other shapes, such as a triangle, square, ellipsoid, or other shape may be used. The outer surface  860 , as shown in  FIG. 8A , may be substantially uniform. The plurality of protrusions  866  and/or depressions  868  in the first interior surface  832  are shown in  FIG. 8A  as generally uniformly distributed about the inner circumference of the first inner surface  862 . 
     The second inner surface  862 ′, 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  862 ′ may define depressions  868 ′ while the midpoint of the lines between each adjacent pair of apexes may define protrusions  866 ′. The plurality of protrusions  866 ′ and/or depressions  868 ′ are shown in  FIG. 8A  as generally uniformly distributed about the inner circumference of the first inner surface  862 ′. 
     The outer surface  860  and the inner surfaces  862 ,  862 ′ may define a plurality of wall thicknesses. For example, the outer surface  860  and the first inner surface  862  may define a first wall thickness  864   a  between the outer surface  860  and the inner surface  862  about a protrusion  866  and/or the outer surface  860  and the second inner surface  862 ′ may define a first wall thickness  864   a ′ between the outer surface  860  and the second inner surface  862 ′ about a protrusion  866 ′. In another example, the outer surface  860  and the first inner surface  862  may define a second wall thickness  864   b  between the outer surface  860  and the first inner surface  862  about a depression  868  and/or the outer surface  860  and the second inner surface  862 ′ may define a second wall thickness  864   b ′ between the outer surface  860  and the second inner surface  862 ′ about a depression  868 ′. 
     The irregular wall design may define a plurality of inner and/or outer dimensions. For example, a first inner dimension  862   a  of the first inner surface  862 , which happens to be the smallest inner diameter within the first inner surface  862 , may be formed through a longitudinal axis between two protrusions  866  and/or a first inner dimension  862   a ′ of the second inner surface  862 ′, which happens to be the smallest inner diameter within the second inner surface  862 ′, may be formed through a longitudinal axis between two protrusions  866 ′. In another example, a second inner dimension  862   b  of the first inner surface  862 , which happens to be the largest inner diameter of the first inner surface  862 , may be formed through a longitudinal axis between two depressions  868  and/or a second inner dimension  862   b ′ of the second inner surface  862 ′, which happens to be the largest inner diameter of the second inner surface  862 ′, may be formed through a longitudinal axis between two depressions  868 ′. An outer dimension  860   a  may also be defined. 
     The irregular wall design formed by the protrusions  866 ,  866 ′ and depressions  868 ,  868 ′, in the present embodiment, may minimize friction between the inner surfaces  862 ,  862 ′ of the introducer sheath  810  and a medical device, such as a closure device delivery apparatus (not shown), to be inserted into the introducer sheath  810 . 
     The irregular wall design may facilitate splitting of one or more of the inner surfaces  862 ,  862 ′ and/or the outer surface  860 . 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  862 ,  862 ′ and/or the outer surface  860 , such as between the two lumens, may facilitate splitting of the introducer sheath  810 . 
     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.