Abstract:
Disclosed is an improved pointed instrument for insertion into blood vessels where an occlusion arises or terminates too closely to the insertion site for proper sheath placement. The pointed instrument exhibits supportive characteristics that allow for a sheath to be placed in an otherwise inaccessible insertion site. One embodiment of the present disclosure features a pointed instrument having a flexible portion, which is generally straight outside the body, but agglomerates once inside a blood vessel.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation-in-part of U.S. patent application Ser. No. 11/656,898, filed on Jan. 22, 2007, by Applicant Richard Heuser, the disclosure of which is incorporated by reference. This application also claims priority to Provisional Application Ser. No. 60/887,277, filed on Jan. 30, 2007, the disclosure of which is incorporated by reference. 
     
    
     BACKGROUND 
       [0002]    Catheters typically are inserted into a blood vessel through a sheath which is fixed in place relative to the blood vessel. The sheath protects the vessel and adjacent derma around the point of insertion while the catheter is advanced and withdrawn as necessary for the particular treatment being applied. The sheath is prepared for insertion by first placing a dilator within the lumen of the sheath and a needle or pointed wire within the lumen of the dilator. The needle or wire is used to pierce the derma and the blood vessel&#39;s wall and then is advanced into the blood vessel&#39;s lumen. Then the dilator is advanced along the wire without moving the needle or wire so that the tip of the dilator passes through the derma and blood vessel wall, expanding the diameter of the opening into the blood vessel. 
         [0003]    At this point, with the dilator tip within the blood vessel lumen, the needle or wire may be withdrawn from the blood vessel. The sheath may then be advanced along the dilator, holding the dilator stationary, until the tip of the sheath is within the blood vessel&#39;s lumen. The sheath typically also expands the opening into the blood vessel. Once the sheath is in the blood vessel at a suitable location, the dilator may be withdrawn and the sheath braced in position, for example by taping the sheath to the patient&#39;s arm or leg adjacent the point of insertion. Then, the catheter is inserted through the sheath and into the blood vessel and maneuvered as necessary to provide the desired treatment. 
         [0004]    The catheter&#39;s outer diameter (o.d.) in such a system is limited by the inner diameter of the sheath, which in turn is limited by the expansion provided by the dilator. A typical dilator-sheath introducer provides a dilator lumen allowing only a 3-French or 0.038 inch o.d. wire, and the dilator must be expanded outwardly relatively abruptly to reach even a modest outer diameter. The sheath lumen then is the same size as the outer diameter of the dilator, and typical size is only a 9-French or 0.118 inch, thus limiting the o.d. of the catheter to 9-French, which limits the types and capabilities of the catheters that can be used with such an introducer. 
         [0005]    The dilator and sheath are typically formed of a plastic material and the tips of the dilator and sheath are sometimes damaged by insertion into the blood vessel. This may cause trauma to the derma and blood vessel, or require a second needle insertion if the tip is damaged to the extent it prevents suitable insertion. 
         [0006]    The sheath typically includes an elastic collar adjacent a proximal end, through which the catheter is inserted. Such elastic collars are typically designed to allow the catheter to be advanced and withdrawn while providing some deterrence to blood leaking out through the sheath between the washer and the catheter. However, blood leakage past the washer is sometimes significant, causing unwanted complications to the catheterization procedure. 
         [0007]    An issue also arises when a physician attempts to enter the vessel from the antegrade common femoral approach, or from the retrograde popliteal approach. An occlusion may arise or terminate in such close proximity to the access site that sheath or dilator placement is difficult. 
       SUMMARY OF THE DISCLOSURE 
       [0008]    A catheter introducer system is provided for inserting a sheath into a human blood vessel to provide a channel for a catheter to be moved within the blood vessel and to be held in a fixed position with minimum blood loss through the sheath. The catheter introducer system may include a trocar or other pointed instrument, such as a needle or pointed wire, for initially piercing the derma and the wall of the blood vessel. One or more dilators may surround the trocar and be sequentially inserted into the blood vessel after the trocar. The sheath surrounds the outermost of the dilators and is inserted last into the blood vessel. After removal of the trocar and dilator(s), the catheter may be inserted into the sheath and maneuvered within the blood vessel as necessary for the desired treatment. 
         [0009]    When the catheter is at a desired location, it may be fixed longitudinally in place and blood loss through the sheath minimized by selective tightening of a hemostasis valve that includes a chuck that radially grips the catheter. The chuck may include a washer held between a base and a clamp and tightened therebetween, with beveled surfaces on the base, clamp, and/or the washer to provide for radial tightening of the chuck on the catheter. 
         [0010]    The disclosure further describes an improved pointed instrument, such as a guidewire or trocar, for insertion into sites where an occlusion arises or terminates too closely to the insertion site for proper sheath or dilator placement. The pointed instrument exhibits supportive characteristics that allow for a sheath or dilator to be placed in an otherwise inaccessible insertion site. One embodiment of the present disclosure features a pointed instrument having a flexible portion, which is generally straight outside the body, but agglomerates once inside a blood vessel. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is an isometric view of a catheter introducer system according to the present invention, including a dilator, a sheath, and a trocar. 
           [0012]      FIG. 2  is an isometric view of the catheter introducer system as shown in  FIG. 1 , the system in this embodiment including two dilators. 
           [0013]      FIG. 3  is an isometric view of the catheter introducer system as shown in  FIGS. 1 and 2 , the system in this embodiment including three dilators. 
           [0014]      FIG. 4  is an isometric, exploded view of a proximal end of a sheath in accordance with the present invention, including a hemostasis valve with a chuck for variably gripping a catheter, the chuck including a base, a clamp coupled to the base by a threaded engagement, and a washer disposed between the base and the clamp. 
           [0015]      FIG. 5  is a cross-sectional view of the proximal end of the sheath shown in  FIG. 4 , with the catheter inserted through the sheath and the washer therein, the clamp positioned to allow the catheter to move longitudinally through the sheath. 
           [0016]      FIG. 6  is a cross-sectional view of the sheath as in  FIG. 5 , with the clamp positioned to tighten the washer onto the catheter. 
           [0017]      FIG. 7  is a close-up pictorial view of the distal tip of the trocar of the catheter introducer system, showing an outer, hollow wire, an inner needle within the lumen of the wire and including a beveled tip extending out of the wire, and a boot at the tip of the wire. 
           [0018]      FIG. 8  is a pictorial view of the trocar of  FIG. 7  with the inner needle withdrawn into the wire and the boot closing to seal off the lumen of the wire. 
           [0019]      FIG. 9  is a close-up end view of an alternative embodiment of the trocar of the catheter introducer system, showing a shutter at the tip of the wire that is open and a needle within the opening of the shutter. 
           [0020]      FIG. 10  is a pictorial view of the trocar in the extended configuration shown in  FIG. 9 . 
           [0021]      FIG. 11  is an end view of the trocar of  FIG. 9  with the needle withdrawn into the wire and the shutter closed. 
           [0022]      FIG. 12  is a pictorial view of the trocar in the withdrawn configuration of  FIG. 11 . 
           [0023]      FIG. 13  is a side, cross-sectional view of the trocar of  FIGS. 7-12  with the needle and wire tip inserted through the derma and into the blood vessel lumen of the patient, with the needle tip still extending out of the distal opening of the wire. 
           [0024]      FIG. 14  is a side, cross-sectional view of the trocar as in  FIG. 13  with the needle withdrawn from the wire and the wire returned to a flexible state within the blood vessel lumen. 
           [0025]      FIG. 15  shows a pointed instrument according to another aspect of the present disclosure. 
           [0026]      FIG. 16  depicts a pointed instrument of the present disclosure being inserted through a layer of skin into a blood vessel. 
           [0027]      FIG. 17  depicts the pointed instrument of  FIG. 16  further into the blood vessel, with the pointed instrument&#39;s flexible tip agglomerating within the blood vessel. 
           [0028]      FIG. 18  shows the pointed instrument of  FIGS. 16 and 17  inserted as far as it will go into the blood vessel. 
           [0029]      FIG. 19  shows a sheath being inserted over the pointed instrument. 
           [0030]      FIG. 20  shows a tubular introducer according to another aspect of the present disclosure approaching the skin and a blood vessel. 
           [0031]      FIG. 21  shows the tubular introducer of  FIG. 20  inserted through the derma and into the lumen of the blood vessel, with a pointed instrument extended through the tubular introducer and into the blood vessel. 
           [0032]      FIG. 22  shows a dilator being advanced down the pointed instrument of  FIG. 21 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0033]    A catheter introducer system in accordance with the present invention is indicated generally at  10  in  FIG. 1 . Catheter introducer system  10  includes a sheath  12  having a generally elongate, typically cylindrical body  14  with a proximal end  16  and a distal end  18 . Body  14  of sheath  12  is coupled at proximal end  16  to a housing  20 . A central, typically cylindrical lumen  22  is defined within sheath  12  extending out through a distal opening  24  and a proximal opening  26 . Sheath  12  is thus configured to receive a catheter  28  ( FIG. 5 ) for longitudinal movement through and torsional movement within lumen  22 . 
         [0034]    Body  14  of sheath  12 , is typically composed substantially of a flexible material, such as a plastic, polymeric material, preferably a hydrophilic material. Body  14  may include a reinforcement, such as stainless steel ring  30 , to prevent buckling or crimping of distal end  18  at opening  24  when sheath  12  is inserted into a human blood vessel. The stainless steel ring  30  on the outermost sheath is radiopaque, as would be understood by those of ordinary skill in the art. 
         [0035]    Catheter introducer system  10  further includes a first dilator  32  configured to be inserted into and disposed substantially within lumen  22  of sheath  12 . First dilator  32  includes a generally elongate, typically cylindrical body  34  having a distal end  36  and a proximal end  38 . Dilator  32  typically also includes a lumen interconnecting a distal opening  40  and a proximal opening  42 , which typically is located in a housing  44  coupled to body  34  adjacent proximal end  38 . Housing  44  may be provided with a luer lock fitting  46 , which typically includes a double threaded engagement portion for coupling to mating devices. 
         [0036]    Sheath  12  and dilator  32  typically are generally cylindrical, as noted above, typically with tapering adjacent distal ends  18 ,  36  to provide a smooth transition as the ends enter the blood vessel. Alternatively sheath  12  and dilator  32 , and one or more intermediate dilators (to be described below), may be tapered substantially along the entire length of their bodies, preferably providing a more gradual, or additional, tapering as compared to the tapered distal ends. In either case, the sheath and dilators are preferably provided with a smooth transition between the body of one dilator and the distal end of the next outer sheath or dilator to prevent the distal end from snagging on the derma or blood vessel during insertion into the blood vessel. 
         [0037]    Dilator  32  is preferably longer than sheath  12  so that distal end  36  and proximal end  38  of body  34  of dilator  32  extend out of the distal and proximal openings of sheath  12 , as shown in  FIG. 1 . As an example, dilator  32  may be on the order of about 24 cm long and sheath  12  may be in the range of about 16 cm to about 20 cm, with other lengths selectable as appropriate for a particular application. 
         [0038]    Catheter introducer system  10  may also include a trocar  48  inserted through dilator  32  and including a distal end  50  with a sharp, pointed tip  52 . Trocar  48  is inserted through dilator  32  to create the initial entrance through the derma and into the blood vessel, and trocar  38  then is withdrawn after distal end  36  of dilator  32  is advanced into the blood vessel. 
         [0039]    As shown in  FIG. 2 , catheter introducer system  10  may include a second, intermediate dilator  54  between the first dilator  32  and sheath  12 . Second dilator  54  typically includes a generally elongate, substantially cylindrical body  56  with a distal end  58  and a proximal end  60 . A housing  62  is coupled to body  56  adjacent proximal end  60 . A central lumen, similar to that for sheath  12  and first dilator  32  interconnects a distal opening  64  and a proximal opening  66 . 
         [0040]    Second dilator  54  preferably has a length greater than that of sheath  12  and less than that of first dilator  32 . Thus, if first dilator  32  is about 24 cm, second dilator  54  is about 20 cm and sheath  12  is about 16 cm in length. The lengths of all the components of the catheter introducer system may be adapted for the particular application. 
         [0041]    Preferably the dilator(s) and sheath are formed of less stiff, more flexible material as one progresses from innermost to outermost. E.g., first dilator  32  may be formed with the most stiff material, and may include a reinforcement, such as a wire  68  ( FIG. 1 ), embedded or otherwise affixed to the material in a coil, web, or other suitable pattern to provide a stiffener. Second dilator  54  is typically formed of a less stiff material, while sheath  12  is formed of a still softer material so that the sheath/dilator bodies tend to be less traumatic to the blood vessel as they get larger. Second dilator, and other intermediate dilators, and sheath are typically progressively more hydrophilic as one proceeds outwardly. Ring  30 , described above, helps to insure that the soft material of sheath  12  will not buckle or flare if the sheath tip catches or snags on the derma on insertion into the blood vessel. A ring may also be provided on the tips of one or more of the dilators in addition to or instead of on sheath  12 . 
         [0042]    With a two-dilator/one-sheath system, some typically available inner diameters (i.d.) in French sizes are shown in the following table: 
         [0000]    
       
         
               
               
               
               
             
               
               
               
               
             
           
               
                   
               
               
                 Two-dilator/ 
                   
                   
                   
               
               
                 one-sheath 
                 First dilator i.d. 
                 Second dilator i.d. 
                 Sheath i.d. 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Ex. 1 
                 3 
                 4 
                 5 
               
               
                 Ex. 2 
                 3 
                 5 
                 6 
               
               
                 Ex. 3 
                 3 
                 5 
                 7 
               
               
                 Ex. 4 
                 3 
                 5 
                 8 
               
               
                 Ex. 5 
                 3 
                 5 
                 9 
               
               
                 Ex. 6 
                 3 
                 8 
                 16 
               
               
                   
               
             
          
         
       
     
         [0043]    Other sizes may be used as appropriate for a particular application. 
         [0044]    As shown in  FIG. 3 , catheter introducer system  10  may include a third, intermediate dilator  70  between the second dilator  54  and sheath  12 . Second dilator  70  typically includes a generally elongate, substantially cylindrical body  72  with a distal end  74  and a proximal end  76 . A housing  78  is coupled to body  72  adjacent proximal end  76 . A central lumen, similar to that for the sheath and the first and second dilators interconnects a distal opening  80  and a proximal opening  82 . 
         [0045]    Third dilator  70  is preferably intermediate in length, in softness, and in hydrophilicity between second dilator  54  and sheath  12 . With a three-dilator/one-sheath system, some typically available inner diameters (i.d.) in French sizes are shown in the following table: 
         [0000]    
       
         
               
               
               
               
               
             
           
               
                   
               
               
                 Three-dilator/ 
                 First 
                 Second 
                   
                   
               
               
                 one-sheath 
                 dilator i.d. 
                 dilator i.d. 
                 Third dilator i.d. 
                 Sheath i.d. 
               
               
                   
               
             
             
               
                 Ex. 7 
                 3 
                 5 
                 7 
                 10 
               
               
                 Ex. 8 
                 3 
                 5 
                 9 
                 11 
               
               
                 Ex. 9 
                 3 
                 5 
                 9 
                 12 
               
               
                 Ex. 10 
                 3 
                 5 
                 9 
                 13 
               
               
                 Ex. 11 
                 3 
                 5 
                 9 
                 14 
               
               
                 Ex. 12 
                 3 
                 5 
                 9 
                 15 
               
               
                 Ex. 13 
                 3 
                 5 
                 9 
                 16 
               
               
                 Ex. 14 
                 3 
                 5 
                 9 
                 17 
               
               
                 Ex. 15 
                 3 
                 5 
                 9 
                 18 
               
               
                   
               
             
          
         
       
     
         [0046]    Other sizes may be used as appropriate for a particular application. 
         [0047]    It will be seen from the foregoing that the system may include any number of dilators to reach a desired sheath size, and, for example, a four-dilator/one-sheath system could use the following sizes: 
         [0000]    
       
         
               
               
               
               
               
               
             
           
               
                   
               
               
                 Four-dilator/ 
                 First dilator 
                 2nd dilator 
                 3rd dilator 
                 4th dilator 
                 Sheath 
               
               
                 one-sheath 
                 i.d. 
                 i.d. 
                 i.d. 
                 i.d. 
                 i.d. 
               
               
                   
               
             
             
               
                 Ex. 16 
                 3 
                 5 
                 9 
                 12 
                 19 
               
               
                 Ex. 17 
                 3 
                 5 
                 9 
                 12 
                 20 
               
               
                 Ex. 18 
                 3 
                 5 
                 9 
                 12 
                 21 
               
               
                 Ex. 19 
                 3 
                 5 
                 9 
                 12 
                 22 
               
               
                 Ex. 20 
                 3 
                 5 
                 9 
                 12 
                 23 
               
               
                 Ex. 21 
                 3 
                 5 
                 9 
                 15 
                 24 
               
               
                 Ex. 22 
                 3 
                 5 
                 9 
                 15 
                 26 
               
               
                 Ex. 23 
                 3 
                 5 
                 9 
                 15 
                 28 
               
               
                   
               
             
          
         
       
     
         [0048]    Other sizes may be used as appropriate for a particular application. 
         [0049]    Sheath  12  as shown in  FIGS. 1-3  includes a side branch or arm  84  in housing  20 , which is commonly used for the introduction of intravenous fluid or medicine during a catheterization procedure. As shown in  FIGS. 2 and 3 , second dilator  54  includes a side branch  86  in housing  62  and third dilator  70  includes a side branch  88  in housing  78 . Although the term dilator is commonly used to refer to a device without a side branch,  FIGS. 2 and 3  illustrate that dilator, as used herein, can refer to a device either with or without a side branch, and the catheter introducer system may be used with sheaths and dilators including any combination of side branches or lack thereof. 
         [0050]    As best seen in  FIGS. 4-6 , housing  20 , which may be identical in the following respects to the housings on any or all of the dilators, includes a hemostasis valve, indicated generally at  90 , for preventing blood leaks between catheter  28  and housing  20 . Such blood leaks typically flow along inner lumen  22  and out proximal opening  26 . Housing  20  is shown in  FIGS. 4-6  with all of the smaller dilators and the trocar withdrawn, and, in  FIGS. 5 and 6  with catheter  28  inserted. 
         [0051]    Hemostasis valve  90  includes a chuck  92  for selectively gripping radially onto catheter  28 . Chuck  92  includes a collar, such as flexible, elastomer washer  94 , defining an opening  96  configured to receive catheter  28  therethrough. Preferably washer  94  fits snugly around catheter  28  in a first configuration, shown in  FIG. 5 , allowing catheter  28  to be moved longitudinally therethrough. 
         [0052]    Valve  90  thus provides for a friction fit around the catheter. The friction fit is selectively adjustable to vary between a first configuration for longitudinal movement of the catheter through the valve and a second configuration for holding the catheter longitudinally in place. A physician operating the catheter introducer system may selectively switch valve  90  to the second configuration, typically when catheter  28  is in a desired location within the blood vessel to perform a catheter procedure, such as installing a stent or applying RF energy at the distal tip of the catheter. 
         [0053]    Preferably the physician selects the second configuration by grasping a threaded cap  98  of valve  90 , and rotating to tighten cap  98  onto a threaded portion  100  of housing  20 . Such tightening of cap  98  drives a clamp  102  within cap  98  to squeeze washer  94  between clamp  102  and a base  104  in housing  20 . Preferably, clamp  102  is a sloped annular ring providing a beveled surface within cap  98 . The ring preferably has an outer circumference  106  generally coincident with an outer circumference of washer  92 , and an inner circumference  110  generally coincident with an inner circumference  112  of washer  92 . Preferably, base  104  is a sloped annular ring, providing a beveled surface that includes an outer circumference  114  and an inner circumference  116  coincident with corresponding circumferences of the washer and the clamp. Inner circumference  112  of washer  92  is nominally at least as large as the o.d. of catheter  28 , although it can be smaller to provide a tighter nominal friction fit. 
         [0054]    In the second configuration, shown in  FIG. 6 , cap  98  has been tightened onto housing  20  so that clamp  102  and base  104  are closer together than a nominal width of washer  92 . Thus washer  92  is pressed radially inwardly by the sloping faces of clamp  102  and base  104 , which tends to reduce the washer&#39;s inner circumference  112  and to close opening  96 , thereby tightening washer  92  onto catheter  28 . Valve  90  may be selectively adjusted by the physician to any degree of tightness, thereby allowing the physician to select an optimal combination of leakage prevention and ease of catheter longitudinal and torsional movement. Preferably, with cap  98  fully tightened, substantially no blood leaks between catheter  28  and washer  92  and catheter  28  is substantially locked longitudinally in place. 
         [0055]    Washer  92  is shown in  FIGS. 4-6  as a flat washer. Washer  92  may alternatively have one or two sloped or beveled surfaces which may correspond to the sloped faces of clamp  102  and base  104 . A washer  118  with two sloped faces  120  is shown in  FIG. 1  incorporated into a hemostasis valve, indicated generally at  122 , on first dilator  32 . Valve  122  operates in a manner generally similar to that of valve  90 . 
         [0056]      FIGS. 7-14  show embodiments of trocar  48 , in particular the structure at distal end  50  of trocar  48 . Trocar  48  may include a hollow, preferably flexible wire  124  defining a central lumen  126  extending out to a distal opening  128 . A hollow, preferably stiff needle  130  provided with a sharp tip, such as beveled end  132 , may be inserted in lumen  126 . In an operative condition, as shown in  FIG. 7 , tip  132  will extend out of opening  128  of wire  124 . A sealing mechanism, such as flexible cuff or boot  134  may be coupled to wire  124  at opening  128 . Sealing mechanism  134  includes an opening  136  which stretches to allow needle tip  132  to extend through the sealing mechanism in the operative condition. Needle  130  includes a proximal end extending out of the proximal end of trocar  48 , which extends out of proximal opening  42  of dilator  32  (see  FIGS. 1-3 ). Needle  130  also includes a central lumen  138  extending from tip  132  to the proximal end. 
         [0057]    As shown in  FIGS. 13 and 14 , the physician may use trocar  48  with needle tip  132  extending out of wire  124  to insert the trocar tip through the patient&#39;s derma and into the blood vessel.  FIG. 13  shows that the flexible wire with the stiff needle inserted therethrough is stiff and insertable into the blood vessel along with the needle tip. The physician can verify that the needle tip is in the blood vessel by the blood that will flow into lumen  138  of needle  130  and out the proximal end. 
         [0058]    Once the wire and needle are verified as inserted into the lumen of the blood vessel, the physician can pull on the proximal end of the stiff needle, withdrawing it from the trocar tip, as shown in  FIG. 14 , at which time wire  124  will again become flexible. The flexible wire presents a less dangerous and traumatic device within the blood vessel, as compared to a stiff wire or needle. The withdrawn needle is also shown in  FIG. 8 , where it can be seen that sealing mechanism  134  has closed to prevent further blood flow through trocar  48 . 
         [0059]    Another embodiment of a sealing mechanism is shown in  FIGS. 9-12 , where wire  124  includes adjacent opening  128  a shutter  140 . A plurality of shutter vanes  142  may be mounted on hinges  144  and preferably may be nominally biased to a closed position ( FIGS. 11 and 12 ). Shutter  140  can be opened by inserting tip  132  of needle  130  through the shutter, as is shown in  FIGS. 9 and 10 . The physician uses the embodiment of  FIGS. 9-12  in the same manner as that of  FIGS. 7 and 8 , inserting the needle tip through the derma and into the lumen of the blood vessel and then withdrawing the needle, allowing the shutter to close and the wire  124  to go limp, as shown in  FIGS. 13 and 14 . 
         [0060]    Another aspect of the present disclosure is shown in  FIG. 15 , where a pointed instrument  210  is shown having a flexible portion  212  with a first proximal end  214  and a first distal end  216 . The distal end  216  may have a sharp tip  218 . The pointed instrument  210  also includes an inflexible portion  220  having a second proximal end  222  and a second distal end  224 , the second distal end  224  being adjacent to the first proximal end  214 . 
         [0061]      FIG. 16  depicts the pointed instrument  210  of  FIG. 15  being inserted into a blood vessel  234  formed by vessel wall  236  and having a diameter  238 . An entry point  230  is a position on the derma  232  that is within close proximity to the vessel  234 . The vessel  234  is blocked in close proximity to the entry point  230  by an occlusion  240 . 
         [0062]    The pointed instrument  210  has been inserted through the derma  232  and the vessel wall  236  to a position within the blood vessel  234 . The first distal end  216  is seen contacting the occlusion  240 . Due to its inherent flexibility, the flexible portion  212  begins to agglomerate (i.e. bunch up), instead of piercing the occlusion  240  or the lower portion of the vessel wall  236 . 
         [0063]    In one embodiment the flexibility may stem from the flexible portion  212  being at least partially comprised of hydrophilic materials. Constructing the flexible portion  212  at least partially of hydrophilic materials would cause it to become malleable upon insertion into fluid. For instance, insertion into the blood vessel  234 , which may be filled with blood, would cause this embodiment of the flexible portion  212  to become malleable. Pressing the distal end  216  of the malleable flexible portion  212  against any foreign surface (i.e. the occlusion  240 ) would cause the portion  212  to agglomerate upon itself. 
         [0064]    Alternatively, the flexible portion  212  may be comprised of a temperature sensitive nitinol alloy. The flexible first portion  212  may have a thermal characteristic, whereby it may be configured to be inflexible when the thermal characteristic is below a first temperature and to agglomerate when the thermal characteristic is above a second temperature. 
         [0065]    In one instance, the flexible first portion  212  may be configured to be inflexible when the thermal characteristic is within a temperature range typically found in an operating room. The flexible portion  212  may likewise be configured to be flexible when the thermal characteristic is at a temperature typically found in a human body. 
         [0066]    In another instance, the flexible first portion  212  may be configured to be inflexible when its thermal characteristic is approximately room temperature. Room temperature may vary from a temperature as low as 16° Celsius to a temperature as high as 28° Celsius. 
         [0067]      FIG. 17  depicts the pointed instrument  210  being further inserted into the vessel  234 , so that the second distal end  224  of the inflexible portion  220  is closer to the occlusion  240  than it was in  FIG. 16 . 
         [0068]      FIG. 18  shows the pointed instrument  210  being inserted as far as it will go into the vessel  234 . The second distal end  224  of the inflexible portion  220  is seen in close proximity with the occlusion  240 , thus preventing the pointed instrument  210  from being advanced further into the vessel  234 . 
         [0069]      FIG. 19  depicts a sheath  244  inserted over the pointed instrument  210 , with the distal tip of the sheath  244  abutting or being in close proximity with the occlusion  240  and the second distal end  224  of the inflexible portion  220 . 
         [0070]      FIGS. 20-22  depict another embodiment, where the flexible first portion  212  is biased towards agglomeration or a coiled configuration. In such an embodiment, a tubular introducer  250  having a distal end  252 , a proximal end  254 , and a sharp tip  256  may be used to pierce the derma  232  and the vessel wall  236 , so that the distal end  252  of the introducer  250  may be extended into the lumen of the blood vessel  234 . One example of a suitable tubular introducer  250  is similar to the hollow needle  130  of  FIGS. 7-14 . Another example can be seen in  FIGS. 20-21 . 
         [0071]    Once the distal tip  252  of the introducer  250  is extended into the lumen of the vessel  234 , the pointed instrument  210  may be extended from within the introducer  250 , and being biased to an agglomerated configuration, the flexible portion  212  will agglomerate (as seen in  FIG. 21 ). The physician may continue to extend the pointed instrument  210  until the second distal end  224  of the inflexible portion  220  is at a position adjacent to the agglomerated flexible portion  212 . 
         [0072]      FIG. 22  shows a possible next step, wherein the tubular introducer  250  is removed, and a dilator  260  is advanced down the pointed instrument  210  into the blood vessel  234 . 
         [0073]    It is believed that the following claims particularly point out certain combinations and subcombinations that are directed to one of the disclosed disclosures and are novel and non-obvious. Disclosures embodied in other combinations and subcombinations of features, functions, elements and/or properties may be claimed through amendment of the present claims or presentation of new claims in this or a related application. Such amended or new claims, whether they are directed to a different disclosure or directed to the same disclosure, whether different, broader, narrower or equal in scope to the original claims, are also included within the subject matter of the disclosures of the present disclosure.