Patent Publication Number: US-2011071432-A1

Title: Fine Needle Aspiration Device with Distal Anchor

Description:
PRIORITY CLAIM 
     The application claims the priority to the U.S. Provisional Application Ser. No. 61/245,446, entitled FINE NEEDLE ASPIRATION DEVICE WITH DISTAL ANCHOR” filed Sep. 24, 2009. The specification of the above-identified application is incorporated herewith by reference. 
    
    
     BACKGROUND 
     Catheters are often employed to inject fluids into and/or to obtain fluid and/or tissue samples from living bodies. In these procedures, a needle is advanced, for example, through a catheter to a target site under guidance from an endoscopic vision system or other imaging technique (e.g., ultrasound). The needle is then advanced distally from the catheter to penetrate the target site. In biopsy procedures, suction may then be applied (e.g., via a syringe) to draw sample tissue into the needle. Furthermore, the needle may be aspirated multiple times to enable the capture of tissue therein. During aspiration, it is vital that a position of the needle remain substantially constant to prevent the inadvertent sampling of non-targeted tissue and to minimize patient trauma. 
     SUMMARY OF THE INVENTION 
     A device for capturing a tissue sample from within a body according to the present invention comprises a needle slidably comprising a needle lumen extending therethrough to a needle opening in the distal end. A stylet may be slidably received in the needle lumen for movement between an extended position in which a tissue penetrating distal tip of the stylet extends out of the needle opening to penetrate target tissue and a retracted position in which the distal tip of the stylet is received within the needle opening to substantially seal the needle lumen. The stylet may further comprise an anchoring feature located proximally of the tissue penetrating distal tip, the anchoring feature comprising a first gripping member including a first proximal facing abutting surface adjacent to a first tissue receiving gap wherein movement of the stylet distally out of the needle lumen brings the first gripping member into engagement with surrounding tissue to anchor the stylet at a desired position within the body. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a side view of a device according to a first exemplary embodiment of the invention in a compressed configuration; 
         FIG. 2  shows a partial cut-through enlarged view of a distal tip of the device of  FIG. 1  in a closed configuration; 
         FIG. 3  shows an enlarged view of a distal tip of the device of  FIG. 1  in an open configuration; 
         FIG. 4  shows an enlarged view of a distal tip of a second exemplary embodiment of the present invention; 
         FIG. 5  shows an enlarged view of a distal tip of a third exemplary embodiment of the present invention; 
         FIG. 6  shows a side view of a the device of  FIG. 5 ; and 
         FIG. 7  shows an enlarged view of a distal tip of a fourth exemplary embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention, which may be further understood with reference to the following description and the appended drawings, relates to a device for the deployment and anchoring of a needle within a living body to perform a procedure such as, for example, a fine-needle biopsy. It is noted, however, that although the exemplary embodiments of the present invention are described with respect to particular procedures, the invention is not limited to these procedures and may be employed in any of a number of procedures requiring the insertion of a needle to a target site within the body. For example, embodiments of the present invention may be employed to remove target tissue from a body for treatment (e.g., removing a tumor) or for analysis. 
     Devices and methods according to exemplary embodiments of the invention teach anchoring a needle at a target site in a body via a stylet inserted therethrough and extending distally therefrom. A user of the device of the present invention operates an external control to push an anchoring stylet distally out of a needle once a target sampling site has been reached. The stylet may include one or more abutments or other shapes that anchor the stylet in place, as will be described in greater detail below. Anchoring the stylet at the target sampling site facilitates sampling target tissue by allowing proximal and distal movement of the needle while ensuring that a base position thereof remains substantially constant. Furthermore, the exemplary embodiment of the present invention also allows the stylet to aid in sampling target tissue by scraping tissue into grooves formed therein, as will also be described in greater detail below. 
     As shown in  FIG. 1 , a device  100  according to a first exemplary embodiment of the present invention comprises an elongated catheter shaft  106  with a lumen  110  extending longitudinally therethrough, the lumen  110  further housing a needle  102  therein. The lumen  110  of the shaft  106  extends from a proximal end (not shown) of the shaft  106  near a handle  130  of the device  100  to an opening at a distal end  104 . It is noted that the use of the term distal herein refers to a direction away from a user of the device while the term proximal refers to a direction approaching a user of the device. The proximal portion of the device  100 , including the handle  130 , remains external to the body and accessible to the user while the distal portion, when in an operative position, extends into the body to a target site to be accessed (e.g., a site from which tissue samples are to be obtained in a biopsy procedure). The handle  130  is also provided with a gripping and manipulation member (not shown) as known in the art. 
     The needle  102  extends from a proximal end (not shown) in the handle  130  to a tapered distal end  114  surrounding a distal opening  117  of a needle lumen  112  extending therethrough to a proximal end (not shown) connectable to one or both of a receiving chamber and a source of suction, as those skilled in the art will understand. The needle lumen  112  and the distal opening  117  are dimensioned so that a stylet  108  as described below may be selectively inserted therethrough to form a fluid seal preventing entry into the needle lumen  112  of non-targeted tissue as the device  100  is moved to and from the target sampling site. The stylet  108  can be formed as an elongated tubular structure  120  extending from a proximal end (not shown) manipulable by a user to a distal end comprising a tapered distal portion  122  with a tissue penetrating tip  116  at a distal end thereof. The tapered distal portion  122  may, for example, be formed so that, when received in the distal opening  117  of the needle lumen  112 , the tapered distal portion  122  and the tapered distal end  114  of the needle form a substantially continuous surface. Thus, when received in the distal opening  117  in a closed configuration as shown in  FIG. 2 , the distal tip  116  of the stylet  108  facilitates insertion of the needle  102  through tissue to reach the target site. 
     The needle  102  is movable between the closed configuration shown in  FIG. 2  and an open configuration shown in  FIG. 3  in which the stylet  108  is extended into tissue adjacent to the distal end  114 , the device  100  is anchored to the this tissue and a base position of the needle  102  relative to the target sampling site is established. In the closed configuration, a distal-most rim  126  of the needle  102  surrounding the distal opening  117  of the needle lumen is adjacent to a proximal-most rim  128  of the tapered portion  122 , wherein a diameter of the distalmost rim  126  is substantially equivalent to a diameter of the proximalmost rim  128  of the tapered tip  122  in order to create a substantially fluid-tight engagement therewith. 
     Once the target sampling site has been reached, the device  100  is moved to the open configuration shown in  FIG. 3 . Specifically, a position of the needle  102  may be held constant while the stylet  108  is moved distally relative thereto to penetrate into the tissue of the target sampling site (e.g., a tumor). Alternatively, the position of the stylet  108  may be held constant while the needle  102  is retracted proximally to expose the hooks  132  to the surrounding tissue. The stylet  108  and needle  102  may be relative to one another by a distance selected to embed in this tissue one or more of a plurality of hooks  132  formed along a distal portion of the stylet  108 . The hooks  132  may be formed as a series of arms extending radially outward from an axis of the stylet  108  and angled proximally to act as barbs resisting movement of the stylet  108  relative to the tissue within which it is embedded as would be understood by those skilled in the art. The hooks  132  may be formed so that radially outer edges thereof will be no further from the axis of the stylet  108  than the proximal-most rim  128  of the tapered portion  122  so that the profile of the stylet  108  is not increased thereby and remains movable within the lumen  112 . The hooks  132  may be distributed circumferentially around the stylet  108  and, in an exemplary embodiment, are provided in a plurality of sets of four hooks  132  evenly disposed circumferentially about the stylet  108  with the sets of four hooks  132  separated from one another longitudinally along the stylet  108  from a distal-most set adjacent to the proximal-most rim  128  along any desired length of the stylet  108 . It is noted that each set of hooks  132  may include only one or any number of hooks and that the number of longitudinally separated sets of hooks  132  may be selected to obtain a desired anchoring force within the tissue to be sampled without deviating from the spirit and scope of the present invention. Pointed proximally facing tips  134  of the hooks  132  are sized and shaped to permit each of the hooks  132  to abut into the target tissue sampling site and anchor in place by providing a barb-like interface therewith. Furthermore, adjacent sets of hooks  132  may be separated from one another longitudinally by a gap  136  sized to permit the entry thereinto and gripping of tissue. The gaps  136  are also useful in retaining sampled tissue, as will be described in greater detail in a method taught hereinafter. 
     In accordance with an exemplary method of use of the device of  FIGS. 1-3 , the catheter shaft  106  is inserted into a living body and traversed to location adjacent to a target site at which tissue is, for example, to be sampled. During or after this insertion, the needle  102  is inserted through the lumen  110  of the catheter shaft  106  to a distal-most position therein with the stylet  108  in the closed configuration as shown in  FIG. 2 . The stylet  108  and the needle  102  may then be pushed further distally so that the puncturing tip  116  of the stylet  108  pierces the target tissue easing the insertion of the distal end  114  of the needle  102  thereinto. Once the needle  102  and the stylet  108  have been moved into the target tissue, the stylet  108  and the needle  102  are moved relative to one another to expose the hooks  132  and engage them with the target tissue by, for example, actuation of a control lever (not shown) on the handle  130 . Specifically, actuation of the control lever (not shown) causes the stylet  108  to move relative to the needle  102 , thus exposing the hooks  132  to the target tissue. Alternatively, the needle  102  may be moved by any other means known in the art. In a preferred embodiment, the needle  102  is retracted so that the distal end  114  thereof lies substantially adjacent a proximal end  138  of the hooks  132 . 
     The user then moves the needle  102  distally and proximally over the stylet  108  to capture sample tissue within the needle lumen  112  while engagement between the surrounding tissue and the hooks  132  each time the hooks are exposed anchors the stylet  108  at a desired position within the target tissue. In this manner, the stylet  108  may be secured in place and the needle  102  may be moved back and forth multiple times to perform a biopsy and effectively dislodge a tissue sample from the surrounding tissue. Suction may be applied via any known apparatus to a proximal end of the needle lumen  112  to aspirate the captured samples from the proximal end for analysis or at least to move the captured samples to a portion of the needle lumen  112  within which they will be free from potentially damaging contact with the hooks  132  of the stylet  108 . That is, the captured samples may be aspirated to an area of the needle lumen  112  which is located proximally of the proximal end  138  of the hooks  132  when the stylet  108  is retracted into the closed configuration. When the sampling has been completed, the stylet may be drawn proximally out of engagement with the surrounding tissue by applying thereto a proximally directed force (e.g., which holding the position of the needle  102  constant) sufficient to separate tissue engaged by the hooks  132  from surrounding tissue. Additional samples may then be obtained from the gaps  136  between adjacent sets of the hooks  132 . Once the stylet  108  has been returned to the closed configuration with the hooks  132  positioned within the needle lumen  112 , a further suction force may be applied to the needle lumen  112  to draw sampled tissue further proximally thereinto to provide space within which to retain further samples (e.g., from other target sites) without the need to remove the needle  102  from the body, as those skilled in the art will understand. In another embodiment of the invention, the stylet  108  may be completely withdrawn from the needle  102  after procuring a first sample. A new stylet (not shown) may then be inserted into the needle  102  while maintaining the position of the needle  102  in the body. Once the biopsy procedure has been completed (e.g., after multiple samples at different sites have been obtained), the stylet  108  is retracted to the closed configuration and the device  100  is withdrawn from the body. Subsequently, an endoscope or other visualization means may be inserted through the lumen  110  of the catheter shaft  106  to determine the efficacy of the procedure, as those skilled in the art will understand. 
     As shown in  FIG. 4 , a device according to an alternate embodiment of the invention includes a stylet  208  selectively movable within a needle  202  comprising a tapered portion  214  at a distal end thereof substantially similar to that described above in regard to the device  100 . However, the stylet  208  comprises a series of sets of serrations  232 , the sets being separated from one another longitudinally along the stylet  208 . Each set of serrations  232  includes 2 serrations  232  with the serrations  232  of each set separated from one another about a circumference of the stylet  208  and facing away from a longitudinal axis of the stylet  208  on the same side of the axis. However, it is noted that any number of serrations may be included in each set and individual sets may differ from one another in the number of serrations  232  included therein to form any of a number of configurations without deviating from the scope of the present invention. The serrations  232  are formed as grooves tapering diagonally from enlarged ends at radially outer edges thereof to points within the body of the stylet  208 . The grooves forming the serrations extend distally from the enlarged radially outer edges to form proximally leaning wedges. A wall  234  of each of the respective serrations  232  is sharpened to enable the anchoring and subsequent severing of tissue caught in a gap  236  between serrations  232  of adjacent sets, as described above with respect to the embodiment of  FIGS. 1-3 . The stylet  208  is also used in accordance with a method substantially similar to the stylet  108  of  FIGS. 1-3 . 
       FIGS. 5-6  depict yet another alternate embodiment of the present invention, wherein a stylet  308  formed with a reverse funnel feature is shown in an open configuration. Specifically, the stylet  308  is formed as an elongated wire  320  formed with a substantially circular cross section. The elongated wire  320  further comprises a taper  318  tapering down to a reduced diameter wire  319 . The reduced diameter wire  319  extends distally to a cup  326  having a diameter substantially equivalent to that of the elongated wire  320 . The cup  326  further comprises a tapered distal tip  322  tapering down to a tissue puncturing tip  316 . The cup  326  and the tapered distal tip  322  are both formed as hollow elements defining a cavity  332  therein serving to anchor the stylet  308  in place in the body by engaging tissue adjacent thereto when in the open configuration. If a tissue sampling procedure is to be performed, a sharpened rim  334  of the cup  326  serves to provide a cutting edge of the stylet  308  so that, upon actuation causing a proximal and distal movement thereof, the edge severs tissue received in the cavity  332  from surrounding tissue. It is noted that although the cup  326  is depicted with a 360° rim, the cup  326  may also comprise a less than a 360° rim depending on the requirements of the tissue being sampled. 
     In use, a needle  302  from which the stylet  308  projects distally is traversed to a target tissue sampling site with the stylet  308  drawn proximally into a lumen of the needle  302  until the tapered distal tip  322  projects from a tapered distal end of the needle  302  with the cup  326  received within the lumen of the needle  302 . As in the previous embodiments, in this closed configuration, the tapered distal tip  322  may form a substantially continuous surface with the tapered distal end of the needle  302  to facilitate tissue penetration and minimize trauma. When the target site has been reached, the needle  302  is moved relative to the stylet  308  (e.g., by moving the stylet  308  distally while holding the needle  302  in position or by holding the stylet  308  in position while retracting the needle  302  proximally), as shown in  FIGS. 5 and 6 . As the stylet  308  is moved into the open configuration, surrounding tissue (e.g., target tissue from the target sampling site) is moved into the cavity  332  due to the pressure from the surrounding tissue anchoring the stylet  308  in place. The needle  302  may be then be moved proximally and distally until a desired sample of the target tissue has been captured in the cavity  332 . Furthermore, the stylet  308  may also be moved proximally and distally to sever tissue within the cavity  332  from the surrounding tissue. As the stylet  308  is drawn into the needle lumen (not shown), suction may be applied thereto draw the tissue in the cavity  332  proximally and thus, permit multiple samplings by the stylet  308  without withdrawing the needle  302  from the body or by inserting a new stylet (not shown) into the needle  302  in the same manner described above. 
       FIG. 7  depicts yet another embodiment of the present invention, in which a flexible stylet  408  is biased to assume a hooked shape when not constricted within a lumen of a needle  402 . Specifically, the stylet  408  may be formed of a flexible material such as, for example, Nitinol. It is noted that although the present invention is described with the use of Nitinol, any other flexible material may he employed therein with the material being bent to a hook-like configuration. For example, the Nitinol of the stylet  408  may exhibit shape memory characteristics allowing the stylet  408  to revert to a desired memorized shape (e.g., the desired hook shape) when elevated to body temperature or may simply be biased toward this shape at all times when not constrained to a substantially straight shape within the lumen of the needle  402 . In this manner, when the stylet  408  is inserted into a living body via a catheter  406  and moved distally out of the needle  402 , the stylet  408  assumes the desired hooked configuration shown in  FIG. 7  anchoring itself in surrounding tissue and resisting inadvertent removal of the stylet  408  and the needle  402  from the target position. Furthermore, a tapered tip  422  provided on the stylet  408  may be formed similar to the cup  326  of  FIGS. 5-6 . The tapered tip  422  may be made hollow to cut and capture tissue as it is drawn into engagement with the needle  402 , as described in greater detail earlier. The tapered tip  422  further comprises a puncturing tip  416  which, when received at the distal end of the needle  402  facilitates insertion of the needle through intervening tissue in the same manner described above. It is further noted that the stylet  408  of the present invention may be modified in a number of ways without deviating from the scope of the invention to achieve desired anchoring and/or tissue capture properties. For example, the stylet  408  may be biased to assume a corkscrew shape at a distal end thereof to further anchor the needle  402  at the target site. Hoops of the corkscrew feature may be sharpened or otherwise treated to further aid in promoting severing of the sample tissue from surrounding tissue. The severed tissue may then be suctioned into the needle  402  in the same manner described above. It is further noted that although the present embodiment is depicted with one stylet  408  extending distally out of the needle  402 , in another embodiment any plurality of hooked stylets may be employed wherein the plurality of hooks may all protrude distally out of the single needle  402  or from a respective number of separate needles  402  all stemming from the catheter  406 . 
     The present invention may be applied to any procedure requiring the insertion of a needle into tissue via a device traversing a tortuous path. Though the present invention has been described with respect to the retrieval of tissue samples, it is submitted that devices for alternate uses such as, for example, the anchoring of needles for injection of fluids to or the withdrawal of fluids from the body may employ to invention without deviating from the spirit and scope of the present invention. Furthermore, although embodiments of the invention have been described with respect to a stylet movable with respect to a needle, alternate embodiments may also comprises a stylet and needle that are both movable relative to one another. In yet another embodiment, any portion of the needle or stylet may be provided with echosonic features to aid in location thereof when inserted to a target site in the body, as those skilled in the art will understand. Thus, these embodiments have been described in an exemplary manner and are not intended to limit the invention which is intended to cover all modifications and variations of this invention that come within the scope of the appended claims and their equivalents.