Abstract:
An implant anchor that holds an implant in place by fibrotic encapsulation or inclusion of surrounding tissue into the anchor. The apparatus of the invention comprises an anchor configured to couple to an implant and which has at least one fibrous surface or portion capable of becoming fibrously encapsulated or included by surrounding tissue. The methods of the invention comprise providing an anchor having at least one porous surface or portion thereon, attaching the anchor to an implant, positioning the implant and attached anchor in a patient incision, and fibrotically encapsulating the anchor.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention pertains generally to implantable drug delivery systems, and more particularly to a porous catheter anchor that provides fibrotic binding to hold a catheter in place.  
       BACKGROUND OF THE INVENTION  
       [0002]     Implantable drug delivery devices are increasingly used as therapeutic tools for treatment of a variety of conditions and diseases, especially where a prolonged period of therapy is required. Implantable drug delivery devices avoid patient inconvenience and discomfort associated with administration of multiple doses of an agent, and further provide for enhanced therapeutic benefits due to avoidance of bolus doses, improved patient compliance with dosage regimens, and providing generally a constant blood serum level of delivered drugs.  
         [0003]     Various implantable drug delivery systems have been developed using different technologies to accomplish movement of drug (typically in a drug formulation) from within a reservoir in the device through an exit port or orifice to a treatment site in the subject. These delivery technologies have been based on, inter alia, diffusive, erodible, and convective mechanisms. Exemplary delivery systems employing convection include, but are not limited to, electromechanical pumps, osmotic pumps, electro-osmotic pumps, electrochemical pumps, hydrolytic systems, piezoelectric pumps, elastomeric pumps, vapor pressure pumps, and electrolytic pumps.  
         [0004]     The implanted catheter must remain in place without longitudinal or transverse migration of the catheter following the implant procedure. The implanted catheter is particularly prone to movement in a longitudinal direction due to inadvertent pulling on the catheter during normal patient movement. Movement of the catheter can result in displacement of the catheter tip or disconnection of the catheter from the implanted pump such that drug delivery does not occur at the intended location, or reconfiguration or re-positioning of the catheter in a manner which otherwise interrupts or interferes with the intended drug delivery therapy for a patient.  
         [0005]     One common technique for prevention of catheter movement is the use of catheter anchors made of a biocompatible polymer material such as silicone. The anchors are attached to the catheter and are sutured into place to hold the catheter in a desired location. The use of such anchors however is intrusive and requires additional surgical procedures, with relatively large incisions required to accommodate the anchor, and suturing of the anchors to hold them in place. Barbed structures have been utilized on catheters to avoid the need for additional suturing. The use of barbed catheters, however, complicates the initial positioning of the catheter during the implant procedure, as the barbs tend to catch on tissue and interfere with the movement of the catheter into its desired position.  
         [0006]     There is accordingly a need for an anchor for catheters and other implanted devices which does not require additional incisions or suturing to hold the anchor in place, and which is quick and easy to position during implanting. The present invention satisfies these needs, as well as others, and generally overcomes the deficiencies found in the background art  
       SUMMARY OF THE INVENTION  
       [0007]     The invention provides an implant anchor that holds an implant such as a catheter in place by fibrotic encapsulation or inclusion of surrounding tissue into the anchor. The apparatus of the invention comprises, in general terms, an anchor configured to couple to an implant and which has a fibrous surface or portion capable of undergoing fibrous encapsulation or inclusion by tissue adjacent to, surrounding, or otherwise associated with the implant. In certain embodiments the anchor may be of tubular configuration, with an inner surface configured to fit over the outer wall of the implant, and with a fibrous outer surface configured to intermesh with surrounding tissue following implantation. The anchor may be used with a catheter and positioned adjacent to an end of the catheter or elsewhere thereon. The anchor may be capable of coupling to a catheter at more than one location such that a loop is formed in a catheter for additional anchoring capability. In other embodiments, the porous anchor may comprise two or more tubular sections joined together, with each tubular section configured to engage different portions of an implant.  
         [0008]     The methods of the invention comprise providing an anchor having a porous surface thereon, attaching the anchor to an implant, and positioning the implant and attached anchor in a patient incision. The methods may additionally comprise fibrotically encapsulating the anchor after implantation to hold the implant in place. In certain embodiments the method of the invention may comprise coupling a first portion of a fibrous anchor to a first portion of an implant and coupling a second portion of a fibrous anchor to a second portion of an implant, positioning the implant and attached anchor in a patient incision, and fibrotically encapsulating the anchor in surrounding tissue. In still other embodiments, the method may comprise coupling a first fibrous anchor to a first portion of an implant, coupling a second fibrous anchor to a second portion of an implant, implanting the implant and attached fibrous anchors into tissue, and fibrotically encapsulating the anchors with surrounding tissue. 
     
    
     BRIEF DESCRIPTIONS OF THE DRAWINGS  
       [0009]     The present invention will be more filly understood by reference to the following drawings, which are for illustrative purposes only.  
         [0010]      FIG. 1  is a perspective view of a porous catheter anchor in accordance with the invention.  
         [0011]      FIG. 2  is a perspective view of the porous catheter anchor of  FIG. 1  shown on a catheter.  
         [0012]      FIG. 3  is a perspective view of an alternative embodiment porous catheter anchor in accordance with the invention.  
         [0013]      FIG. 4  is a perspective view of the porous catheter anchor of  FIG. 3  shown on a catheter.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0014]     Referring more specifically to the drawings, for illustrative purposes the present invention is embodied in the apparatus and method shown generally in  FIG. 1  through  FIG. 4 . It will be appreciated that the apparatus may vary as to configuration and as to details of the parts, and that the method may vary as to details and the order of the steps, without departing from the basic concepts as disclosed herein. The invention is disclosed primarily in terms of use with an implanted catheter. The invention may be used to anchor a variety of surgically implants or implanted devices, and use of the subject implant anchor apparatus and methods is intended to encompass such implants.  
         [0015]     The definitions herein are provided for reason of clarity, and should not be considered as limiting. The technical and scientific terms used herein are intended to have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains.  
         [0016]     It should be noted that, as used in this specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the content clearly dictates otherwise. Thus, for example, reference to “a catheter” includes one or more such catheters, and “an anchor” includes one or more anchors, and the like.  
         [0017]     As used herein, “patient”, individual”, “host” and “subject” and grammatical equivalents thereof means a member or members of any mammalian or non-mammalian species that may have a surgical implant or be in need of a surgical implant.  
         [0018]     Referring now to  FIG. 1  and  FIG. 2 , there is shown an implant anchor apparatus  10  in accordance with the invention. Anchor  10  is shown as having a tubular or cylindrical body  13  with a bore or channel  12  extending therethrough such that anchor  10  has an inner surface  14  and an outer surface  16 . The dimensions and shape of bore  12  and inner surface  14  of anchor may be varied as required to engage or couple to a variety of surgical implants.  
         [0019]     As shown in  FIG. 1  and  FIG. 2  and described further below, anchor  10  is configured for use with an implantable catheter  18 . Catheter  18  may be a resilient or flexible elongated tube of the type commonly used for drug delivery to a selected site. The inner diameter of anchor  10  as defined by inner surface  14  is structured and configured to conform to the outer diameter of catheter  18  and to allow anchor  10  to be secured to catheter  18  when catheter  18  is engaged in bore  12 . Anchor  10  may be coupled or attached to catheter  18  by use of a biocompatible adhesive material (not shown) that adheres the inner surface of  14  of anchor to catheter  18 , by use of clips, clamps or fasteners (also not shown), by friction between the inner surface  14  of anchor  10  and catheter, or by other coupling means.  
         [0020]     Anchor  10  comprises a porous or fibrous material that is capable of becoming fibrotically encapsulated by surrounding tissue after implantation. In other words, the material of anchor  10  or at least a portion of anchor  10  is suitably porous or fibrous such that a plurality of interstices (not shown) are defined, and human or other implant host tissue can penetrate into the interstices and enmesh with the material of the anchor  10  to hold the anchor  10  in place within the surrounding tissue. In the embodiment shown in  FIG. 1  and  FIG. 2 , outer surface  16  of anchor  10  provides a fibrous or porous portion or section suitable for fibrotic encapsulation when anchor  10  is coupled to or otherwise associated with an implanted item such as catheter  18 . Anchor  10  may be fabricated from a single integral piece of fibrous or porous material that is woven or bound together to define anchor  10 . In other embodiments, anchor  10  may comprise a fibrous outer portion adjacent outer surface  16  that is adhered to a non-fibrous inner portion adjacent inner surface  14 . Anchor  10  is shown as having fibrous material associated with the entire outer surface  16 . Anchor  10  may, in some embodiments, include fibrous material on only a portion or portions of outer surface  16 .  
         [0021]     The fibrous material of anchor  10  may comprise any biologically compatible fibrous material that is capable of becoming fibrotically encapsulated in tissue. Various fibrous materials suitable for implantation are known and include, for example, polyester, polyamide, nylon, polyether, fluorocarbon, or other natural or man-made polymeric materials capable of forming fibers and fibrous networks. DACRON® polyester of Du Pont Inc. and KODEL® polyester of Kodak Inc. are, for example, two well known polyester fiber materials that are usable as medical implant materials. Various other fibrous materials suitable for use with the will suggest themselves to those skilled in the art.  
         [0022]     In the methods of the invention, anchor  10  is suitably coupled to a catheter  18  or other implanted item, Anchor  10  includes first and second ends  20 ,  22 , and is coupled to catheter  18  by inserting an end  24  of catheter  18  into the bore  12  of anchor  10  at end  20 . The catheter end  24  is pushed or otherwise manipulated through bore  12  until catheter end  24  exits end  22  of anchor  10 . Once thus inserted through bore  12 , the outer surface of catheter  18  frictionally interacts with the inner surface  14  of anchor to couple or attach anchor  10  to catheter  18 . In some embodiments of the invention, an adhesive may be used to adhere anchor  10  to catheter  18 . The adhesive may be applied to the inner surface  14  of anchor prior to insertion of catheter  18  into bore  12 , or the adhesive may be applied through the fibrous material of anchor  10  after anchor  10  has been suitably positioned on catheter  18 . Various biologically compatible adhesives are commercially available and may be used to secure anchor  10  onto catheter  18  or other implantable device.  
         [0023]     Once the anchor  10  has been suitably coupled to catheter  18 , anchor and catheter  18  are implanted within an incision (not shown) in a patient or host, and the incision is sutured closed in a conventional manner. Following implantation, the tissue surrounding anchor  10  penetrates into the outer surface  16  of anchor  10  and into the interstices of the fibrous material of anchor such that the anchor becomes fibrotically encapsulated within the surround tissue to hold the anchor  10 , and the attached catheter  18 , in place within the incision. Fibrotic encapsulation of anchor  10  by surround tissue occurs relatively rapidly, with some fibrotic encapsulation occurring within a few hours, and complete fibrotic encapsulation of anchor  10  occurring within a few days.  
         [0024]     Once fibrotic encapsulation in the above manner has occurred, the anchor  10  and catheter  18  are securely held at the desired location within the implant incision. Inadvertent or pressure or pulling on the catheter  18  thus will not result in undesirable repositioning catheter  18  or catheter end  24  after implantation. Anchor  10  and catheter  18  may be removed or detached from surrounding tissue following fibrotic encapsulation by creating a new incision in a conventional manner and removing the catheter  18  and attached anchor  10  from the incision.  
         [0025]     Multiple anchors  10  may be coupled to multiple portions of a single catheter  18  to provide additional anchoring capability. Thus, a first anchor  10  may be coupled to catheter  18  near one end thereof to maintain the catheter end at a desired drug delivery site, while a second anchor  10  is coupled near the other end to prevent disconnection of the catheter from an implanted drug pump or reservoir (not shown). Anchor  10  may be elongated or truncated in shape to increase or reduce the portion of fibrous surface area available for fibrotic encapsulation by surrounding tissue.  
         [0026]     Referring now to  FIG. 3  and  FIG. 4  there is shown an alternative embodiment  26  of an implant anchor in accordance with the invention. The anchor  26  comprises first and second tubular portions  28   a,    28   b  each having a corresponding bore or channel  30   a,    30   b  extending therethrough to define inner surfaces  32   a,    32   b.  Tubular portions  28   a,    28   b  respectively include fibrous or porous outer surfaces  34   a,    34   b  capable of undergoing fibrotic encapsulation of surrounding tissue in the manner described above. Tubular portions  28   a,    28   b  are joined together by a bridge or connecting region  36 . The tubular portions  28   a,    28   b  and connecting region  36  of anchor  26  may comprise integral portions of a single piece of fibrous material such as DACRON® polyester.  
         [0027]     In using the anchor  26 , catheter end  24  is inserted through both bores  30   a,    30   b  of portions  28   a,    28   b  such that catheter  18  is engaged in both bores  30   a,    30   b  and a loop or fold  38  is defined in catheter  18  as shown in  FIG. 4 . Anchor  26  thus is coupled to catheter  18  at two points or locations to define loop  38 . The anchor  26  and attached catheter  18  is implanted within an incision in the manner described above. The combined fibrous surface areas of the outer surfaces  34   a,    34   b  of tubular portions  28   a,    28   b  and connecting region  36  provide a relatively large area or region of fibrous material to provide a greater amount of fibrotic encapsulation by surround tissue, and thus greater anchoring effect, than is provided by the anchor  10  described above. The fold or loop  38  in catheter  18  can also act as an anchor within the surrounding tissue. The dual tubular portions  28   a,    28   b,  in coupling to different portions of catheter  18 , also provide stronger coupling between the anchor  26  and catheter  18 .  
         [0028]     While the present invention has been described with reference to the specific embodiments thereof, it should be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the true spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation, material, composition of matter, process, process step or steps, to the objective, spirit and scope of the present invention. All such modifications are intended to be within the scope of the claims appended hereto.