Abstract:
A catheter and a guidewire exchange system includes a catheter and a guide member. The catheter includes a lumen extending through the shaft and sized to receive the guidewire, and a longitudinal guideway enabling transverse access from the shaft exterior surface to the lumen. The guide member includes a housing, a catheter passageway extending through the housing and adapted to slidably receive the catheter, a guidewire passageway extending from one end of the housing into the catheter passageway and including a tube adapted to merge the guidewire transversely through the guideway and into the first lumen, and an fluid flow reduction body that is positioned in the guidewire passageway and impedes fluid flow therethrough.

Description:
TECHNICAL FIELD  
       [0001]     The present invention generally relates to medical catheters and medical apparatuses involving medical catheters. The present invention more particularly relates to mechanical devices adapted to improve the seal between the catheter and hemostasis valve during use.  
       BACKGROUND  
       [0002]     Cardiovascular disease, including atherosclerosis, is a leading cause of death in the U.S. The medical community has developed a number of methods and devices for treating coronary heart disease, some of which are specifically designed to treat the complications resulting from atherosclerosis and other forms of coronary arterial narrowing.  
         [0003]     One method for treating atherosclerosis and other forms of coronary narrowing is percutaneous transluminal coronary angioplasty, commonly referred to as “angioplasty” or “PTCA.” The objective in angioplasty is to enlarge the lumen of the affected coronary artery by radial hydraulic expansion. The procedure is accomplished by inflating a balloon of a balloon catheter within the narrowed lumen of coronary artery.  
         [0004]     In addition to PTCA, catheters are used for delivery of stents or grafts, therapeutic drugs (such as anti-vaso-occlusion agents or tumor treatment drugs) and radiopaque agents for radiographic viewing. Other uses for such catheters are well known in the art.  
         [0005]     The anatomy of coronary arteries varies widely from patient to patient. Often a patient&#39;s coronary arteries are irregularly shaped, highly tortuous and very narrow. The tortuous configuration of the arteries may present difficulties to the physician in proper placement of a guidewire, and advancement of a catheter to a treatment site. A highly tortuous coronary anatomy typically will present considerable resistance to advancement of the catheter over the guidewire.  
         [0006]     Therefore, it is important for a catheter to be highly flexible. However, it is also important for a catheter shaft to be stiff enough to push the catheter into the vessel in a controlled manner from a position far away from the distalmost point of the catheter.  
         [0007]     Catheters for PTCA and other procedures may include a proximal shaft, a transition section and a distal shaft having a flexible distal tip. In particular, the catheters have a proximal shaft, which is generally rigid for increased pushability and a more flexible distal shaft with a flexible distal tip for curving around particularly tortuous vessels. The proximal shaft may be made stiff by the insertion of a thin biocompatible tube, such as a stainless steel hypotube, into a lumen formed within the proximal shaft. The transition section is the portion of the catheter between the stiffer proximal shaft and the more flexible distal shaft, which provides a transition in flexibility between the two portions.  
         [0008]     With some types of catheter construction, when an increase in resistance occurs during a procedure there is a tendency for portions of the catheter to collapse, buckle axially or kink, particularly in an area where flexibility of the catheter shaft shifts dramatically. Consequently, the transition section is often an area where the flexibility of the catheter gradually transitions between the stiff proximal shaft and the flexible distal shaft. It is known in the art to create a more gradual flexibility transition by spiral cutting a distal end of the hypotubing used to create stiffness in the proximal shaft. Typically, the spiral cut is longitudinally spaced father apart at the hypotube proximal end creating an area of flexibility, and longitudinally spaced closer together at the hypotube distal end creating an area of even greater flexibility.  
         [0009]     In a typical PTCA procedure, it may be necessary to perform multiple dilatations, for example, using various sized balloons. In order to accomplish the multiple dilatations, the original catheter must be removed and a second catheter tracked to the treatment site. When catheter exchange is desired, it is advantageous to leave the guidewire in place while the first catheter is removed to properly track the second catheter.  
         [0010]     Two types of catheters commonly used in angioplasty procedures are referred to as over-the-wire (OTW) catheters and rapid exchange (RX) catheters. A third type of catheter with preferred features of both OTW and RX catheters, which is sold under the trademarks MULTI-EXCHANGE, ZIPPER MX, ZIPPER, MX and/or MXII, is discussed below. An OTW catheter&#39;s guidewire lumen runs the entire length of the catheter and may be positioned next to, or enveloped within, an inflation shaft. Thus, the entire length of an OTW catheter is tracked over a guidewire during a PTCA procedure. A RX catheter, on the other hand, has a guidewire lumen that extends within only the distalmost portion of the catheter. Thus, during a PTCA procedure only the distalmost portion of a RX catheter is tracked over a guidewire.  
         [0011]     If a catheter exchange is required while using a standard OTW catheter, the user must add an extension wire onto the proximal end of the guidewire to maintain control of the guidewire, slide the catheter off of the extended guidewire, slide the new catheter onto the guidewire and track back into position. Multiple operators are required to hold the extended guidewire in place while the original catheter is exchanged in order to maintain its sterility.  
         [0012]     A RX catheter avoids the need for multiple operators when exchanging the catheter. With a rapid exchange catheter, the guidewire runs along the exterior of the catheter for all but the distalmost portion of the catheter. As such, the guidewire can be held in place without an extension when the catheter is removed from the body. However, one problem associated with RX catheters is the guidewire, and most of the catheter, must be removed from the body in order to exchange guidewires. Essentially the procedure must then start anew because both the guidewire and the catheter must be retracked to the treatment site. An OTW catheter, with the guidewire lumen extending the entire length of the catheter, allows for simple guidewire exchange.  
         [0013]     A balloon catheter capable of both fast and simple guidewire and catheter exchange is particularly advantageous. A catheter designed to address this need is sold by Medtronic Vascular, Inc. of Santa Rosa, Calif. under the trademarks MULTI-EXCHANGE, ZIPPER MX, ZIPPER, MX and/or MXII (hereinafter referred to as the “MX catheter”). An MX catheter is disclosed in U.S. Pat. No. 4,988,356 to Crittenden et al.; co-pending U.S. patent application Ser. No. 10/116,234, filed Apr. 4, 2002; co-pending U.S. patent application Ser. No. 10/251,578, filed Sep. 18, 2002; co-pending U.S. patent application Ser. No. 10/251,477, filed Sep. 20, 2002; co-pending U.S. patent application Ser. No. 10/722,191, filed Nov. 24, 2003; and co-pending U.S. patent application Ser. No. 10/720,535, filed Nov. 24, 2003, all of which are incorporated by reference in their entirety herein.  
         [0014]     The MX catheter includes a catheter shaft having a guidewire lumen positioned side-by-side with an inflation lumen. The MX catheter also includes a longitudinal cut that extends along the catheter shaft and that extends radially from the guidewire lumen to an exterior surface of a catheter shaft. A guide member through which the shaft is slidably coupled cooperates with the longitudinal cut such that a guidewire may extend transversely into or out of the guidewire lumen at any location along the longitudinal cut&#39;s length. By moving the shaft with respect to the guide member, the effective over-the-wire length of the MX catheter is adjustable.  
         [0015]     The guidewire is threaded into a guidewire lumen opening at the distal end of the catheter and out through the guide member. The guidewire lumen envelopes the guidewire as the catheter is advanced into the patient&#39;s vasculature while the guide member and guidewire are held stationary. Furthermore, the indwelling catheter may be removed by withdrawing the catheter from the patient while holding the proximal end of the guidewire 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 guidewire is of a sufficiently short length that the catheter may be drawn over the proximal end of the guidewire without releasing control of the guidewire or disturbing its position within the patient.  
         [0016]     While MX catheters provide many advantages over RX and OTW catheters, both RX and MX catheters need to be sealed effectively at the hemostasis valve. OTW catheters are readily sealed at the valve since the guidewire is within the catheter shaft which extends through the valve. RX and MX catheters have a catheter shaft and guidewire separated proximal to the hemostasis valve and thus an effective valve seal must take into consideration the catheter and guidewire separation for an RX catheter and with the guide member in the case of the MX catheter. For example, in a typical dye injection, the physician may pull a slight negative pressure to ensure no air bubbles are within the system prior to injecting the dye. If the physician pulls a very heavy negative pressure, there remains a possibility that air may enter the patient through the hemostasis valve if not sealed sufficiently around the catheter, guide wire and guide member of an MX catheter. Similarly, when a hemostasis valve has an active/passive gasket, if the valve is not properly closed down on an RX catheter shaft and guidewire, air may be drawn into the system when a very heavy vacuum is drawn.  
         [0017]     Accordingly, it is desirable to provide an apparatus that can reduce or eliminate the opportunity for unwanted air aspiration at the hemostasis valve when using a MX catheter. In addition, it is desirable to provide such an apparatus that does not slow down guidewire insertion or other medical processes involving the catheter. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.  
       BRIEF SUMMARY  
       [0018]     A system is provided for exchanging a catheter and a guidewire. The system includes a catheter with a guide member. The catheter includes an elongate shaft having an exterior surface, a proximal end, and a distal end; a first lumen extending through the shaft from the shaft proximal end to the shaft distal end, and sized to receive a guidewire; and a longitudinal guideway extending distally from the shaft proximal end, and enabling transverse access from the shaft exterior surface to the first lumen. The guide member includes a housing having a proximal end and a distal end; a catheter passageway extending through the housing from the proximal end to the distal end and adapted to slidably receive the catheter; a guidewire passageway extending from the housing proximal end into the catheter passageway, and including a tube adapted to merge the guidewire transversely through the guideway and into the first lumen; and sealing body that is positioned in the guidewire passageway.  
         [0019]     A guide apparatus is also provided for advancing and retracting a guidewire and a catheter having a lumen, an exterior surface, and a longitudinal guideway that enables transverse access from the catheter exterior surface to the lumen in a patient. The apparatus includes a housing having a proximal end and a distal end; a catheter passageway extending through the housing from the proximal end to the distal end and adapted to slidably receive the catheter; a guidewire passageway extending from the housing proximal end into the catheter passageway, and comprising a tube adapted to merge the guidewire transversely through the guideway and into the first lumen; and sealing body that is positioned in the guidewire passageway. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]     The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and  
         [0021]      FIG. 1  is a perspective view of a guide member with a guide wire extending through a guide member and into a catheter according to the present invention;  
         [0022]     FIGS.  2 A-D are cross sectional views of a catheter at points A-A, B-B, C—C, and D-D illustrated in  FIG. 1 ;  
         [0023]      FIG. 3  is a perspective cross sectional view of an oval proximal shaft;  
         [0024]      FIG. 4  is a cross sectional view of a circular proximal shaft;  
         [0025]      FIG. 5  is a sectional view of a guide member and its components according to the present invention;  
         [0026]      FIG. 6  is a perspective view of a guide member that is sectioned to depict a guidewire tube extending through a passageway within the guide member according to an embodiment of a passive seal according to the present invention;  
         [0027]      FIG. 7  is a sectional view of an o-ring body as another embodiment of a passive seal positioned in the guidewire entrance port according to the present invention;  
         [0028]      FIG. 8  is a sectional view of a labyrinth type seal as another embodiment of a passive seal positioned in the guidewire entrance port according to the present invention; and  
         [0029]      FIG. 9  is a sectional view of a gel seal as another embodiment of a passive seal positioned in the guidewire entrance port according to the present invention;  
         [0030]      FIG. 10  is a sectional view of a quad ring seal as an embodiment of an active seal positioned in the guidewire entrance port according to the present invention;  
         [0031]      FIG. 11  is a sectional view of a half quad ring seal as another embodiment of an active seal positioned in the guidewire entrance port according to the present invention;  
         [0032]      FIG. 12  is a sectional view of an hour glass seal as another embodiment of an active seal positioned in the guidewire entrance port according to the present invention;  
         [0033]      FIG. 13  is a sectional view of a rocking seal as another embodiment of an active seal positioned in the guidewire entrance port according to the present invention;  
         [0034]      FIG. 14  is a sectional view of a half rocking seal as another embodiment of an active seal positioned in the guidewire entrance port according to the present invention;  
         [0035]      FIGS. 15A and 15B  are sectional views of a guide member with a passageway that is modified to include flexible flaps according to an embodiment of the present invention; and  
         [0036]      FIGS. 16A and 16B  are sectional views of a guide member with a passageway that is modified to include an inflatable balloon according to an embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0037]     The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description.  
         [0038]     The present invention is used with an MX catheter, an exemplary embodiment of which is illustrated in  FIG. 1 . The catheter  12  includes an elongate, flexible, cylindrical main body having a distal shaft  20  and a proximal shaft  22 . According to the present embodiment, the catheter  12  is a delivery catheter for such procedures as PTCA or stent delivery and has a balloon  24  mounted around the catheter body near the catheter distal end  18 . The balloon  24  may be inflated and deflated through the catheter inflation lumen  26 . The inflation lumen  26  communicates with a fitting  28  at the catheter proximal end, and extends the catheter length to terminate in communication with the balloon interior at the catheter distal end  18 . The catheter  12  also includes a guidewire lumen  30  that receives the guidewire  14  and extends the entire catheter length. A longitudinal cut extends into the guidewire lumen  30  along the length of most of the proximal shaft  22  to form a guideway  32 . The proximal shaft distal section  34  does not include the guideway  32 . The guidewire lumen  30  and the inflation lumen  26  are coaxially arranged in the distal shaft  20  according to the present embodiment.  
         [0039]     The present invention includes a guide member for the MX catheter  12 .  FIG. 1  depicts a guide member  10  according to an embodiment of the invention, with a guide wire  14  extending through the guide member  10  and into the MX catheter  12 .  FIGS. 2A  to  2 D are cross sections of the catheter  12  at points A-A, B-B, C—C, and D-D along the catheter length. The guide member  10  serves as a juncture in which the catheter  12  and guidewire  14  may be merged or separated so that the guidewire portion that extends proximal to the guide member  10  is separated from the catheter  12 , and the guidewire portion that is located distal to the guide member  10  is contained and housed within the catheter, although the guidewire distal end  16  may protrude out of the catheter distal end  18 .  
         [0040]     The catheter proximal shaft  22  described above can be modified to suit various needs. For example, the proximal shaft can be a tri-lumen shaft to provide passage for various drugs, fluids, wires, or other necessary compositions or equipment. Further, the proximal shaft may be oval, circular, or other suitable shape.  FIG. 3  is a perspective cross sectional view of an oval proximal shaft  22  according to one embodiment of the invention, and  FIG. 4  is a cross sectional view of a circular proximal shaft  48  according to another embodiment of the invention. Each of the proximal shafts  22 ,  48  has a respective guidewire lumen  30 ,  52  that is accessible through a guideway  32 ,  54  located along the proximal shaft length. Each of the proximal shafts  22 ,  48  also includes an inflation lumen  26 ,  62  that extends side by side with the guidewire lumen  30 ,  52  along the proximal shaft length. The inflation lumens  26 ,  62  are preferably supported by a stiffening member  60 ,  64  such as a hypotube. The inflation lumen  62  in the embodiment depicted in  FIG. 4  is crescent shaped and the hypotube stiffening member  64  also is formed in the same shape to withstand force transmission along the catheter length. The stiffening members may further include a transition section at their respective distal sections in conjunction with a transition between the relatively stiff proximal shaft to the relatively flexible distal shaft and avoid shaft kinking at the junction therebetween. For example, the hypotube  60  may be skived at its distal end, with the skived portion extending into the distal section as depicted in  FIG. 2C .  
         [0041]     Returning to  FIG. 1 , the proximal shaft  22  can be formed from suitable biomedical grade materials such as polyethylene, cross-linked polyethylene, polyolefins, polyamides, blends of polyamides and polyolefins, fluoropolymers, polyesters, polyketones, polyimides, polysulphones, polyoxymethylenes, and compatibilizers based on polyolefins, including grafted polyolefins, and other comparable materials. A lubrication additive may also be used with any polymer and may include polyethylene micro-powders, fluoropolymers, silicone based oils, fluoro-ether oils, molybdenum disulphide and polyethylene oxide. Additionally, a reinforcing additive may be used such as nano-clays, graphite, carbon fibers, glass fibers, and polymeric fibers. The distal shaft  20  can be made of a suitable polyethylene or polyolefin that readily bonds to the proximal shaft  22 .  
         [0042]     Turning now to  FIG. 5 , the guide member  10  and its components will be discussed according to one embodiment of the invention. The guide member  10  surrounds the proximal shaft  22  and includes proximal and distal ends  92 ,  94 . An outer tubular member  96  freely rotates around an inner main body  98  and hence is decoupled from the inner main body  98 . An inwardly extending distal annular wall  70  prevents the main body  98  from slipping out of the outer member  96 . A retaining clip  71  includes a tab  72  that extends into a space  73  formed by two main body walls  74 ,  75 . Additional tabs may be used as necessary to retain the inner main body  98  within the tubular member  96 .  
         [0043]     The guide member main body  98  includes a catheter passageway  88  extending longitudinally in a generally straight line from the guide member proximal end  92  to the guide member distal end  94 . A guidewire passageway  80  extends distally from the guide member proximal end  92  through an entrance port  82  into a tube  86  and then into the catheter guidewire lumen  30 , although the catheter is not depicted in  FIG. 5 . The passageway  80  is configured to slidingly receive the proximal shaft  22 , and has a cross sectional shape that approximates the proximal shaft shape, whether the proximal shaft is circular, oval, triangular, shamrock shaped, or otherwise shaped. The passageway  80  enlarges in a central area to provide space for a keel  84  that is aligned with the passageway  80  and positioned to spread the catheter guideway  32  and extend into the catheter guidewire lumen  30  to enable guidewire insertion during use.  
         [0044]     The entrance port  82  is configured to mate with a conventional wire introducer tool and is tapered to aid in loading such a tool. The tube  86  may vary in its length, although in an exemplary embodiment of the invention the tube  86  extends through the catheter guidewire lumen  30  approximately thirty-five millimeters past the guide member distal end  94 . The tube  86  may be formed from a flexible material such as a polyimide, and particularly the tube region that extends through the catheter guidewire lumen  30 . In one embodiment of the invention the tube region that introduces the guidewire  14  into the guidewire lumen  30  may be substantially rigid to provide the necessary support for the guidewire  14 .  
         [0045]     The guide member  10  is made of blends of polyamides and polyolefins in an exemplary embodiment of the invention. Other exemplary materials include ceramics, metals such as stainless steel, and other polymers such as polyamides and liquid crystal polymers. Lubrication additives such as polyethylene micro-powders, fluoropolymers, silicone-based oils, fluoro-ether oils, molybdenum disulphide, and polyethylene oxide may be included. Reinforcing additives such as nano-clays, graphite, carbon fibers, glass fibers, polyesters, polyketones, polyimides, polysulphones, polyoxymethylenes, polyolefins, cross-linked polyolefins may also be included, along with compatibilizers based on polyolefins, such as grafted polyolefins, ceramics, and metals.  
         [0046]     An exemplary guide member operation will now be described, although the procedures in the following description clearly set forth only one of many operations enabled by the guide member  10 . After the guidewire  14  and a guide catheter (not shown) are inserted into a patient, the catheter  12  is inserted with a backloading operation. The guidewire  14  is inserted into the catheter distal end  18  and threaded proximally through the guidewire lumen  30  until the guidewire tube  86  captures the guidewire proximal end and directs it into the passageway  80  and then out of the guide member proximal end  92 . This procedure can be accomplished with the guide member  10  adjacent the catheter guideway distal end. As the distal shaft  20  enters the patient, the guide member  10  will reach the hemostatic valve (not shown). The guide member  10  is not intended to enter the valve and is seated adjacent to the valve. The proximal shaft  22  is then advanced through the guide member, and the keel  84  engages the catheter guideway  32 . After the catheter  12  is inserted, the hemostatic valve may be closed down on the catheter shaft at a region that is distal to the guide member  10 . Since the tube  86  extends in to the distal shaft  20 , it is subjected to the valve clamping force. If a wire change is required, one simply withdraws the guidewire  14  from the guide member  10  as the guide member  10  is seated against the valve and as the proximal shaft  22  remains in the patient. A new guidewire is then inserted into the catheter through the passageway  80 . If a catheter exchange is required, one simply holds the guidewire  14  in place and begins moving the proximal shaft  22  proximally through the guide member. Another catheter may then be backloaded onto the guidewire  14  and introduced into the patient as described above after the catheter has been separated from the guidewire.  
         [0047]     Passageway  80  is adapted to include a seal that prevents or minimizes fluid movement through the passageway. Exemplary airflow reduction bodies according to the present invention are described below and categorized as either passive seals or active seals. Passive seals are generally defined as bodies that prevent or substantially minimize fluidflow without changing shape or orientation. Active seals are generally defined as bodies that minimize fluid flow without changing shape or orientation, but may substantially minimize or entirely prevent fluid flow due to a change of shape or orientation. Such a change of shape is typically caused due to the force of inrushing fluid on one side of the airflow reduction body when the guidewire  14  is advanced through the passageway  80 .  
         [0048]     The following four seals are all exemplary passive seals.  FIG. 6  is a perspective view of the guide member  10  with a modified passageway according to one embodiment of a passive seal. The guide member  10  is sectioned in the figure in order to depict the guidewire tube  86  extending through the passageway  80 . The tube  86  has a substantially uniform inner diameter, but includes a fixed reduced diameter region  83  that prevents air movement therethrough. The term “fixed” in this sense means that the reduced diameter region  83  is a passive, unchanging airflow reduction body unlike some of the active airflow reduction bodies described hereinafter. The small diameter region  83  has a smaller diameter than the rest of the tube  86 , or at least a diameter that is smaller than the small diameter region&#39;s immediate or nearby vicinity, and consequently substantially reduces the amount of air that flows through the tube  86  without impeding guidewire movement. The small diameter region  83  is formed proximally with respect to the keel  84 , as depicted in  FIG. 6 . However, the small diameter region  83  may be formed elsewhere within the passageway, or even distal to the guide member  10  if the tube  86  extends beyond the guide member within the guidewire lumen  30 .  
         [0049]     The small diameter region  83  may be formed by slightly constricting the tube  86  using an annular body  81  that is connected to the tube. In an exemplary embodiment of the invention, the annular body  81  is a bracket, a clamp, a sleeve, or other device. The annular body  81  may surround the tube outer surface. Alternatively, the annular body  81  may also be attached to the tube interior surface. In another exemplary embodiment, the bracket  81  interrupts the continuity of the polyimide or other tube material, and is manufactured in-line with the tube  86 . In such an embodiment, the tube  86  is joined to the bracket  81  by applying heat, an adhesive, or any other suitable joining tool or composition.  
         [0050]     In another exemplary embodiment, an annular body is not used to create the small diameter region  83 . Rather, the polyimide or other tube material is simply manufactured to have a discrete region that has a smaller diameter than the rest of the tube  86 , or at least a smaller diameter than that of the discrete region&#39;s immediate or nearby vicinity.  
         [0051]     One reason that the small diameter region  83  is highly effective at restricting fluid passage through the tube  86  is the seal uniformity across the region  83 . A full seal entirely surrounding tube  86  is preferred. Fluid flow prevention also is found to be positively related to the length of the longitudinal length of the small diameter region  83 . Consequently, doubling the small diameter region length has the effect of approximately doubling the resistance to fluid flow.  
         [0052]      FIG. 7  is a sectional view of an o-ring body  61  as another embodiment of a passive seal, positioned in the guidewire entrance port  82  adjacent to the tube  86 . The o-ring body can be formed of a flexible material, although a substantially rigid material will reduce friction with the guidewire  14 . The o-ring body  61  can be positioned in any suitable location in the guidewire passageway  80  to effectively prevent or substantially minimize fluid flow therethrough. An exemplary location for the o-ring body  61  is the entrance port  82 , although the o-ring body  61  may be in any suitable position within the guidewire passageway  80 , including the tube  86  or even the keel  84 . The o-ring body  61  has an outer diameter  63  that can approximate the inner diameter of the guidewire passageway area in which the o-ring body is positioned. The o-ring body  61  also has an inner diameter  65  that approximates the guidewire diameter in order to provide a substantially fluid tight seal with the guidewire  14 .  
         [0053]      FIG. 8  is a sectional view of a labyrinth type seal as another embodiment of a passive seal, positioned in the guidewire entrance port  82  adjacent to the tube  86 . The labyrinth seal can be positioned in any suitable location in the guidewire passageway  80  to effectively prevent or substantially minimize fluid flow therethrough. An exemplary location for the labyrinth seal is the entrance port  82 , although the seal may be in any suitable position within the guidewire passageway  80 .  
         [0054]     The labyrinth seal includes a set of stacked disks  51  with an air space  53  between each pair of disks  51 . Each disk  51  includes a slit  56  wide enough to slidably receive the guidewire  14 . Each slit  56  is shorter than the disk diameter and is provided to allow the flow of only a small amount of inrushing fluid. In an exemplary embodiment, each slit  56  is rotated with respect to a slit  56  in an adjacent disk  51  to prevent a direct pattern for fluid flow. For example, the slit in each disk in the embodiment depicted in  FIG. 8  is oriented at a 45° angle with respect to the slit in the adjacent disk. Consequently, the force produced by inrushing fluid caused by factors such as a pressure drop due to vacuum drawn on guide catheter, or by guidewire advancement, is substantially eliminated after one or more disks have blocked and distributed the force. Each disk  51  is separated by spacing bodies  55  that are o-shaped bodies in an exemplary embodiment. The disks  51  are separated by a width that is close to the disk width in the embodiment depicted in  FIG. 11 , although the spacing can be adjusted to optimize the distribution of inrushing fluid and buffer the force that the inrushing fluid creates on the proximal side of each disk  51 . Additional disks can be added, or fewer disks can be utilized in order to effectively block air passage, and as few as one disk can be utilized in some cases.  
         [0055]      FIG. 9  is a sectional view of a gel seal as another embodiment of a passive seal, positioned in the guidewire entrance port  81  adjacent to the tube  86 . The gel seal can be positioned in any suitable location in the guidewire passageway  80  to effectively prevent or substantially minimize fluid flow therethrough. An exemplary location for the gel seal is the entrance port  82 , although the seal may be in any suitable position within the guidewire passageway  80 .  
         [0056]     The gel seal includes a gel center  57  that is secured in the guidewire passageway  80  using a capsule  58 . The gel center  57  may include any biocompatible gel composition such as silicone or another polymer suspended in a biocompatible dispersion medium such as water or a saline solution. The polymer is viscous enough to prevent leakage through guidewire access holes  59  molded in the capsule  58 . The polymer is also sufficiently fluid to allow the guidewire  14  to advance or retract with little to negligible friction. The capsule  14  is a molded body formed from two separate pieces in the exemplary embodiment depicted in  FIG. 9 , although the capsule  14  can be any housing that essentially encapsulates the gel center  57  to prevent the gel from leaking when the guide member  10  is inverted or rotated.  
         [0057]     The following seven seals are all exemplary active seals.  FIG. 10  is a sectional view of a quad ring active seal  31  positioned in the guidewire entrance port  81  adjacent to the tube  86 , and  FIG. 11  is a sectional view of a half quad ring active seal  35  similarly positioned. The quad ring seal  13  or the half quad ring seal  35  can be positioned in any suitable location in the guidewire passageway  80  to effectively prevent or substantially minimize fluid flow therethrough. An exemplary location for either of these seals is the entrance port  82 , although the seals may be secured in any suitable position within the guidewire passageway  80 .  
         [0058]     Both the quad ring seal  31  and half quad ring seal  35  include an annular central member  36  that includes an inner diameter  37  that is slightly larger than the guidewire diameter. The central member  36  is essentially an o-ring body. In the half quad ring seal  35 , the central member  36  is formed continuous with an annular flexible body  33  that is foldable against the guidewire  14  to prevent inrushing fluid from reaching the catheter guidewire lumen  30 . The flexible body  33  has a central aperture  38  for slidingly receiving the guidewire  14 . The central aperture  38  has a diameter that is slightly larger than the guidewire diameter, but is smaller than the central member inner diameter  37 . The flexible body  33  is formed as a cone with a truncated tip that produces the central aperture  38 . The flexible body  33  is configured to collapse from the conical shape to form a fluid tight seal around the guidewire  14  as a result of the force from inrushing fluid. As shown in  FIG. 13 , the quad ring seal  31  includes two flexible bodies  33  that flank the central member  36 . The two flexible bodies  33  are disposed oppositely with respect to the central member  36 .  
         [0059]      FIG. 12  is a sectional view of an hour glass active seal  41  positioned in the guidewire entrance port  81  adjacent to the tube  86 . The hour glass seal  41  can be positioned in any suitable location in the guidewire passageway  80  to effectively prevent or substantially minimize fluid flow therethrough. An exemplary location for these seal  41  is the entrance port  82 , although the seal  41  may be secured in any suitable position within the guidewire passageway  80 .  
         [0060]     The hour glass seal  41  includes a continuous molded body  47   a - d  that is hollowed to define a passageway  45  through which the guidewire  14  extends. The passageway  45  narrows as it extends from the seal proximal end  47   b  to a small diameter neck  43 . From the neck  43 , the passageway  45  widens until it reaches the seal distal end  47   d . In an exemplary embodiment, the passageway  45  has a symmetrical configuration, meaning that the passageway  45  on the proximal side of the neck  43  is identical to the passageway  45  on the distal side of the neck  43 . The neck  43  has a smaller diameter than the rest of the passageway  45 , and the neck diameter is sized to slidably receive the guidewire  14 . The neck diameter is also slightly larger than the guidewire diameter, and the neck  43  is defined by a hollow flexible wall  47   c  that is continuously formed with the remaining molded body  47   a, b, d . The force of inrushing fluid against the walls  47   a  causes the neck  43  to constrict as the flexible material  47   c  changes shape to form a substantially fluid tight seal around the guidewire  14 . To ensure that the wall  47   c  changes shape and thereby causes the neck  43  to constrict due to the force of inrushing fluid, the wall  47   c  is substantially less rigid than the adjacent walls  47   a  in an exemplary embodiment of the invention. In order to make the wall  47   c  substantially less rigid wall than the adjacent walls  47   a , the wall  47   c  can be substantially thinner than the adjacent walls  47   a , or the wall  47  can be formed from a less rigid material than that of the adjacent walls  47   a.    
         [0061]     If the walls  47   a  in the molded body are not rigid enough, or do not span a sufficient width, to support the entire hour glass seal  41  together with the walls that define the guidewire passageway  80 , the walls can be radially extended at the seal proximal and distal ends  47   b ,  47   d  as depicted in  FIG. 12 . Further, a rigid support member  49  can be provided around a periphery of the hour glass seal  41  to provide further support if necessary. If the rigid support member  49  conforms or nearly conforms to the hour glass seal periphery, a vent  50  may be included in the support member  49 . The vent  50  allows external fluid to fill any space between the support member  49  and the hour glass seal  41 , and consequently enables the wall  47   c  to constrict the neck  43 .  
         [0062]      FIG. 13  is a sectional view of a rocking seal  120  positioned in the guidewire entrance port  81  adjacent to the tube  86 .  FIG. 14  is a sectional view of a half rocking seal  125  similarly positioned. The rocking seal  120  or half rocking seal  125  can be positioned in any suitable location in the guidewire passageway  80  to effectively prevent or substantially minimize airflow therethrough. An exemplary location for these seals  120 ,  125  is the entrance port  82 , although the seals  120 ,  125  may be secured in any suitable position within the guidewire passageway  80 .  
         [0063]     The rocking seal  120  is a continuously formed structure that includes two substantially cylindrical walls  134   a ,  134   b  that are continuously joined with an elongate neck  133 . The elongate neck  133  is defined by a wall that is formed of a flexible material and has a diameter that is smaller than the diameter formed by the cylindrical walls  134   a ,  134   b . The elongate neck inner diameter is slightly larger than the guidewire diameter, and is sized to slidingly receive the guidewire  14 . The cylindrical walls  134   a ,  134   b  and the elongate neck  133  are joined by folded walls  131   a ,  131   b  that double back inwardly and form annular pockets  132   a ,  132   b  that surround a portion of the elongate neck  133 .  
         [0064]     When the guidewire passageway  80  is subjected to a vacuum force, inrushing fluid is received by the annular pocket  132   a  that is proximal to the elongate neck  133 . The force of the inrushing air pushes the folded wall  131   a  toward folded wall  131   b . The wall that defines the elongate neck  133  is flexible and consequently buckles or otherwise changes shape, causing the elongate neck inner diameter to constrict so that a substantially airtight seal is formed around the guidewire  14 . To ensure that the wall defining the elongate neck  133  changes shape and thereby causes the elongate neck  133  to constrict due to the force of inrushing fluid, the wall is substantially less rigid than the adjacent folded walls  131   a ,  131   b  and the cylindrical walls  134   a ,  134   b  in an exemplary embodiment of the invention. In order to make the wall defining the elongate neck  133  substantially less rigid, the wall can be substantially thinner than the adjacent folded walls  131   a ,  131   b  and the cylindrical walls  134   a ,  134   b  or the wall can be formed from a less rigid material than that of the adjacent folded walls  131   a ,  131   b  and the cylindrical walls  134   a ,  134   b.    
         [0065]     If the walls  137 ,  138  in the molded body are not rigid enough, or do not span a sufficient width, to support the entire rocking seal  120  together with the walls that define the guidewire passageway  80 , the walls  137 ,  138  can be radially extended at the seal proximal and distal ends as depicted in  FIG. 13 . Further, a rigid support member  136  can be provided around a periphery of the rocking seal  120  to provide further support if necessary. A vent  139  may be included in the support member  136  as necessary to allow external fluid to fill any space between the support member  136  and the rocking seal  120 , and consequently enables the elongate neck  133  to constrict around the guidewire during guidewire advancement or other vacuum creating force.  
         [0066]     The half rocking seal  125  is similar to the rocking seal  120  described above, except the cylindrical wall  134   b , and folded wall  131   b  from the rocking seal are replaced with a large annular rib  135  that is continuously formed with the elongate neck  133  and extends radially to span the guidewire passageway  80 . The half rocking seal  125  functions in the same manner as the rocking seal  120  to form a substantially fluid tight seal around the guidewire  14 .  
         [0067]     If the walls in the molded body are not rigid enough, or do not span a sufficient width, to support the entire rocking seal  120  or half rocking seal  125  together with the walls that define the guidewire passageway  80 , the walls can be radially extended at the seal proximal and distal ends  137 ,  138  as depicted in  FIG. 13 , or the annular rib  135  can be extended further than as depicted in  FIG. 14 . Further, a rigid support member  136  can be provided around a periphery of either seal  120 ,  125  to provide further support if necessary. If the rigid support member  136  conforms or nearly conforms to the cylindrical wall periphery, a vent  139  may be included in the support member  136 . The vent  139  allows external air to fill any space between the support member  136  and either seal  120 ,  125 , and consequently enables the elongate neck  133  to constrict during guidewire advancement or other vacuum creating force.  
         [0068]      FIGS. 15A and 15B  are sectional views of the guide member  10  with a modified passageway including active seals according to another embodiment of the invention. The guidewire  14  is illustrated extending through the guidewire passageway  80  including the entrance port  82  and tube  86 . Fluid intake in a dye injection syringe, guidewire advancement through the tube  86 , and other vacuum creating forces may draw air into the tube  86  by way of the entrance port  82 . To prevent the inrushing air from reaching the catheter guidewire lumen  30 , the entrance port is equipped with one or more annular flaps  85 . Each flap  85  has a central aperture for slidingly receiving the guidewire  14 . Each flap  85  is formed from a flexible material that is formed as a cone with a truncated tip that produces the central aperture. As depicted in  FIG. 5A , the cone shaped flaps  85  are positioned with the smaller diameter portion proximal to the larger diameter portion, and the point where the flaps  85  are joined to the entrance port  82  forms an annular pocket that receives inrushing air when the guidewire is advanced through the guide member  10  and into the catheter guidewire lumen  30 . As depicted in  FIG. 15B , the flexible flaps  85  are configured to collapse from their biased conical shape, each collapsed flap forming fluid tight seals around the guidewire  14  as a result of the force from the inrushing fluid.  
         [0069]     The flaps  85  are formed using a flexible polymer in an exemplary embodiment, although there are many materials that may be used to form the flaps  85  and provide a substantially fluid tight seal about the guidewire  14 . Also, although the flaps  85  are shown to be positioned within the entrance port  82 , they may be in any suitable position within the guidewire passageway  80 , including the entrance port  82  and the tube  86 .  
         [0070]     Another embodiment of the invention involving active seals is depicted in  FIGS. 16A and 16B . The entrance port  82  includes at least one balloon  87  that is inflatable as a result of the force produced by inrushing fluid. As depicted in  FIG. 16A , the balloon  87  does not substantially impinge on the entrance port  87  when deflated, and the deflated balloon  87  may even be positioned entirely outside of the guidewire passageway  80 . As depicted in  FIG. 16B , the inflated balloon  87  occludes the entrance port  82  and thereby prevent inrushing air from entering the tube  86 .  
         [0071]     The balloon  87  can be formed using any one of many known materials that may be used to form inflatable balloons as long as the inflated balloon  87  can provide a substantially airtight seal about the guidewire  14  without creating a detrimental amount of friction that would impede guidewire advancement. Also, although the balloon  87  is depicted to be positioned within the entrance port  82 , the balloon  87  may be in any suitable position within the guidewire passageway  80 .  
         [0072]     The balloon  87  may have an annular shape that consequently surrounds the guidewire  14  by itself Alternatively, a plurality of balloons may be positioned around the guidewire  14  such that the balloons, when inflated, together form a single airtight seal. Any number of balloons may be used to provide the airtight seal about the guidewire  14 .  
         [0073]     Any of the above passive or active seals that are capable of being secured in the entrance port  82  or other guidewire passageway component may be secured using by a friction force. The various sealing bodies or assemblies may be made from, or housed in a material that has a high friction coefficient to prevent the bodies or assemblies from adjusting out of the desired position. The sealing bodies or assemblies may also be secured using an adhesive, a bracket or other fastening device.  
         [0074]     While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing the exemplary embodiment or exemplary embodiments. It should be understood that various changes can be made in the function and arrangement of elements without departing from the scope of the invention as set forth in the appended claims and the legal equivalents thereof.