Abstract:
An improved splittable medical device introducer designed to introduce a medical device such as a lead or catheter, into a patient&#39;s vasculature without loss of blood or the introduction of air is described. The introducer assembly is designed to easily separate in a smooth tactile manner without disrupting placement of the medical device during removal of the introducer. The introducer is composed of a fluoropolymeric material which combined with an internal stress confining structure propagates a stress initiated by the operator that tears the entire introducer assembly in two without creating a jagged separated edge.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority from U.S. provisional Application Ser. No. 61/107,447, filed Oct. 22, 2008. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention generally relates to introducers and introducing assemblies. Specifically, the present invention is directed to a splittable introducer with a hemostatic valve. 
         [0004]    2. Prior Art 
         [0005]    Introducer devices are employed for inserting catheters, guide wires, or other medical devices into patients. A typical procedure provides for insertion of a needle into the vasculature of a patient. After insertion of the needle, a guide wire is inserted through the needle, and the needle is removed. A dilator and sheath are inserted over the guide wire, and the dilator and guide wire may be removed leaving the sheath protruding from the patient&#39;s vein. A diagnostic or therapeutic catheter (e.g. a central venous access catheter) or guide wire or other medical device, is then inserted through the sheath into the patient. 
         [0006]    Peelable sheaths that can be peeled off of a catheter are available. Examples of these types of sheaths are shown in U.S. Pat. Nos. 5,125,904 and 5,312,355, both to Lee. As shown in  FIGS. 1 and 2 , the Lee patents describe a peelable or splittable valved introducer sheath assembly  10  comprising a splittable sheath  12  connected to a splittable hemostatic valve assembly  14 . A sidearm  16  provides for flushing the introducer as needed. The valve assembly  14  includes a valve membrane  18  ( FIG. 2 ) through which a lead or catheter may be introduced into a patient&#39;s vasculature without leakage. Both the sheath  12  and valve assembly  14  are splittable or have a peel-away construction that permits their removal while leaving the lead or catheter in place. This peel-away feature is made possible by a pair of longitudinal score lines  20  and  22  that have a V-shaped cross section and a depth part-way through the thickness of the respective sheath  12  and valve assembly  14 . The score lines  20 ,  22  are positioned diametrically opposed to each other and run the entire axial length of the sheath  12  and valve assembly  14 . At the end of an operation, the physician grasps the opposing flange portions  24  and  26  to peel the sheath  12  and valve assembly  14  apart as the sheath is pulled out of the vasculature, leaving the lead in place. 
         [0007]    According to the prior art, in addition to the V-shaped groove the score line can be a linear perforation, linear slit, linear slot, linear tab, linear severing, linear weakening or linear tear that runs partially or completely along the axial length of the sheath  12  and valve assembly  14  to permit the entire length of introducer sheath  10  to be manually separated. Of course, the score line cannot be entirely through the thickness of the sheath  12  and valve assembly  14 . That would create a leak and defeat the hemostatic function of the splittable introducer and valve assembly. 
         [0008]    While not described in the Lee patents, it is know that the sheath  12  and valve assembly  14  are made of a PEBAX polymeric material. Even with the score line structure, the sheath  12  and valve assembly  14  typically experience considerable resistance to being pulled apart and separated.  FIG. 2  is an illustration showing a separated valved introducer according to Lee having a “saw-tooth” edge  26 . The problem is that the score lines  20 ,  22  provide the physician with a jerking tactile feel that makes it difficult to separate the two halves of the sheath  12  and valve assembly  14  from each other. This means that many physicians are reluctant to use the Lee valved introducer. The concern is that as the sheath and valve assembly are being separated, the jerking, saw-tooth manner in which that occurs can inadvertently move the lead or catheter out of its proper position. This, of course, is completely unacceptable. 
         [0009]    Accordingly, a valved introducer is needed that readily provides for moving a medical device, such as a lead or a dialysis catheter, into the vasculature of a patent and that is subsequently removable from the vasculature in a smooth tactile manner without disrupting placement of the medical device. The introducer must also seal around the medical device to substantially prevent blood lose there through and air embolism into the vasculature. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a perspective view of an introducer apparatus  10  constructed in accordance to the prior art. 
           [0011]      FIG. 2  is a perspective view of the prior art introducer apparatus  10  after having been separated into two halves along the score line  20  shown in  FIG. 1 . 
           [0012]      FIG. 3  is a front elevational view, partly in cross section, of a valved introducer assembly  100  according to the present invention. 
           [0013]      FIG. 4  is a perspective view, partly broken away, of the valved introducer assembly of the present invention shown in FIG. 
           [0014]      FIG. 4A  is a partial exploded view of the valved introducer assembly  100  of the present invention. 
           [0015]      FIG. 5  is a side elevational view of the valved introducer assembly  10  of the present invention after the sheath  102  has been partially torn in half. 
           [0016]      FIG. 6  is a perspective view, partly broken-away, of a preferred embodiment of a stress confining structure  200  for the proximal section  102 B of the sheath  102  in the form of an inlet with a diametrically opposed circular cutout  166  and circular perforations  116 . 
           [0017]      FIG. 6A  is an enlarged overview perspective of the proximal end of the confining structure  200  of  FIG. 6 . 
           [0018]      FIG. 6B  is an enlarged cross section of the confining structure  200  along line  6 B- 6 B of  FIG. 6A   
           [0019]      FIG. 7  is a perspective view, partly broken-away, of a preferred embodiment of a stress confining structure  200  for the proximal section  102 BG of the sheath  102  in the form of an inlet with diametrically opposed V-shaped inlets  108 . 
           [0020]      FIG. 7A  is an enlarged overview perspective of the proximal end of the stress confining structure  200  of  FIG. 7 . 
           [0021]      FIG. 7B  is an enlarged cross section of the confining structure  200  along line  7 B- 7 B of  FIG. 7A   
           [0022]      FIGS. 8 to 17  illustrate alternate embodiments of stress confining structures  200  for the sheath  102  according to the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0023]      FIGS. 3 to 6B  illustrate one preferred embodiment of a valved introducer assembly  100  according to the present invention. The valved introducer assembly  100  comprises a sheath  102  seal connected to a valve housing  104  supporting a valve membrane  106 . The sheath  102  is an elongate member having a sidewall  102 A extending along a longitudinal axis  105  from a proximal section  102 B to a distal end  102 C. The thickness of the sidewall  102 A including the proximal section  102 B extending to the distal end  102 C is from about 0.001 inches to about 0.050 inches 
         [0024]    A lumen or passage  110  provides for open communication along the entire length of the sheath  102  and into the valve housing  104 . This lumen  110  allows for a medical device, such as a lead or catheter, to be advanced through the assembly  100 . The lumen  110  preferably has a diameter from about 0.05 inches to about 0.50 inches. 
         [0025]    The valve housing  104  comprises a lower valve body  104 A and an upper cap  104 B. The lower valve body  104 A is over-molded onto the proximal sheath section  102 B and includes spaced apart wings  112  and  114  which give the valve housing  104  a butterfly appearance. 
         [0026]    In the preferred embodiment shown in  FIGS. 3 to 6B , the proximal sheath section  102 B comprises a cylindrical portion  102 D leading to a frusto-conical portion  102 E that extends downwardly and inwardly toward the remainder of the sheath sidewall  102 A to the distal end  102 C thereof. In the alternative, the proximal section  102 B can have a similar diameter as the remainder of the sheath sidewall  102 A. 
         [0027]    The cylindrical sidewall portion  102 D includes a stress confining structure  200  for the sheath  102  in the form of diametrically opposed circular perforations  166  (only one shown) that penetrate completely through the thickness thereof. While the perforations  166  are preferably circular, they can be of other shapes including, but not limited to, triangular, diamond-shaped, squared or star-shaped. 
         [0028]    As will be described in detail hereinafter, the perforations  166  help propagate splitting of the sheath  102  once the valve housing  104  has been at least partially split apart. The perforations  166  have a preferred diameter ranging from about 0.01 inches to about 0.10 inches and are located relatively close to the proximal end of the cylindrical portion  102 D. This distance is labeled as “X” in  FIG. 6  and preferably ranges from about 0.01 inches to about 0.05 inches from the proximal end of the cylindrical portion  102 D. 
         [0029]    As particularly shown in  FIGS. 6 to 6B , the proximal section  102 B has a diameter ranging from about 0.01 inches to about 0.50 inches. The length of the cylindrical portion  102 D labeled as “Y” in  FIG. 6  is from about 0.1 inches to about 0.4 inches. The frusto-conical portion  102 E has a preferred length from about 0.1 inches to about 0.6 inches. The combined length of the cylindrical portion  102 D and the frusto-conical portion  102 E labeled as “Z” is from about 0.2 inches to about one inch. 
         [0030]    The cylindrical portion  102 D of the proximal sheath section  102 B includes a series of perforations  116  that are evenly spaced about the circumference thereof. These perforations  116  are in addition to the stress confining perforations  166  and are preferably circular with a diameter ranging from about 0.01 inches to about 0.05 inches. They are located relatively close to where the cylindrical portion  102 D meets the frusto-conical portion  102 E, or about 0.05 inches to about 0.3 inches from the proximal end of the cylindrical portion  102 D. When the valve body  104 A is over-molded onto the proximal sheath section  102 B, the polymeric material of the valve body fills into these perforations  116  to lock the two together. If desired, the proximal sheath section  102 B can also be surface treated to increase its rugosity and thereby enhance the sealed relationship between the valve body  104 A and the sheath  102 . 
         [0031]    The valve membrane  106  is of a relatively pliable polymeric material in the form of a disc, preferably having an oval shape, provided with a central opening  118 . The central opening  118  comprises an upper cylindrical portion  118 A leading to a bellow portion  118 B having a pleated, expansible shape which, in turn, leads to a lower cylindrical portion  118 C of a diameter preferably somewhat less than the upper cylindrical portion  118 A and the bellows  118 B. This structure allows medical devices such as leads and catheters to easily and smoothly pass through the valve membrane  106  while preventing any substantial amount of body fluids, and particularly blood, from leaking out or any appreciable amount of ambient air from leaking in. A pair of cylindrically-shaped through holes  119  is provided through the thickness of the valve membrane  106  on opposite sides of the central opening  118 . The valve membrane  106  further includes a score line  106 A. 
         [0032]    An annular ledge  120  is formed in the lower valve body  104 A and provides a seat for the valve membrane  106 . A pair of upstanding posts  120 A resides on opposite sides of a through opening  121  in the lower valve body  104 A. The posts  120 A are received in the through holes  119  to help keep the valve membrane  106  seated on the annular ledge  120 . The lower valve body  104 A includes two pairs of side-by-side protrusions  122 ,  124  located on opposite sides of the body (only the protrusions on the front side are shown in  FIG. 4 ). 
         [0033]    The valve cap  104 B comprises front and back sidewalls  126  and  128  depending from a central web  130 . The web  130  supports an upstanding tube  132  that preferably provides a Leur-type fitting. The sidewalls  126 ,  128  include side-by-side windows  134 ,  136  sized to receive the protrusions  122 ,  124 . The valve membrane  106  is then locked into position supported on the annular ledge  120  when the valve cap  1045  is snap attached to the lower valve body  104 A with the protrusions  122 ,  124  received in the respective windows  134 ,  136 . In that position, the central opening  118  of the valve membrane  106  is in axial alignment with the opening  121  in the lower valve body  104 A and the longitudinal axis of the sheath lumen  110 . The valve membrane opening  118  is a self-sealing structure that is sized to permit passage of the medical device such as the lead or catheter there through while sealing about the periphery thereof. 
         [0034]    As is well known by those skilled in the art, a dilator (not shown) received inside the lumen  110  allows for the valved introducer assembly to be introduced into the vasculature of a patient, for instance, over a guide wire (not shown). This positions the distal end  102 C of the sheath  102  inside the vasculature while the proximal section  102 B and the valve assembly  104  remain outside the patient. After the introducer assembly  10  is inserted into a patient and the dilator has been removed from the sheath  102 , other medical instruments can be easily inserted into and through the sheath  12  and introduced into the patient. All the while, the valve assembly  104  prevents blood and other body fluids from leaking out of the vasculature and outside air from getting in. 
         [0035]    Then, once the lead or catheter is properly positioned in the vasculature, the valved introducer assembly  100  of the present invention is split apart for removal from the vasculature. This is done by holding the wings  112 ,  114  between the thumb and fore finger and counter rotating them with respect to each other while slowly moving the wings further apart. The valve housing  104  including the valve membrane  106  are readily separated. This occurs at a score line  138  running along the lower valve body  104 A and the valve cap  104 B including the Leur type fitting  132  and at the score line  106 A in the valve membrane  106 . 
         [0036]    As the wings  112 ,  114  of the valve housing  104  are moved apart, the resulting halves of the valve housing begin to exert a force on the proximal section  102 A of the sheath. These forces are sufficient to tear apart the relatively short web  168  located between the proximal end  102 F of the cylindrical portion  102 D and the perforation  166 . The force generated by further manipulation of the wings  112 ,  114  is concentrated at the lower extent or distal stress point/area  166 A of each perforation of the stress confining structure  200 . This concentrated force is sufficient to cause the material of the cylindrical portion  102 D distal of the perforation  166  to sever or tear apart. The sheath of the present invention is preferably of polytetrafluoroethylene (PTFE). 
         [0037]    The preferred PTFE material for the sheath  102  has a unique molecular structure. Once a sufficient amount of force is exerted at the stress points  166 A of the stress confining structure  200 , the molecules comprising the cylindrical portion  102 E of the proximal sheath section  102 B begin to sever. Further pulling force causes the resulting tear  140  ( FIG. 5 ) to propagate in a linear manner along the entire length of the sheath sidewall  102 A to its distal end  102 B. The tear  140  is extremely straight and parallel to the longitudinal axis  105  of the sheath  102 . Importantly, the tear  140  is smooth and provides the physician with an even tactile feel that is a vast improvement over the saw-toothed tear afforded by the prior art Lee valved introducer  10 . 
         [0038]    In that respect, PTFE has a unique molecular structure that completely obviates the need for any scoring, weakening or mechanical alteration to facilitate precise, smooth and controllable splitting along the length of the sheath  102 , thereby producing separated edges  140 A after splitting that lack any perceptible “saw tooth” texture. The surfaces that are formed by splitting the sheath  102  made of PTFE, therefore, exhibit complete uniformity; they are devoid of localized variations in cross-sectional contour, thickness, surface annularity, or weakening by any means whatsoever. Further still, use of the PTFE material eliminates otherwise required steps in the manufacturing process of the prior art Lee introducer shown in  FIGS. 1 and 2  that are potential opportunities for manufacturing errors and quality variations, such as improperly formed score lines, and the like, and that could potentially lead to product failures and patient endangerment. 
         [0039]    While PTFE is the most preferred material for the sheath  102 , other fluoropolymeric materials are also contemplated. These include polyhexafluoropropylene, tetrafluoroethylene-hexafluoropropylene copolymers, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymers, polytrifluoroethylene, ethylene-tetrafluoroethylene copolymers, fluoroethylene-hydrocarbon vinyl ether copolymers, polychlorotrifluoroethylene, ethylene-chlorotrifluoroethylene copolymers, polyvinyl fluoride, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymers, fluorinated (meth)acrylate resins, 2-fluoroacrylate resins, fluorinated epoxy resins, fluorinated epoxy (meth)acrylate resins, fluorinated polyether resins, fluorinated polyimide resins, fluorinated polyester resins, fluorinated polyamide resins, fluorinated polycarbonate resins, fluorinated polyformal resins, fluorinated polyketone resins, fluorinated polyazomethine resins, fluorinated polyazole resins, and fluorinated polyallyloxysilane resins, vinylidene fluoride-hexafluoropropylene fluoroelastomer, vinylidene fluoride-tetrafluoroethylene fluoroelastomer, tetrafluoroethylene-perfluoroalkyl vinyl ether fluoroelastomer, vinylidene fluoride-tetrafluoroethylenehexafluoropropylene fluoroelastomer, vinylidene fluoride-tetrafluoroethylene-perfluoroalkyl vinyl ether fluoroelastomer, tetrafluoroethylene-perfluoroalkyl vinyl ether fluoroelastomer, propylene-tetrafluoroethylene fluoroelastomer, fluorosilicone rubber, fluorinated phosphazene rubber, fluorinated thermoplastic rubbers, and flexible fluorocarbon resins. 
         [0040]    Another preferred embodiment of a stress confining structure  200  according to the present invention is illustrated in  FIGS. 7 to 7B  and comprises diametrically opposed V-shaped inlets  108 . The V-shaped inlet  108  has a height designated as “L” in  FIG. 7  measured from the proximal end  102 F of the cylindrical portion  102 D to the stress point  108 A. The maximum width of the V-shaped inlet  108  at its mouth located at the proximal end  102 F of the sheath is designated by the distance “M”. The width N is measured as a straight line and not a circumferential distance between the two spaced apart locations  108 B and can range from a maximum being the diameter of the cylindrical sheath portion  102 D to a distance about 50% of that diameter. The height L is from about 5% to 300% of the distance M. More preferably, the height L is from about 50% to about 250% of the distance M. 
         [0041]    As is the case with the previously described perforations  166 , stresses initiated by manipulation of the wings  112 ,  114  are propagated to the point  108 A of the V-shaped stress confining structure. Further manipulation of the wing structures  112 ,  114 , causes the stresses to propagate the entire length of the sheath  102  to the distal end  102 C thereof in a smooth and even tactile manner. 
         [0042]    The present invention thus provides the proximal section  102 B of the valved introducer  100  with structures that concentrate the tearing forces created by moving the wings  112 ,  114  apart to stress confining structures located diametrically opposite each other in the sheath sidewall  102 A. The unique molecular properties of PTFE permit the separating forces concentrated at the stress point of the stress confining structures  200 , such as circular perforations  166  or the V-shaped inlets  108 , to propagate the entire length of the sheath. However, the present invention is not meant to be limited to the perforations  166  and V-shaped inlet  108 . Any structure located at the proximal section  102 B of the sheath that serves to concentrate the tearing forces to a confined area is contemplated by the scope of the present invention. 
         [0043]    Alternate embodiments include the diametrically opposed V-shaped inlets  142  shown in  FIG. 8  that are similar to the V-shaped inlets shown in  FIG. 7 , except that their troughs are somewhat radiused where the stress points  142 A are formed. 
         [0044]      FIG. 9  illustrates another embodiment of a stress confining structure for initiating a tearing separation of the sheath  102 . The stress confining structure  200  is somewhat similar to the V-shaped inlets  108  shown in  FIG. 7 , but it is cut a significant distance into the length of the cylindrical portion  102 D of the proximal sheath section  102 B. This provides opposed upstanding webs  146  and  148  having a radius curvature. The transition between the webs  146 ,  148  and the V-shaped inlets  150  is somewhat squared off. The V-shaped inlets  150  provide stress points  150 A that function in a similar manner as stress points  108 A. 
         [0045]      FIG. 10  shows another embodiment of V-shaped inlets  152  that is similar to inlets  150 . However, the transition between the webs  154 ,  156  and the V-shaped inlets  152  is rounded-off. 
         [0046]    In the embodiment illustrated in  FIG. 11 , diamond-shaped openings  158  are provided at diametrical locations on the cylindrical portion  102 D of the proximal sheath section  1025 . With this structure, similar to the circular perforation in  FIG. 6 , the tearing force exerted against the proximal section  102 B must be sufficient to break through the relatively small length of material or web indicated by numerical designation  160 . Then, the tearing forces are concentrated at the stress points  158 A of the diamond-shaped openings. 
         [0047]      FIG. 12  illustrates another embodiment of a stress confining structure  200  for initiating a tearing separation of the sheath  102 . The stress confining structure is a radius cut-out  162  extending about half way around the circumference of the cylindrical portion  102 D of the proximal sheath section  102 B. This creates diametrically opposed stress points  162  located at the step  164  between the cut-out  162  and the cylindrical portion  102 D of the proximal sheath section  102 B. 
         [0048]      FIG. 13  illustrates another embodiment of a stress confining structure comprising opposed radiused troughs  170 . 
         [0049]      FIG. 14  is similar except the radiused troughs  172  begin some distance into the length of the cylindrical portion  102 D of the proximal sheath section  102 A. This forms radiused webs  174 ,  176 , each having opposed planer sides (only the planar sides  174 A,  176 A leading to the front radiused trough  172  are provided with numerical designations). In both structures, the tearing forces are directed to the respective stress areas  170 A,  172 A at the bottom of the troughs  170 ,  172  and the tear propagates from there along the entire length of the sheath to its distal end  102 C. 
         [0050]      FIG. 15  illustrates another embodiment of stress confining structure comprising radiused troughs  178  similar to those shown in  FIGS. 13 and 14 , but leading to a circular inlets  180 . In  FIG. 16 , the radiused troughs  182  lead to diamond-shaped inlets  184 . In both structures, the tearing forces are directed to the stress areas  180 A or  184 A at the bottom of the respective circular inlets  180  or the V-shaped inlets  184 . The tear propagates from there the entire length of the sheath  102  to its distal end  102 C. 
         [0051]      FIG. 17  illustrates another embodiment of a stress confining structure comprising diametrically opposed V-shaped inlets  186  leading to circular inlets  188 . In this case, the tearing forces are directed to the stress areas  188 A at the bottom of the circular inlets  188 . The tear propagates from there the entire length of the sheath to its distal end  102 B. 
         [0052]    Thus, the present invention has described several structures suitable for as stress confining structures for concentrating the separating forces exerted at the proximal section  102 B of the sheath  102  by a pulling manipulation of the wings  112 ,  114 . In each structure, the total forces imparted to the wings  112 ,  114  are concentrated at either diametrically opposed points  108 A,  142 A,  150 A,  152 A,  158 A,  162 A,  166 A,  170 A,  172 A,  180 A,  182 A and  186 A. Together with the unique molecular properties afforded by PTFE as the preferred material for the sheath  102 , once a tear begins it propagates the entire length of the sheath, no matter how long, in an extremely smooth manner that provided the physician with a very desirable tactile feel. 
         [0053]    It is, therefore, apparent that there has been provided, in accordance with the present invention, an introducer assembly comprising a valve housing supported on the proximal end of a PTFE sheath having a novel structure for removal from the venous system of a patient. While this invention has been described in conjunction with preferred embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the broad scope of the appended claims.