Abstract:
A catheter sheath introducer comprises a hub and a tubular sheath having an inner lining with one or more dampers to improve retention of medical devices received or passed through the sheath without significantly increasing the force required to advance the medical device through the sheath. The dampers are made of a friction inducing material, for example, rubber-based materials, and configured as fingers, bumps or flaps that are unidirectional by means of an asymmetrical shape relative to a longitudinal axis of the sheath.

Description:
FIELD OF INVENTION 
       [0001]    The present invention is directed to a novel catheter sheath introducer. 
       BACKGROUND 
       [0002]    Catheter sheath introducers are well known in the health care industry as a means of providing access to the circulatory system for a number of applications. In a now well know process, the catheter sheath introducer is placed in a desired blood vessel to facilitate various procedures. Among these medical procedures, for example, are mapping, ablation and balloon angioplasty which require the manipulation of catheters through the circulatory system. 
         [0003]    Catheter introducers typically include a tubular sheath and a hub attached to a proximal end of the sheath. Throughout a medical procedure, a number of medical devices may be received or fed through the hub and sheath, including a dilator, a guide wire and/or one or more catheters. Catheters especially may have long shafts that require much manipulation to pass through the hub and sheath in order to reach the desired position in the body to effect the medical procedure. However, catheter shafts can slip rotationally and/or longitudinally in the sheath, increasing the effort needed to correctly position the diagnostic or therapeutic distal portion of the catheter within the body. 
         [0004]    Accordingly, a need exists for a catheter sheath introducer with improved hold and retention of catheters and other medical devices extending there through without significantly increasing the force required to advance the catheter or medical device through the sheath. 
       SUMMARY OF THE INVENTION 
       [0005]    In accordance with the present invention, a catheter sheath introducer comprising a hub and a tubular sheath having an inner lining with one or more dampers is provided. The dampers are unidirectional so as to improve retention of medical devices received or passed through the sheath without significantly increasing the force required to advance the medical device through the sheath. 
         [0006]    In one embodiment, the dampers extend from an inner circumferential lining of the sheath and project inwardly in a lumen of the sheath so as to contact a medical device received in or passed through the lumen of the sheath. The dampers are made of a friction inducing material, for example, rubber-based materials, and configured as fingers, bumps or flaps that are unidirectional by means of an asymmetrical shape relative to a longitudinal axis of the sheath so that the medical device encounters less frictional impedance when being advanced distally relative to the sheath and more frictional impedance with being withdrawn proximally relative to the sheath. 
         [0007]    A more detailed explanation of the invention is provided in the following description and claims and is illustrated in the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    These and other features and advantages of the present invention will be better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings. It is understood that selected structures and features have not been shown in certain drawings so as to provide better viewing of the remaining structures and features. 
           [0009]      FIG. 1  is a perspective view of a catheter sheath introducer of the present invention in accordance with one embodiment. 
           [0010]      FIG. 2  is an elevational view, with portions broken away, of the catheter sheath introducer of  FIG. 1 . 
           [0011]      FIG. 3  is an enlarged side cross-sectional view of dampers within a sheath of  FIG. 2 . 
           [0012]      FIG. 3A  is an end cross-sectional view of the dampers of  FIG. 3 , taken along line A-A. 
           [0013]      FIG. 4  is an enlarged side cross-sectional view of the dampers of  FIG. 2 , engaged with a medical device being advanced distally through the sheath. 
           [0014]      FIG. 4A  is an end cross-sectional view of the dampers and medical device of  FIG. 4 , taken along line A-A. 
           [0015]      FIG. 5  is an enlarged side cross-sectional view of the dampers of  FIG. 2  applying a retention force on the medical device. 
           [0016]      FIG. 5A  is an end cross-sectional view of the dampers and medical device of  FIG. 5 , taken along line A-A. 
           [0017]      FIG. 6  is an enlarged side cross-sectional view of dampers in accordance with another embodiment, engaged with a medical device being advanced distally through a sheath. 
           [0018]      FIG. 6A  is an end cross-sectional view of the dampers and medical device of  FIG. 6 , taken along line A-A. 
           [0019]      FIG. 7  is an enlarged side cross-sectional view of the dampers of  FIG. 6 , engaged with a medical device being advanced distally through the sheath. 
           [0020]      FIG. 7A  is an end cross-sectional view of the dampers and medical device of  FIG. 7 , taken along line A-A. 
           [0021]      FIG. 8  is an enlarged side cross-sectional view of the dampers of  FIG. 6  applying a retention force on the medical device. 
           [0022]      FIG. 8A  is an end cross-sectional view of the dampers and medical device of  FIG. 8 , taken along line A-A. 
           [0023]      FIG. 9  is an enlarged side cross-sectional view of dampers in accordance with yet another embodiment, engaged with a medical device being advanced distally through a sheath. 
           [0024]      FIG. 9A  is an end cross-sectional view of the dampers and medical device of  FIG. 9 , taken along line A-A. 
           [0025]      FIG. 10  is an enlarged side cross-sectional view of the dampers of  FIG. 9 , engaged with a medical device being advanced distally through the sheath. 
           [0026]      FIG. 10A  is an end cross-sectional view of the dampers and medical device of  FIG. 10 , taken along line A-A. 
           [0027]      FIG. 11  is an enlarged side cross-sectional view of the dampers of  FIG. 9  applying a retention force on the medical device. 
           [0028]      FIG. 11A  is an end cross-sectional view of the dampers and medical device of  FIG. 11 , taken along line A-A. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0029]    Referring to the drawings,  FIGS. 1 and 2  show a catheter sheath introducer  10  having a tubular sheath  12  and a hub  14 . The sheath  12  has a distal end  12 D and a proximal end  12 P, and the hub  14  is attached to the proximal end  12 D. The catheter sheath introducer  10  also includes a hemostasis valve  16  to provide sealing of the sheath around a medical device  18 , e.g., a dilator unit. A branch conduit  20  and a locking sleeve  21  off of hub  14  are provided to allow for, among other things, connections to saline solution or medicines and access to other medical procedures. An end cap  24  is provided at the proximal end of hub  14 . A guide wire  22  is also shown as it is often used with such devices as balloon angioplasty catheters. 
         [0030]      FIG. 2  shows the catheter sheath introducer  10  cut away to expose some of the internal structure. The sheath  12  is joined to the internal body of hub  14 . The sheath  12  is a tubular structure with at least one layer  26  providing an inner circumferential surface or lining  28  surrounding a lumen  30 . The layer  26  be constructed of any suitable material that is sufficiently pliant, elastic, flexible and friction-inducing with medical devices extending through the sheath  12 . Suitable materials include rubber-based materials, e.g., silicon rubber, or a thermoplastic elastomer, or extrudable tacky plastic, e.g., polyethylene, polypropylene. 
         [0031]    In accordance with a feature of the present invention, one or more dampers  32  are formed on in inner surface  28  of the sheath  12 . The dampers  32  include raised formations that project inwardly from into lumen  30  to at least partially occlude the lumen  30 . In the embodiment of  FIGS. 2 ,  3  and  3 A, the dampers  32  are configured like “fingers”, each with a base  34 , two generally parallel side edges  36  and an unattached outer edge  38 . In the illustrated embodiment, the dampers  32  are arranged in diametrical pairs that oppose each other in the lumen  30  and equally spaced from each other around the circumference and each damper has a generally uniform thickness. When the lumen  30  is empty, each pair of dampers  32  are in their neutral configuration with the outer edges  38  of one or more pairs of dampers being in contact with each other, although it is understood that equal spacing and contact are not necessary in every embodiment of the present invention. In the neutral configuration, the dampers  32  point toward the distal end  12 D of the sheath where each side edge  36  defines an inner angle θ ranging between about 0 and less than 90 degrees, preferably between about 20 and 60 degrees and more preferably about 45 degrees, relative to the inner surface  28  of the sheath  12 . Each damper  32  has a length such that at least a distal portion of each damper is distal of the base  34  of the respective damper. The plurality of dampers may vary as needed or desired. In one embodiment, the plurality ranges between about two and six, and more preferably about three or four. 
         [0032]    When a user advances a medical device  18  through the lumen ( FIGS. 4 and 4A ), the medical device comes into contact with one or more dampers  32 . Angled distally, the dampers deform, e.g., elongating and/or becoming further distally angled, under the advancing force of the device  18  and allow further distal advancement of the device  18  through the lumen  30 . 
         [0033]    When the medical device  18  is released by the user, elasticity of the dampers  32  aided by their friction-inducing property causes the dampers to at least initially shorten and thicken before stabilizing in a compressed state thereby providing a retention force acting on the device  18  to hold it in place. The retention force prevents slippage of the medical device in terms of rotational and/or longitudinal movement that may be caused by other forces acting on the device, including the body&#39;s circulatory system and/or deformation/elasticity of the device itself due to kinks or bends along its length. The retention force is sufficient to hold the device  18  in place but a relatively low static coefficient of friction provided by the dampers against the device  18  allows the device to be withdrawn proximally when actively pulled by the user. The unidirectional geometry of the dampers  32  by means of their shape and configuration allows the sheath introducer  10  to provide “hands-free” utility so that the user need not maintain a hand on the device at all times while the device is inside the sheath introducer. 
         [0034]    In an alternate embodiment as illustrated in  FIGS. 6 and 6A , the dampers  32  are configured as “bumps” with greater radial and circumferential thicknesses compared to the above-described “finger” dampers. The thickness may be uniform and/or nonuniform in the radial and/or circumferential direction. In the illustrated embodiment, the thickness in the radial direction is tapered, that is, thicker at the base  34  and thinner at an outer edge  38 . Compared to the “finger” dampers, the “bump” dampers may have a more curved profile. However, the bump dampers are also unidirectional in that the curved profile is angled distally, where the outer edge has a more linear proximal portion  38 P and a more curved distal portion  38 D. 
         [0035]    In another alternate embodiment as illustrated in  FIGS. 7 and 7A , the dampers  32  are configured as “flaps” with a lesser radial thickness but a thicker base  34 . The dampers are also unidirectional and thus are angled toward the distal end  12 D of the sheath. Both side edges  36  form an angle θ, as defined above. 
         [0036]    The preceding description has been presented with reference to presently preferred embodiments of the invention. Workers skilled in the art and technology to which this invention pertains will appreciate that alterations and changes in the described structure may be practiced without meaningfully departing from the principal, spirit and scope of this invention. As understood by one of ordinary skill in the art, the drawings are not necessarily to scale. Some features are exaggerated for purposes of discussion. Accordingly, the foregoing description should not be read as pertaining only to the precise structures described and illustrated in the accompanying drawings, but rather should be read consistent with and as support to the following claims which are to have their fullest and fair scope.