Abstract:
Designs and methods for devices that prevent accidental or inadvertent lateral removal of a guidewire from the guidewire entry tool of a rapid exchange catheter. A first device takes the form of a funnel sized and shaped to slide into the guidewire entry tool. Another illustrative device is shaped and adapted to slide into the guidewire exit slot of the guidewire entry tool, blocking the slot until the converter is removed. In further embodiments, guidewire entry tools include a guidewire exit slot allowing for selective movement of a guidewire laterally from within a catheter. The slot may be designed with structures adapted to prevent inadvertent lateral movement of a guidewire from within the slot. The slot may be formed in a zigzag shape or may include a number of protrusions. Alternatively, the guidewire entry tool may include a split ring that rotates from a first position to a second position, the first position allowing lateral removal of a guidewire and the second position preventing such removal.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Ser. No. 60/911,678 filed Apr. 13, 2007, the entire disclosure of which is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention is related to the field of medical devices. More particularly, the present invention relates to the field of rapid exchange catheters. 
       BACKGROUND OF THE INVENTION 
       [0003]    Minimally invasive operations using catheters are known for use in a number of different parts of the anatomy and for a number of purposes. Many such procedures are performed with the aid of a guidewire. The guidewire is advanced to a desired anatomical location. A catheter, such as (to name a few illustrative devices) a biliary sphincterotome, a fluid infusion cannula or a balloon catheter, may be advanced over the guidewire to the desired location. In early development of such procedures, the entire catheter would pass over the guidewire, requiring a long guidewire lumen for such an “over the wire” device. 
         [0004]    For some procedures, it may become necessary to exchange one catheter for another. With an over-the-wire configuration, exchanging one catheter for another over the guidewire requires a guidewire that is twice as long as the catheter so that the distal end of the guidewire can remain in the desired anatomical location while the catheter is removed. This requires guidewire lengths of several meters, requiring extra hands and hence extra personnel in the operating arena. 
         [0005]    To combat the problem of undue guidewire length, among other issues, rapid exchange technologies were developed. These technologies are known as rapid-exchange devices and are designed such that only a distal portion of a catheter tracks over a guidewire. One illustrative rapid exchange technology includes the use of a guidewire channel that is sized to receive a guidewire along the majority of the length of a catheter, with the distal end of the guidewire channel leading into a guidewire lumen. When rapid exchange is desired, the catheter and guidewire are peeled apart, with the guidewire exiting the channel laterally out of the catheter. The channel may take on a U or C cross-section shape, depending on the catheter. Alternatively, the guidewire may be directed into a guidewire lumen that is thinned, slit, perforated, or has an otherwise weakened wall or missing wall portion allowing for lateral removal of the guidewire. 
         [0006]    Several rapid exchange devices further include guidewire entry tools that make entry of a guidewire to a guidewire channel easier.  FIG. 1  illustrates a prior art guidewire entry tool. The guidewire entry tool  10  includes a proximal end  12  and a distal end  14 , with the entry tool  10  tapering from the proximal end to the distal end. The entry tool  10  is attached to a catheter  16 . The catheter  16  includes a guidewire lumen that is accessible along a majority of its length, shown as a channel  18 . The entry tool  10  directs a guidewire inserted at its proximal end  12  into the guidewire channel  18  of the catheter. 
         [0007]    A slot  20  in the entry tool  10  allows a guidewire to be passed out of the entry tool  10  so that the guidewire and catheter  16  may be peeled apart from one another if catheter exchange is desired. In use, it has been noted that on occasion the guidewire can inadvertently slip out of the entry tool  10 , making use of the catheter  16  in an over-the-wire manner (i.e. with the guidewire fully inserted into the channel and providing support that improves the pushability and anti-kink characteristics of the catheter  16 ) difficult, as well as risking loss of the desired anatomical position at the distal end of the catheter  16 . Furthermore, if the guidewire does inadvertently move out of the slot  20 , it can be difficult to place the guidewire back into its desired location. Finally, the ability of the guidewire to move laterally out of the catheter  16  and entry tool  10  reduces the ability of the guidewire to transmit axial forces, since it is more susceptible to buckling. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention, in several illustrative embodiments, includes devices adapted for use with a rapid exchange catheter having a guidewire entry tool. The illustrative devices are converters shaped and sized to couple to a guidewire entry tool and prevent a guidewire passing into a channel/lumen of a catheter through the guidewire entry tool from moving laterally out of the guidewire entry tool. A first illustrative device takes the form of a funnel, sized and shaped to slide into the guidewire entry tool. 
         [0009]    Another illustrative converter device is designed for use with a guidewire entry tool having a slot for allowing a guidewire to laterally exit the guidewire entry tool. The converter device is shaped and adapted to slide into the guidewire exit slot of the guidewire entry tool, blocking the slot until the converter is removed. The converter may include a sheath for receiving and passing a guidewire. 
         [0010]    In further embodiments, the present invention includes guidewire entry tools including a slot allowing for selective movement of a guidewire laterally from within a catheter. The slot may be designed with structures adapted to prevent inadvertent lateral movement of a guidewire from within the slot. In one such embodiment, the slot is formed in a zigzag shape, while in another embodiment, the guidewire insertion tool includes a number of protrusions that extend partially across the slot. 
         [0011]    In yet another embodiment, the guidewire entry tool includes a split ring that can be rotated from a first position to a second position, wherein a guidewire axially passing through the guidewire entry tool is laterally restrained in the first position, and free to move laterally in the second position. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0012]      FIG. 1  is a perspective view of a prior art guidewire entry tool and catheter; 
           [0013]      FIG. 2  is an elevation view from above of a guidewire entry tool and catheter; 
           [0014]      FIG. 3  is an elevation view from below of a guidewire blocking member; 
           [0015]      FIG. 4  is a side view illustrating how the guidewire blocking member of  FIG. 3  engages the guidewire entry tool of  FIG. 2 ; 
           [0016]      FIGS. 5A and 5B  are cut-away and cross-sectional views of a guidewire blocking insert for use with a guidewire entry tool; 
           [0017]      FIGS. 6A and 6B  are elevation and cross-sectional views of a guidewire entry tool and catheter; 
           [0018]      FIGS. 7A and 7B  are cross-sectional and cut-away views of a split ring; 
           [0019]      FIGS. 8A-8B  are overhead elevation views of a guidewire entry tool incorporating a split ring as in  FIGS. 7A-7B ; 
           [0020]      FIG. 9  is an elevation view of a guidewire entry tool incorporating a number of protrusions in the guidewire exit opening; 
           [0021]      FIG. 10  is an elevation view of the guidewire entry tool of  FIG. 9  having a guidewire extending therethrough; 
           [0022]      FIG. 11  is an elevation view of a guidewire entry tool having a zigzag in the guidewire exit opening; 
           [0023]      FIG. 12  is an elevation view of a combination sheath and insert guidewire blocking apparatus; 
           [0024]      FIG. 13  is an elevation view of the apparatus of  FIG. 12  engaged with a guidewire entry tool; and 
           [0025]      FIG. 14  is a perspective view of another illustrative insert guidewire blocking apparatus 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0026]    The following detailed description should be read with reference to the drawings. The drawings, which are not necessarily to scale, depict illustrative embodiments and are not intended to limit the scope of the invention. 
         [0027]    Throughout the present description, the term “catheter” should be understood to imply any of various medical devices adapted for insertion to the body, though the term “catheter” need not imply a guidewire. In particular, “catheter” is meant to include cannulae as well as catheters incorporating secondary devices (such as inflatable balloons, cutting wires, or ablation blades) near their distal ends. 
         [0028]      FIG. 2  is an elevation view from above of a guidewire entry tool and catheter. The guidewire entry tool  50  has a proximal end  52  and tapers to a distal end  54 , with a guidewire exit opening in the form of a slot  56 . The guidewire entry tool  50  is secured to a catheter  58  which includes a guidewire lumen shown in the form of a channel  60 . In use, a guidewire is directed into the proximal end  52  of the guidewire entry tool  50  and advanced distally. The taper of the guidewire entry tool  50  directs the guidewire into the guidewire lumen (channel  60 ) of the catheter  58 . 
         [0029]      FIG. 3  is an elevation view from below of a guidewire blocking member. The guidewire blocking member  62  includes an inserted portion  64 , an external portion  66 , and a coupling portion  68  that attaches the inserted portion  64  and external portion  66 . The coupling portion  68  is sized and shaped to fit into the slot  56  ( FIG. 2 ) of a corresponding guidewire entry tool  50  ( FIG. 2 ). The external portion  66  is sized and shaped to block off the guidewire exit opening of the guidewire entry tool  50  ( FIG. 2 ), while the inserted portion  64  is sized and shaped to slide into the guidewire entry tool  50  ( FIG. 2 ). 
         [0030]      FIG. 4  is a side view illustrating how the guidewire blocking member  62  of  FIG. 3  engages the guidewire entry tool  50  of  FIG. 2 . The guidewire blocking member  62  can be inserted from the proximal end  52  toward the distal end  54  of the guidewire entry tool  50 . The coupling piece  68  slides into the groove  56  (noted but not visible), with the insert piece  64  sliding inside the guidewire entry tool  50  and the external piece  66  covering over the groove  56 , thereby preventing a guidewire from inadvertently escaping. The guidewire blocking member  62 , in a further embodiment, is adapted to be removably coupled to the guidewire entry tool  50  by including a tab or other structure (not shown) allowing a physician to grasp the converter and remove it. 
         [0031]      FIGS. 5A and 5B  are cut-away and cross-sectional views, respectively, of a guidewire blocking insert for use with a guidewire entry tool. The cross section of  FIG. 5B  is taken at line  5 B- 5 B of  FIG. 5A . As shown in  FIG. 5A , the guidewire blocking insert  80  has a tapered end  82  and defines a guidewire lumen. As shown by  FIG. 5B , the guidewire lumen  84  is defined by an outer wall  86 . A tab, string, or other structure, such as a loop  85 , may be attached to the blocking insert  80  to allow for easy removal from a corresponding guidewire entry tool. A longitudinal slit  81  can be included to allow lateral placement and removal of the guidewire blocking insert  80  after sliding longitudinally out of a guidewire entry tool. 
         [0032]      FIGS. 6A and 6B  are side and cross-sectional views, respectively, of a guidewire entry tool and catheter. It should be noted that the view of  FIG. 6B  is taken looking proximally from line  6 B- 6 B of  FIG. 6A . As shown in the side view of  FIG. 6A , the guidewire entry tool  88  is secured to a catheter  90 . The guidewire entry tool  88  includes a tapered portion  92  extending distally from its proximal end  94 . The cross section of  FIG. 6B  shows the interior space  96  which is connected to the catheter lumen  98  via a slot  100  that extends up and out of the guidewire entry tool  88 . The slot  100  is sized to allow a guidewire to pass laterally therethrough. 
         [0033]    Referring generally to  FIGS. 5A-5B  and  6 A- 6 B, the tapered end  82  of the blocking insert  80  is shaped to slide into the tapered portion  92  of the guidewire entry tool  88 . This enables the outer wall  86  of the blocking insert  80  to block off the slot  100 , preventing a guidewire entering the catheter  90  through the guidewire entry tool  88  from inadvertently laterally exiting the guidewire entry tool  88 . 
         [0034]      FIGS. 7A and 7B  are cross-sectional and cut-away views of a split ring for use in another alternative embodiment. The ring  110  includes a slot  112  that is sized to allow a guidewire to pass therethrough. The ring also defines a lumen  114 . The lumen  114  may be sized to rotate around a catheter. The relative size of the slot  112  with respect to the lumen  114  and/or the ring  110  may vary, depending upon the relative guidewire and catheter sizes used in a particular embodiment. 
         [0035]      FIGS. 8A-8B  are overhead elevation views of a guidewire entry tool incorporating a split ring as in  FIGS. 7A-7B . In the illustration of  FIG. 8A , a split ring  110  is shown in a first position with the slot  112  in line with a guidewire exit slot for a guidewire entry tool  120  (the guidewire exit slot is shown as a tool slot  122 ), as well as a channel  126  on the catheter  124 . The split ring  110  may also be rotated to the configuration shown in  FIG. 8B . In the illustration of  FIG. 8B , the slot  112  of the split ring  110  does not align with the tool slot  122  and the channel  126 , thereby preventing a guidewire from exiting the guidewire entry tool  120  laterally. 
         [0036]      FIG. 9  is an elevation view of a guidewire entry tool incorporating a number of protrusions in the guidewire exit opening. The guidewire entry tool  140  is shown secured to a catheter  142 . The guidewire entry tool  140  includes a slot  144 . A number of protrusions  146  extend into the slot  144 . The protrusions  146  are shown extending about half-way into the slot  144 , but do not completely block off the slot  144 . Preferably the protrusions  146  leave a gap wide enough to allow a guidewire to pass by the protrusions  146  through the slot  144 , but are placed and shaped such that the guidewire must be manipulated intentionally to deform the protrusion and/or get through the gap. 
         [0037]      FIG. 10  is an elevation view of the guidewire entry tool of  FIG. 9  having a guidewire extending therethrough. The guidewire  148  is shown partially laterally removed from the guidewire entry tool  140 . In order to remove the guidewire  148 , it must be peeled around the several protrusions  146  to exit the slot  144  laterally. Once laterally removed from the guidewire entry tool  140 , the guidewire  148  may then be peeled away from the catheter  142  during a rapid exchange step. 
         [0038]      FIG. 11  is an elevation view of a guidewire entry tool having a zigzag in the guidewire exit opening. The guidewire entry tool  180  is shown secured to a catheter  182 . The guidewire entry tool  180  includes a guidewire exit opening in the form of a slot  184 . The slot  184  defines a path having several changes in direction, including a zigzag  186 . Any number of directional changes may be incorporated into the slot  184 . In order for a guidewire to exit through the slot  184 , the guidewire must be manipulated through the several changes in direction, because ordinarily, the guidewire will not adopt a complicated axial configuration, and will define either a straight line or a single curve. 
         [0039]      FIG. 12  is an elevation view of a combination sheath and insert guidewire blocking apparatus. The apparatus  200  includes a wing portion  202 , an intermediate portion  204 , and an insert portion  206 , with the insert portion  206  attached to a sheath  208  that includes a flare  210 . The flare  210  may be included to make it easier to insert a guidewire at that end. The wing portion  202 , intermediate portion  204 , and insert portion  206  may be similar to those shown above with respect to  FIGS. 3 and 4 . 
         [0040]      FIG. 13  is an elevation view of the apparatus of  FIG. 12  engaged with a guidewire entry tool. The guidewire entry tool  220  is secured to a catheter  222  and includes a guidewire exit opening that takes the form of a channel  224  (not visible, but indicated). The channel  224  may be similar to that shown above in  FIG. 1 . The intermediate portion  204  passes into the channel  224  such that the wing portion  202  is outside the guidewire entry tool  220 , and the insert portion  206  is secured partially inside the guidewire entry tool  220 . The sheath  208  enters the guidewire entry tool  220  and prevents a guidewire passing therethrough from exiting the guidewire entry tool  220  via the channel  224 . The apparatus  200  can be placed as shown before a guidewire is inserted, with the flare  210  aiding the insertion of a guidewire. Alternatively, the apparatus  200  may pass over a guidewire, with the guidewire passing through the sheath  208 , until the intermediate portion  204  enters the channel and removably secures the apparatus  200  to the guidewire entry tool  220 . 
         [0041]      FIG. 14  is a perspective view of another illustrative insert guidewire blocking apparatus. The blocking apparatus  300  includes an insert portion  302 , a wing portion  304 , and an intermediate portion  306 . As with the above embodiments, the apparatus  300  is adapted for use with a guidewire entry tool having a guidewire exit slot into which the intermediate portion  306  can fit. The insert portion  302  includes, for illustrative purposes, a larger proximal end  308  sized to make insertion of a guidewire relatively easy, and tapers to a distal end portion  310 . The distal end portion  310  may be sized for insertion to a guidewire channel, and may be relatively flexible and lubricious for allowing easy insertion to a guidewire channel as well as easy insertion of a guidewire therethrough. The insert portion also includes a tapered portion  312  that may be shaped and sized to fit snugly into a guidewire insertion tool. The tapered portion  312  may be sized such that, when inserted fully, the proximal end  308  butts up against the proximal end of a guidewire insertion tool. Alternatively, the guidewire insertion tool, if flexible, may be elastically expanded as the apparatus  300  is inserted such that a friction fit is achieved to keep the apparatus  300  in place. Though a circular shape is shown for the tapered portion  312 , other shapes, such as a rounded polygon, may also be provided. 
         [0042]    Those skilled in the art will recognize that the present invention may be manifested in a variety of forms other than the specific embodiments described and contemplated herein. Accordingly, departures in form and detail may be made without departing from the scope and spirit of the present invention as described in the appended claims.