Patent Document

CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     The present invention claims priority under 35 USC 119 based on U.S. provisional patent application No. 60/511,152, filed Oct. 14, 2003. The complete disclosure of the referenced provisional application is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to implantable subcutaneous vascular access ports, for implanting beneath the skin of a patient, and for allowing vascular access for medicines to be repeatedly injected into a patient, or for drawing blood, without damaging the access site. More particularly, the present invention relates to a subcutaneous vascular access port having a uniquely-shaped internal chamber therein.  
         [0004]     2. Description of the Background Art  
         [0005]     A number of different implantable subcutaneous vascular access ports are known, for allowing a medical professional to repeatedly inject medicine into a patient over time. This is useful, for example, in a patient who is receiving chemotherapy treatment for cancer. Examples of some brand names for known implantable subcutaneous vascular access ports include X-Port™, Port-A-Cath®, and VorteX™. A number of these known access ports are manufactured and sold by the C. R. Bard Company of Murray Hill, N.J.  
         [0006]     Examples of some of the known implantable subcutaneous vascular access ports include those disclosed in U.S. Pat. Nos. 4,929,236, 5,053,013, 5,092,849, 5,180,365, 5,176,641, 5,263,930, 5,743,873, 6,039,712, 6,290,677, and 6,613,013, as well as the references cited in each of these patents.  
         [0007]     A generic example of a known prior art access port is shown in cross-section in  FIGS. 1 and 2 . This known port apparatus  10  includes a main port body  12  having a hollow chamber  14  formed therein. The chamber  14  is substantially cylindrical in shape, and has a substantially flat floor  16 . The known access port also includes a flexible septum  18 , attached to the main port body  12  and covering the hollow chamber  14 . The septum  18  is formed from a resiliently deformable material such as a silicone elastomer.  
         [0008]     The access port  10  of  FIGS. 1-2  also includes a hollow outlet tube  20 , attached to the main port body  12  and in fluid communication with the hollow chamber  14  thereof, via an outlet aperture  22  formed in a side wall of the main port body  12 , at a location spaced above the floor  16  thereof, as shown.  
         [0009]     Where used, one of the known implantable subcutaneous vascular access ports  10  is implanted beneath the skin of a patient&#39;s upper chest or arm, with a proximal end  21  of a catheter  24  connected to the outlet tube  20  of the device. The other, distal end of the catheter  24  is fed through the internal jugular vein, subclavian vein or arm vein, respectively, and into the central venous system. The access port  10  and the attached catheter  24  are left in place inside of the patient&#39;s body for a period of time, which may be a number of years, in some cases.  
         [0010]     After the port apparatus  10  and attached catheter  24  are in place in the patient, a medical professional first confirms the location of the port, and also confirms that the catheter is in the venous system. Then, the appropriate skin surface is cleaned, and the medical professional is able to withdraw blood and/or inject medicine into the patient, by inserting the tip of a hypodermic needle through the overlying skin, through the septum  18  of the device, and into the chamber beneath the septum, and subsequently drawing blood or dispensing the medicine into the patient&#39;s bloodstream via the catheter.  
         [0011]     As noted above, the access port and the attached catheter remain inside of the patient&#39;s body for a period of time. Over time, tissue may form around the port body  12 , helping to embed it in place.  
         [0012]     As time passes with the access port and catheter implanted inside the patient&#39;s body, the body&#39;s natural immune system may accumulate antibodies, myelin, fibrin and/or other materials from the blood on the tip of the catheter, which can eventually form a sheath over the catheter. This sheath can obstruct or even block fluid flow through the catheter. After such time, it often becomes necessary to follow a sequence of steps to remove the sheath, in order to clean the tip end of the catheter and resume normal operation.  
         [0013]     When such blockage is suspected, it is normal practice to inject a dye into the access port  10 . The dispersion pattern of the dye may be viewed on an X-ray of the affected area, which will enable a physician to determine whether or not the catheter tip is blocked with a sheath.  
         [0014]     If a sheath is found to be blocking the distal end of the catheter  24 , it has previously been the practice, in such an instance, to open a femoral vein and to insert a loop snare thereinto, and to advance the working end of the loop snare to the location of the sheath.  
         [0015]     Examples of known snares usable for this purpose are described in U.S. Pat. Nos. 6,203,552 and 4,326,530, the disclosures of which are hereby incorporated by reference. The loop of the snare is then placed around the sheath-covered catheter and the loop is then manually tightened around the sheath and catheter. The sheath is then pulled off the catheter, by carefully withdrawing the loop snare while it holds the sheath.  
         [0016]     It has been discovered that during the conventional procedure described above, a number of complications can arise.  
         [0017]     The wire loop portion of the loop snare can be sharp, and if it is tightened too aggressively, the wire loop can cut off the tip of the catheter, which then floats uncontrolled in the bloodstream. Another complication can arise while withdrawing the loop snare, because the distal end of the catheter may break off, in response to pulling pressure, instead of releasing the sheath. The broken catheter tip then becomes a floating hazard in the bloodstream.  
         [0018]     In either scenario discussed in the proceeding paragraph, a loose piece of the catheter tip, which has been fractured from the distal end of the catheter, becomes a foreign body which may float freely in the bloodstream, and will eventually lodge in the heart or lung, where it causes a blockage. In such a situation, further medical intervention, up to and including surgery may be necessitated, in order to retrieve the broken-off catheter tip.  
         [0019]     Therefore, a method and apparatus is needed for reducing the risk of a tip portion of a catheter becoming loose in a patient&#39;s vascular system.  
         [0020]     Although the known devices have some utility for their intended purposes, a need still exists in the art for an improved implantable access port, and for a method of removing a sheath from a catheter tip connected to an access port. In particular, there is a need for an improved method which will anticipate, and provide for controlled movement of a catheter fragment, in a situation where a catheter tip breaks off of a catheter during a sheath-removal procedure.  
       SUMMARY OF THE INVENTION  
       [0021]     The present invention provides an improved implantable access port, having a main port body with an internal chamber formed therein, in which the internal chamber is configured to readily receive a guide wire therein, and to direct the tip of the guide wire to an outlet. Optionally, the chamber in the main port body may be formed in a directionally aimed conical shape, similar to the shape of a bubble pipe bowl, or an old-fashioned ear trumpet. The central axis of the chamber curves approximately ninety degrees from the inlet to the outlet of the access port.  
         [0022]     Accordingly, it is an object of the present invention to provide an improved implantable access port assembly, and a method of using same. It is another object of the present invention to provide an access port assembly and method in which the internal chamber of the access port is configured to passively direct the tip of a guide wire to an outlet thereof.  
         [0023]     The invention also relates to a specialized needle, having a curved tip with an opening formed therein. The top inner and the bottom outer surfaces of the needle, adjacent the tip opening, are made non-sharp to avoid damaging a guide wire when used therewith.  
         [0024]     According to one aspect of the invention, a kit may be provided which includes an access port and a specialized needle. Optionally, the kit may also include a guide wire.  
         [0025]     For a more complete understanding of the present invention, the reader is referred to the following detailed description section, which should be read in conjunction with the accompanying drawings. Throughout the following detailed description and in the drawings, like numbers refer to like parts. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0026]      FIG. 1  is a sagittal cross-sectional view of an access port apparatus according to a prior art design;  
         [0027]      FIG. 2  is a coronal cross-sectional view of the access port apparatus of  FIG. 1 , taken along a vertical plane which is orthogonal to that of  FIG. 1 ;  
         [0028]      FIG. 3  is a top plan view of an access port apparatus according to a selected illustrative embodiment of the present invention;  
         [0029]      FIG. 4  is a sagittal cross-sectional view of the access port apparatus of  FIG. 3 , taken along the line  4 - 4  therein;  
         [0030]      FIG. 5  is a coronal cross-sectional view of the access port apparatus of  FIG. 3 , taken along the line  5 - 5  therein, and along a vertical plane which is orthogonal to that of  FIG. 4 ;  
         [0031]      FIG. 6  is an axial cross-sectional top view of the apparatus of  FIG. 3 , taken along the line  6 - 6  in  FIG. 4 , and showing the directed conical shape of the chamber formed therein;  
         [0032]      FIG. 7  is a perspective view of a specialized needle apparatus according to another aspect of the present invention;  
         [0033]      FIG. 8  is a detail view of the tip of the needle of  FIG. 7 , taken in the circled area  8  thereof;  
         [0034]      FIG. 9  is a sagittal cross-section of the needle tip of  FIG. 8 ;  
         [0035]      FIG. 10  is a sagittal cross-section of the access port apparatus of  FIG. 3 , with the needle apparatus of  FIG. 7  inserted therein;  
         [0036]      FIG. 11  is a sagittal cross-section similar to that of  FIG. 10 , also showing a guide wire being slidably inserted through the needle apparatus and into a catheter;  
         [0037]      FIG. 12  is a simplified diagram of a patient&#39;s central venous system, showing a first stage of a method according to another aspect of the present invention;  
         [0038]      FIG. 13  is a diagram similar to  FIG. 12 , showing a second stage of the method;  
         [0039]      FIG. 14  is another diagram similar to  FIG. 12 , showing a third stage of the method; and  
         [0040]      FIG. 15  is another simplified diagram of a patient&#39;s central venous system similar to  FIG. 12 , showing a simplified method of relocating a catheter tip according to another aspect hereof.  
         [0041]      FIG. 16  is another simplified diagram of a patient&#39;s central venous system similar to  FIG. 12 , showing a simplified method of positioning the loop snare  77  over the catheter  75  and the fibrin sheath with the glide wire  70  in place with its distal end in the inferior vena cava.  
         [0042]      FIG. 17  is another simplified diagram of a patient&#39;s central venous system similar to  FIG. 12 , showing a simplified method of snaring the fibrin sheath and pulling it distally off the catheter  75 .  
         [0043]      FIG. 18  is another simplified diagram of a patient&#39;s central venous system similar to  FIG. 12 , showing a hazard which may occur without the inventive device.  
         [0044]      FIG. 19  is another simplified diagram of a patient&#39;s central venous system similar to  FIG. 12 , showing how the position of a broken fragment is controlled during a procedure according to the present invention.  
     
    
     DETAILED DESCRIPTION  
       [0045]     Throughout the present specification, relative positional terms like ‘upper’, ‘lower’, ‘front’, ‘rear’, ‘top’, ‘bottom’, ‘horizontal’, ‘vertical’, and the like are used to refer to the orientation of the apparatus as shown in the drawings. These terms are used in an illustrative sense to describe the depicted embodiments, and are not meant to be limitative. It will be understood that the depicted apparatus may be placed at an orientation different from that shown in the drawings, such as inverted 180 degrees or transverse to that shown, and in such a case, the above-identified relative positional terms will no longer be accurate. In fact, while the access port hereof is shown and discussed in one possible orientation thereof, it will be understood that when surgically installed in a patient, the access port may be oriented differently from the orientation shown in some of the Figures.  
         [0046]     Referring now to  FIGS. 3-6 , an implantable access port apparatus, according to a selected illustrative embodiment of the present invention, is shown generally at  30 .  
         [0047]     According to one aspect of the invention, a kit may be provided which includes an access port  30  and a specialized needle  50  ( FIG. 7 ), to be discussed subsequently. Optionally, the kit may also include a guide wire  70  ( FIG. 11 ).  
       Structure of the Access Port Apparatus  
       [0048]     The access port apparatus  30  of  FIGS. 3-6  includes a main port body  32  having a hollow chamber  34  formed therein. The main port body  32  is formed generally in a truncated conical shape with a flat top, modified to have one flat side, as shown. The bottom of the main port body  32  is generally flattened.  
         [0049]     The main port body  32  has an annular channel  33  formed therein above the chamber  34 , to receive an edge portion of a septum  38  therein. The main port body  32  is formed from a biocompatible material, such as titanium, a titanium alloy or another biocompatible corrosion-resistant metal, or from a strong biocompatible plastic. Where plastic is used for the main port body  32 , a titanium liner may be provided for placement inside of the chamber  34 .  
         [0050]     The chamber  34  is formed in an orthogonally directed conical shape, resembling a bowl portion of a bubble pipe, or an old-fashioned ear trumpet, as shown. The chamber  34  is configured with a curved inner wall  35 , which slopes gradually downwardly toward an outlet aperture  42 . The inner wall  35  is concavely curved to resemble the interior of a bowl, as will be seen by comparing the cross-sectional views of  FIGS. 3 and 4 .  
         [0051]     The chamber  34  is shaped essentially as a substantially orthogonally directed curved funnel, to passively direct contents thereof in a curved path toward the outlet aperture  42 . These contents may be fluids, such as medicines which have been injected into the chamber.  
         [0052]     Alternatively, a tip of a guide wire  70  may be inserted into the chamber  34 , and may be guided towards the outlet aperture  42  by the shape of the chamber, as will be further discussed below.  
         [0053]     The directed conical shape of the chamber  34  promotes more complete flushing of fluids such as blood and theraputic medicated fluids therethrough, than the previously known access ports.  
         [0054]     The main port body  32  may have one or more round or ovoid eyelets  37  formed substantially vertically through edge portions thereof, to allow tissue to grow through the port apparatus  30  and anchor it in place in a patient&#39;s body. These eyelets  37 , where used, may be optionally filled with a silicone elastomeric material, to facilitate removal of the access port apparatus  30 , when it is no longer needed. In either case, these eyelets  37  are designed to allow a needle to be driven through them and into tissue to tie down the port in the subcutaneous tissue  
         [0055]     The access port apparatus  30  also includes a pierceable septum  38 , attached to the main port body  32  and covering the hollow chamber  34 . The septum  38  is formed from a resiliently deformable material, such as a silicone elastomer. The septum  38  includes a thickened central portion  37  which is substantially cylindrical in shape, and a thinner edge portion  39  for placement in the annular channel  33 , to anchor the septum in place in the main port body  32 .  
         [0056]     The access port  30  of  FIGS. 3-6  also includes a hollow outlet tube  40 , attached to the main port body  32 . The outer surface of the outlet tube  40  is configured to retentively receive a proximal end of a catheter  75  thereon ( FIG. 11 ). The outlet tube  40  may be integrally formed as part of the main port body  32 , may be cast in place in the main port body, or may be a separate and removable piece. The outlet tube  40  is in fluid communication with the hollow chamber  34  of the main port body  32  via an outlet aperture  42  formed in the wall thereof. In the access port apparatus  30  hereof, the outlet aperture  42  is located at substantially the lowest area of the chamber  34 , as shown. In the embodiment of  FIGS. 3-6 , it will be noted that the outlet aperture  42  is formed at the bottom of the chamber  34 .  
       Structure of the WYR-GYD™ Needle  
       [0057]     Referring now to  FIG. 7 , a specialized WYR-GYD™ needle  50  is shown, which is configured to be used with the access port  30  hereof, in a method which will be subsequently described herein.  
         [0058]     The WYR-GYD™ needle includes a hollow, tubular needle body  51  with a curved tip  52 . The needle  50  also includes a hollow reservoir body  54  having a space  56  formed therein. The reservoir body  54  is in fluid communication with the needle body  51 , and has a directional pointer  57  formed thereon which points in the same direction as the needle tip  52 . The pointer  57  is provided to assist the user in orienting the needle  50  when it is in place in the access port  30 .  
         [0059]     Referring now to  FIGS. 7-9 , it will be seen that the needle tip  52  has sharply pointed extremity  53  so that the needle can pierce through skin and through the septum  38  of the access port  30 . The leading part of the needle is designed not to core the septum of the port. The needle tip  52  also has an opening  58  formed therein, to allow a user to feed a guide wire  70  ( FIG. 11 ) outwardly from the needle  50 . The needle tip  52  has a non-sharp rounded lower edge portion  60  formed thereon at a lower, outwardly facing edge of the opening  58 , and also has a non-sharp rounded upper edge portion  62  formed thereon at an upper, inwardly facing edge of the opening  58 . These non-sharp edge portions  60 ,  62  are important in the practice of the present invention, because where the selected guide wire  70  has a hydrophilic coating thereon, such as the Teflon® coating on the GLIDEWIRE® brand guide wires, the rounded non-sharp edge portions  60 ,  62  allow such coating to slide therepast undamaged.  
         [0060]     In contrast, if a needle having sharp edge portions were used, instead of the non-sharp edge portions  60 ,  62 , such sharp edges could scrape the hydrophilic coating off of the guide wire, as the guide wire is extended and retracted through the needle.  
       Method of Using  
       [0061]     The access port  30  hereof is specifically intended to be used in conjunction with a guide wire, according to a procedure which will be described below.  
         [0062]     The following procedure is only intended to be followed by medical professionals such as doctors, physician assistants or other specially trained and qualified medical personnel. For purposes of the present discussion, it will be assumed that the access port apparatus  30  of  FIGS. 3-6  has been surgically implanted in a patient&#39;s chest or arm below the skin, and that the outlet tube  40  thereof has been connected to a catheter  75  which has been installed with its distal tip in a selected location in the patient&#39;s central venous system, such as, e.g., the superior vena cava. This arrangement of the access port  30  and catheter  75  is depicted in  FIG. 12 .  
         [0063]     As a preliminary step, the area of a patient&#39;s skin which covers the port  30  must be cleansed and sterilized. Then, a specialized WYR-GYD™ needle  50  is inserted through the skin of the patient, and through the septum  38  of the access port  30 , until the tip  52  of the needle  50  is inside of the port chamber  34 . The WYR-GYD™ needle  50  is shown in place in the access port  30  in  FIG. 10 .  
         [0064]     Once the needle  50  is in place, a guide wire is fed through the needle tip  52  and into the chamber  34 . One example of a suitable guide wire which is usable in the method hereof, is the polytetrafluoroethylene-coated guide wire sold by the Terumo Medical Corporation under the trademark “GLIDEWIRE®”. The guide wire is shown being threaded through the WYR-GYD™ needle, through the access port  30 , and into the catheter  75  in the illustration of  FIG. 11 .  
         [0065]     The orthogonally directed, conical shape of the chamber  34  passively directs the tip of the guide wire to the outlet aperture  42 , and the guide wire is fed through the outlet aperture  42 , through the outlet tube  40 , and into the catheter  75 . Since the outlet aperture  42  is located at substantially the lowest portion of the chamber  34 , this makes it easier to thread the guide wire through the outlet aperture than it would otherwise be, with the previously known ports.  
         [0066]     In contrast, in the conventional access port design where the outlet aperture is situated at an elevated level in the chamber, as it is in the prior art port  10  of  FIGS. 1-2 , then threading a guide wire through the septum and into the outlet port is very difficult to accomplish.  
         [0067]     Slowly and carefully, the wire tip is advanced in the catheter  75  until it reaches the tip thereof, and is then further advanced until it reaches the inferior vena cava (IVC).  
         [0068]     If a sheath  79  is present, the guide wire tip may pierce or tear the sheath  79  as it is pushed out of the catheter tip. This movement of the guide wire through the catheter  75  helps to clean any accumulated material off the interior walls thereof, but is not a complete procedure, and may not effectively remove a sheath  79  from the catheter tip.  
         [0069]     If the catheter tip has been dislodged from its normal resting place, at the junction between the superior vena cava (SVC) and the right atrium (RA), as shown in  FIG. 15 , then feeding the guide wire through the catheter  75  may be all that is needed to re-position the catheter tip to the SVC/RA junction.  
         [0070]     However, if it has been determined by preliminary venogram or angiogram that a blockage, such as a sheath  79  is present on the distal portion of the catheter  75 , then the next step is to access a femoral vein of the patient, and to advance a loop snare  77  through the femoral vein to the IVC. The insertion of a loop snare  77  into the femoral vein is illustrated in  FIG. 13 . The loop snare is then placed over the tip of the guide wire, and is advanced further, following the guide wire up the venous system, until it reaches the catheter tip. The loop snare is then placed over the sheath  79  and the catheter tip, as will be further described.  
         [0071]     Once the loop of the loop snare reaches the tip of the catheter  75 , the loop is placed over the catheter tip, and is advanced to the proximal portion of the sheath  79 . The loop of the snare is then carefully tightened in place around the sheath  79  and catheter  75 , and is then pulled down to the exposed guide wire, thereby slidably removing any sheath  79  covering the catheter tip. This step may be repeated two or more times, to make sure that the sheath  79  has been completely removed from the catheter  75 .  
         [0072]     If the catheter tip is broken off during this step, the broken piece is retained on the guide wire, instead of floating freely in the venous system, and this retention on the guide wire makes any broken piece more easily retrievable than a loose broken piece would be.  
         [0073]     The sheath  79  may then be withdrawn along the guide wire, and removed from the body, by slowly withdrawing the loop snare through the femoral access site.  
         [0074]     After the loop snare and the sheath  79  have been removed, the guide wire  70  is then removed from the patient&#39;s body. The catheter  75  and port  30  are then flushed with at least 10 ml of normal saline solution. Heparin® may be instilled into the port and catheter at this stage to resist clotting.  
         [0075]     Finally, the specialized WYR-GYD™ needle is withdrawn from the port. The site is then covered in a sterile manner, and the patient is allowed to recuperate.  
         [0076]     Although the present invention has been described herein with respect to a specific illustrative embodiment, the foregoing description is intended to be illustrative, and not restrictive. Those skilled in the art will realize that many modifications of the preferred embodiment could be made which would be operable. All such modifications, which are within the scope of the present disclosure, are intended to be within the scope and spirit of the present invention.

Technology Category: 1