Abstract:
A catheter and system for delivering viscous fluid, under high pressures, into the vasculature of a patient includes a catheter body having a proximal end and a distal end, a reinforcing member surrounding at least a portion of the proximal end, and a compression fitting surrounding the reinforcing member for holding the proximal end of the catheter body. A strain relief element shrouds a portion of the proximal end to prevent kinking of the catheter body. Accordingly, the reinforcing member, the compression fitting and the strain relief element cooperate to hold the catheter body in a luer fitting and to prevent the proximal end of the catheter body from kinking under bending, and to prevent leakage or bursting under pressure.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention pertains to catheters for injecting viscous fluid into the body, and particularly to catheters that deliver viscous embolization agents into the vasculature.  
         BACKGROUND  
         [0002]    Catheters have been used for decades to infuse fluids into the blood stream. For the most part, the infused fluids disperse in the blood to effectuate treatment of the patient.  
           [0003]    The assignee of the present invention is a developer of bio-compatible agents that are particularly useful for embolization of diseased (e.g. aneurysmal) sites in the vasculature of a patient. U.S. Pat. No. 5,851,508, issued Dec. 22, 1998, describes various embolization agents. The disclosure of this U.S. patent is incorporated herein by reference. These embolization agents are typically insoluble in blood and are highly viscous to enable delivery to a particular situs in the vasculature without dispersion.  
           [0004]    Delivery catheters used for dispensing embolization agents have been made sturdy enough to deliver the embolization agents to various parts of the vascular system. However, such catheters are often too large in diameter to effectuate treatment in the distal most reaches of the vasculature.  
           [0005]    The diagnosis and treatment of neurovasculature disease can be of the utmost importance because neurovasculature disease (e.g. aneurysmal disease) could devastate the patient. Unfortunately, the vessels of the distal reaches of the neurovasculature are tortuous, having diameters of 3 mm, or less, and having bends exceeding 90 degrees. Tortuous vessels are difficult to reach with full-sized delivery catheters.  
           [0006]    The amount of pressure required to dispense a viscous fluid from a small diameter tube is much greater than the pressure required to dispense the same fluid through a larger diameter tube. Accordingly, the smaller the delivery catheter, the higher the pressure required to deliver the viscous fluid.  
           [0007]    Pressure experienced by a viscous fluid delivery catheter is normally greatest at the proximal end. The pressure decrease towards the distal end, approaching zero at the distal most tip. In testing, standard luer fittings (e.g. ISO 594-1 standard luer fittings) may fail when supplied with pressures exceeding 500 psi. Typically, a leak between the luer fitting and the catheter denotes a failure. Further, standard syringes may fail when used for pressing highly viscous fluid through catheters having relatively small diameters.  
           [0008]    What is desired is a viscous fluid delivery system that can deliver viscous fluids to the distal reaches of the vasculature, including the neurovasculature. What is also desired is a micro-catheter that can withstand high pressures to deliver viscous fluids.  
         SUMMARY  
         [0009]    A catheter for delivering viscous fluid into the vasculature of a patient includes a catheter body having a proximal end and a distal end, a reinforcing member surrounding at least a portion of the proximal end, and a compression fitting surrounding the reinforcing member for holding the proximal end of the catheter body.  
           [0010]    The reinforcing member prevents radial compression and/or expansion of the proximal end of the catheter body, thus enabling the use of a compression fitting to hold the proximal end. The reinforcing member is tube-shaped and is either inserted within the proximal end, surrounds the proximal end, or both.  
           [0011]    According to one aspect of the invention, the reinforcing member is integrated in the proximal end of the catheter body to resist radial deformation of the catheter body.  
           [0012]    According to one aspect of the invention, the reinforcing member includes a tube that fully surrounds the proximal end. The tube is rigid, being fabricated from a tube of stainless steel less than 0.5″ long that bonds to the proximal end. Preferably, the compression fitting threads into a luer fitting and thus connects the luer fitting and the proximal end in fluid communication to enable viscous fluid to be delivered via the luer fitting and through the distal end of the catheter.  
           [0013]    A sheath covers the reinforcing member. The sheath is compressible to enable the compression fitting to squeeze the sheath and thereby grip the reinforcing tube. Preferably, the sheath is fabricated of like material as the proximal end of the catheter body and is preferably over-molded around the stainless steel tube of the reinforcing member. Accordingly, the sheath integrates the reinforcing member in the catheter body.  
           [0014]    The catheter includes a luer fitting with threaded connectors. The compression fitting threadibly attaches the proximal end of the catheter body to the luer fitting.  
           [0015]    According to one aspect of the invention, the compression fitting includes a locknut having a threaded outer surface and an inner surface. The inner surface defines an opening for circumscribing the reinforcing member. The outer surface of the locknut has threads. When the locknut threads into a luer fitting, for example, the inner surface presses against the proximal end and the reinforcing member of the proximal end of the catheter body. The reinforcing member thus prevents significant deformation such as a significant reduction of the inner diameter of the proximal end by the locknut.  
           [0016]    The luer fitting includes a strain relief element that covers the compression fitting and a portion of the proximal end to inhibit radial deformation of the proximal end when a viscous fluid is delivered by the catheter. Preferably, the strain relief element attaches to the compression fitting.  
           [0017]    Many ways of attaching the strain relief element to the catheter are possible. According to one aspect of the invention, the strain relief element attaches directly to the luer fitting. In a further aspect, the strain relief element attaches to both the luer fitting and to the compression fitting. According to another aspect of the invention, the strain relief element bonds to the compression fitting. According to another aspect of the invention, the strain relief element and the compression fitting press-fit. According to yet another aspect of the invention, the compression fitting has an annular recess that holds the strain relief element. According to still another aspect of the invention, the strain relief element bonds to both the compression fitting and to the proximal end of the catheter body.  
           [0018]    The strain relief element tapers from the luer fitting towards the catheter body to eliminate the possibility of kinking the catheter body during normal use. The taper may assume any of a variety of configurations. Preferably, however, the taper extends between 1″-3″, and more preferably, the taper extends about 1.5″.  
           [0019]    A system in accordance with the present invention includes the catheter and a high pressure device for delivering viscous fluid to the catheter. The high pressure device includes a syringe having a blunt needle. The needle includes a removable barb press-fit on the blunt needle. The barb is configured for piercing a vial holding viscous fluid to enable the syringe to draw the viscous fluid from the vial. The barb slides off of the needle when the needle is removed from the vial.  
           [0020]    A method of filling a syringe with viscous fluid in accordance with the present invention includes providing a syringe having a needle and a vial of viscous fluid, press fitting a removable barb on the blunt needle, piercing the vial with the barb, drawing viscous fluid into the syringe from the vial, and removing the needle from the vial and thereby causing barb to slide off of the needle so that the barb remains in the vial. Another step in accordance with this method includes inserting the needle into a catheter and delivering the viscous fluid to the neurovasculature of a patient via the catheter.  
           [0021]    The dimensions of the catheter body are preferably adapted for accessing the distal and tortuous reaches of the neurovasculature. Accordingly, the distal end has an outside diameter of 0.040″ or less to facilitate insertion of the catheter into tortuous regions of the vasculature. More preferably, the distal end has an outside diameter of less than 0.029″.  
           [0022]    The distal end further includes a delivery lumen with lumen walls. The lumen walls being at least 0.0012″ thick to withstand pressures associated with the delivery of a viscous fluid. The proximal end of the catheter body being configured for attachment to a luer fitting and for withstanding pressures exceeding 2000 psi. Also, the syringe, the luer fitting and medial portions of the catheter body are also configured for withstanding pressures of 2000 psi or more.  
           [0023]    The syringe attaches to the luer fitting with a syringe locknut. The syringe needle inserts into the syringe locknut and the syringe locknut to holds the needle when the syringe locknut threads into the luer fitting.  
           [0024]    According to one aspect of the luer fitting, the luer fitting is bifurcated, having a three threaded portions to simultaneously receive and attach two syringes to two of the threaded portions, and to attach the compression fitting and the catheter body to the remaining threaded portion, respectively. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0025]    [0025]FIG. 1 is a side view of a catheter in accordance with the present invention.  
         [0026]    [0026]FIG. 2 is an exploded view of the catheter of FIG. 1 shown partly in cross-section.  
         [0027]    [0027]FIG. 3 is a cross-section of the proximal end of a catheter body in accordance with the present invention.  
         [0028]    [0028]FIG. 4 is a cross-section of the distal end of a catheter body in accordance with the present invention.  
         [0029]    [0029]FIG. 5 is a shows a syringe inserted into a vial of viscous fluid.  
         [0030]    [0030]FIG. 6 shows the syringe of FIG. 5 withdrawn from the vial.  
         [0031]    [0031]FIG. 7 shows an alternate embodiment of a luer fitting in accordance with the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0032]    [0032]FIG. 1 shows a catheter generally designated with the reference numeral  10 . The catheter  10  includes a catheter body  12  with a proximal end  14  and a distal end  16 . The catheter  10  also includes a luer fitting  18  with a compression fitting  20  and a strain relief element  22 . The compression fitting  20  attaches the proximal end  14  of the catheter body to the luer fitting  18 .  
         [0033]    The catheter  10  has a syringe  24  with a needle  26  inserted into the luer fitting  18 . The syringe  24  includes a syringe locknut  30  that removably attaches the luer fitting  18  to the syringe  24  in fluid communication. The syringe  24  is capable of delivering viscous fluid under pressures of at least between 1000 psi and 2000 psi.  
         [0034]    The catheter  10  is particularly designed for delivering viscous fluids at high pressures to within the body of a patient. While the catheter  10  can be used within the digestive track, and in various internal tissues and organs, the primary use for the catheter  10  is to deliver embolization agents to address aneurysmal disease. Accordingly, the catheter  10  is sized for use in tortuous regions of the vasculature in order to reach the distal reaches of the neural vasculature, where aneurysmal disease can have great impact.  
         [0035]    Commonly assigned U.S. Pat. Nos. 5,667,767, 5,580,568, 5,830,178, and 6,051,607 describe various embolization agents including cellulose diacetate compositions, dimethylsulfoxide compositions, and Ethyl Lactate compositions, having relatively high viscosity, that are injectable in a viscous fluid form into a diseased or injured portion of the vasculature to improve the blood vessel integrity. The disclosures of these U.S. patents are incorporated herein by reference.  
         [0036]    Some of these embolization agents, and others, have been successfully used to fill aneurysms, thereby structurally strengthening the blood vessel. Methods of embolizing blood vessels are described in commonly assigned U.S. Pat. Nos. 5,702,361 and 6,017,977, the disclosures of which are incorporated herein by reference.  
         [0037]    During a vascular application, the viscous embolization agent typically injects via a vascular catheter without dispersion in the blood. The viscous embolization agent sets over a period to structurally strengthen the blood vessel.  
         [0038]    While it can be appreciated that embolization agents are used in the vasculature, there are many other applications for such embolization agents such as to treat urinary incontinence, to facilitate plastic surgery, to treat ruptured spinal disks, gynecologic dysfunction, treating endoleaks, etc. The present invention can be applied to these applications, and more. Further, while the catheter  10  disclosed herein is used to inject the agents is typically a vascular catheter, the geometry and integrity of the catheter  10  can be particularly adapted to address virtually any site within the body. The catheter  10  is useful for dispersing both dispersable and non-dispersable embolization agents.  
         [0039]    The luer fitting  18  has two ends  32  and  34 . Both of the ends  32  and  34  have internal threads. The end  34  is threaded for receiving the compression fitting  20 . The end  32  receives either an introducer locknut that is sized in accordance with ISO 594-1, or a syringe locknut  30 . An introducer locknut of standard configuration is used prior to attachment of the high pressure syringe for introduction of a guidewire, contrast agent, saline, medicine or any other adapter requiring an ISO 594-1 standard luer fitting connection.  
         [0040]    The syringe locknut  30  that holds the needle  26  of the syringe  24  in the end  32 . Removal of the syringe locknut  30 , and the syringe  24 , enables alternate attachment of a second syringe to the end  32  of the luer fitting  18 .  
         [0041]    The proximal end  14  of the catheter body  12  attaches to the end  34  of the luer fitting to enable the luer fitting  18  and the proximal end  14  of the catheter body  12  to withstand operational pressure exceeding 2000 psi. The compression fitting  20  attaches the proximal end  14  of the catheter body to the luer fitting  18 . The compression fitting  20  enables the luer fitting  18  and the proximal end  14  of the catheter body  12  to withstand high operational pressures.  
         [0042]    The distal end  16  of the catheter body  12  includes marker bands  28  to enable an operator to locate the distal end  16  during use. The distal end  16  is particularly configured for accessing tortuous regions of the neurovasculature. Tortuous regions are defined as those vascular regions having bend exceeding 90 degrees and having a vascular diameter of 3 mm or less. Accordingly the distal end  16  has an outside diameter of 0.040″ or less. The distal end includes a delivery lumen with lumen walls, the lumen walls being at least 0.0012″ thick to withstand pressures associated with the delivery of viscous fluids.  
         [0043]    [0043]FIG. 2 shows the syringe  24 , the syringe locknut  30 , the luer fitting  18 , the compression fitting  20 , the catheter body  12  and the strain relief element  22 . The syringe locknut  30  is one form of compression fitting. There are other compression fittings, however, including compression fittings formed from thermal bonding techniques, insert-moldings and over-moldings, for examples. These alternate forms of compression fittings can be substituted for the syringe locknut  30  in accordance with the present invention.  
         [0044]    The syringe locknut  30  is hollow, having a centrally defined opening  33  for receiving the needle  26  of the syringe  24 . The syringe locknut  30  compresses against the needle  26  to hold and seal the needle  26 .  
         [0045]    The syringe locknut  30  includes a threaded portion  31  and an angled section  37 . The syringe locknut  30  rotates to thread the threaded portion  31  to the end  32  of the luer fitting  18 . When the needle  26  inserts into the luer fitting  18 , and the syringe locknut  30  slide forward in place with respect to the luer fitting  18  and rotates, the needle  26  does not significantly deform, instead, the angled section  37  of the syringe locknut  30  radially compresses to hold the needle  26  within the opening  33 .  
         [0046]    The compression fitting  20 , according to one aspect of the invention, is a locknut that radially compresses to hold the proximal end  14  of the catheter body  12  when threaded to the luer fitting  18 . The compression fitting  20  includes an opening  35  axially defined in the compression fitting  20 . When the proximal end  14  of the catheter body  12  inserts into the opening  35 , and the compression fitting  20  rotates to thread into the end  34  of the luer fitting  18 , then the compression fitting radially compresses against the proximal end  14  of the catheter body  12 .  
         [0047]    In order to allow the compression fitting to hold the proximal end  14  of the catheter body, the proximal end  14  has a rigid tip  39  that resists radial compression.  
         [0048]    The compression fitting  20  includes an annular recess that holds the strain relief element  22 . The strain relief element  22  thus attaches to the luer fitting  18 . It can be appreciated, however, that there are many ways to attach the strain relief element  22  to the luer fitting  18 .  
         [0049]    The strain relief element  22  includes a length “l ”. A portion of the length “l ” has a taper “t”. The taper “t” extends in a direction from the luer fitting towards the catheter body  12  to support the proximal end  14  of the catheter body  12 . Preferably, the taper extends between 1″-3″, and more preferably the taper extends about 1.5″.  
         [0050]    The strain relief element  22  is soft to support proximal end  14  and to allow flexibility of the proximal end  14 , while minimizing any potential for kinking of the proximal end  14 .  
         [0051]    [0051]FIG. 3 shows the rigid tip  39  of the catheter body  12 . The rigid tip  39  includes a portion of the proximal end  14 , a reinforcing member  38  and a sheath  40 . The reinforcing member  38  surrounds at least a portion of the proximal end  14  to inhibit radial deformation. The sheath  40  surrounds the reinforcing member  38 .  
         [0052]    According to an alternate aspect of the invention, the reinforcing member  38  is sized to insert into the proximal end  14  to inhibit radial deformation. According to a further aspect of the invention, the reinforcing member is under-molded in place with respect to the proximal end  14 .  
         [0053]    The reinforcing member  38  is preferably a band of stainless steel that circumscribes the proximal end  14  to enable the proximal end  14  to resist deformation caused by the compression fitting  20  (FIG. 2). The reinforcing member  38  also prevents radial expansion of the proximal end  14 . Preferably the reinforcing member  38  has a length that does not exceed a length of the compression fitting  20 . However, it can be appreciated that the length can be modified if operating pressures require the proximal end  14  to have additional reinforcement.  
         [0054]    [0054]FIG. 4 shows the marker bands  28  circumscribing the distal end  16  of the catheter body  12 . The catheter body  12  is hollow, defining a viscous fluid delivery lumen  56 . The catheter body has an outside diameter  58  of 0.040″ or less to facilitate insertion of the distal end  16  into tortuous regions of the vasculature. The distal end  16  includes lumen walls  60 . The lumen walls  60  are at least 0.0012″ thick to withstand pressures associated with delivery of viscous fluid. Preferably, the delivery lumen  56  has an inside diameter of 0.025″ or less. For some applications, the delivery lumen  56  is adapted to have an inside diameter of less than 0.005″.  
         [0055]    [0055]FIG. 5 shows the syringe  24  having a barb  44  with a sharpened tip  52  attached to the needle  26  in a friction fit around the needle  26 . The syringe  24  inserts into a vial  46  of viscous fluid  48  in the direction of the arrow  42 .  
         [0056]    The syringe  24  includes a blunt needle  26 . The barb  44  is removable and press-fits on to the needle  26 . The vial  46  has a cap  50 .  
         [0057]    A method of filling the syringe  24  with viscous fluid  48  includes press-fitting the removable barb  44  on the blunt needle  26 . The next step includes piercing the cap  50  of the vial  46  with the tip  52  of the barb  44 . Further inserting the barb  44  and the needle  26  enables access to the viscous fluid  48 . The syringe draws the viscous fluid  48  via the needle  26  from the vial  46  and into the syringe  24 . Although a syringe  24  is used to withdraw the viscous fluid  48 , it can be appreciated that other mechanisms can withdraw fluid from a vial.  
         [0058]    [0058]FIG. 6 shows the syringe  24  and needle  26  removing from the vial  46 . The cap  50  remains fixed on the vial  46 . Withdrawal of the syringe in the direction of the arrow  54  causes the barb  44  to slide off the needle  26 . The barb  44  remains in the vial  46 . Accordingly, movement of the syringe  24  and the integrity of the cap cooperate to cause the barb  44  to slide off of the needle  26 .  
         [0059]    Once the syringe  24  is filled with viscous fluid  48 , the needle  26  is inserted into the luer fitting  18  (FIG. 1) for delivering the viscous fluid to a patient via the catheter.  
         [0060]    [0060]FIG. 7 shows an embodiment of the luer  18  having a bifurcated design. The luer fitting  18  has three of threaded portions  62 ,  64  and  68 . The threaded portion  68  attaches to the compression fitting  20 . The threaded portions  62  and  64  attach, respectively to fluid delivery systems such as syringes.  
         [0061]    While the present invention is described in terms of particular embodiments shown in the drawings, there are various ways to design, assemble and use the invention which may depart from the exemplary description provided herein. Accordingly, the claims should be limited only by the claims as set forth below.