Abstract:
An implantable vascular access device includes a housing having an inlet, an outlet, an interior chamber defined therein and a valve positioned between the inlet and the interior chamber. The valve is subcutaneously manipulated between an open position, in which fluid can flow between the inlet and the interior chamber, and a closed position in which the valve occludes the inlet. The device may include any combination of multiple inlets, outlets and/or interior chambers. In the preferred embodiment, the housing includes two separate interior chambers suitable for the inflow and outflow of a typical hemodialysis procedure. A method for accessing a vascular structure is provided which includes the steps of subcutaneously implanting the device connecting one end of a cannula to the outlet of the device and another end of the cannula to a selected vascular structure. The valve of the device is manipulated to permit fluid communication between the inlet of the device and the selected vascular structure. A needle is introduced through the inlet opening to access the selected vascular structure.

Description:
PRIORITY CLAIM 
     This application is a Continuation application of U.S. patent application Ser. No. 10/342,913 filed on Jan. 15, 2003 now U.S. Pat. No. 7,252,649 entitled “Implantable Vascular Access Device” which is a Continuation of U.S. patent application Ser. No. 09/957,619 filed on Sep. 20, 2001 now U.S. Pat. No. 6,540,717 entitled “Implantable Vascular Access Device” and which is a Continuation of U.S. patent application Ser. No. 09/398,887 filed on Sep. 20, 1999 now U.S. Pat. No. 6,319,226 entitled “Implantable Vascular Access Device”. The entire disclosures of these prior applications are considered as being part of the disclosure of the accompanying application and hereby expressly incorporated by reference herein. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field Of Invention 
     The present invention relates to implantable vascular access devices used in the delivery and/or withdrawal of fluids to and from the body and more particularly relates to a self-sealing device which permits intermittent vascular access. 
     2. Description Of The Prior Art 
     Conventional vascular access devices are surgically implanted under the skin to allow for intermittent access to a selected vascular structure, such as an artery or a vein, for introducing and/or withdrawing fluids to and from the selected vascular structure. Typically, such devices generally include an interior chamber having an outlet opening connected via a cannula to a vascular structure within the body and a penetrable membrane which serves as a cover for the interior chamber of the device. The penetrable membrane or septum is comprised of a material, such as silicone rubber, which automatically reseals itself after being penetrated by a hypodermic needle or a needle introduced catheter. 
     In operation, a needle passes through the skin and through the penetrable membrane into the interior chamber allowing fluid to be injected into the chamber and expelled through the cannula into the selected vascular structure or, conversely, fluid may be withdrawn. The advantages of an implantable device over acute catheter procedures include reduced infection, easier patient maintenance and improved aesthetics. Typical implantable vascular access devices are shown in U.S. Pat. No. 5,318,545 to Tucker and U.S. Pat. No. 5,755,780 to Finch, Jr. et al. 
     The advancement of modern hemodialysis procedures have brought with it the development of vascular access devices for the purpose of acquiring and returning large quantities of blood for passage through a hemodialysis unit. To facilitate adequate dialysis flow rates, relatively large diameter needles and/or catheters in the range of 14 gauge or higher are required. A major drawback of conventional vascular access devices, particularly those used in hemodialysis procedures, is the deterioration of the rubber membranes as a result of repeated penetration with such large gauge needles. Additionally, typical vascular access devices provide for only one needle port resulting in chronic breach of the skin at the same location. This in turn results in increased skin trauma and possible infection. 
     Accordingly, it is desirable to provide a vascular access device which can withstand multiple insertions with a large diameter needle and which provides reduced skin trauma and easier patient maintenance. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a vascular access device which can withstand a high number of large gauge needle insertions without deterioration. 
     It is another object of the present invention to provide a vascular access device which is easily subcutaneously manipulated and which prevents the escape of fluids from the device. 
     It is yet another object of the present invention to provide a vascular access device having multiple needle ports thereby reducing the skin trauma caused by repeated needle sticks at the same location. 
     It is still a further object of the present invention to provide a vascular access device suitable for hemodialysis procedures which incorporates two interior chambers into a single body. 
     In accordance with one form of the present invention, a vascular access device generally includes a housing having an inlet, an outlet, an interior chamber defined therein and a valve positioned between the inlet and the interior chamber. The valve is movable between an open position, in which fluid can flow between the inlet and the interior chamber, and a closed position in which the valve occludes the inlet. Preferably the valve comprises an elongate member having a through-hole formed therein which aligns with the inlet when the valve is in the open position. One or both ends of the elongate member protrudes through the housing and is palpable through the skin of the patient. The elongate member is resiliently urged to its closed position by a spring and is opened by subcutaneously pressing the end of the member protruding through the housing. 
     The device includes a cannula having a proximal end connected to the outlet of the housing and a distal end connected to a selected vascular structure. In one embodiment, the distal end of the cannula includes a distal valve positioned within the cannula adjacent the outlet of the cannula. The distal valve is connected to the housing valve and is preferably a tubular member having an outer wall and an interior passage. Along with the housing valve, the distal valve is simultaneously movable within the cannula between an open position in which fluid can flow between the housing outlet and the cannula outlet through the interior passage of the tubular member and a closed position in which the outer wall of the tubular member occludes the cannula outlet. The tubular member is resiliently urged to its closed position by a spring attached to the cannula. 
     The present invention may include any combination of multiple inlets, outlets and/or interior chambers. In the preferred embodiment, the housing includes two separate interior chambers suitable for the inflow and outflow of a typical hemodialysis procedure. The device further includes multiple inlets in fluid communication with each interior chamber. Several elongate members are moved simultaneously to an open position by a single push button protruding through the outer surface of the housing. Each elongate member includes through-holes which are aligned with respective inlets when the push button is depressed to move the elongate members to their open position. When the button is released, a spring urges the elongate members to their closed position thereby occluding the inlets. Each interior chamber is in fluid communication with an outlet which is connected to a selected vascular structure by means of a cannula for permitting fluid communication between the vascular structure and the interior chamber of the device. 
     A method for accessing a vascular structure is provided which includes the steps of surgically implanting a device as described above, connecting one end of a cannula to the outlet of the device and another end of the cannula to a selected vascular structure, subcutaneously manipulating the valve of the device for permitting fluid communication between the inlet of the device and the selected vascular structure and introducing a needle or a needle-introduced catheter through the inlet opening to access the selected vascular structure. 
     A preferred form of the vascular access device, as well as other embodiments, objects, features and advantages of this invention will be apparent from the following detailed description of illustrative embodiments thereof which is to be read in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A and 1B  are cross-sectional views of the vascular access device formed in accordance with the present invention showing the valve in its closed and open positions, respectively. 
         FIGS. 2A and 2B  are cross-sectional views of an alternate embodiment of the device including a distal cannula valve and showing the valves in their closed and open positions, respectively. 
         FIG. 3  a perspective view of the preferred embodiment of the device shown in  FIGS. 1A and 1B . 
         FIG. 4  is a cross-sectional view of the device shown in  FIG. 3  taken along the line  4 - 4 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIGS. 1A and 1B , an implantable vascular access device formed in accordance with the present invention is shown. The vascular access device  10  is designed to be surgically implanted under the skin and generally includes a housing  11  and a valve  12 . The housing  11  and the valve  12  may be made from any suitable biocompatible material possessing sufficient hardness to resist being damaged or gouged by needles or other devices which will be repeatedly inserted into the device. Plastic constructions are advantageous in that they are inexpensive to fabricate utilizing conventional molding techniques and are available in a variety of biocompatible materials. Surgical metals, however, are also suitable. 
     The housing  11  includes an interior chamber  13  formed therein, and an inlet  14  and an outlet  15  extending through an external surface  16  of the housing and communicating with the interior chamber. The outlet  15  may be formed with a cuff  17  to facilitate connection to a cannula  18 . The opposite end (not shown) of the cannula is connected or grafted to a selected vascular structure (e.g. an artery or a vein) in a conventional manner. The housing  11  also includes a peripheral rim  19  having apertures  20  for securing the device to fascia underlying the skin by means of sutures threaded through the peripheral apertures. 
     The valve  12  preferably comprises an elongate member  21  having a transverse bore or through-hole  22  formed in a body portion  23  thereof. The elongate member  21  further includes a neck portion  24  which protrudes through the external surface  16  of the housing. The elongate member  21  is supported within a bore  25  formed in the housing  11  and is retained within the housing by a retaining clip  26  fixed to the external surface  16  of the housing. The valve  12  may be positioned anywhere along the interior chamber  13  between the housing inlet  14  and the housing outlet  15 . To maintain the proper orientation of the elongate member  21  with respect to the interior chamber  13 , the neck portion  24  and/or the body portion  23  is formed with a non-circular cross-section which prevents the elongate member from rotating when fitted in close sliding relationship within the correspondingly sized bore  25  and retaining clip  26 . A deformable element  27  fixed to the external surface  16  of the housing  11  is preferably provided over the protruding neck portion  24  of the elongate member  21 . Sealing rings (not shown) may also be provided on the elongate member  21  to prevent tissue ingrowth and/or leakage to and from the bore  25 . 
     A spring  28  is positioned within the bore  25  at the end of the elongate member  21  opposite the neck portion  24 . The spring  28  is also made from a biocompatible material and is captured within the bore  25  for resiliently urging the elongate member  21  to its closed position, i.e., to the right as shown in  FIGS. 1A and 1B . Although a spring is preferred, other biasing devices may also be utilized for resiliently urging the elongate member  21  to its closed position. For example, the spring  28  may be removed and the bore  25  may be sized to form a compression chamber behind the elongate member  21  wherein the trapped air pressure acts upon the body portion  23  of the elongate member to urge it to its closed position. 
     In use, the vascular access device  10  is surgically implanted such that it is entirely subcutaneous. In its normally closed position, the body portion  23  of the elongate member  21  blocks or occludes the inlet opening  14  thereby preventing fluid communication between the inlet and the interior chamber  13 . When the protruding end of the body portion  23  is subcutaneously depressed, the elongate member  21  moves to its open position in which the transverse through-hole  22  aligns with the inlet opening  14  thereby permitting fluid communication between the inlet opening and the interior chamber  13  through the elongate member. When the valve  12  is in its open position, a needle  29  or a needle-introduced catheter may be percutaneously inserted through the inlet  14  into the interior chamber  13  to introduce or withdraw fluid from the selected vascular structure via the cannula  18 . Once the needle  29  is inserted, the needle will hold the elongate member  21  in its open position thereby allowing the protruding end of the body portion  23  to be released. Once the needle  29  is removed, the spring  25  will automatically return the elongate member  21  to its closed position in which the inlet opening  14  is again occluded and blood reflux is prevented. 
       FIGS. 2A and 2B  show an alternate embodiment of the device wherein a cannula valve  50  is also provided. In this embodiment, the housing  11  includes an interior chamber  51  formed therein as opposed to the interior chamber  13  described above. The housing valve  52  comprises an elongate member  53  having a body portion  54  and a neck portion  55  for accommodating a spring  56 . A transverse bore or through-hole  57  is formed in the body portion  54  to provide fluid communication between the inlet  14  and the interior chamber  51  when the elongate member  53  is in its open position. The elongate member  53  is supported within opposite support holes  58  formed in the housing  11  such that both the body portion  54  and the neck portion  55  protrude through the housing. The neck portion  55  and/or the body portion  54  is formed with a non-circular cross-section which when fitted in a correspondingly sized support hole  58  maintains the elongate member  53  in its proper orientation. The elongate member  53  is retained within the housing by a retaining clip  59  fixed to the protruding neck portion  55  and deformable skins (not shown) are preferably provided over both protruding portions to prevent tissue ingrowth as described above. 
     The cannula  18  includes a cannula valve  50  positioned within the cannula adjacent a cannula outlet  60  for selectively permitting fluid flow between the housing outlet  15  and the selected vascular structure. The cannula valve  50  comprises a biocompatible tubular member  61  having an outer wall  62  and an interior passage  63 . The tubular member  61  is connected to the housing valve  12  via a taut wire  64  such that manipulation of the housing valve simultaneously activates the cannula valve. A tension spring  65  is provided at the distal end of the cannula  18  to resiliently urge the tubular member  61  to a closed position wherein the outer wall  62  of the tubular member occludes the cannula outlet  60 . 
     In use, depressing the body portion  54  of the elongate member  53  of the housing valve  52  moves the housing valve to its open position, i.e., to the left as shown in  FIGS. 2A and 2B , thereby simultaneously pulling the cannula valve  50  to an open position via the wire  64 . In the open position, the outer wall  62  of the tubular member  61  no longer occludes the cannula outlet  60  and fluid may flow through the interior passage  63  of the tubular member between the housing outlet  15  and the cannula outlet. When the housing valve  12  is released, the tension spring  65  returns the tubular member  61  to its closed position whereby the outer wall  62  of the tubular member again occludes the cannula outlet  60 . 
     Referring now to  FIGS. 3 and 4 , a preferred form of the implantable vascular access device  30  is shown. The multi-port device  30  shown in  FIGS. 3 and 4  includes a housing  31  formed with two separate interior chambers  32 , an outlet  33  in fluid communication with each interior chamber and a plurality of inlets  34 . The housing  31  shown in  FIGS. 3 and 4  includes three external access surfaces  35  each with a pair of inlets  34  which communicate with a respective interior chamber  32 . However, any geometric configuration for the housing, such as additional access surfaces, additional interior chambers or additional inlets may be utilized. 
     The multi-port device  30  includes a valve which comprises three elongate members  36  each having a spring  37  fixed at one end thereof and a push button  38  with a push plate  39  adjacent the other end. The elongate members  36  are formed with transverse through-holes  40 , as described above, and are slidably supported in longitudinal bores  41  formed in the housing. The springs  37  are captured between the elongate members  36  and the bottom walls  42  of the longitudinal bores  41  formed at one end of the housing  31 . An end cap  43  is fixed to the opposite end of the housing  31  for retaining the push button  38  and the push plate  39 . The end cap  43  is formed with a recess  44  for retaining the push plate  39  and a counter bored opening  45  through which the push button  38  protrudes. The push button  38  is formed with a shoulder portion  46  which is retained by the counter bored opening  45  so that the push button is held within the end cap  43 . The depth of the recess  44  allows the push plate  39  to travel a predetermined distance when the push button  38  is depressed. 
     Operation of the multi-port device  30  is similar to that as described above. The springs  37  resiliently urge each of the individual elongate members  36  into their normally closed position in which the elongate members occlude the inlet openings  34 . When the push button  38  is subcutaneously depressed, the elongate members  36  are simultaneously moved to their open position by the push plate  39  (i.e., to the right as shown in  FIG. 3 ) wherein the transverse through-holes  40  of the elongate members align with respective inlet openings  34 . Again, the elongate members  36  may be formed with non-circular cross-sections so that their proper orientation with respect to the inlets  34  is maintained. Once the elongate members  36  are moved to their open position any one or more of the inlets  34  may be accessed with a needle for withdrawing or introducing fluid through the interior chambers  32 . In a typical hemodialysis procedure, an infusion needle is inserted through an inlet  34  into one of the interior chambers  32  and an aspiration needle is inserted through another inlet into the other separate chamber. The interior chambers are in fluid communication with at least one selected vascular structure by means of the cannulas  47 , as described above. Again, once the needles are inserted the push button  38  may be released and upon removing the needle the springs  37  automatically urge the elongate members  36  back to their normally closed position. Preferably, needles should be inserted in corresponding pairs of inlets  34  on the same access surface  35  so that when the push button  38  is released the remaining elongate members not being accessed will return to their closed position. 
     As a result of the present invention, a multi-port vascular access device is provided which can withstand numerous needle insertions without deterioration. Additionally, the multi-port design allows for needle insertion at different locations on the skin thereby allowing the skin more time to heal before reinsertion of a needle. Furthermore, the dual interior chamber design of the present invention is particularly suitable for hemodialysis procedures requiring simultaneous inflow and outflow. 
     Although the illustrative embodiments of the present invention have been described herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various other changes and/or modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the invention, and it is intended to claim all such changes and/or modifications as fall within the scope of the invention.