Abstract:
A method of manufacturing a braid-reinforced peelable tubular body is disclosed herein. In one embodiment, the method includes: providing a braided tubular body; forming at least one longitudinally extending slit in tho braided tubular body, resulting in a longitudinally slit braided tubular body, the at least one longitudinally extending slit including slit edges and a severed braid layer of the braided tubular body; placing the longitudinally slit braided tubular body on a mandrel; placing a heat shrink tube about the longitudinally slit braided tubular body; subjecting the heat shrink tube and longitudinally slit braided tubular body to bonding conditions, such as, for example, reflow, laser bonding, thermoforming, etc., thereby causing the slit edges to be joined to each other and resulting in a braid-reinforced peelable tubular body; and removing the braid-reinforced peelable tubular body from the mandrel.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to medical apparatus and methods. More specifically, the present invention relates to tubular delivery devices, such as catheters and sheaths, and methods of using and manufacturing such tubular delivery devices. 
       BACKGROUND OF THE INVENTION 
       [0002]    Tubular delivery devices, such as catheters and sheaths, are used to deliver implantable medical devices, such as implantable medical leads, to an implantation site within a patient. For example, a catheter or sheath may be routed through the vasculature of the patient such that the distal end of the catheter or sheath is located near the implantation site within the patient&#39;s heart. The distal end of the implantable medical lead may then be distally routed through the central lumen of the catheter or sheath to cause the lead distal end to be delivered to the implantation site within the patient. Once the lead distal is properly located at the implantation site within the patient&#39;s heart, the tubular delivery device must be removed from about the lead. 
         [0003]    A lead connector end on the lead proximal end is used to couple the lead proximal end to an implantable pulse generator, such as a pacemaker or implantable cardioverter defibrillator (“ICD”), which is used to deliver cardio electrotherapy to the implantation site via the lead. Typically, the diameter of the lead connector end exceeds the diameter of the lumen of the tubular delivery device. Thus, to remove the catheter or sheath from about the implanted lead without displacing the lead distal end relative to the implantation site, the tubular body of the catheter or sheath must be longitudinally split. Longitudinal splitting of the tubular body may be accomplished via a slitting tool that slits or cuts the “slittable” tubular body as the tubular body is proximally displaced against the blade of the slitting tool. Alternatively, longitudinal splitting of the tubular body may be accomplished via peeling of the “peelable” tubular body when the tubular body is configured to have a longitudinally extending stress concentration. The stress concentration may be in the form of a longitudinally extending groove formed in the wall of the tubular body or a longitudinally extending strip of material that is different in mechanical properties from the material forming the rest of the tubular wall. 
         [0004]    Tubular bodies of catheters and sheaths may be reinforced with braid layers formed of metal or other materials to enhance the mechanical properties (e.g., torqueability, stiffness, kink resistance, pushability, curve retention, etc.) of the tubular bodies. Braid layers may be employed in tubular bodies and still result in tubular bodies that are slittable because the slitting tool is capable of slitting such braid-reinforced tubular bodies. However, this has not been the case with peelable tubular bodies. Specifically, heretofore, no tubular body for a catheter or sheath has been available that is both braid-reinforced and peelable because the presence of a braid layer made the tubular body incapable of being peeled. 
         [0005]    Many physicians prefer the peeling process over the slitting process because the peeling process offers more simplicity and control compared to the slitting process and does not require a separate tool. However, because peelable tubular bodies have heretofore lacked the ability to be braid-reinforced and, therefore, lacked the mechanical properties (torqueability, stiffness, kink resistance, pushability, curve retention, etc.) of a braid-reinforced slittable tubular body, slittable catheters and sheaths have historically outsold peelable catheters and sheaths by large amounts (e.g., three to one). 
         [0006]    There is a need in the art for a catheter or sheath having a braid-reinforced tubular body that is peelable and still offers mechanical characteristics similar to braid-reinforced tubular bodies known in the art. There is also a need in the art for methods of manufacturing and using such a peelable, braid-reinforced tubular body for catheter or sheath. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    A method of manufacturing a braid-reinforced peelable tubular body is disclosed herein. In one embodiment, the method includes: provide a braided tubular body; form at least one longitudinally extending slit in the braided tubular body, resulting in a longitudinally slit braided tubular body, the at least one longitudinally extending slit including slit edges and severing a braid layer of the braided tubular body; place the longitudinally slit braided tubular body on a mandrel; place a heat shrink tube about the longitudinally slit braided tubular body; subject the heat shrink tube and longitudinally slit braided tubular body to bonding conditions (e.g., reflow, laser bonding, thermoforming, etc.), thereby causing the slit edges to be joined to each other and resulting in a braid-reinforced peelable tubular body; and remove the braid-reinforced peelable tubular body from the mandrel. 
         [0008]    A braid-reinforced peelable tubular body manufactured according to the above-mentioned method is also disclosed herein. 
         [0009]    A catheter or sheath is also disclosed herein. In one embodiment, the catheter or sheath may include a braid-reinforced peelable tubular body having a wall with a circumference. The wall may include a braid layer and at least one longitudinally extending stress concentration. The braid layer may extend uninterrupted along the circumference except in a longitudinally extending region of the stress concentration. 
         [0010]    While multiple embodiments are disclosed, still other embodiments of the present invention will become apparent to those skilled in the art from the following Detailed Description, which shows and describes illustrative embodiments of the invention. As will be realized, the invention is capable of modifications in various aspects, all without departing from the spirit and scope of the present invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is an isometric view of a catheter or sheath having a braided peelable tubular body. 
           [0012]      FIG. 2  is a transverse cross section of the braided tubular body as taken along section line  2 - 2  in  FIG. 1 . 
           [0013]      FIG. 3  is a longitudinal side view of a portion of the braided tubular body, wherein various layers of the tubular body are removed in some locations to reveal layers or structure below that would otherwise be hidden from view. 
           [0014]      FIG. 4  is a flow diagram illustrating three embodiments of a method of manufacturing the braided peelable tubular body. 
           [0015]      FIG. 5  is an isometric of a traditional braided tubular body that has been slit in preparation for manufacturing the braid-reinforced tubular body depicted in  FIGS. 1-3 . 
           [0016]      FIG. 6  is a cross section of the braid-reinforced tubular body halves assembled onto a reflow mandrel. 
           [0017]      FIG. 7  is the same view as  FIG. 6 , except of another embodiment. 
           [0018]      FIG. 8  is the same view as  FIG. 6 , except of yet another embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    A tubular delivery device  10 , such as, for example, a catheter or sheath  10 , is disclosed herein. The catheter or sheath  10  may include a braided or braid-reinforced peelable tubular body  12 . The catheter or sheath  10  may also include a splittable hub  14  coupled to a proximal end  16  of the braid-reinforced peelable tubular body  12 . The hub  14  may facilitate a hemostasis valve or other device to be coupled to the proximal end  16  of the tubular body  12 . The catheter or sheath  10  advantageously provides the mechanical characteristics of a braided tubular body while being readily peelable. 
         [0020]    The following description presents preferred embodiments of the braid-reinforced peelable tubular body  12  and its method of manufacture and represents the best mode contemplated for practicing the braid-reinforced peelable tubular body  12  and its method of manufacture. This description is not to be taken in a limiting sense, but is made merely for the purpose of describing the general principles of the braid-reinforced peelable tubular body  12  and its method of manufacture, the scope of both being defined by the appended claims. 
         [0021]    For a detailed discussion regarding the braid-reinforced catheter or sheath  10 , reference is made to  FIGS. 1 and 2 .  FIG. 1  is an isometric view of an embodiment of the catheter or sheath  10  employing the braid-reinforced peelable tubular body  12 , and  FIG. 2  is a transverse cross section of the braid-reinforced tubular body  12  of the catheter or sheath  10  as taken along section line  2 - 2  in  FIG. 1 . As indicated in  FIG. 1 , the catheter or sheath  10  may include a braided or braid-reinforced peelable tubular body  12 , a proximal end  13 , a splittable hub  14  at the proximal end  13 , and a distal end  15 . The tubular body  12  may include a proximal end  16  and a distal end  18 . 
         [0022]    The hub  14  may be employed to couple a hemostasis valve or other medical device to the proximal end  13  of the catheter or sheath  10 . The hub  14  may be longitudinally splittable via the presence of a longitudinally extending stress concentration  20  defined in the wall  22  of the hub  14 . The hub wall stress concentration  20  may be in the form of a splitting groove defined in the hub wall  22 . As can be understood from  FIG. 1 , the hub wall  22  may have two longitudinally extending stress concentrations  20 ′,  20 ″ defined in the wall  22  at opposite locations from each other in the circumference of the wall  22 . Thus, the hub wings  24  may be grasped and forced apart to cause the hub  14  to split into two generally equal halves on account of the two oppositely located stress concentrations  20 ′,  20 ″. In other embodiments, the hub  14  may have a greater or lesser number of stress concentrations  20 . 
         [0023]    As shown in  FIGS. 1 and 2 , the tubular body  12  may include two longitudinally extending stress concentrations  26 ′,  26 ″ formed in the wall  28  of the tubular body  12 . The wall  28  defines an outer circumferential surface  30  of the tubular body  12  and an inner circumferential surface  32  of the tubular body  12 . The inner circumferential surface  32  may define a central lumen  34  of the tubular body  12 . 
         [0024]    Similar to the stress concentrations  20 ′,  20 ″ of the hub  14 , the stress concentrations  26 ′,  26 ″ of the tubular body  12  may be formed in the wall  28  of the tubular body  12  at opposite locations from each other in the circumference of the wall  28 . These oppositely located tubular body stress concentrations  26 ′,  26 ″ may be generally aligned with the hub stress concentrations  20 ′,  20 ″ such that the splitting of the hub  14  may be used to peel the tubular body  12  into two generally equal halves. In other embodiments, the tubular body  12  may have a greater or lesser number of stress concentrations  26 . 
         [0025]    As indicated in  FIG. 2 , in one embodiment, the stress concentrations  26 ′,  26 ″ may be formed by a groove  36  defined in the inner circumferential surface  32  of the tubular body  12  and extending the length of the stress concentrations  26 ′,  26 ″. In other embodiments, the groove  36  may be defined in the outer circumferential surface  30  or in both the inner and outer circumferential surfaces  32 ,  30 . 
         [0026]    As can be understood from  FIG. 2 , the stress concentrations  26 ′,  26 ″ may be formed of a material  38  or have a makeup or configuration that is mechanically dissimilar from the mechanical characteristics of the material  40  or makeup or configuration that may form the majority of the non-stress concentration portions  42  of the wall  28 . In some embodiments, the wall  28  may include an inner layer  44  and an outer layer  46  extending about the inner layer  44 . In such an embodiment, the stress concentrations  26 ′,  26 ″ and the outer layer  46  may be formed of a first type of polymer material (e.g., polyether block amide (“PEBAX”), nylon, polyurethane, etc.), while the inner layer  44  may be formed of second type of polymer material (e.g., PEBAX (preferably of a durometer higher than the PEBAX of the outer layer), nylon, polyurethane, polytetrafluoroethylene (“PTFE”), fluorinated ethylene propylene (“FEP”), etc.) different from the first type of polymer material and including a braid layer  48  embedded therein. 
         [0027]    Further understanding regarding the configurations of the braid layer  48  and stress concentrations  26  of the braid-reinforced peelable tubular body  12  of  FIGS. 1 and 2  may obtained from  FIG. 3 , which is a longitudinal side view of a portion of the braid-reinforced tubular body  12 , wherein various layers of the tubular body  12  are removed in some locations to reveal layers or structure below that would otherwise be hidden from view. As shown in  FIG. 3 , the outer layer  46  may extend over the braid layer  48 , which may extend over the inner layer  44 , the braid layer  48  being embedded in the outer layer  46 . In another embodiment, as depicted in  FIG. 2 , the outer layer  46  may extend over the inner layer  44 , which contains the braid layer  48  embedded therein. Regardless of which layer the braid  48  is embedded in, as can be understood from  FIGS. 2 and 3 , the tubular body  12  is braid-reinforced throughout its entire circumferential extent, except along the length of the stress concentrations  26 ′,  26 ″. The lack of braid layer  48  in the vicinity of the stress concentrations  28 ′,  28 ″ enables the tubular body  12  of the catheter or sheath  10  to be peeled in a fashion identical to a traditional peelable catheter while still offering mechanical properties very similar to those of a traditional braided catheter due to the presence of the braid layer  48  in all other areas of the tubular body  12 . 
         [0028]    For a discussion regarding a first embodiment of a method of manufacturing the braid-reinforced peelable tubular body  12 , reference is first made to  FIGS. 4 and 5 .  FIG. 4  is a flow diagram illustrating three embodiments of the manufacturing method, and  FIG. 5  is an isometric of a traditional braided tubular body  12 ′ that has been slit in preparation for manufacturing the braid-reinforced tubular body  12  described above. 
         [0029]    A traditional braided tubular body  12 ′ is provided, wherein the braid layer of the traditional braided tubular body  12 ′ is circumferentially continuous [block  100  of  FIG. 4 ]. Such a traditional braided tubular body  12 ′ may be constructed from a two-process extrusion, reflow, or any other commonly used tubular body manufacturing processes. 
         [0030]    As can be understood from  FIG. 5 , the traditional braided tubular body  12 ′ may be longitudinally slit into two halves  12   a ′,  12   b ′ along its entire length, with the exception of a most proximal segment  50  of the tubular body  12 ′ having a length of approximately one inch, the most proximal segment  50  remaining un-slit [block  105  of  FIG. 4 ]. The most proximal segment  50  may remain un-slit to aid in handling. As indicated in  FIG. 5 , the tubular body  12 ′, on account of the manufacturing processes used to manufacture the traditional braided tubular body  12 ′, may have two thin strips  52   a,    52   b  constructed of softer material as compared to the material adjacent the strips  52   a,    52   b  in the traditional braided tubular body  12 ′. The slitting process may be accomplished using a simple blade fixture, laser, or other cutting mechanism common to tubular body manufacturing. 
         [0031]    When the traditional tubular body  12 ′ is slit according to [block  105 ] of  FIG. 4 , the traditional tubular body  12 ′ may be slit along these strips  52   a,    52   b  to form corresponding strip edges  52   a ′,  52   a ″ and  52   b ′,  52   b ″, as depicted in  FIG. 5 . These strip edges  52   a ′,  52   a ″ and  52   b ′,  52   b ″, which may extend the entire length of the slit traditional tubular body  12 ′, may be used to surround and form the score features  26 ′,  26 ″ of the peelable braid-reinforced tubular body  12  described above with respect to  FIGS. 1-3 . 
         [0032]    As shown in  FIG. 6 , which is a cross section of the tubular body halves  12   a ′,  12   b ′, the braid-reinforced tubular body halves  12   a ′,  12   b ′ are assembled onto a reflow mandrel  54  [block  110  of  FIG. 4 ]. The mandrel  54  may include protruding geometry  56  to form score lines. A shrink tube  58  formed of FEP or other shrink tube material may be pulled or otherwise provided about the outer circumferential surface of the braid-reinforced layer  44  provided by the tubular body halves  12   a ′,  12   b ′ [block  115  of  FIG. 4 ]. When tubular body halves  12   a ′,  12   b ′ and heat shrink tube  58  are assembled on the mandrel  54  as indicated in  FIG. 6 , gaps  60  may exist between the strip edges  52   a ′,  52   a ″ and  52   b ′,  52   b ″. The assembly depicted in  FIG. 6  may be subjected to a reflow process [block  120  of  FIG. 4 ]. In other words, the assembly depicted in  FIG. 6  is subjected to bonding conditions (e.g., reflow, laser bonding, thermoforming, etc.) that cause the strip edges  52   a ′,  52   a ″ and  52   b ′,  52   b ″ to flow into the gaps  60 , filling the gaps  60  and forming the stress concentration lines  26 ′,  26 ″ that join the tubular body halves  12   a ′,  12   b ′ into a braid-reinforced tubular body  12  that is similar to that of  FIG. 1-3 , less the outer layer  46 . The protruding geometry  56  of the mandrel  54  forms the score lines  36  in the interior surface  32  in the vicinity of the stress concentrations  26 ′,  26 ″. Once the reflow process is completed, the material forming the shrink tube  58  may be removed from about the completed tubular body  12 . The completed peelable braid-reinforced tubular body  12  that is similar to that of  FIGS. 1-3 , less the outer layer  46 , may be removed from the mandrel  54  [block  125  of  FIG. 4 ]. The approximately one inch long non-slit portion  50  discussed above with respect to  FIG. 5  (i.e., the portion  50  of the braid-reinforced tubular body  12 ′ not slit in [block  105  of  FIG. 4 ]) may be cut from the completed peelable braid-reinforced tubular body  12  [block  130  of  FIG. 4 ]. 
         [0033]    As can be understood from the process described above with respect to  FIGS. 1-6 , the reflow performed with the heat shrink tube  58  serves the purpose of re-forming the tubular body  12 ′, which was slit in [block  105  of  FIG. 4 ]. During the reflow process, the tubular body  12 ′ re-assumes its original shape. However the score sections  26 ′,  26 ″ remain free of braid  48  due to the original slit process, thereby resulting in a peelable braid-reinforced tubular body  12  similar to that depicted in  FIGS. 1-3 . 
         [0034]    For a discussion of a second manufacturing embodiment, reference is made to  FIG. 7 , which is the same view as  FIG. 6 , except of the second manufacturing embodiment. In the second manufacturing embodiment, prior to the placement of the heat shrink tube  58  about the outer surfaces of the tubular body halves  12   a ′,  12   b ′ and, wherein the tubular body halves  12   a ′,  12   b ′ may not have any or sufficient strip edges  52   a ′,  52   a ″ and  52   b ′,  52   b ″ to fill in the gaps  60 , a soft durometer polymer tube  62  may be placed about the outer circumferential surfaces of the tubular body halves  12   a ′,  12   b ′ [block  135  of  FIG. 4 ]. The soft durometer polymer tube  62  may be formed of the same material as what the strip edges  52   a ′,  52   a ″ and  52   b ′,  52   b ″ would have been made of, for example, soft durometer PEBAX, polyurethane, nylon, etc. The heat shrink tube  58  may be pulled over the soft durometer polymer tube  62  [block  140  of  FIG. 4 ]. The assembly depicted in  FIG. 7  may be subjected to the bonding conditions or reflow process [block  120  of  FIG. 4 ]. Once the reflow process is completed, the material forming the shrink tube  58  may be removed from about the completed tubular body  12 . The completed peelable braid-reinforced tubular body  12  may be removed from the mandrel  54  [block  130  of  FIG. 4 ]. The non-slit end  50  may then be trimmed from the complete peelable braid-reinforced tubular body  12  [block  135  of  FIG. 4 ]. The resulting peelable braid-reinforced tubular body  12  may have the configuration depicted in  FIG. 2 , wherein the soft durometer polymer tube  62  forms the outer layer  46  and the stress concentration lines  26 ′,  26 ″ that join the tubular body halves  12   a ′,  12   b ′ into the braid-reinforced tubular body  12  of  FIG. 1-3 , and the braided halves  12   a ′,  12   b ′ form the inner layer  44 . 
         [0035]    For a discussion of a third manufacturing embodiment, reference is made to  FIG. 8 , which is the same view as  FIG. 6 , except of the third manufacturing embodiment. In the third manufacturing embodiment, prior to the placement of the heat shrink tube  58  about the outer surfaces of the tubular body halves  12   a ′,  12   b ′, a polymer beading  64  may be placed in each of the gaps  60  between the tubular body halves  12   a ′,  12   b ′ [block  145  of  FIG. 4 ]. In a first version of embodiment three, the polymer beading  60  may be provided where the tubular body halves  12   a ′,  12   b ′ may not have any or sufficient strip edges  52   a ′,  52   a ″ and  52   b ′,  52   b ″ to fill in the gaps  60 . In a second version of embodiment three, the polymer beading  60  may be provided despite the tubular body halves  12   a ′,  12   b ′ having sufficient strip edges  52   a ′,  52   a ″ and  52   b ′,  52   b ″ to fill in the gaps  60 . In the second version of embodiment three, the strip edges  52   a ′,  52   a ″ and  52   b ′,  52   b ″ may be made of, for example, PEBAX, nylon, polyurethane, etc., and the polymer beading  64  may be made of another material such as PTFE, FEP, etc. The difference in materials between the strip edges  52   a ′,  52   a ″ and  52   b ′,  52   b ″ and the polymer beading  64  may enhance the resulting stress concentrations and the peelability of the resulting braid-reinforced peelable tubular body  12 . 
         [0036]    The heat shrink tube  58  may be pulled over the polymer beading  64  and tubular body halves  12   a ′,  12   b ′ [block  150  of  FIG. 4 ]. The assembly depicted in  FIG. 8  may be subjected to the bonding conditions or reflow process [block  120  of  FIG. 4 ]. Once the reflow process is completed, the material forming the shrink tube  58  may be removed from about the completed tubular body  12 . The completed peelable braid-reinforced tubular body  12  may be removed from the mandrel  54  [block  130  of  FIG. 4 ]. The non-slit end  50  may then be trimmed from the completed peelable braid-reinforced tubular body  12  [block  135  of  FIG. 4 ]. The resulting peelable braid-reinforced tubular body  12  may have a configuration similar to that depicted in  FIG. 2 , less the outer layer  46 . In other words, the polymer beading  64  forms the stress concentration lines  26 ′,  26 ″ that join the tubular body halves  12   a ′,  12   b ′ into a braid-reinforced tubular body  12  similar to that of  FIG. 1-3 , less the outer layer  46 , and the braided halves  12   a ′,  12   b ′ form the inner layer  44 . 
         [0037]    The embodiments depicted in  FIGS. 1-8  depict tubular bodies  12  with two stress concentration lines  26 ′,  26 ″ and score lines  36  located at  180  degrees from each other about the circumference of the tubular bodies  12 . However, in other embodiments, the tubular bodies  12  may have more than or less than two stress concentration lines  26 ′,  26 ″ and score lines  36 , and such peel enabling features may be spaced apart from each other by spacings other than 180 degrees. 
         [0038]    Although the present invention has been described with reference to preferred embodiments, persons skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.