Abstract:
A catheter provided with a guidewire catheter lumen having a thin covering that is easily punctured by a guidewire at virtually any desired point along the catheter length. The thin covering may be integral with the catheter shaft, or may be a separate component that covers only the portion of the catheter shaft immediately adjacent the outer portion of the guidewire lumen, or may be a thin tubular construct that surrounds the entire catheter shaft. The covering is preferably relatively translucent, allowing for good visualization of the location of the end of the guidewire to enable puncturing of the covering at the desired location along the length of the catheter shaft. The covering is also preferably tear resistant at puncture sites. The catheter shaft is preferably made of a material having a color that provides good visibility against an operating field, and more preferably is phosphorescent either entirely or in part. Materials suitable for the catheter shaft are polymeric materials well known in the art; the catheter shaft may optionally be provided with metallic stiffening components such as wires or hypotubes along all or part of the catheter length.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a divisional of application Ser. No. 10/402,083, filed Mar. 28, 2003, which is a continuation-in-part of application Ser. No. 10/346,977, filed Jan. 17, 2003 (abandoned). 
     
    
     FIELD OF THE INVENTION 
     Background of the Invention 
       [0002]    A variety of different therapies can be delivered within the human body by catheter devices. Therapeutic devices such as dilation balloons, stents, and embolic filters, and therapeutic agents such as drugs and radiation sources, may be positioned at or near the distal end of the catheter for delivery to a desired site within the body. The proximal end of the catheter is considered to be the end that remains outside of the body, manipulated by the medical practitioner. 
         [0003]    To aid in positioning of the distal end of the catheter within the body, typically the distal end of a guidewire is first navigated to the treatment area. After the guidewire has been positioned, the wire can then be used to guide the distal end of the catheter into place. Additionally, a guide catheter may be used to further facilitate the positioning of the guidewire and/or delivery catheter. The interaction between the guidewire and the catheter is critical, as the physician needs to easily track the distal end of the catheter along the path of the guidewire. A number of interaction issues can arise, including but not limited to, having to use more than one person, having to use a long wire, having the advancement of the catheter affect the position of the wire, having the catheter not able to track the wire through tortuous anatomy, having excessive friction between the catheter and the wire, and having a difference between the amount of axial motion applied to the proximal end of the catheter and the amount of axial movement at the distal end of the catheter. 
         [0004]    In various attempts to address these issues, a number of catheter designs have been introduced that have defined the interaction between the guidewire and the catheter. Two of the primary applications of catheter systems are percutanous transluminal coronary angioplasty (PTCA) and coronary stent delivery. Two main types of catheter designs, over-the-wire (OTW) and rapid-exchange (RX), dominate these applications. Each of these designs has its advantages and disadvantages. OTW catheters track over their entire length on a guidewire, which allows them to follow the wire easily and allows the direct transmission of longitudinal force over the guidewire. Additionally, these catheters allow for guidewires to be exchanged once the catheter has been advanced into position, which may be desirable when different guidewire attributes (e.g., tip curvature or radiopaque markers) are needed. However, these systems require the use of a long guidewire (e.g., 300 cm in length) and cannot be effectively operated by one person. 
         [0005]    RX catheters typically use shorter guidewires (e.g., 180 cm in length) which allow the catheter to be operated by a single physician. The physician is able to hold the guide catheter and guidewire with one hand while using his other hand to advance or retract the catheter along the guidewire. However, because the entire length of the RX catheter does not slide over the guidewire, the direct transmission of longitudinal force along the path of the guidewire may be compromised, and wire exchange can not be performed once the proximal catheter guidewire port is advanced into the patient. 
         [0006]    Among various catheter designs intended for stent delivery is a system taught by U.S. Pat. No. 5,534,007 to St. Germain et al. This system includes a tubular exterior sleeve with an adjustable length section that, under axial compression, shortens via corrugations to cause another sleeve at the distal end of the catheter to be withdrawn in a proximal direction, releasing the stent. The overall length of the catheter remains the same during the axial compression of the exterior sleeve, and in particular, the length of the guidewire lumen is not adjustable. 
         [0007]    U.S. Pat. Nos. 5,334,147 and 5,380,283 to Johnson teach the construction of a balloon catheter having a proximal portion that includes an aperture through the wall of the catheter into the guidewire lumen. The aperture is covered by a frangible wall (e.g., a thin-walled tube sealed to the catheter body in a position to cover the aperture portion). The frangible wall may be punctured by a guidewire, allowing the guidewire to exit the catheter guidewire lumen via the aperture. 
         [0008]    U.S. Pat. No. 5,472,425 to Teirstein describes a catheter having a guidewire lumen covered by a rupturable membrane that extends along substantially the entire length of the catheter, whereby the membrane may be intentionally punctured at any desired location by the guidewire. The use and general construction of the catheter are related, although no materials or specific constructions for the rupturable membrane are taught. 
       SUMMARY OF THE INVENTION 
       [0009]    The present invention relates to a catheter provided with a guidewire catheter lumen having a thin covering that is easily punctured by the back end (i.e., the proximal end) of a guidewire at virtually any desired point along the catheter length. The thin covering may be integral with the catheter shaft, or may be a separate component that covers only the portion of the catheter shaft immediately adjacent the outer portion of the guidewire lumen, or may be a thin tubular construct that surrounds the entire catheter shaft. The covering is preferably adequately translucent to allow for good visualization of the location of the back end of the guidewire in order to enable puncturing of the covering at the desired location along the length of the catheter shaft. The catheter shaft is preferably made of a material having a color that provides good visibility against an operating field, and more preferably is luminous or phosphorescent either entirely or in part. Materials suitable for the catheter shaft are polymeric materials well known in the art; the catheter shaft may optionally be provided with metallic stiffening components such as wires, wire braids or hypotubes along all or part of the catheter length. 
         [0010]    In a preferred embodiment, the thin covering is made from a thin tape of porous expanded polytetrafluoroethylene (ePTFE) helically wrapped about the exterior of a catheter shaft. Most preferably, the wrapping is accomplished in two opposing directions parallel to the length of the catheter shaft, resulting in a bias-ply construction. This thin covering offers good transparency and is easily punctured by the end of a guidewire, and yet is resistant to tearing at the puncture site. 
         [0011]    Other materials may be used for the puncturable thin covering, including polyethylene terephthalate (PET). These materials may also offer good translucency, but may be less tear resistant than the helically wrapped ePTFE thin coverings. 
         [0012]    The thin covering (either integral with the catheter shaft or a separate covering) may optionally be provided with a multiplicity of small, pre-formed openings through the thickness of the covering to allow for passage of the back end of a guidewire through any of these openings. The openings would preferably be arranged in a single line extending directly above the guidewire lumen. 
         [0013]    The thin covering may optionally be in the form of a braid or helically-wound filaments that allow the guidewire to be passed through any of the multiplicity of openings or interstices that exist between adjacent filaments of the braid or winding. The braid or winding may be of either various polymeric or metallic materials. The braid or winding may be exposed around the entire exterior of the catheter shaft or alternatively may be exposed over only the side of the guidewire lumen closest to the exterior of the catheter shaft. 
         [0014]    For many embodiments, the guidewire lumen is in the form of a slot made into the catheter shaft, with the slot provided with the thin covering. Preferably, the slot extends for most or even all of the length of the catheter shaft. It may optionally extend through a balloon or other device located at the distal end of the catheter. The slot is covered with by a thin tubular covering that coaxially encloses the entire catheter shaft or alternatively a strip of thin tape-like covering material that covers the slot and is adhered to the surface of the catheter shaft immediately adjacent both sides of the slot. A multiplicity of pre-formed openings may be provided through the thin covering as noted above. Also as noted above, the slot covering material may take the form of a braid or winding of filaments. This braid or winding of filaments may optionally be covered with a thin polymeric tube except for the filaments immediately over the top of the slot which preferably remain exposed and allow for passage of the end of a guidewire through any interstice between adjacent filaments. 
         [0015]    Other embodiments using the catheter shaft may be provided with a puncturable tubular form inserted into the slot. This tubular form may be made with filaments braided into the tubular form, or a tubular form made of helically wound filaments or from a thin polymeric material, with the tube having an inside diameter adequately large to accommodate a guidewire of the desired size. These tubes are fitted and secured into the slot formed into the catheter shaft, with the result that the outer surface of the braided or helically wound tube covers the exposed part of the slot and allows for the back end of a guidewire contained within the tube to be passed through any interstice between adjacent filaments of the braided or helically wound tube. When the tubular form is made from the thin polymeric material, the resulting tube inserted into the catheter shaft slot is puncturable at any desired location by the back end of a guidewire. 
         [0016]    In addition to being puncturable by the back end of the guidewire, the guidewire catheter lumen may optionally be made to be adjustable in length. The adjustable length catheter guidewire lumen is the conduit, or catheter, or tube, or space that contains the guidewire or provides a space for the passage of a guidewire therethrough. The space may be adjustable in length, as will be further described. 
         [0017]    By adjustable length is meant that the length of the adjustable length guidewire catheter lumen may be changed by the application of easily applied manual axial force. In its axially extended or fully lengthened state, the adjustable length guidewire catheter lumen is at least 10% longer than when in the axially compressed, fully shortened state. More preferably, the adjustable length guidewire catheter lumen is adjustable by an amount of at least about 20%, or 30%, or 40%, or 50%, or 75%, or 100%, or 200%, or 400%, or 1000%, or 2000%. 
         [0018]    The adjustable length guidewire catheter lumen is adjustable in length by virtue of being scrunchable. This means that this tubular component is easily shortened in length under axial force, without telescoping as by the successive sliding of overlapped concentric tubular sections. Various means of providing a scrunchable tube for use as the adjustable length guidewire catheter lumen include the provision of corrugations (i.e., wrinkles, or accordion pleats or folds), or by the use of a porous tube that compresses axially by reduction in total void space. These are further described below. 
         [0019]    Suitable materials for the adjustable length lumen include ePTFE, polyethylene terephthalate (PET), polyamide, or other thermoplastic or thermoset polymers, or other such relatively inelastic materials. Alternatively, an elastomeric material may be used for the adjustable length lumen, which materials elongate by the application of an extending axial force. The term “elastomeric” is intended to describe a condition whereby a polymer displays stretch and recovery properties similar to an elastomer, although not necessarily to the same degree of stretch and/or recovery. 
         [0020]    The ability of the catheter to be punctured by the back end of a guidewire at any desired location along the length of the puncturable section of the catheter allows the catheter assembly to be used effectively as desired in either OTW or RX mode. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]      FIG. 1A  shows a longitudinal cross section of a catheter having a puncturable guidewire lumen covering. 
           [0022]      FIG. 1B  shows a longitudinal cross section of the catheter of  FIG. 1A  in use with the catheter, the guidewire having punctured the puncturable guidewire lumen covering. 
           [0023]      FIGS. 1C and 1D  show transverse cross sections of the catheter of  FIG. 1B  with the guidewire within and without the puncturable section. 
           [0024]      FIG. 1E  shows a longitudinal cross section of a catheter that is a variation of the design shown in  FIGS. 1A and 1B  wherein the guidewire operates in a slot provided in the exterior wall of a lumen of the catheter. 
           [0025]      FIGS. 1F ,  1 G and  1 H show transverse cross sections taken at three different locations along the length of the catheter shown in  FIG. 1E . 
           [0026]      FIG. 2A  shows a perspective view of a preferred slotted catheter shaft. 
           [0027]      FIG. 2B  is a perspective view of the preferred slotted catheter shaft of  FIG. 2A  provided with a helical wrap of a polymeric tape that forms a puncturable thin cover over the slot. 
           [0028]      FIG. 2C  is a perspective view of the preferred slotted catheter shaft of  FIG. 2A  provided with a puncturable thin cover in the form of a thin tubular sheath. 
           [0029]      FIG. 2D  is a perspective view of the catheter shaft of  FIG. 2C  wherein the thin tubular sheath is formed by a cigarette wrap. 
           [0030]      FIG. 2E  is a perspective view of the preferred slotted catheter shaft of  FIG. 2A  provided with a puncturable thin cover in the form of a strip or tape of a polymeric material adhered over the surface of the catheter shaft immediately adjacent to both sides of the slot. 
           [0031]      FIG. 2F  is a perspective view of an alternative embodiment wherein the puncturable guidewire lumen covering is integral with the catheter shaft. 
           [0032]      FIG. 2G  is a perspective view of an alternative embodiment wherein the thin cover over the guidewire lumen is provided with a multiplicity of pre-formed openings which allow passage of the back end of a guidewire through any opening chosen by the user. 
           [0033]      FIGS. 3A-3C  are transverse cross sectional views showing variations of the embodiment described by  FIG. 2E   
           [0034]      FIG. 4A  is a perspective view of the preferred slotted catheter shaft of  FIG. 2A  provided with a puncturable thin cover in the form of a braid. 
           [0035]      FIG. 4B  is a perspective view of the braid-covered catheter shaft of  FIG. 3A  further provided with a thin exterior tubular sheath over the braid. 
           [0036]      FIG. 4C  is a perspective view of the braid-and-sheath covered catheter shaft of  FIG. 3B  wherein the portion of the sheath covering the catheter slot has been removed. 
           [0037]      FIG. 4D  is a perspective view of catheter shaft with an alternative braid-covered slot wherein a braided tube is fitted and secured into the slot. 
           [0038]      FIG. 4E  is a variation of  FIG. 4A  wherein the braided tubular cover is replaced with a helically wound tubular cover. 
           [0039]      FIG. 4F  is a variation of  FIG. 4D  wherein the braided tube is replaced with a helically wound tube. 
           [0040]      FIG. 4G  is a variation of  FIGS. 4D and 4F  wherein the tubular cover is made from a thin polymeric material. 
           [0041]      FIG. 5  shows a longitudinal cross section of a basic embodiment of the catheter of the present invention, without a y-fitting but including a hub on the proximal end of the inflation lumen, a puncturable adjustable length guidewire catheter lumen (shown in its axially compressed or shortened state) located distal to the hub and a tubular slider for controlling the proximal end of the adjustable length lumen. 
           [0042]      FIG. 6  is a perspective view of a tool useful for bending of the catheter shaft during puncturing of the thin puncturable cover by the back end of a guidewire. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0043]      FIGS. 1A-1H  describe the catheter  10  of the present invention provided with a thin, puncturable cover  102  over the guidewire lumen  18 . Typically, catheter  10  may include devices such as a catheter balloon  20  and/or stent  21  at its distal end  17  and a hub  14  at the proximal end  16 . As shown by  FIGS. 1A-1H , the thin, puncturable cover  102 , in this instance a thin-walled a thin tubular sheath  13  (forming guidewire lumen  18 ) designed to be punctured by the back end of a guidewire  19 , may be placed coaxially about the inflation lumen  22 . The length of the thin tubular sheath  13  may extend over all or part of the length of catheter shaft. 
         [0044]    After feeding guidewire  19  through the distal section of the guidewire lumen  18  and into the thin-walled tubular sheath  13 , the physician may chose any desired location along the length of thin-walled tubular sheath  13  at which to puncture the thin, puncturable cover  102  with the guidewire  19 . In this fashion the physician may select his preferred length of the guidewire lumen  18 . 
         [0045]      FIG. 1A  shows a longitudinal cross section of a catheter  10  having a puncturable guidewire lumen covering  102 , while  FIG. 1B  shows a longitudinal cross section of the catheter of  FIG. 1A  in use with the guidewire  19 , the guidewire having punctured the puncturable covering  102 .  FIGS. 1C and 1D  show, respectively, transverse cross sections of the catheter of  FIG. 1B  with the guidewire  19  within and outside of the puncturable section  102 . 
         [0046]      FIG. 1E  shows a longitudinal cross section of a catheter that is a variation of the design shown in  FIGS. 1A and 1B  wherein the guidewire operates in a slot  104  provided in the exterior wall of a lumen of the catheter. It is apparent that the thin, puncturable cover  102  may be provided only over this slot portion and is not required to enclose the entire circumference of the inner catheter.  FIGS. 1F ,  1 G and  1 H show transverse cross sections taken at three different locations along the length of the catheter shown in  FIG. 1E . 
         [0047]    The puncturable guidewire lumen may be made in a variety of ways. 
         [0048]    In a preferred embodiment, catheter  10  including inflation lumen  22  and guidewire lumen  18  is made using a catheter shaft  15  as shown in the perspective view of  FIG. 2A  wherein guidewire lumen  18  is in the form of a slot  104 . The catheter shaft  15  may be made in this form by extrusion (using any known polymeric material suitable for the application), or may alternatively be extruded with fully enclosed lumens and then have the extruded material covering the guidewire lumen skived away. Preferred materials will be of a color offering good contrast with the operational field, and most preferably are fluorescent or phosphorescent. 
         [0049]    Optionally, such a catheter shaft may be stiffened along all or part of its length as necessary by the inclusion of stiffening wires running parallel to the longitudinal axis of the catheter, or by adding a tubular metal reinforcing braid to the catheter shaft, or by inserting a length of metal hypotube, tubular braid or helically wound wire into the inflation lumen  22 . These stiffening methods may be used in combination if desired. For simplicity, these well-known stiffening methods are not shown in the figures. 
         [0050]    If it is desired to use a hypotube to stiffen only a portion of the length of the catheter shaft, it may be desirable to cut a helically-oriented slot through the wall of the end of the hypo tube that will be located within the length of the catheter shaft to reduce the abrupt stiffness transition of the stiffened section to the unstiffened section. 
         [0051]    As shown by the perspective view of  FIG. 2B , the slotted catheter shaft  15  is provided with a helically-wrapped covering of tape  24 . Preferably, the wrapping is applied in two layers wherein adjacent wrappings have overlapping edges and the second layer is applied over the first with an opposite pitch, meaning that the two wrappings are applied beginning from opposite ends of the catheter shaft  15 . The use of the two layers of tape  24  wrapped from opposing directions results in a strong covering that is resistant to tearing following puncture by the guidewire back end. 
         [0052]    While a variety of thin, flexible polymer materials such as polyethylene, polypropylene, polyamide, polyethylene terephthalate, etc. may be used for the tape  24 . Porous polymers, optionally provided with a thin, non-porous coating, may be advantageously used because of their excellent flexibility. Tape  24  is most preferably made from a thin porous expanded PTFE (ePTFE) film that has been provided with a porous or non-porous coating of a thermoplastic such as a thermoplastic fluoropolymer, preferably fluorinated ethylene propylene (FEP). ePTFE films are generally made as taught by U.S. Pat. Nos. 3,953,566 and 4,187,390 to Gore. Most preferred ePTFE films for the present application are taught by U.S. Pat. No. 5,476,589 to Bacino. The construction of thin, helically-wrapped tubes from ePTFE films and thermoplastic-coated ePTFE films, and the method of providing the coating onto the ePTFE films, are taught by U.S. Pat. No. 6,159,565 to Campbell et al. 
         [0053]    An example of a helically-wrapped catheter shaft as shown by  FIG. 2B  was made using an FEP-coated ePTFE tape. The tape had a width of about 6 mm and a thickness of about 0.005 mm. The ePTFE had mean fibril length of about 50 microns and a bulk density of about 0.5 g/cc. The ePTFE film was provided with a non-porous coating of FEP on one side. After the coated film was cut into a narrow tape, the tape was helically wrapped onto a stainless steel mandrel of diameter larger that the outside diameter of the chosen catheter shaft. The first layer of the wrapping was applied with the FEP coated side of the tape facing away from the mandrel and the second layer was wrapped in the opposite direction from the first with the coating facing toward the mandrel and first layer. The wrapped mandrel was then heated for about 8 minutes in a convection oven set at 320° C. to melt-bond the helically-wrapped layers of the tube together. Following removal from the oven and cooling to about room temperature, the helically-wrapped tube was removed from the mandrel and fitted over a length of the desired catheter shaft  15  that was shorter than the length of the helically-wrapped tube. The opposite ends of the helically wrapped tube were gripped using pliers and tension was applied to cause the helically-wrapped tube to elongate and reduce in diameter, thereby tightly conforming to the outer surface of the catheter shaft. The ends of the helically-wrapped tube were adhered to the outer surface of the catheter shaft using a cyanoacrylate adhesive. The ends of the covered catheter shaft  15  were then transversely cut to the desired length with a sharp blade. If desired, the hub component typically fitted to the proximal end of the catheter shaft may be fitted over the helical wrap. 
         [0054]    The thickness of the thin tubular tape covering  102  was determined to be about 0.012 mm by measuring the diameter of the catheter shaft at 90 degrees to the orientation of the slot  104  using a laser micrometer both before and after the application of the helically-wrapped covering. 
         [0055]    The covered catheter  10  that resulted from this process retained the good flexibility of the precursor catheter shaft  15  prior to covering. When a guidewire  19  was inserted into the guidewire lumen  18 , the thin cover  102  exhibited good transparency, meaning that the back end of the guidewire  19  was visible to the unaided eye as it passed through the length of the guidewire lumen  18 . It was not difficult to stop the progression of the guidewire back end at a desired point along the length of the guidewire lumen, and by bending the catheter with the guidewire slot oriented to the outside of the bend, the covering  102  was readily punctured by the back end of the guidewire  19 . When a large portion of the length of the guidewire was pulled through the puncture site, the puncture site exhibited no sign of tearing or of appreciable enlargement of the puncture. 
         [0056]      FIG. 2C  is a perspective view of a catheter  10  including a tubular sheath  13  for use as the thin puncturable cover  102  over slot  104 . The sheath may be in the form of a thin extruded tube of, for example, PET. It may be applied similarly to the above-described helically-wrapped tube using a tubular sheath  13  of slightly larger inside diameter than the outside diameter of the catheter shaft  15  to be covered. The outer surface of the catheter shaft  15  may be provided with a thin coating of a suitable adhesive if desired, after which the thin tubular sheath  13  is fitted over the catheter shaft  15  and tensioned to cause it to elongate and reduce in diameter to conform to the outer surface of the catheter shaft  15 . Sheath  13  may also be made from a shrink tubing that is heated after being fitted about the outer surface of the catheter shaft  15  to cause it to conform thereto. 
         [0057]      FIG. 2D  is a perspective view of the catheter  10  of  FIG. 2C  wherein the thin tubular sheath is formed by a cigarette wrap, wherein the braid-covered catheter shaft is additionally covered by an adequately long strip of thin polymeric material that has a width equal to or slightly greater than the circumference of the braid covered catheter shaft. This strip is wrapped around the catheter shaft as shown and adhered by thermal bonding or by the use of a suitable adhesive. 
         [0058]    Another alternative for the puncturable thin cover  102  is shown in the perspective view of  FIG. 2E  wherein a thin tape  24  is adhered to the outer surface of the catheter shaft  15  adjacent to the edges of slot  104 . In another embodiment, the guidewire lumen  18  may be extruded or otherwise formed to have an integral, thin, puncturable covering  102  as shown by the perspective view of  FIG. 2F .  FIG. 2G  is a perspective view of the catheter  10  of  FIG. 2F  wherein pre-formed openings  25  are formed through the thin puncturable cover  102  to allow passage of the back end of a guidewire through any pre-formed opening  25  chosen by the user. It is apparent that these pre-formed openings  25  may be used with many of the various described embodiments. 
         [0059]      FIGS. 3A-3C  show transverse cross sectional views that represent a variation on the embodiment of  FIG. 2E . As shown by  FIG. 3A , tape cover  24  may be provided so as to increase the space available in the guidewire slot  104  by applying the tape so that it bridges the slot with additional tape width, resulting in the raised aspect shown by this thin puncturable cover  102 . This can allow for the use of a larger guidewire if desired. When slot  104  is unoccupied by a guidewire, the thin and flexible tape  24  may take on a non-uniform appearance, giving the guidewire lumen and thin puncturable cover  102  an irregular cross section as shown by  FIGS. 3B and 3C . It is apparent that the appearance of each of these three transverse cross-sections may exist at different locations along the length of the same catheter. 
         [0060]    The puncturable cover  102  may also be made using threads, wires or other filaments. For example, threads may be wound around a slotted catheter shaft  15  in various desired patterns to form a covering over a guidewire lumen  18  that effectively contains a guidewire  19  but allows the back end of the guidewire to be passed through any of the multiplicity of spaces between adjacent threads of the wrapped covering. The threads may, for example, be provided as a helically-wrapped pattern, a braided pattern or a knit (e.g. warp knit) pattern. By orienting the threads in close proximity to one another, the guide wire will preferentially stay within a lumen of which the thread defines a portion of the wall. However, the end of the wire can be maneuvered to exit this lumen between the threads. By using a wound thread, the structure is never damaged allowing the catheter to be reused multiple times. By controlling the spacing between adjacent threads, the ease of which the end of the wire exits the lumen may be altered. Preferentially, small diameter threads can be used, for example, with diameters from 0.012 to 0.5 mm. Any variety of thread materials may be used, included common thermoplastic (e.g., polyamide, polypropylene, polyester, etc), thermosets, fluoroplastics (e.g., ePTFE) or various metal wires including stainless steels and nitinol. 
         [0061]    As shown by the perspective view of  FIG. 4A , a catheter shaft  15  is over-braided with filaments  31 . The braid may have numerous configurations including, but not limited to, number of filaments, pick count and pitch angle. As well, filaments  31  may be of various cross sections such as round, square or rectangular. 
         [0062]      FIG. 4B  shows a preferred embodiment wherein catheter  10  of  FIG. 4A  is provided with an outer sheath  13  applied over catheter shaft  15  and braid  31  and attached by any of various methods such as heat or adhesive. Following the addition of sheath  13 , an appropriately-sized mandrel is inserted into the guidewire lumen  18 . The catheter is mounted in a laser (e.g., a 20 watt CO 2  laser, Applied Laser Technology, Beaverton Oreg.) with the laser beam directed to slot  104 . The laser is used to ablate the polymer material of sheath  13  covering slot  104  along the desired length of the catheter  10 , resulting in cutaway slot  33  through sheath  13  exposing slot  104  beneath braid  31 . The laser power parameters are such that the polymer material of sheath  13  is ablated yet metallic braid filaments  31  are left undamaged. The indwelling mandrel effectively blocks the laser energy from damaging the opposite side of the catheter shaft  15 . The resultant catheter  10  is left with a braided underlying chassis and an outer polymer sheath  13  in which a “strip” of braid is exposed directly above slot  104 , whereby guidewire lumen  18  lies immediately below the exposed strip  33  of braid  31 . A clinician may then use the back end of a guide wire to part the braid filaments at any suitable user-defined position along this strip  33 , thus exiting the guidewire from catheter  10  through the selected interstice of braid  31 . 
         [0063]      FIG. 4D  describes an alternative embodiment whereby a braided tube  37  is procured, this tube having an outside diameter corresponding to the inside diameter of slot  104  of catheter shaft  15 . The braided tube  37  is made to have a suitable inside diameter to provide adequate clearance for passage therethrough of an intended guidewire. Braided tube is fitted into slot  104  by interference, or by joining with an adhesive. In use, as with the previously described braided construct, the guidewire may be passed through any desired interstice of the braid  31  to exit catheter  10 . 
         [0064]      FIG. 4E  describes a variation of  FIG. 4A  wherein braid  31  is replaced by helically wound filament  41 , which may be of polymeric or metallic material.  FIG. 4F  shows an alternative to  FIG. 4D  wherein braided tube  37  is replaced by helically wound tube  47 . Again, the helically wound tube may be of polymeric or metallic material. The embodiments of  FIGS. 4E and 4F  are desirable in that the space between adjacent helical windings will widen when the catheter shaft is bent with the exposed winding on the outside of the bend, making it easier to pass the back end of a guidewire through any desired space between adjacent helical windings. 
         [0065]      FIG. 4G  is a perspective view of an alternative embodiment to those shown by  FIGS. 4D and 4F  wherein tube  49  inserted into slot  104  is made from a thin polymeric material. This tube is preferably made by helically wrapping a thermoplastic-coated ePTFE film about a mandrel of suitable size, bonding the wrapping together to result in a cohesive tube, inserting the tube and mandrel into slot  104  and finally removing the mandrel. Alternatively if desired, the mandrel may be removed from within the tube prior to insertion of the tube  49  into slot  104 . 
         [0066]      FIG. 5  shows a longitudinal cross section of an alternative embodiment of catheter  10 , including a hub  14  on the proximal end  16  of the inflation lumen  22 . In this embodiment, catheter  10  is provided with a puncturable adjustable length guidewire lumen  18  that is in the form of a thin tubular sheath  13  puncturable by guidewire  19  as shown. A tubular slider  24  is used in place of a conventional y-fitting, distal to hub  14  for attachment and control of the proximal end of the adjustable length guidewire catheter lumen  18 . Adjustable length guidewire catheter lumen  18  is shown in its axially compressed or shortened state. Tubular slider  24  is provided with only a small clearance between the inner diameter of slider  24  and the outer diameter of the inflation lumen  22 . Adjustable length guidewire catheter lumen  18  may be made from a variety of thin, flexible polymer materials such as polyethylene, polypropylene, polyamide, polyethylene terephthalate, etc. Porous polymers, optionally provided with a thin, non-porous coating, may be advantageously used because of their excellent flexibility. Adjustable length guidewire catheter lumen  18  is preferably made from a porous expanded PTFE (ePTFE) film that has been provided with a porous or non-porous coating of a thermoplastic fluoropolymer as described previously. 
         [0067]    The thin-walled tube is preferably made from an FEP-coated ePTFE film that has been cut into a tape (width, e.g., 12.7 mm) and helically wrapped on a mandrel with the FEP coating placed on the exterior of the wrapping. The helically wrapped tube is then placed into an oven for a suitable time (e.g., 8 minutes in an oven set at a temperature of 320° C.) to thermally bond the overlapped edges of the helical wrapping together, thereby forming a coherent tube. After removal from the oven and cooling, the resulting tube is removed from the mandrel and may be used as the adjustable length lumen component in the catheter of the present invention. The ends of this tube may be joined to the adjacent components by overlapping the tube end over the adjacent component and adhering the overlapped areas with an adhesive such as a cyanoacrylate (e.g., Loctite 401, Rocky Hill, Conn.) or an ultraviolet adhesive (e.g., Loctite 3311). Alternatively, the tube may be everted to orient the FEP-coating toward the lumen, and an adequate heat source may be used to melt-bond the FEP coating to catheter components such as metal hypotubes. 
         [0068]    For use as the puncturable, adjustable length lumen tubular component of a catheter, the ePTFE tube may be provided with corrugations (e.g, accordion pleats or folds) with various methods such as those taught by U.S. Pat. No. 3,105,492 to Jeckel and U.S. Pat. No. 6,016,848 to Egres, Jr. Alternatively, it is not required to provide the thin-walled tube with preformed corrugations as, during axial compression from the fully extended length to the shortened, fully compressed length, the tube will wrinkle and corrugate in a non-uniform but entirely suitable manner for use as the adjustable length lumen portion  18  of catheter  10 . In another alternative, an elastomer may be used for the adjustable length portion  18  that would be in its relaxed state prior to loading over the guidewire and would extend into a tensioned condition when the distal end of the catheter is advanced. 
         [0069]    Longitudinally extruded and expanded tubes of PTFE, that is, seamless ePTFE tubes, may be used in thinwall form as the puncturable, adjustable length guidewire catheter lumen. Under axial compression, the interconnecting fibrils of the node-and-fibril microstructure of ePTFE will progressively bend and fold. This allows the tubular material to axially compress in a substantially uniform fashion, retaining the longitudinal uniformity of the tube wall (macroscopically), without corrugations. This bending of the fibrils within the microstructure of the wall of the ePTFE tube during axial compression is described in U.S. Pat. No. 4,877,661 to House et al. Longer mean fibril length tubes are preferred to maximize the compressible length, e.g., ePTFE tubes of about 50 micron or greater mean fibril length. 
         [0070]    A catheter having a puncturable, adjustable length guidewire lumen was constructed using a very thin walled (e.g., 0.03 mm) sheath material. The sheath material is required to be thin enough to corrugate in small folds, allowing the length of the sheath to be reduced to less than 50% of its original length by compressing into the small amplitude folds. A 0.01 mm thick ePTFE film provided with a non-porous FEP coating on one side was chosen for the sheath material. This film was slit to a 6.4 mm width, thereby forming a tape. 
         [0071]    An ePTFE tube, having an inner diameter of about 1.6 mm and a wall thickness of about 0.13 mm, was fitted over a 1.6 mm diameter stainless steel mandrel having a length of about 180 cm. The 6.4 mm wide tape was then helically wrapped about the outer surface of the ePTFE tube with a 50% overlap, resulting in a helically-wrapped tube covered with two layers of tape. The resulting assembly was then placed into an air convection oven set at 320° C. for 8 minutes, after which it was removed from the oven and allowed to cool in an ambient environment. 
         [0072]    After cooling, the helically-wrapped tube was removed from the mandrel by withdrawing the mandrel from the tube. The end of the extruded tube that had not been helically-wrapped was clamped in a vise. The end of the helical wrapping closest to the vise was simultaneously pinched on opposite sides of the tube using the thumb and forefingers of both hands, and the helical-wrapping was stripped from the underlying ePTFE tube by everting the helically-wrapped tube while pulling it away from the vise. 
         [0073]    This thin-walled tube had an approximate wall thickness of 0.03 mm (measured using Mitutoyo Snap Gauge, Model #1D-C112EBS) and an inner diameter of approximately 1.7 mm (measured using a certified minus pin gauge with a tolerance of 0.01 mm). When this tube was loaded on a 1.2 mm diameter mandrel, it was able to be easily compressed to about 5% of its original length using light digital pressure. 
         [0074]    Continuing assembly of the catheter, this sheath was then coaxially mounted over a conventional Percutaneous Transluminal Coronary Angioplasty (PTCA) catheter with a maximum outer diameter proximal of the balloon of less than approximately 0.040″ (1.02 mm). The PTCA catheter used was a rapid exchange type, having a proximal guidewire exit port at a location significantly distal of its hub. Prior to mounting the sheath, a 9 Fr (3.0 mm) inner diameter hemostasis y-arm valve (P/N 80348, Qosina, Edgewood, N.Y.) was slid onto the catheter from the catheter&#39;s distal end (hemostasis valve oriented away from the back end of the catheter). Next, a female luer (P/N 65206. Qosina, Edgewood, N.Y.) was slid onto the catheter and the luer connection of these two components was engaged. A 2.0 mm inside diameter by 2.1 mm outside diameter  304  stainless steel tube (Microgroup, Medway, Mass.) was then swaged down to approximately 1.4 mm inside diameter by 1.6 mm outside diameter, and then trimmed to a length of approximately 19 mm. 
         [0075]    This tube was slid coaxially over the catheter and bonded to the distal end of the female luer with an approximate 6 mm overlap using cyanoacrylate adhesive (Loctite 401, Loctite Corp., Rocky Hill, Conn.). Next, the helically-wrapped sheath described above was slid over the distal tip of the catheter and its proximal end attached by sliding it over the exposed end of the hypotube. These overlapped surfaces were bonded using the cyanoacrylate adhesive, after which 2.3 mm inside diameter polyolefin 2-to-1 shrink ratio shrink tubing was fitted over the junction and heated to conform to the surface of the junction. The distal end of the sheath was then trimmed to a length of approximately 135 cm, equal to the desired working length of the catheter (i.e. length from the distal tip of the catheter to the distal end of the strain relief on the catheter&#39;s hub). The distal end of the sheath was then attached at a location approximately 2 mm distal of the proximal guidewire port in the wall of the PTCA catheter. This attachment was made using the cyanoacrylate adhesive between the sheath and catheter, and then over-wrapping this attachment point with cyanoacrylate adhesive and 0.13 mm diameter ePTFE suture (CV-8, WL Gore and Associates, Flagstaff, Ariz.). 
         [0076]    To complete the catheter a hemostasis y-fitting was slid distally on the catheter until it was just proximal of the proximal hole of the original PTCA catheter. This compressed the sheath to approximately 15% of its original approximately 135 mm length. A guidewire was then fed into the distal tip of the catheter and carefully threaded through the catheter, including the sheath component, and out from the proximal end of the catheter through the side arm of the y-fitting. 
         [0077]    With the guidewire inserted, the user was able to hold the guidewire and hemostasis y-fitting in a fixed position while advancing the distal tip of the catheter relative to the guidewire. Compared to a standard catheter with a proximal guidewire side port fixed distally of the proximal hub, this inventive catheter significantly improved the ability of the section of the catheter, distal to the hemostasis y-fitting, to track the guidewire and allow push forces applied to the proximal portion of the catheter shaft to be transferred directly to the distal tip of the catheter. 
         [0078]      FIG. 6  is a perspective view of catheter  10  in use with a puncturing tool  63  that enables puncturing of the cover  102  by the back end of guidewire  19 . While such a tool is deemed unnecessary for many applications, for others it may prove advantageous. As shown, tool  63  is simply a short length of tubing that may be either polymeric tubing or metallic tubing. It is most easily made by bending the short length of tubing (before it is fitted about a catheter) and cutting away a portion of the wall along one side of the tube in the region of the middle of the length of the tube, resulting in opening  62 . In use, tool  61  is fitted coaxially about catheter  10  and moved along the length of catheter  10  to the location at which it is desired to puncture cover  102  with the back end of guidewire  19 . The tool  61  is oriented so that the opening  62  exposes cover  102  on the side of the catheter where the guidewire is or will be contained. When a guidewire  19  is inserted into the catheter  10  to the location at which it is desired to puncture the catheter, with this location exposed at opening  62  in tool  61 , both the catheter  10  and tool  61  are bent as shown by  FIG. 6 . This bending results in puncturing of cover  102  by the back end of guidewire  19 . The bending of catheter  10  is the result of force applied at three points  63 , with the middle point being on the inside of the bend along the middle of the length of the bend and the two outer points being on the outside of the bend at the two opposite ends of the bend. It is apparent that the tool may take any suitable form that provides this three point contact during bending wherein the act of bending enables or results in puncturing of cover  102  at the desired location by the back end of guidewire  19 . Following puncture, the tool is moved out of the way by sliding it coaxially along the length of the guidewire. 
         [0079]    While the principles of the invention have been made clear in the illustrative embodiments set forth herein, it will be obvious to those skilled in the art to make various modifications to the structure, arrangement, proportion, elements, materials and components used in the practice of the invention. To the extent that these various modifications do not depart from the spirit and scope of the appended claims, they are intended to be encompassed therein.