Abstract:
A catheter and guide wire exchange system including a catheter that has a guide wire lumen with a guide way extending along a length of the proximal shaft. A guide member is slidably disposed about the proximal shaft for directing a guide wire into or out of the guide way and the guide wire lumen. A transition section joins the bilumen proximal shaft to a coaxial distal shaft.

Description:
FIELD OF THE INVENTION 
     The present invention relates to catheters used with guide wires in the cardiovascular system and, in particular, to a system for facilitating exchange of such catheters and guide wires, and for transporting such catheters and guide wires to selected sites within a patient. 
     BACKGROUND OF THE INVENTION 
     Catheters are inserted to various locations within a patient for a wide variety of purposes and medical procedures. For example only, one type of catheter is used in percutaneous catheter intervention (PCI) for the treatment of a vascular constriction termed a stenosis. In this instance, the catheter has a distally mounted balloon that can be placed, in a deflated condition, within the stenosis, and then inflated to dilate the narrowed lumen of the blood vessel. Such balloon dilation therapy is generally named percutaneous transluminal angioplasty (PTA). The designation PTCA, for percutaneous transluminal coronary angioplasty, is used when the treatment is more specifically employed in vessels of the heart. PTCA is used to open coronary arteries that have been occluded by a build-up of cholesterol, fats or atherosclerotic plaque. The balloon at the distal end of the catheter is inflated, causing the site of the stenosis to widen. 
     The dilation of the occlusion, however, can form flaps, fissures and dissections, which may result in reclosure of the dilated vessel or even perforations in the vessel wall. Implantation of a stent can provide support for such flaps and dissections and thereby prevent reclosure of the vessel or provide a patch repair for a perforated vessel wall until corrective surgery can be performed. A stent is typically a cylindrically shaped device formed from wire(s) or a tube and is intended to act as a permanent prosthesis. Stents may include therapeutic coatings or deliver therapeutic drugs to further treat the vessel and prevent reclosure of the vessel. A stent is deployed in a body lumen from a radially compressed configuration into a radially expanded configuration that allows it to contact and support a body lumen. A stent can be implanted during an angioplasty procedure by using a balloon catheter bearing a compressed stent that has been loaded onto the balloon. The stent radially expands as the balloon is inflated, forcing the stent into contact with the body lumen, thereby forming a supporting relationship with the lumen walls. Alternatively, self-expanding stents may be deployed with a sheath-based delivery catheter. Deployment is effected after the stent has been introduced percutaneously, transported transluminally and positioned at a desired location by the delivery catheter. In addition to angioplasty and stenting procedures, other therapeutic procedures require use of a delivery catheter, such as drug delivery, filters, occlusion devices, diagnostic devices and radiation treatment. 
     Typically, the placement of such therapeutic delivery catheters involves the use of a guide wire, which may be inserted into the patient&#39;s vasculature through the skin, and advanced to the location of the treatment site. The delivery catheter, which has a lumen adapted to receive the guide wire, then is advanced over the guide wire. Alternatively, the guide wire and the delivery catheter may be advanced together, with the guide wire protruding from the distal end of the delivery catheter. In either case, the guide wire serves to guide the delivery catheter to the location to be treated. 
     To treat small diameter vessels remote from the entry point into the patient, a guide catheter is used to span the distance. For example, in PTCA or stent delivery, a guide catheter  10  is typically inserted into a large artery  12  near the patient&#39;s groin, and then advanced toward the heart  14  to the entry opening, or ostium, of the diseased coronary artery as illustrated in FIG.  1 A. The guide catheter  10  provides a tubular conduit through which catheters and guide wires, designated generally as  16 , can be passed from outside the patient to the vessel being treated. 
     There are three general types of catheters: “over-the-wire” (OTW) catheters, “rapid exchange” (RX) or single operator catheters and “fixed wire” (FW) or “a balloon on a wire” catheters. An over-the-wire catheter comprises a guide wire lumen that extends the entire length of the catheter. The guide wire is disposed entirely within the catheter guide wire lumen except for the distal and proximal portions of the guide wire, which extend beyond the distal and proximal ends of the catheter respectively. An OTW catheter typically has a “co-axial” catheter construction, as shown in  FIGS. 2A and 3A , wherein two hollow tubes are nested together such that the lumen  22  of the inner tube can slidably receive guide wires, such as guide wire  24 , and the annular luminal space  26  formed between the inner and outer tubes is used for inflation/deflation, fluid. An alternative “multilumen” OTW catheter construction has an elongate shaft made from a single extruded tube  18  having two lumens  22 ′ and  26 ′ formed side-by-side, as shown in  FIGS. 2B and 3B . OTW catheters that contain both multilumen segments and coaxial segments are also known. 
     Over-the-wire catheters have many advantages traceable to the presence of a full-length guide wire lumen such as good stiffness and pushability for readily advancing the catheter through the tortuous vasculature and across tight stenoses. The full-length guide wire lumen permits removal and replacement of a guide wire in an indwelling catheter, as may be required to alter the shape of the guide wire tip. It is also sometimes desirable to exchange one guide wire for another guide wire having a different stiffness. For example, a relatively soft, or flexible guide wire may prove to be suitable for guiding a PTCA catheter through a particularly tortuous anatomy, whereas following up with a stent-delivery catheter through the same vasculature region may require a guide wire that is relatively stiffer. The full-length guide wire lumen is also available for transporting radiocontrast dye to the stenosed artery, for making pressure measurements, for infusing drugs and for other therapies. 
     Over-the-wire catheters do suffer some shortcomings, however. For example, it often becomes necessary, in the performance of a PCI, to exchange one indwelling catheter for another catheter. In order to maintain a guide wire in position while withdrawing the catheter, the guide wire must be gripped at its proximal end to prevent it from being pulled out of the blood vessel with the catheter. For example, a PTCA catheter, which may typically be on the order of 135 centimeters long, is longer than the proximal portion of the standard guide wire that protrudes out of patient. Therefore, exchanging an over-the-wire PTCA catheter requires an exchange guide wire of about 300 centimeters long, whereas a standard guide wire is about 165 centimeters long. 
     In one type of over-the-wire catheter exchange, the standard length guide wire first is removed from the lumen of the indwelling catheter. Then, a longer exchange guide wire is passed through the catheter to replace the original wire. Next, while holding the exchange guide wire by its proximal end to control its position in the patient, the catheter is withdrawn proximally from the blood vessel over the exchange guide wire. After the first catheter has been removed, the next OTW catheter is threaded onto the proximal end of the exchange guide wire and is advanced along the exchange guide wire, through the guiding catheter, and into the patient&#39;s blood vessels until the distal end of the catheter is at the desired location. The exchange guide wire may be left in place or it may be exchanged for a shorter, conventional-length guide wire. In an alternative type of catheter exchange procedure, the length of the initial guide wire may be extended by way of a guide wire extension apparatus. Regardless of which exchange process is used, the very long exchange guide wire is awkward to handle, thus requiring at least two operators to perform the procedure. 
     Catheter designs have been developed in an attempt to eliminate the need for guide wire extensions or exchange guide wires. One such catheter design is the rapid exchange (RX) type catheter. Catheters of this type are formed so that the guide wire is located outside of the catheter except for a short guide wire lumen that extends within only a comparatively short distal segment of the catheter. The rapid exchange catheter&#39;s proximal exit port for the guide wire is typically located about 5 cm (2.0 in) to 100 cm (11.8 in) proximal to the catheter&#39;s distal end. In use, the guide wire is placed initially in the patient&#39;s vascular system. The distal segment of the RX catheter then is threaded onto the wire. The catheter can be advanced alongside the guide wire with its distal segment being attached to and guided along the guide wire. The RX catheter can be removed and exchanged for another RX catheter without the use of a very long exchange guide wire and without requiring withdrawal of the initially placed guide wire. 
     Although an RX catheter system may avoid the requirement for using a very long exchange wire, it presents several difficulties. First, without a full-length guide wire lumen, the proximal shaft of an RX catheter lacks an OTW catheter&#39;s coaxial interrelationship with the guide wire, which provides optimal transmission of force to push the distal end of the catheter through tight stenoses and/or tortuous blood vessels.  FIGS. 2A and 3A  illustrate guide catheter  10 , a shaft segment of OTW catheter  18  extending there through, and guide wire  24  disposed within guide wire lumen  22  in the common construction of coaxial tubes. The nested tubes result in an inner guide wire lumen  22  and an annular inflation lumen  26  formed between the tubes. The coaxial interrelationship with guide wire  24  provides an optimal transmission of force along the catheter length. In  FIGS. 2B and 3B , inflation lumen  26 ′ extends parallel to guide wire lumen  22 ′ in a side-by-side arrangement. Although guide wire lumen  22 ′ and guide wire  24 ′ are located off-center in catheter  18 ′, guide wire  24 ′ is confined within catheter  18 ′ throughout its length. Even if catheter  18 ′ begins to buckle slightly when the distal tip of the catheter is being forced through a tight stenosis, there is very little misalignment with guide wire  24 ′, such that most of the push force is transmitted to the distal tip. Therefore, despite their disadvantages during catheter exchange procedures, OTW catheters remain popular in the United States, due in part to the coaxial alignment between the catheter shaft and the guide wire, and the resulting excellent pushability of the device. 
     While improvements to RX catheters have incorporated stiff, metal proximal shafts and axial overlap between the shaft and the guide wire lumen to overcome the deficiencies discussed above, such RX catheters still are not optimal.  FIGS. 4 and 5  depict prior art RX catheter  30  incorporating such a reinforced shaft  32 , disposed over guide wire  34  within guide catheter  36 . However, even with continuous column support of reinforced shaft  32 , the non-aligned or offset arrangement of guide wire  34  and shaft  32  of catheter  30  can cause shaft buckling within the guiding catheter, as illustrated generally at  38  in  FIG. 4 , especially when the distal tip of the catheter is being forced through a tight stenosis. Such a non-coaxial misalignment causes displacement of push forces and an associated resistance to catheter advancement, especially in the region of proximal guide wire port  40 . 
     A second difficulty associated with RX catheters is that it is not possible to exchange guide wires in an indwelling RX catheter, as can be done advantageously with OTW catheters. A guide wire can be withdrawn, sometimes unintentionally, from the proximal guide wire port, thus derailing an indwelling RX catheter. However, neither the first guide wire, nor a replacement guide wire, can be directed back into the catheter&#39;s proximal guide wire port, which is hidden remotely in the guiding catheter within the patient.  FIG. 6  illustrates the problem of blindly steering the tip of guide wire  42  within guiding catheter  44  in an attempt to find and engage proximal guide wire port  46  of RX catheter  48 . 
     A third difficulty associated with RX catheters is that, if the guide wire lumen is so short that the proximal guide wire port exits from the distal end of the guiding catheter, then the guide wire will be exposed. Such an RX device presents a risk of what is called the “cheese cutter effect,” which is damage to the delicate inner surface of a curved artery from straightening tension applied to the exposed guide wire during push-pull maneuvers to advance the catheter. The short-lumen RX device also presents an increased risk of guide wire entanglement in those procedures where multiple guide wires are used, because the guide wires are exposed within the blood vessel. Furthermore, the exposed, unprotected portion of the guide wire can become kinked or tangled within the patient&#39;s vessel, adding complications to the procedure. 
     A fourth difficulty associated with RX catheters is encountered at the proximal end of the catheter system. There, the RX catheter and the guide wire extend from the guiding catheter side-by-side, making it awkward to seal the system against blood loss during manipulation of the components. The sealing, or “anti-backbleed” function is typically accomplished with a “Tuohy-Borst” fitting that has a manually adjustable gasket with a round center hole that does not conform well to the side-by-side arrangement of a catheter shaft and guide wire. A final difficulty associated with RX catheters is that the lack of a full-length guide wire lumen deprives the clinician of an additional lumen that may be used for other purposes, such as pressure measurement, injection of contrast dye distal to the stenosis, or infusing a drug. 
     An over-the-wire catheter designed to eliminate the need for guide wire extensions or exchange wires is disclosed in U.S. Pat. No. 4,988,356 (Crittenden et al.). This over-the-wire/short wire (OTW/SW) catheter includes a catheter shaft having a cut that extends longitudinally between the proximal end and the distal end of the catheter and that extends radially from the catheter shaft outer surface to the guide wire lumen. A guide member slidably coupled to the catheter shaft functions to open the cut such that the guide wire may extend transversely into or out of the cut at any location along its length. By moving the guide member, the effective over-the-wire length of the OTW/SW catheter is adjustable. 
     When using the OTW/SW catheter, the guide wire is maneuvered through the patient&#39;s vascular system such that the distal end of the guide wire is positioned across the treatment site. With the guide member positioned near the distal end of the catheter, the proximal end of the guide wire is threaded into the guide wire lumen opening at the distal end of the catheter and through the guide member such that the proximal end of the guide wire protrudes out the proximal end of the guide member. By securing the guide member and the proximal end of the guide wire in a fixed position, the catheter may then be transported over the guide wire by advancing the catheter toward the guide member. In doing so, the catheter advances through the guide member such that the guide wire lumen envelops the guide wire as the catheter is advanced into the patient&#39;s vasculature. In a PTCA embodiment, the OTW/SW catheter may be advanced over the guide wire in this manner until the distal end of the catheter having the dilatation balloon is positioned within the stenosis and essentially the entire length of the guide wire is encompassed within the guide wire lumen. 
     Furthermore, the indwelling OTW/SW catheter may be exchanged with another catheter by reversing the operation described above. To this end, the indwelling catheter may be removed by withdrawing the proximal end of the catheter from the patient while holding the proximal end of the guide wire and the guide member in a fixed position. When the catheter has been withdrawn to the point where the distal end of the cut has reached the guide member, the distal portion of the catheter over the guide wire is of a sufficiently short length that the catheter may be drawn over the proximal end of the guide wire without releasing control of the guide wire or disturbing its position within the patient. After the catheter has been removed, another OTW/SW catheter may be threaded onto the guide wire and advanced over the guide wire in the same manner described above with regard to the OTW/SW catheter. The OTW/SW catheter not only permits catheter exchange without the use of the very long exchange guide wire and without requiring withdrawal of the initially placed guide wire, but it also overcomes many of the other difficulties discussed in association with RX catheters. 
     Despite these advantages, original OTW/SW catheters in accordance with the &#39;356 patent had difficulties related to movement of the guide wire through the guide member. As disclosed in the &#39;356 patent, the use of a hypodermic tubing member to direct a guide wire into and out of the guide wire lumen was found to be effective while the guide wire was stationary within the guide member, and while the catheter was moved therethrough. However, if the guide wire were to be withdrawn through the guide member, the hypodermic tubing member would often scrape pieces of a lubricious coating from the guide wire. The resulting shavings, designated generally as  50  in  FIG. 7 , would become jammed in the annular space between the guide wire  52  and the hypodermic tubing member  54 , preventing further movement of the guide wire. 
     In a more significant problem with the original OTW/SW catheter, it could fail to adequately contain the guide wire within the guide wire lumen during normal operation. In particular, as the catheter was advanced over the guide wire, the catheter could bend or buckle such that the guide wire could protrude from the catheter shaft. If the guide wire protruded from the catheter shaft, it could subsequently become pinched, and the distal end of the guide wire could be pulled out of or pushed beyond the treatment site, thus complicating the procedure and requiring repositioning within the patient&#39;s vasculature. Bending or buckling of a OTW/SW catheter could also occur proximal to the guide member, where the guide wire is absent from the guide wire lumen. Furthermore, the transition between the proximal shaft containing the longitudinal cut and the distal part of the catheter is also a potential kink location. It is among the general objects of the invention to provide an improved device that overcomes the foregoing difficulties. 
     SUMMARY OF THE INVENTION 
     The present invention is a catheter and guide wire exchange system comprising an elongate flexible catheter having proximal and distal ends and first and second lumens extending there through, the first lumen being open at the shaft distal end and being sized and shaped to slidably receive a guide wire. The second lumen is an inflation lumen. The catheter has a bilumen proximal shaft and a coaxial distal shaft. The distal and proximal shafts are coupled through a transition section. At the transition section, an outer tubular portion of distal shaft overlaps the outer surface of the proximal shaft distal end. Proximal end of distal shaft inner tubular member is positioned within the first lumen of the proximal shaft. The shafts are then fused forming the transition section. 
     A guide member is mounted on catheter proximal shaft and is received in a guide way formed from a longitudinal cut in catheter proximal shaft to enable transverse access to the first lumen through the elongate flexible catheter. The guide way extends along a major portion of the length of the proximal shaft from a location adjacent the proximal end of the catheter to a location proximal to the proximal shaft distal end. A stop is located on the exterior of the proximal shaft distal end proximal to the transition section. The guide member cannot travel distally past the stop. An elongate stiffening member is disposed within the second lumen from the catheter proximal shaft to a location past the guide way distal end through the transition section and into the catheter distal shaft. A balloon is mounted about catheter distal segment, the balloon being in fluid communication with the second lumen. The guide member has a catheter passageway for slidably receiving the catheter shaft and a guide wire passageway for slidably receiving the guide wire. The guide member merges the guide wire and the catheter by guiding the guide wire transversely through the guide way in the catheter and into the first lumen. Conversely, the guide member can be used for separating the guide wire and catheter by guiding the guide wire transversely out of the first lumen through the guide way. The guide wire lumen may further include a ramp or recess to assist in aligning the guide wire with the guide wire passageway. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features, aspects and advantages of the present invention will become better understood with reference to the following description, appended claims, and accompanying drawings where: 
         FIG. 1A  is a diagrammatic illustration of a patient showing the manner in which a balloon catheter is advanced from the femoral artery through the aorta and into the patient&#39;s heart; 
         FIG. 1B  is an enlarged portion of  FIG. 1A  showing the present invention positioned with the guide catheter and extending into the femoral artery; 
         FIG. 2A  is a longitudinal sectional illustration of a section of a prior art coaxial over-the-wire catheter and guide wire system; 
         FIG. 2B  is a longitudinal sectional illustration of a section of a prior art multilumen over-the-wire catheter and guide wire system; 
         FIG. 3A  is a transverse sectional illustration of a coaxial prior art over-the wire catheter and guide wire system, taken along the line  3 A— 3 A of  FIG. 2A ; 
         FIG. 3B  is a transverse sectional illustration of a multilumen prior art over the-wire catheter and guide wire system, taken along the line  3 B— 3 B of  FIG. 2B ; 
         FIG. 4  is a longitudinal sectional illustration of a section of a prior art rapid exchange catheter and guide wire system; 
         FIG. 5  is a transverse sectional illustration of a prior art rapid exchange catheter and guide wire system, taken along the line  5 — 5  of  FIG. 4 ; 
         FIG. 6  is partial longitudinal sectional illustration of a section of a prior art rapid exchange catheter and guide wire system, shown within a guiding catheter; 
         FIG. 7  is a partial longitudinal sectional illustration of a section of a prior art OTW/SW catheter and guide wire system; 
         FIG. 8  is an illustration of the catheter and guide wire of the present invention in an assembled configuration; 
         FIG. 8A  is a cross-section taken along line A—A of  FIG. 8 ; 
         FIG. 8B  is a cross-section taken along line B—B of  FIG. 8A ; 
         FIG. 8C  is a cross-section taken along line C—C of  FIG. 8A ; 
         FIG. 8D  is a cross-section taken along line D—D of  FIG. 8A ; 
         FIG. 9  is a transverse sectional illustration of the transition section of the present invention; 
         FIG. 10A  is a large view of the present invention extending from the guide catheter at the ostium of the heart; 
         FIG. 10B  is a cross-section of the guide catheter showing the present invention extending through the aortic arch of  FIG. 1A ; 
         FIGS. 11A-11C  are schematic illustrations of the construction of the stop member of the present invention; 
         FIGS. 12A-12E  are schematic illustrations of the construction of the transition section of the present invention; 
         FIG. 13  is a transverse sectional illustration of an alternative embodiment of the transition section of the present invention; 
         FIG. 14  is a transverse cross-sectional view of the guide member of the present invention; 
         FIGS. 15A-15C  show the guide member positioned on the proximal shaft and illustrating the inter-relation between the guide member and the proximal shaft; 
         FIG. 16  is an alternative embodiment of the transition section with a ramped guide wire lumen; and 
         FIG. 17  is a second alternative embodiment of the transition section with a recessed guide wire lumen. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As shown in  FIG. 8A , the invention includes a catheter, indicated generally by the reference character  100 , on which a guide member  102  is slidably mounted. Guide wire  104  is illustrated as extending through the guide member  102 . Guide member  102  serves as a juncture in which the catheter  100  and guide wire  104  may be merged or separated so that the portion of guide wire  104  which extends proximally of guide member  102  (to the left as seen in  FIG. 8A ) is separated from catheter  100  and the portion of guide wire  104  which is located distally of guide member  102  (to the right as seen in  FIG. 8A ) is contained and housed within catheter  100  except for distal end  106  of guide wire  104  which may protrude distally out of distal end  108  of catheter  100 . 
     Catheter  100  includes an elongate, flexible, cylindrical main body, which may be formed from an extruded plastic material such as, for example, polyethylene or polyethylene block amide (PEBA) copolymer. Catheter  100  has a distal shaft  110  and a proximal shaft  112  with a transition section designated  114 . The embodiment shown in  FIG. 8A , a catheter, such as for PTCA or stent delivery, having balloon  116  mounted around the catheter body near the distal end  108  of catheter  100 . Balloon  116  may be inflated and deflated through inflation lumen  118  formed through the body of the catheter  100 . Inflation lumen  118  extends from the proximal end of catheter  100 , where it communicates with fitting  120  and extends the length of catheter  100 , terminating in communication with the interior of balloon  116 . Fitting  120  may be connected to a suitable source of pressurized fluid or a partial vacuum (not shown) to inflate or deflate balloon  116 . Catheter  100  includes lumen  122  for receiving guide wire  104 . Guide wire lumen  122  extends the full length of catheter  100 , terminating at distal end  108  and proximal fitting  120 . 
     In accordance with the invention, the body of proximal shaft catheter  100  is formed with longitudinal guide way  124  which, when catheter  100  is viewed in cross-section, as in  FIG. 8A , may be considered as defining a pair of flaps  126  and  128  which normally close together at guide way  124  to define enclosed guide wire lumen  122 . Guide wire lumen  122  may be circular in cross-section or may be non-circular; in either case, the cross-sectional dimensions of guide wire lumen  122  are greater than the cross-sectional dimension of guide wire  104  to permit relative longitudinal movement between guide wire  104  and catheter  100 . Inflation lumen  118  encompasses elongate stiffening member  130 , which causes the shaft of catheter  100  to have greater bending stiffness than guide wire  104 . Stiffening member  130  extends at least through the length of catheter  100  that includes guide way  124 , thus preventing the shaft from bending such that guide way  124  could buckle allowing guide wire  104  to protrude from the catheter shaft and it may extend into distal shaft  110 . Guide way proximal end  132  may terminate at or near fitting  120 . In the embodiment shown in  FIG. 8A , guide way distal end  136  terminates short of proximal shaft distal end  138 , thereby leaving distal section  140  of proximal shaft  112  in which guide wire lumen is defined by a continuous surrounding wall as shown in FIG.  8 B. Stop  142  is located approximate guide way distal end  136 . Stop  142  is a raised portion on the proximal shaft as seen in FIG.  8 A. The raised portion may be annular or multiple areas spaced around the shaft circumference such as the two raised areas  162  and  164  spaced 180 degrees apart on the long axis of oval proximal shaft  112  as shown in FIG.  11 C. 
     Turning now to  FIGS. 8B ,  8 C and  9 , catheter  100  transforms from its proximal side-by-side lumen configuration to a distal coaxial configuration adjacent guide way distal end  136 . Distal catheter shaft  110  preferably comprises a coaxial arrangement of two tubes  144  and  146 , with inner tube lumen  148  communicating with proximal shaft guide wire lumen  150 . Outer tube  146  encompasses the inner tube  144 , forming an annular lumen  152  that extends proximal inflation lumen  154  to balloon  116 . The length of catheter  100  is such that it can pass easily through the curved aortic arch as shown in  FIGS. 10A and 10B . In these views, guide catheter  156  stops proximate the ostium of the heart and prior to the diseased coronary artery. Guide catheter  156  provides tubular conduit through which catheter  100  and guide wire  104  are passed through the patient from outside the patient to the vessel being treated, as illustrated in  FIGS. 1A ,  1 B,  10 A and  10 B. As seen in  FIG. 10B , transition section  114  is proximal of guide catheter opening  158  with distal shaft  110  extending out from guide catheter  156 . 
     Prior to forming the transition section  114 , stop  142  is formed on proximal shaft  112  as is seen in  FIGS. 11A-C . Preferably, a tubular member  160 , preferably made of polyethylene or other suitable material that may be fused with the proximal shaft, is placed over proximal shaft distal section  138 , as shown by the arrows A and B, and positioned proximate guide way distal end  136  as seen in FIG.  11 A. Heat, designated by the arrows A, B and C in  FIG. 11B , is applied to fuse tubular member  160  to proximal shaft  112 . As is well known to those of skill in the art, heat can be applied by any suitable heat source such as a hot air source or a laser source. By fusing the tubular member  160  onto generally proximal shaft  112 , preferably two raised areas  162  and  164  spaced on opposing exterior surfaces of proximal shaft  112  are formed creating stop  142  as shown in FIG.  11 C. Additionally, an annular raised surface may be formed about the exterior surface of proximal shaft  112  such as shown in FIG.  8 . Stop  142  increases the outer diameter of proximal shaft  112  by an amount sufficient to prevent guide member  102  from moving distally past stop  142 . Alternatively, stop  142  may be formed integrally with proximal shaft  112  when it is initially extruded or tubular member  160  may be secured with an adhesive as will be understood by those of skill in the art. 
     Turning now to FIGS.  9  and  12 A- 12 E, the formation of transition section  114  will be described. As shown, proximal shaft portion  164  adjacent guide wire lumen  150  is cut with an angle to assist in the assembly of catheter  100 . Distal shaft inner tube  144  is inserted into proximal shaft guide wire lumen  150  as shown by arrow A. Proximal shaft  112  contains stiffening member  166  that is preferably a hypotube that has a spiral cut section  168  to assist in forming a smooth transition from proximal shaft  112  to distal shaft  110 . Hypotube distal section  170  extends from proximal shaft inflation lumen  154  and is inserted into distal shaft inflation lumen  152  as indicated by arrow B. Outer tube proximal end  172  is positioned to overlap proximal shaft distal end  146  as indicated by arrows C and D. The amount of overlap is preferably the minimal such as 3 to 6 mm. Mandrels (not shown) are inserted into guide wire and inflation lumens  148 ,  150 ,  152  and  154  to prevent closure of the lumens during application of heat, represented by arrows E-H, to form transition bond  174  as shown in FIG.  12 D. While any appropriate heat source may be used, application of laser heat is preferred for a forming a fusion bond that is minimal in size to avoid creating a potential kink point in the catheter while also being fluid tight and able to withstand the necessary pressures in a procedure. Alternatively, other bonding methods may be used such as use of an adhesive.  FIG. 12E  illustrates the path of guide wire through guide wire lumens  148  and  150  forming overall catheter guide wire lumen  122 , designated by arrows  176   a-d , and likewise arrows  178   a-dc  illustrate the pathway of the inflation fluid through lumens  152  and  154  forming overall catheter inflation lumen  118 . 
       FIG. 13  shows an alternative embodiment for transition section  114  that incorporates a connecting tube  180 . In this embodiment, proximal shaft  112  may be formed from a commonly used catheter material, such as polyethylene. Distal shaft outer tube  146  may likewise be formed from a polyethylene or multilayer extrusion that has an inner layer that readily fuses with the material of proximal shaft  112 . Inner tube  144  distal shaft  110  may be made from a commonly used catheter multilayer extrusion having a nylon or polyamide block copolymer outer layer, a polyethylene inner layer and an intermediate tie layer. The nylon or polyamide block copolymer outer layer of inner tube  144  will not readily bond to the polyethylene of proximal shaft  112 . Connecting tube  180  is preferably made of polyethylene and is used to assist in bonding tube  144  with the surface of inflation lumen  150  to form a fluid tight seal necessary for the integrity of overall catheter inflation lumen  118 . Distal end  182  is inserted into proximal end  184  of inner tube  144  and the tubes are bonded or fused together to form a fluid tight seal. Proximal end  186  is inserted into distal end  188  of inflation lumen  150  and proximal end  190  of outer tube  146  is inserted over distal end  192  of proximal shaft  122 . The bonding process to form transition section  114  can then proceed as described with respect to  FIGS. 12A-12E . 
     Guide member  102  has proximal and distal ends  200  and  202 , respectively, as shown in FIGS.  14  and  15 A- 15 C. Catheter passageway  204  extends longitudinally in a generally straight line from guide member proximal end  200  to guide member distal end  202 . Guide wire passageway  206  extends from its end  208  through tube  210  into guide wire lumen  122  at its end  212 . Guide wire tube  210  is preferably made of polyimide. Catheter proximal shaft  112  extends through catheter passageway  204 , engaging keel  214 , which extends through guide way  124  in catheter  100  to spread flaps  126  and  128  apart as shown in  FIGS. 15A-15C . Guide wire  104  extends through guide wire tube  210  that enters guide wire lumen  122  through spread-apart flaps  126  and  128 . During advancement of catheter  100  through guide member  102 , flaps  126  and  128  draw together under the influence of the inherent resiliency of the catheter body to close guide way  124 , thus enclosing guide wire  102  within guide wire lumen  122 . Guide wire  104  is contained within guide wire lumen  122  from guide member  102  to catheter distal end  108 . Guide wire  104  may be inserted or removed through guide wire tube  210 , while guide member  102  is held stationary with respect to catheter  100  as shown by the arrows A and B in FIG.  15 A. In this fashion, guide wire  104  can be exchanged within catheter  100 . In yet another type of manipulation, guide member  102  can be held relatively still while catheter  100  is moved through catheter passageway  204 , thus bringing guide wire  104  and catheter  100  apart or together, depending on which direction catheter  100  is moved as indicated by arrow A in FIG.  15 B. 
     In an alternative embodiment shown in  FIG. 16 , guide wire lumen  122  may include a ramp  220  approximate the distal position of guide wire tube distal end  212 . Ramp  220  assists in aligning guide wire  104  into the guide wire passageway  206  as guide wire  104  is back loaded into catheter  100 . In a back-loading operation, guide wire  104  is inserted into catheter distal end  108  and threaded proximally through guide wire lumen  122  until guide wire passageway distal end  212  captures the proximal end  222  of guide wire  104  and directs it into guide wire passageway  206 . This procedure is typically performed while guide member  102  is positioned adjacent guide way distal end  136 . Guide wire passageway distal end  212  may be positioned to be coaxial with guide wire lumen  122 . In the guide wire back loading procedure, guide wire  104  may move along lower surface  224  of guide wire lumen  122  and move against lower edge  226  of tube  210  instead of moving into guide wire passageway  206 . Ramp  220  acts to assist in aligning guide wire passageway distal end  212  with guide wire proximal end  222  by preventing it from moving against lower edge  226  of tube  210  in order to complete the “back-loading” operation. Ramp  220  may be formed during the extrusion process or by adding the ramp prior to forming the transition section. Alternatively, the ramp may be formed as a part of process for forming the stop or transition section by selecting an appropriate mandrel selected for the guide wire lumen that will permit formation of the ramp. 
       FIG. 17  shows another embodiment of guide wire lumen  122  which includes a recess  228  approximate the distal position of guide wire passage way distal end  212 . Recess  228  has distal and proximal sloped surfaces  230  and  232 . Recess  228  assists in aligning guide wire  104  with guide wire passageway  206  as guide wire  104  is back loaded into catheter  100 . In a back-loading operation, guide wire  104  can be inserted into and threaded proximally through guide wire lumen  122  until guide wire proximal end  222  reaches recess  224 . Distal and proximal surfaces  230  and  232  are selected such that if as guide wire proximal end  222  is threaded proximally it is received in recess  228 , the sloped surfaces will direct guide wire  104  into guide wire passageway  206  when guide member  102  is positioned adjacent guide way distal end  136 . Recess  228  may be formed by removing material prior to the bonding process for the stop or the transition section. Alternatively, an appropriately designed mandrel may be used to form the recess during the heating process for either the formation of the stop or transition section. 
     While the invention has been particularly shown and described with reference to the preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and detail may be made there in without departing from the spirit and scope of the invention.