Abstract:
Described is a method and a device for inserting a helical member into a living body. The device may include a handle having an actuator lever rotatably coupled thereto. The device may also include a helical member which has a tissue piercing distal tip. The helical member is coupled to the handle via a linkage operating so that, as the actuator lever is rotated in a first direction relative to the handle, the helical member is rotated and moved distally to screw into tissue along a substantially helical path.

Description:
PRIORITY CLAIM 
       [0001]    This invention claims priority to U.S. Provisional Patent Application Ser. No. 60/856,978 entitled “Corkscrew Helical Inserter Port” filed Nov. 3, 2006, the disclosure of which is incorporated, in its entirety, herein. 
     
    
     BACKGROUND INFORMATION 
       [0002]    Implantable infusion ports are routinely used to provide semi-permanent, repeated access to the vascular system to facilitate the provision fluids thereto and/or the withdrawal therefrom without requiring the repeated insertion of a needle into a blood vessel. Such infusion ports, which may be implanted subcutaneously or flush with the skin or which may be sutured to the skin, typically include a resilient self-sealing surface, or septum, serving as a barrier between the interior of the infusion port and the surrounding environment. Such a port is accessed by piercing the septum which is generally formed of silicone or another polymeric element that can withstand repeated piercing while continuing to reseal the puncture pore, or pathway, after the needle has been withdrawn. However, after multiple injections, the durability of the septum deteriorates, eventually reaching a point at which it is no longer be able to provide a dependable seal, requiring replacement of the septum and/or the infusion port, increasing discomfort and introducing risks such as infection and blood vessel damage. 
       SUMMARY OF THE INVENTION 
       [0003]    The present invention relates to a device for inserting a helical member into a living body. The device may include a handle which has an actuator lever rotatably coupled thereto. The device may also include a helical member which has a tissue piercing distal tip. The helical member is coupled to the handle via a linkage operating so that, as the actuator lever is rotated in a first direction relative to the handle, the helical member is rotated and moved distally to screw into tissue along a substantially helical path. 
         [0004]    In another exemplary embodiment of the present invention The device may also include a fluid line which is coupled to a proximal end of the helical member. The helical member may include a lumen extending therethrough to an opening formed in the distal tip. 
         [0005]    In another exemplary embodiment of the present invention, the device may also include a substantially straight needle coupled to the handle for movement with the helical member. The needle includes a lumen extending therethrough to an opening in a distal tip thereof. 
         [0006]    In another exemplary embodiment of the present invention, the straight needle of the device extends substantially along a central axis of the helical member. 
         [0007]    In another exemplary embodiment of the present invention, the straight needle of the device rotates with the helical member. 
         [0008]    In another exemplary embodiment of the present invention, the straight needle of the device is non-rotatably coupled to the handle. 
         [0009]    In another exemplary embodiment of the present invention, the device may include a rack member slidably coupled to the handle for movement relative thereto proximally and distally along an axis. The linkage includes a geared surface formed on the handle mating with a corresponding geared surface on the rack member. 
         [0010]    In another exemplary embodiment of the present invention, the device may also include a helical member guide slidably receiving the helical member so that, to move proximally and distally therethrough. The helical member is forced to rotate about the axis. 
         [0011]    In another exemplary embodiment of the present invention, the device may also include a mounting surface contoured and positioned to rest against a portion of a subject&#39;s anatomy to stabilize the device during use. 
         [0012]    In another exemplary embodiment of the present invention, the device may also include a rotatable coupling fluidly coupling the lumen of the helical member to the fluid line. 
         [0013]    In another exemplary embodiment of the present invention, a diameter of the helical member of the device is between 17 and 22 gauge. 
         [0014]    In another exemplary embodiment of the present invention, a pitch of the helical member of the device is selected so that adjacent points are separated from one another as to allow 1-3 coils per inch. 
         [0015]    In another exemplary embodiment of the present invention, a pitch of the helical member of the device is between 0.25 inches to 1 inch. 
         [0016]    In another exemplary embodiment of the present invention, an inside coil diameter of the helical member of the device is between 0.125 inches to 0.50 inches. 
         [0017]    The present invention also relates to a method for inserting a needle into a subcutaneous port. An injection device is aligned so that a helical member of the device is positioned over a portion of skin covering a subcutaneously implanted port. A lever of the injection device is rotated in a first direction relative to a handle coupled thereto to move a tissue piercing distal tip of the helical member distally toward the portion of skin while rotating the helical member so that the tissue piercing distal tip screws itself into the portion of skin and passes through the portion of skin and a resealable septum of the port along a helical path to enter a reservoir of the port. The lever is rotated in a direction opposite the first direction to withdraw the helical member from the septum and the skin along the helical path. 
         [0018]    In another exemplary embodiment of the present invention, the helical member includes a fluid lumen extending therethrough to an opening formed in the tissue piercing distal tip. An injection of fluid to or a withdrawal of fluid from the port via the fluid lumen is performed. 
         [0019]    In another exemplary embodiment of the present invention, the injection device includes a substantially straight needle extending substantially parallel to a central axis of the helical member. The needle includes a fluid lumen extending therethrough to an opening formed in the tissue piercing distal tip. An injection of fluid to or a withdrawal of fluid from the port via the fluid lumen is performed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1  is an exemplary injection assembly according to the present invention; 
           [0021]      FIG. 2  shows a cross section of a septum showing a conventional needle puncture pathway; 
           [0022]      FIG. 3  is a three-dimensional representation of the conventional needle puncture pathway of  FIG. 2 ; 
           [0023]      FIG. 4  shows a section of a septum showing a helical needle puncture pathway according to the present invention; 
           [0024]      FIG. 5  shows a three-dimensional representation of the helical needle puncture pathway of  FIG. 4 ; 
           [0025]      FIG. 6  is a diagram showing an alternative embodiment of an injection assembly anchoring a straight needle; 
           [0026]      FIG. 7  shows an acute needle tip for use in conjunction with the injection assembly according to the present invention; 
           [0027]      FIG. 8  shows a flat needle tip for use in conjunction with the injection assembly according to the present invention; and 
           [0028]      FIG. 9  shows a side view of a portion of a needle for use in conjunction with the injection assembly according to the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0029]    The present invention may be further understood with reference to the following description and the appended drawings, wherein like elements are referred to with the same reference numerals. The invention relates to methods and devices for needle delivery into an implantable port and more specifically relates to a helical injection assembly for use in conjunction with a self-sealing implantable infusion port. Throughout the specification, reference is made to surfaces of the septa and various planes relative to these septa. For example, reference may be made to an angle at which a needle passes through a septum relative to a plane of an outer surface of the septum. However, those skilled in the art will understand that this does not mean that the surface is planar. Rather, this simply refers to a plane most consistent with the orientation of the outer surface. For example, for a generally disc shaped septum, this refers to the angle of the needle relative to a plane symmetrically located with respect to inner and outer surfaces of the septum. Using this convention, the axial direction is defined as substantially perpendicular to this plane (i.e., the most direct path through the surface to a reservoir within the port) while the radial direction refers to lines substantially parallel to this plane. 
         [0030]    As shown in  FIG. 1 , an exemplary assembly  100  for injecting and/or withdrawing fluids via an infusion port  150  comprises a body  105 , a helical needle  110  including a sharp distal needle tip  115 , a plunger lever  120 , a rotatable locknut  130 , and a needle support  135 . The tip  115  includes an aperture  116  which opens a lumen  117  extending through the needle  110  to the exterior. A proximal end of the needle  110  is coupled to an inlet/outlet tube  111  which extends proximally from the needle  110  to a source of fluid to be injected or to a reservoir or other structure for receiving fluids withdrawn from the body. The tube  111  is coupled to the needle  110  by a rotating coupling  113  which maintains fluid communication between the lumen  117  and a lumen of the tube  111  while allowing relative rotation between the needle  110  and the tube  111 . According to this embodiment of the present invention, the tube  111  may connect with the rotating coupling  113  of the assembly  100  via a luer attachment. Once attached to the assembly  100 , the tube and the luer attachment may freely rotate about the rotating coupling  113  while remaining in fluid communication with the lumen  117 . 
         [0031]    In another embodiment of the present application, the rotating coupling  113  may be a rotating fluid coupler having a bayonet design. Specifically, the bayonet design of the rotating coupler  113  may include male and female thermoplastic components with an o-ring between the male and female components allowing the coupling  113  to freely rotate while maintaining a fluid seal between the tube  111  and the lumen  117 . 
         [0032]    In a further alternative embodiment of the present invention, the tube  111  may be fixedly attached to the needle  110  in order to maintain fluid communication between the tube  111  and the lumen  117 . According to this embodiment, the tube  111  may rotate with needle  110  during the insertion of the needle  110 . As described below the pitch of the needle may be selected to control an amount of rotation of the needle  110  as it is inserted. For example, depending on its length, a needle  110  with a pitch of one to three coils per inch may complete only 2 to three rotations during insertion. In this case, a tube  111  connected to the needle  110  may simply be allowed to wind without substantially impacting the flow through the lumen  117 . 
         [0033]    A rotatable locknut  130  or other known coupling may be used to couple the proximal end of the helical needle  110  to the needle support  135  while allowing the needle  110  to freely rotate relative to the needle support  135  about an injection/withdrawal axis of the needle. The plunger lever  120  according to this embodiment includes a geared surface  122 , teeth of which mate with teeth of a geared surface  124  formed on the needle support  135 . The mating geared surfaces  122 ,  124  ensure that the needle support  135  is raised or lowered as the plunger lever  120  is rotated relative to the body  105  about a hinge pin  125 . Rotation of the plunger lever  120  clockwise as seen in  FIG. 1  moves the needle  110  in an injection direction while rotation of the plunger lever  120  counterclockwise moves the needle  110  in a withdrawal direction. The body  105  according to this embodiment of the invention includes optional anchor arms  107  distal to the needle support  135  for securely attaching the assembly  100  in a desired location on or near the body or to provide a stable base on which to rest the assembly  100  against the patient&#39;s body. The assembly  100  further includes an injection guide  136  including a guide aperture  137  formed therein with the needle  110  passing through the guide aperture  137 . The guide aperture  137  is offset from the injection/withdrawal axis by a distance substantially equal to a radius of the helix of the needle  110  so that movement of the needle  110  proximally and distally through the guide aperture  137  forces the needle  110  to rotate within the guide aperture  137 . In this embodiment, the injection guide  136  is mounted between the anchor arms  107 . However, those skilled in the art will understand that the injection guide  136  may be mounted at any point along the length of the needle  110  proximal of a position of the tip  115  of the needle  110  when the needle  110  is fully withdrawn. That is, as the needle support  135  moves the needle  110  distally through the guide aperture  137 , the needle  110  rotates counterclockwise as viewed from a proximal side of the injection guide  136  as each point on the helix of the needle  110  passes through the fixed location of the guide aperture  137 . As the needle  110  is withdrawn proximally, the guide aperture  137  directs the needle  110  to rotate in the opposite direction. 
         [0034]    In use, the anchor arms  107  are placed against a desired part of the body so that the tip  115  of the needle  110  is aligned with the septum  140  of an infusion port and the plunger lever  120  is rotated clockwise as seen in  FIG. 1  to move the needle support  135  and the needle  110  distally. As described above, as the needle  110  moves distally through the needle guide aperture  137 , the needle  110  is rotated about a longitudinal injection/withdrawal axis thereof in an injection direction (i.e., clockwise for a helical needle  110  wrapped clockwise about the injection/withdrawal axis from the proximal end to the distal tip  115 ). The rotating tip  115  of the needle  110  contacts the surface of the septum  140  (e.g., after passing through the skin), and draws itself distally into the septum  140 , passing through the septum  140  along a helical path  401 , as shown in  FIG. 5 . When a desired depth of injection has been reached (e.g., when the distal tip  115  has passed completely through the septum  140  into a fluid chamber of the port  150 ) fluids may be injected and or withdrawn through the aperture  116  in a manner similar to that used with conventional needles. 
         [0035]    After the fluid injection/withdrawal has been completed, the plunger lever  120  is rotated counterclockwise as seen in  FIG. 1  to rotate the needle  110  in the withdrawal direction, drawing the needle  110  and the tip  115  proximally, through the septum  140  along the path  401  in a direction opposite to that in which it was inserted until the tip  115  is completely withdrawn from the septum  140  and the skin. This provides a stabilized and controlled means of inserting the helical needle  110  into the port  150  and withdrawing the needle  110  therefrom. Furthermore, as described above, to enhance stability of the assembly  100  during injection, anchoring arms  107  of the assembly  100  may be secured to a fixed location with the helical needle  110  in a desired alignment with the infusion port  150 . Once the needle  110  and the infusion port  150  have been properly aligned and the anchoring arms  107  are fixed in position, the user gradually lowers the plunger lever  120  causing the connected helical needle  110  to descend and rotate toward the infusion port  150  until the tip  115  penetrates a septum  140  of the port  150  to establish fluid communication between a reservoir of the port  150  and an interior lumen (not shown) of the needle  110 . 
         [0036]    After administering fluids to the infusion port  150  (or alternatively, removing fluids therefrom), the helical needle  110  is withdrawn by raising the plunger lever  120  to rotate the helical needle  110  in the opposite direction while drawing the needle  110  through the septum  140  and out of infusion port  150 . 
         [0037]    The helical puncture pathway along which the helical needle  110  penetrates the septum  140  enhances the self-sealing qualities and life of the septum  140 . As shown in  FIGS. 2 and 3 , a puncture pathway  201  formed through a septum  140  by the insertion of a conventional needle (i.e., a Seldinger needle) is substantially linear and usually extends substantially perpendicular to a surface of the septum  140 . This puncture displaces the resilient material of the septum  140  radially away from the puncture pathway  201  so that the resiliency of the septum  140  must push edges of this puncture pathway radially inward toward one another to reseal itself. 
         [0038]    As shown in  FIGS. 4 and 5 , a puncture pathway  401  formed by a helical needle according to the present invention differs from the conventional puncture pathway  201  in two significant respects. First, each puncture pathway  401  made by a the helical needle  110  is oblique in relation to an outer surface of the septum  140 . These diagonal puncture pathways  401  wrap around the injection/withdrawal axis which is generally perpendicular to the outer surface of the septum  140  enhancing the ability of the septum  140  to reseal itself by increasing the length and, consequently, the surface area of the portions of the septum  140  defining the pathway  401 . Furthermore, as the pathways  401  extend through the septum  140  oblique with respect to the outer surface, expansion of the septum  140  after withdrawal of the needle  110  both radially and axially aids in resealing the pathway  401  as would be understood by those skilled in the art. Improving the ability to reseal increases the durability of the septum  140  and the time during which the infusion port  150  will reliably perform, reducing the frequency of procedures to replace or service the port  150  and/or the septum  140 . 
         [0039]    In addition to the improvement in the resealing of the septum  140 , the oblique angle of the puncture path  401  creates a physical barrier enhancing the resistance of the needle  110  to accidental withdrawal from the septum  140  during injection. In contrast, conventional needles are retained within their linear needle pathways only by the friction applied to that portion of the needle extending through the septum. However, in addition to the mechanical resistance the septum provides to pulling out a helical needle, the friction force applied to the helical needle is longer as the helical path  401  is longer than that for conventional needles. That is, the downward rotation causes the helical needle  100  to spiral through the resilient material in a circular pattern having a diameter substantially the same as that of the helical needle  110 , anchoring the needle  110  in the septum  140 . 
         [0040]    As shown in  FIG. 6 , a further exemplary embodiment of the present invention utilizes an assembly  100 ′ as an anchoring mechanism aiding in the insertion of a conventional straight needle  620  into an infusion port  150 . As the helical anchor  610  of the assembly  100 ′ is not used for injections, it need not contain a lumen. The straight  620  needle is preferably coupled to the helical anchor  610  so that axial movement of the helical anchor  610  causes a corresponding axial movement of the straight needle  620 . The straight needle  620  in this embodiment, is located within the coil formed by the helical anchor  620  and preferably extends substantially along a central axis of the coil. 
         [0041]    The helical anchor  610  is preferably actuated by a mechanism substantially the same as that described above in regard to  FIG. 1  with the helical anchor  610  and the needle  620  coupled to a rotatable locknut similar to the locknut  130  of the embodiment of  FIG. 1 . Those skilled in the art will understand that, alternatively, the needle  620  may be coupled to a non-rotatable component as the needle  620  need no rotate during injection. Raising and lowering the assembly  100 ′ is substantially the same as that described above for the embodiment of  FIGS. 1-5  so that, as the helical anchor  610  is screwed into the septum  140 , the needle  620  is drawn into the septum until a distal end of the needle  620  and an opening to an internal lumen thereof are within the port  150 . When screwed into the septum  140 , the helical anchor  610  provides a secure connection between the assembly  100 ′ and the infusion port  150 . However, as stated above, these alternative systems and method may include the addition of the attachable straight needle  620 . 
         [0042]    Alternatively, the straight needle  620  may initially be decoupled from the assembly  100 ′. After the helical anchor  610  has been screwed into the septum  140 , the needle  620  may then be inserted through an opening in the rotatable locknut  135  to pass along the central axis of the coil to penetrate the septum  140 . In addition, the needle  620  may include a latch to secure the needle to the assembly  100 ′ in a desired position (e.g., at a depth at which the distal opening of the needle  620  is open to a reservoir of the port  150 ) and a coupling for attachment to a fluid supply/withdrawal line. As would be understood by those skilled in the art, the coupling for attachment to a fluid supply/withdrawal line may be a luer or other known coupling. Thus, the needle  620  will be anchored in the desired position by the assembly  100 ′ and may be withdrawn automatically as the helical anchor  610  is unscrewed from the septum  140 . 
         [0043]    In further alternate embodiments, the geometry of the needle tip  115  of the helical needle  110  may be modified to minimize damage. For example, as shown in  FIGS. 7 and 8 , the pitch of the coil of a helical needle of anchor may be varied to optimize a path of the tips  701 ,  801  through the septum  140  and/or to prevent damage thereto. Distal surfaces of the reservoirs of ports such as the port  150  are often formed of substantially rigid material to act as needle stops. Thus, as would be understood by those skilled in the art, the closer the tip of the helical needle/anchor is to parallel with such a distal surface of a reservoir, the less likely it will be that the tip will be damaged by contact therewith. Of course, those skilled in the art will understand that the pitch of the helical needle/anchor may preferably be selected to optimize its positive impact on the resealing of the septum  140  while minimizing the possibility of damage to the needle tip. It is important to note that a further alternate embodiment for the geometry of the needle  110  may be a hybrid between the needles illustrated in  FIGS. 7 and 8 . Accordingly, the alternative embodiment of the needle  110  may have loose coils as depicted in  FIG. 7  with a deflected tip (e.g., extending substantially perpendicular to the injection/withdrawal axis) similar to the  801  of  FIG. 8 . As those skilled in the art will understand, the deflected tip minimizes damage to the needle tip  115  when the needle tip  115  makes contact with the base of the port  150 . 
         [0044]      FIG. 9  shows an embodiment of the helical needle  110 , wherein the needle  110  has a wire diameter D, an inside coil diameter ID, an outside coil diameter OD, an overall length L and a pitch P (i.e., the distance between centers of adjacent coils of the needle  110 ). Those skilled in the art will understand that the pitch P of the needle  110  determines how tightly or loosely the coils of the needle  110  are positioned with a shorter pitch resulting in a tighter coil. Alternatively, the tightness of the coils may also be measured by specifying the number of active coils within a set length. For example, the tightness of the needle  110  may be described as a number of coils per inch. The needle  110  may be a loose coil (i.e., a low number of coils per inch) in order to minimize the number of revolutions required to penetrate the septum  140  of the port  150 . In reference to  FIG. 9 , an exemplary helical needle  110  has a D value within the range of 17-22 gauge, a coil ID within the range of 0.125-0.5 inches and a coil OD in the range of 0.130-0.525 inches. Depending on the depth at which the port to be accessed has been implanted, the exemplary needle  110  preferably has a length L within the range of 0.25-1 inch and a pitch P of 1 to 3 coils per inch. Those skilled in the art will understand that the aforementioned ranges for the dimensions of the needle  110  are merely intended to serve as exemplary values and that any of these values may be expanded outside the described ranges to suit the particular needs of specific applications. 
         [0045]    The present invention has been described with reference to specific embodiments. However, other embodiments may be devised that are applicable to other types of catheters and procedures. Accordingly, various modifications and changes may be made to the embodiments, without departing from the broadest spirit and scope of the present invention as set forth in the claims that follow. The specification and drawings are accordingly to be regarded in an illustrative rather than restrictive illustrative rather than restrictive sense.