Abstract:
An insert is disclosed that is placed in the slit in a slit tipped catheter during storage of the catheter. This insert prevents opposite of the slit from contacting and forming bonds that tend to close the slit. When the catheter is to be used, the insert is removed and the catheter is used in its intended way.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to catheters used to drain cerebrospinal fluid from the ventricles of a brain and more particularly relates to a device for preventing the closure of such a catheter having a slit tip at the end of the shunt. 
     2. Description of Related Art 
     A typical adult has a total of about 120-150 cc of (cerebrospinal fluid) CSF with about 40 cc in the ventricles in the brain. A typical adult also produces about 500 cc/day of CSF, all of which is reabsorbed into the blood stream on a continuous basis. CSF is comprised primarily of water but also includes small amounts of minerals and proteins. 
     Hydrocephalus is a condition of excessive accumulation of CSF in the ventricles or brain cavities. Hydrocephalus can result from congenital conditions interfering with normal CSF circulation or as the result of a problem with CSF reabsorbtion. 
     Excessive accumulation of CSF, due to hydrocephalus causes increased pressure upon the brain. Whatever the cause, over time, this increased CSF pressure causes damage to the brain tissue. It has been found that shunting the excess CSF to another area of the body pressure is therapeutically beneficial and generally allows the patient to lead a full and active life. 
     To treat the condition of hydrocephalus a shunt is used as a conduit to transport CSF from one location in the body to another. A typical shunt for transporting CSF from the ventricle to another part of the body is comprised of a ventricular catheter, valve and distal catheter. CSF shunts also exist for transporting fluid from the spine to another part of the body. 
     A common material for shunt catheters is silicone. Examples of systems to continuously drain excess CSF from the ventricles of the brain are the Delta® Shunt and the CSF—Flow Control Shunt Assembly made and sold by Medtronic—PS Medical of Goleta, Calif. Such systems use a catheter  2  that is placed in the patient&#39;s ventricle  4  in the brain  6  (FIG. 14) to drain the excess CSF. 
     All of these systems continuously transport excess accumulation of CSF from the patient&#39;s ventricle through the catheter  2  to another part of the family. It has been shown to be highly advantageous to use fiber-optic technology to help place a ventricular catheter such as catheter  2  in the ventricles  4  of a brain  6 . To this end, as shown in FIG. 5, endoscopes  8  have been developed that are passed through the central lumen  16  of the catheter  2 . These endoscopes  8  are advanced beyond the ultimate ventricular end  10  of the catheter  2  once the catheter  2  has been placed in the ventricle  4  of the brain  6 . 
     As the endoscope  8  is advanced beyond the ultimate ventricular end  10  of the catheter  2 , the physician is able to view the environment of the ventricle  4  to determine whether the catheter  2  is placed at a desirable location. If the catheter  2  is not located at a desirable location, the physician can change the location of the catheter  2  and confirm, by viewing the location through the endoscope  8 , that the final location of the ultimate ventricular end  10  of catheter  2  is a desired location. 
     In such a system incorporating both an endoscope  8  and a catheter  2 , catheter  2  is preferably of the type disclosed in U.S. Pat. No. 5,738,666 issued to David A. Watson and Lori Cone Speckman on Apr. 14, 1998 entitled “Slit Tip Ventricular Catheter and Method of Manufacturing Same”, the teaching of which is incorporated herein in its entirety by reference. Such a catheter is shown in FIGS. 1-6 generally labeled  2 . Catheter  2  has a proximal end  12 , a distal end  14  and a central lumen  16 . A plurality of holes  18  are located at the distal end  14 . A valve is attached proximal to the plurality of holes  18 . 
     A slit  20  is located at the ultimate ventricular end  10 . Slit  20  extends across the ultimate ventricular end  10 . Slit  20  is defined by a first side wall  22  and a second side wall  24  that meet at contact points  26  and  28 . First and second side walls  22 ,  24  each have a midpoint  30 . When slit  20  is closed, first side wall  22  is in contact with second side wall  24  along substantially the entire length of both first and second side walls  22 ,  24 . When slit  20  is open, first and second side walls  22 ,  24  are separated at their respective midpoints  30 . Such a catheter  2  is the Model #99102 “Innervision Catheter” sold by Medtronic—PS Medical of Goleta, Calif. 
     In use, as shown in FIG. 2, when the distal end  34  of an endoscope  8  is passed through catheter  2 , the distal end  34  will contact slit  20 . As shown in FIG. 3, as distal end  34  is advanced distally, distal end  34  will pass through slit  20  and extend distally beyond the ultimate ventricular end  10  of catheter  2 . 
     Catheter  2  is typically made. of silicone. During storage, slit  20  will be in the “closed” position so that first and second side walls  22 ,  24  will be in contact along substantially their entire lengths. A problem with this is that when silicone comes into contact with silicone for an extended time period, silicone to silicone bonds forms. This phenomenon is called “contact bonding”. With catheter  2 , when catheter  2  is in the “closed” position, contact bonding begins to occur between first and second side walls  22 ,  24 . This tends to “close” slit  20  so that slit  20  will not easily “open” when needed as the distal end  34  of endoscope  8  is advanced through slit  20 . This is a problem in need of a solution. 
     Although catheter  2  has been described as being made of silicone, the problem of the slit  20  closing due to bond formation may also occur in catheters made of any polymeric material susceptible to contact bonding. Examples of such polymeric material include, but are not limited to, natural and synthetic latex, plastized PVC, thermoplastic elastomers and polyurethanes as will be clear to those skilled in the art. 
     SUMMARY OF THE INVENTION 
     An insert is disclosed that is placed in the slit in a slit tipped catheter during storage and transport of the catheter. This insert prevents the opposite sides of the slit from contacting and forming bonds that tend to close the slit. When the catheter is to be used, the insert is removed and the catheter is used in its intended way. 
     It is therefore a primary object of the invention to provide a device that prevents the slit in a slit tipped catheter made of a material susceptible to contact bonding from closing due to bonds forming between opposite sides of the slit during storage and transport of the catheter. 
     It is another object of one embodiment of the invention to provide a device that prevents the slit in a slit tipped catheter made of a material susceptible to contact bonding from closing due to bonds forming between opposite sides of the slit during storage and transport of the catheter that will not adversely affect the ultimate operation of the catheter. 
     These and other objects of the invention will be clear from the description of the invention given herein and particularly with reference to the attached drawings and the Detailed Description of the Invention. Throughout this description, like reference numbers refer to like elements. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side view of a slit tip catheter. 
     FIG. 2 is a side cross-sectional view of the catheter of FIG.  1 . 
     FIG. 3 is an end view of the catheter of FIG.  1 . 
     FIG. 4 is a side cross-sectional view of the catheter of FIG.  1  and an endoscope being advanced through the catheter. 
     FIG. 5 is a side cross-sectional view of the catheter of FIG.  1  and an endoscope with the endoscope at the distal end of the catheter. 
     FIG. 6 is a side cross-sectional view of the catheter of FIG. 1 with the endoscope in use to place the catheter in the ventricles of a brain. 
     FIG. 7 is a top view of the catheter of FIG. 1 in an “open” position. 
     FIG. 8 is a top view of the catheter of FIG. 1 in an “closed” position. 
     FIG. 9 is a side view of the present invention. 
     FIG. 10 is a top view of the preferred embodiment of the present invention. 
     FIG. 11 is a top view of an alternate embodiment of the present invention. 
     FIG. 12 is a side view of the slit tip catheter of FIG.  1  and the present invention aligned for insertion of the invention into the slit tip catheter. 
     FIG. 13 is a side view of the slit tip catheter of FIG.  1  and the present invention with the invention inserted into the slit tip catheter. 
     FIG. 14 is a perspective view of a human brain with the ventricles shown in phantom. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to FIGS. 9 and 16, the invention, shown generally labeled  36 , consists of an insert. Insert  36  has a lumen portion  38  and a grip portion  40 . 
     In use, as will be described hereafter, lumen portion  38  will extend into lumen  16  of catheter  2  through slit  20 . As a result, lumen portion  38  is preferably sized to have a height “A” about equal to the diameter “D” of the lumen  16  of catheter  2 . In this way, when insert  36  is in place within catheter  2 , lumen portion  38  will prevent first and second side walls  22 ,  24  from contacting each other and forming contact bonds between each other. 
     As can be seen in FIG. 10, insert  36  is preferably narrow at both lumen portion  38  and grip portion  40 , having a width “B” as small as possible but in any case less than the diameter “D” of the lumen  16  of catheter  2 . Insert  36  is preferably as narrow as possible so that slit  20  will form as close to a closed configuration as possible with lumen portion  38  in place in lumen  16  through slit  20 . In this way, during storage and transport of the catheter  2 , as little undesirable stress as possible is applied to slit  20  so that, when used, catheter  2  is most likely to perform as desired. 
     For example, catheter  2  may have a central lumen with a diameter “D” of about 0.050″. In the preferred embodiment, the height “A” of lumen portion  38  would then be about 0.045″. As mentioned, the width “B” of lumen portion  38  should be as small as possible. Using currently available materials, the width “B” is preferably about 0.005-0.006″. The previous specific dimensions are given as an illustration of the invention and are not intended to limit the scope of the invention. 
     The preferred way to make this embodiment of insert  36  is to cut out or stamp out insert  36  from a single sheet of material having a thickness equal to width “B”. Alternately, insert  36  could be molded in one piece from the desired material as explained above. 
     In an alternate embodiment shown in FIG. 11, lumen portion  38  has the height “A” described above but grip portion  40  has a width “C” larger than width “B”. In this embodiment, the increased width of grip portion  40  may make it easier to grasp grip portion  40  since there is more material to grip. But, a disadvantage of this embodiment is that more material and a more complex manufacturing process is required to produce this embodiment than is needed to produce the preferred embodiment. In this embodiment, insert  36  may be molded in one piece or lumen portion  38  and grip portion  40  may be made separately and joined together using well known joining techniques. 
     Both the lumen portion  38  and the grip portion  40  of insert  36  are preferably made of a material that is immune to contact bonding with the material of first and second side walls  22 ,  24 . The preferred material of insert  36  is a spunbonded HDPE (High Density Polyethylene) that is sold under the brand name “Tyvek” by E. I. du Pont de Nemours and Company of Wilmington, Del. Although spunbonded HDPE is the preferred material of insert  36 , other material can be used as well so long as the material serves the key function of serving as a barrier between the first and second side walls  22 ,  24  of slit  20 . Examples of such alternate material include, but are not limited to, polyolefins, plastics, paper, ceramic and cellulose. 
     Although the preferred embodiment has both the lumen portion  38  and the grip portion  40  being made of a material that serves as a barrier between the first and second side walls  22 ,  24  of slit  20 , it is within the scope of an alternate embodiment to have only the lumen portion  38  made of such a material and to have the grip portion  40  made of any other material. Of course, in this embodiment the material of grip portion  40  should allow grip portion  40  to be gripped and should allow grip portion  40  to be connected to lumen portion  38 . Grip portion  40  can be connected to lumen portion  38  through adhesives, mechanical, chemical or other means as will be clear to those skilled in the art. In addition, grip portion  40 , in any embodiment, may have ridges, grooves, bumps or other surface modifications  42  to allow better gripping of grip portion  40  as will be clear to those skilled in the art. 
     In use, lumen portion  38  of insert  36  is aligned with slit  20  as shown in FIG.  12 . Lumen portion  38  is then passed through slit  20  into lumen  16  of catheter  2  so that the plane of lumen portion  38  is aligned with the plane of slit  20  (FIG.  13 ). In this way, first and second side walls  22 ,  24  contact opposite sides of lumen portion  38  and are thus prevented from contacting each other along their entire lengths. Because lumen portion  38  is made of a material resistant to bonding with the material of first and second side walls  22 ,  24 , no bonds will be formed between first and second side walls  22 ,  24  and the material of lumen portion  38 . 
     When it is desired to use catheter  2 , the clinician will grasp the grip portion  40  of insert  36  and gradually pull the lumen portion  38  from lumen  16  of catheter  2 . When lumen portion  38  is clear of slit  20 , first and second side walls  22 ,  24  will come into contact with each other and form the intended seal at the ultimate ventricular end  10  of catheter  2 . The insert  36  may be discarded as is appropriate. When the distal end  34  of endoscope  8  is advanced to slit  20 , the distal end  34  will pass through slit  20  beyond the ultimate ventricular end  10  of catheter  2  to allow the physician to verify placement of the catheter  2  at the desired location in the ventricle  4  of the brain  6 . 
     The description contained herein is intended to be illustrative and not exhaustive. Many variations and alternatives will occur to one of ordinary skill in this art. All these alternatives and variations are intended to be included within the scope of the attached claims. Those familiar with the art may recognize other equivalents to the specific embodiments described herein which equivalents are also intended to be encompassed by the claims attached hereto.