Abstract:
Guidewire exit ramp members that may be placed over a tubular member having a guidewire lumen, which longitudinally extending and laterally accessible, and methods of use. The guidewire exit ramp member can be placed to force a guidewire loaded through the lumen in a first direction to be forced out of the lumen via an opening, slit or channel. The guidewire exit ramp member, in an illustrative embodiment, takes the form of a relatively short member having a proximal portion and a distally extending flap. The flap may be designed to enter and remain in a longitudinally accessible guidewire lumen. Combinations of such ramp members and device shafts having longitudinally extending laterally accessible guidewire lumens are also disclosed, as are methods for securing such combinations together. A method of backloading a guidewire into a catheter while causing lateral exit of the guidewire at a desired location is also shown.

Description:
RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 12/939,899, filed Nov. 4, 2010, now U.S. Pat. No. 8,221,357; which is a continuation of U.S. application Ser. No. 11/543,320, filed Oct. 5, 2006, now U.S. Pat. No. 7,833,197; which is a continuation of U.S. application Ser. No. 10/917,974, filed Aug. 12, 2004, abandoned, the entire disclosures of which are incorporated herein by reference. 
    
    
     FIELD 
     The present invention is related to the field of medical devices. More particularly, the present invention is related to catheters and other elongate medical devices incorporating guidewire lumens. 
     BACKGROUND 
     The use of catheters for minimally invasive medical procedures has become widespread. In many such procedures, a guidewire is used to help place the distal end of a catheter at a desired location. In practice, the use of a guidewire and an elongate medical device such as a catheter can create a number of difficulties. 
     If a guidewire or catheter proves unsuitable once inserted into a patient, it is removed and replaced. With early technologies, the catheter typically tracked over the guidewire along its entire length. When a catheter was removed, these early technologies required allowing the entire length of the catheter (typically 150 cm or longer) to pass over the guidewire without releasing the proximal end of the guidewire. This required a guidewire having a length of at least 300 cm, or a shorter guidewire used in combination with a guidewire extension. Such long guidewires required extra hands in the operating arena, increasing costs and creating a greater risk of loss of sterility, as well as making procedures last longer. 
     Rapid exchange catheters and single operator exchange catheters have been developed to make it easier and quicker to substitute one catheter or guidewire for another. An example single operator exchange catheter is the Autotome™ RX sphincterotome, marketed by Boston Scientific Corporation, Natick, Mass., which makes use of an elongated guidewire lumen in the form of a C-shaped channel. 
     The C-shaped channel allows lateral movement of a guidewire out of the guidewire lumen through the opening in the C-shaped channel over the longitudinal length of the channel. Such an opening, as well as openings or accesses created by the use of C-shaped, U-shaped, perforated or slit guidewire lumens, makes the longitudinally extending guidewire lumen a laterally accessible guidewire lumen. Lumens having a weakened, thin, or thinned wall through which a guidewire may tear for removal may also be considered as including a laterally accessible guidewire lumen. 
     SUMMARY 
     The present invention, in an illustrative embodiment, includes a guidewire exit ramp member that may be placed over a tubular member having a longitudinally extending guidewire lumen that is laterally accessible generally continuously over at least a portion of the length of the tubular member. The guidewire exit ramp member can be placed to force a guidewire passing into the guidewire lumen in a first direction to be forced out of the lumen via an opening, slit or channel. The guidewire exit ramp member, in an illustrative embodiment, takes the form of a ramp member having a proximal portion and a distally extending flap. The flap may be designed to enter and remain in a longitudinally extending laterally accessible guidewire lumen. 
     Another illustrative embodiment includes a method of providing a guidewire exit location for an elongate medical device. A guidewire exit ramp member is placed on an elongate member having a longitudinally extending guidewire lumen with a slit or opening therein over a certain length. The elongate member may include a skive or other opening into the guidewire lumen. The guidewire exit ramp member is placed near the skived portion or opening and slid in a direction such that a flap of the guidewire exit ramp member goes through the skive into the guidewire lumen. In some embodiments, the guidewire exit ramp member may be secured in place by heat bonding, adhesive, or the other attachment methods. When the method is complete, a guidewire passed through the guidewire lumen in a first direction is forced out of the guidewire lumen by the flap of the guidewire exit ramp member. In a further embodiment, the flap is flexible enough such that, when a guidewire is passed through the guidewire lumen in a second direction, the guidewire readily passes by the flap with little or no added resistance. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a partial elevational view of a medical device shaft having a longitudinally extending laterally accessible guidewire lumen; 
         FIG. 1B  is a cross-sectional view along line  1 B- 1 B of  FIG. 1A ; 
         FIG. 2  is a plan view of a cannula including a longitudinally extending laterally accessible guidewire lumen; 
         FIG. 3  is a perspective view of a guidewire exit ramp member for use in conjunction with a medical device shaft having a longitudinally extending laterally accessible guidewire lumen; 
         FIG. 4  is an elevation view of the illustrative guidewire exit ramp member of  FIG. 3  showing the flap; 
         FIG. 5  is a side view of the illustrative guidewire exit ramp member of  FIG. 3 ; 
         FIG. 6  is an end view from a distal location of the illustrative guidewire exit ramp member of  FIG. 3 ; 
         FIG. 7  is an elevation view of an alternative example guidewire exit ramp with a curved flap; 
         FIG. 8A  is an elevation view of an illustrative guidewire exit ramp coupled with a medical device shaft having a longitudinally extending laterally accessible guidewire lumen; 
         FIG. 8B  is a section view along line  8 B- 8 B of  FIG. 8A ; 
         FIGS. 9A-9C  are section views along lines  9 A- 9 A,  9 B- 9 B, and  9 C- 9 C of  FIG. 8A ; 
         FIGS. 10A-10C ,  11 A- 11 C, and  12 A- 12 C illustrate placement of a guidewire exit ramp on another medical device shaft having a closed longitudinally extending laterally accessible guidewire lumen; 
         FIGS. 13A-13C  illustrate in elevation and section views an alternative embodiment using a relatively stiff plastic guidewire exit ramp member; and 
         FIGS. 14A-14C  illustrate placement of the embodiment of  FIGS. 13A-13B  on an elongate medical device shaft. 
     
    
    
     DETAILED DESCRIPTION 
     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. 
       FIG. 1A  is a partial elevational view of a medical device shaft having a longitudinally extending laterally accessible guidewire lumen. The shaft  10  includes a channel  12  for laterally accessing a guidewire lumen passing therethrough.  FIG. 1B  is a cross-sectional view along line  1 B- 1 B of  FIG. 1A . As illustrated by  FIG. 1B , the guidewire lumen  14  includes the channel  12 . Two auxiliary lumens  16 ,  18  are also illustrated. While a triple lumen shaft  10  is illustrated, any number of lumens, from a single lumen up to 3, 4, or more lumens, may be provided in a shaft for use with the present invention. 
     The channel  12  is illustrated for providing access to a generally U-shaped guidewire lumen. Instead of a U-shape, a C-shape may be provided, the C-shape helping to retain a guidewire in the lumen  14 . Additionally, a slit may be used. Alternatively, instead of a channel  12  creating an opening, a wall for the lumen  14  where the channel is shown may be thin or intentionally thinned to enable a guidewire to be torn therethrough. Perforations may also be provided to make the longitudinally extending guidewire lumen  14  laterally accessible. Laterally accessible, as used herein, refers to a guidewire lumen that can be accessed along a length thereof, where access can be had either through an existing opening or by tearing a guidewire disposed in the guidewire lumen laterally through a slit, thin, thinned, perforated, or otherwise relatively weak lumen wall section. 
       FIG. 2  is a plan view of a cannula including a longitudinally extending laterally accessible guidewire lumen. The cannula  20  may incorporate a shaft  10  as illustrated in  FIGS. 1A and 1B  having a distal end  22  and a proximal end  24 . A slit  26  extends along a length of the shaft toward the distal end  22 ; while not shown, the slit  26  may extend proximally to a guidewire entry adaptor  28 . The example also illustrates marker bands near the distal end. Proximal of the adaptor  28  is a manifold  30  including two fluid infusion ports. The cannula in  FIG. 2  may have a similar cross section to that shown in  FIG. 1B , except to the extent that a slit  26  is used instead of an opening. The fluid infusion ports on the manifold  30  may be coupled to the auxiliary lumens of the cannula shaft for infusing fluids to a location at or near the distal end  22 . 
     The adaptor  28  shown functions by having a side-directed ramp/lumen with an opening allowing for lateral removal of a guidewire therefrom. The proximal end of the guidewire is controlled proximal of the adaptor  28  such that there is no need to force a backloaded guidewire from the guidewire lumen. The guidewire can be removed through the slit  26  once the exchange procedure starts. However, the exact location where the guidewire exits the slit  26  is not controlled. In particular, if a guidewire is backloaded into such a rapid exchange catheter, the adaptor  28  does not force the guidewire out of the catheter. 
     An example and description of such an adaptor  28  is given by Windheuser et al., in U.S. Pat. No. 6,606,515, the disclosure of which is incorporated herein by reference. The adaptor  28  has a relatively large profile in order to achieve ease of guidewire entry through a funnel-shaped portion, as further discussed by Windheuser et al., and is designed to prevent passage of the entire adaptor through a side port in an endoscope. Such sizing would also typically prevent passage through a guide catheter used in a vascular procedure. 
     During a catheter exchange procedure, with the guidewire already in place at a desired location in the patient (i.e., a vascular location, a location in the biliary tract, or any other cannulated location), the guidewire will extend through the guidewire lumen from the adaptor  28  to the distal end  22 . To exchange the cannula  20 , the guidewire is moved laterally out of the adaptor  28  and held in place as the cannula  20  is withdrawn. As the cannula  20  is withdrawn, the guidewire passes through the slit  26 , remaining in its internal location in the patient without requiring a guidewire extension. The slit  26  may extend to the distal end  22 , or may stop proximal of the distal end. 
       FIG. 3  is a perspective view of a guidewire exit ramp member for use in conjunction with a medical device shaft having a longitudinally extending laterally accessible guidewire lumen. The illustrative example guidewire exit ramp member includes a proximal portion  50 , a proximal end  53 , a flap  52 , a distal portion  54 , and a distal end  55 . The distal portion  54  of the guidewire exit ramp may further include a slot  51  defined therein. The proximal portion  50  surrounds and/or tracks over an elongate medical device on which the guidewire exit ramp member is used. The shape is shown as cylindrical but may instead be oval, polygonal, or other shapes including polygons with one or more curved sides. 
     In other illustrative examples, the proximal portion  50  may only partly surround an elongate medical device, and may instead take the form of a partial cylinder, or may have one or more gaps. In several embodiments, the form illustrated in  FIG. 3  is used for its low profile, allowing the guidewire exit ramp member to be readily placed and used even in situations where low profile is a concern. 
       FIG. 4  is an elevation view of the illustrative guidewire exit ramp member of  FIG. 3  showing the flap  52  more clearly. The flap  52  may have a proximal end  57  connected to the proximal portion  50  of the guidewire ramp member and extending distally therefrom to a distal end  59 . In some instances, the distal end  59  of the flap may be flat. As can be seen, the example flap  52  has rather angular distal ends, extending distally relative to, but shorter than, the distal portion  54 . In other embodiments the flap  52  may be longer than the distal portion  54 , and, in one embodiment, the distal portion  54  may be entirely omitted. For some embodiments, the flap  52  will be inserted through a transversely cut opening in an elongate medical device, as further explained below. For such embodiments, the inclusion of the distal portion  54  may help maintain the shape, pushability, and/or anti-kinking characteristics of the elongate medical device across the transverse cut since the transverse cut may weaken the elongate medical device. 
       FIG. 5  is a side view of the illustrative guidewire exit ramp member of  FIG. 3 . The distal portion  54  has a reduced profile due to the flap  52 .  FIG. 6  is an end view of the illustrative guidewire exit ramp member of  FIG. 3 . The flap  52  is shown extending down into the lumen defined by the distal portion  54 , which is in line with the lumen formed in the proximal portion  50 . In an illustrative embodiment, the flap  52  is biased to bend down as illustrated by FIGS.  3  and  5 - 6 . 
     In one embodiment, the guidewire exit ramp member shown in  FIGS. 3-6  is formed by a molding process. In other embodiments, the guidewire exit ramp member may be formed by cutting a tubular member. The ramp member may be sized to correspond to a given size of elongate medical device shaft. For example, given a 6-French elongate medical device shaft, the inner diameter defined by the proximal portion of the ramp member may be just large enough to slide over such a device shaft. The inner surface of the ramp member may include a lubricious coating to allow easy movement and placement over the device shaft. Alternatively, the material chosen for making the ramp member may be chosen for its lubricious properties. 
     The ramp member may be formed of a wide variety of materials. In some embodiments the ramp member is formed of a nylon material, which is inexpensive and easy to mold, as well as being a popular material for medical applications. Polycarbonate may also be used, as well as any of a wide variety of polymers, copolymers and metals or alloys known for use in medical devices, catheters, cannulas, endoscopes, and the like. Any other suitable biocompatible material may also be used and/or incorporated. 
       FIG. 7  is an elevation view of an alternative example guidewire exit ramp member with a curved flap. As illustrated, the guidewire exit ramp member includes a proximal portion  60 , a proximal end  63 , a flap  62 , a (optional) distal portion  64 , and a distal end  65 . The distal portion  64  of the guidewire exit ramp may further include a slot  61  defined therein. As shown at  66 , the flap  62  has curved ends, which may allow the flap  62  to extend into and generally match the contours of a guidewire lumen having curved interior contours. Rather than a simple curve as shown, the flap  62  may be designed to match a particular guidewire lumen shape/cross section. 
       FIG. 8A  is an elevation view of an illustrative guidewire exit ramp coupled with a medical device shaft having a longitudinally extending laterally accessible guidewire lumen. A device shaft  100  is shown with a guidewire exit ramp member  102  placed thereover. The ramp member  102  may include a proximal end  103  and a distal end  105 . The ramp member  102  may further include a slot  101  extending proximally from the distal end  105  The ramp member  102  includes a flap  104  having a proximal end  107  and a distal end  109 . The flap  104  is aligned with and enters a channel  106  (shown as a U-shaped channel for the purposes of illustration). The longitudinal cross section of  FIG. 8B  illustrates that the ramp member  102  has a proximal portion that surrounds the device shaft  100 , with the flap  104  extending down into the channel  106 . 
     The transverse section views of  FIGS. 9A-9C  illustrate that the device shaft  100  is shown having the channel  106  as well as auxiliary lumens  108  and  110 . As shown in  FIG. 9B , along line  9 B- 9 B in  FIG. 8A , the flap  104  extends partly into the channel  106 , with the optional distal portion of the ramp member  102  extending around the device shaft  100  at that location.  FIG. 9C  is taken at a more distal location along the device shaft  100  and ramp member  102 , as shown by line  9 C- 9 C of  FIG. 8A . By this point, the flap  104  extends down to the base of the channel  106 . If a guidewire is backloaded into the channel  106 , the flap  104  will force the guidewire out of the channel  106 . However, if a guidewire is passed distally from a more proximal location, as can be seen in  FIG. 8B , the slant of the flap  104  will allow the flap  104  to deflect so that the guidewire may pass with little resistance generated by the flap  104 . 
       FIGS. 10A-10C ,  11 A- 11 C, and  12 A- 12 C illustrate placement of a guidewire exit ramp on another medical device shaft having a closed longitudinally extending laterally accessible guidewire lumen. Referring to  FIGS. 10A-10C , a guidewire exit ramp member  200  having a flap  202  is shown placed on a device shaft  204 , the device shaft  204  having an opening shown as skive  206 . The ramp member  200  may include a proximal end  203  and a distal end  205 . The ramp member  200  may further include a slot  201  extending proximally from the distal end  205 . The flap  204  may have a proximal end  207  and a distal end  209 . The ramp member  200  is shown some distance proximal of the skive  206  on the device shaft  204 . 
     As highlighted in  FIG. 10B , (a section view along line  10 B- 10 B of  FIG. 10A ) the device shaft  204  includes a guidewire lumen  208  having a thinned wall  210 , as well as an additional auxiliary lumen  212 . The thinned wall  210  enables a guidewire to laterally exit the guidewire lumen  208  by tearing through the thinned wall  210 . To further weaken the wall, perforations may be provided. The thinned wall  210  may be provided during extrusion or by post-extrusion machining. The longitudinal cross section of  FIG. 10C  illustrates the skive opening into the guidewire lumen  208 . 
     Turning to  FIGS. 11A-11C ,  FIG. 11A  shows that the ramp member  200  has been advanced such that the flap  202  partly enters the skive  206  in the device shaft  204  such that the distal end  209  is disposed within the guidewire lumen  206 .  FIG. 11B  shows in transverse cross section that the flap  202  reaches partly down into the guidewire lumen  208  through the skive  206 . As shown by  FIG. 11C , the skive  206  enables easy entry of the flap  202  down into the guidewire lumen  208  through the thin wall  210 . In some embodiments, the flap  202  may be biased downward such that it readily extends through the skive  206 . It should be noted that the thinned wall  210  would not be necessary to use the guidewire ramp member  200  in the fashion shown, since the flap  202  simply enters through an opening into the guidewire lumen  208 . 
     Referring now to  FIGS. 12A-12C , the ramp member  200  is moved distally along the device shaft  204  until the flap  202  completely enters the guidewire lumen  208  through the skive  206 . Once this location is reached, the flap  202  may rest against an interior wall of the guidewire lumen  208 . When so located, a guidewire proximal end passing in a proximal direction through the guidewire lumen  208  may be forced laterally out of the device shaft  204  by the flap  202 . Thus backloading of a guidewire into the device shaft  204  can be performed easily with an assurance that a guidewire will exit the device shaft  204  at a desired location defined by the skive  206  and the ramp member  200 . In various illustrative embodiments, the ramp member  200  may be moveable with respect to the shaft or secured (by adhesive or welding, for example) to the device shaft  204  once placed as shown in  FIG. 12A . 
       FIGS. 13A-13C  illustrate in elevation and section views of an alternative embodiment making use of a pinch or squeeze type of ramp. As can be seen, the ramp member  300  includes a proximal portion  302  and a pinching portion  304 . The pinching portion  304  may be sized to reduce the internal diameter or cross-sectional area of the ramp member sufficient to collapse a portion of a guidewire lumen. In one embodiment, the reduced diameter/area is sized to prevent pinching of any auxiliary lumens of an associated medical device, though some compression may be acceptable. It should be noted that the pinching portion need not be cylindrical and may take on a variety of shapes adapted for use with various catheter shafts. As shown in  FIG. 13C , the transverse section of the pinching portion  304  is shaped to receive a catheter shaft without pinching any auxiliary lumens, instead being shaped to compress only the guidewire lumen. The dashed lines of  FIG. 13C  represent, in phantom, the locations of a guidewire lumen and two auxiliary lumens for a catheter shaft received and pinched by the ramp member  300 . It can be seen that two of the lumens (the auxiliary lumens) would not be significantly blocked. 
       FIGS. 14A-14C  illustrate placement of the embodiment of  FIGS. 13A-13B  on an elongate medical device shaft. As shown in  FIG. 14A , the elongate medical device shaft  310  is provided with a transverse cut  312  that may take the form of a skive or slit. If desired, the shaft  310  may include a guidewire lumen having a thinned or weakened wall. As shown in  FIG. 14B , the ramp member  300  is slid onto the shaft  310  until the ramp member  300  engages the transverse cut  312 . At the location of the transverse cut  312 , the shaft  310  will be inherently weaker due to the transverse cut  312  across a portion of the wall of the guidewire lumen. Turning to  FIG. 14C , it can be seen that the ramp  304  of the ramp member  300  collapses a portion of the wall of the guidewire lumen  314 , but the auxiliary lumen  316  is not significantly affected. The proximal portion  302  aids in letting the ramp  306  collapse the wall of the guidewire lumen  314 . A guidewire backloaded into the shaft  310  will now be forced out of the guidewire lumen  314  at the ramp  304 . Any suitable plastics may be used for the shaft  310  and the ramp member  300 . For the alternative embodiments of  FIGS. 13A-13B  and  14 A- 14 C, the ramp member  300  may be formed of a stiffer material than the material used to define the guidewire lumen  314 . To preserve the patency of the auxiliary lumen  316 , some embodiments may make use of a reinforcing member to support the auxiliary lumen  316 . 
     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.