Abstract:
An endoscopic instrument comprises a first flexible insertion member sized for insertion through a body lumen to a target site and a needle coupled to the insertion member for penetration of tissue, the needle including a plurality of flexibility enhancing grooves formed therein along at least a first portion of the length of the needle.

Description:
BACKGROUND 
       [0001]    Conventional sclerotherapy catheters include needles which are extendable and retractable beyond distal ends thereof. Such a catheter is typically inserted through an endoscope located at a desired position within the body. The catheter is pushed distally through the endoscope until a distal end of the catheter extends beyond a distal end of the endoscope. The needle is then extended from the catheter and inserted into the target tissue and a sclerosing agent is administered thereto to cause the target tissue to thicken or harden. 
         [0002]    The needles typically utilized in conjunction with such sclerotherapy catheters are rigid, which hinders maneuverability of the catheters within endoscopes. Also, these needles often have a length of at least 1 cm to allow them to successfully puncture tissue and administer a sclerosing agent. The rigidity and length of the needles present difficulties in attempting to guide the sclerotherapy catheter through an endoscope and/or through a body lumen. That is, if advancing the catheter through an endoscope requires bending the sclerotherapy catheter around a tight radius, the needle may be exposed, puncturing the catheter and/or the endoscope. In some cases, the needle may prevent the sclerotherapy catheter from moving past the tight radius. 
       SUMMARY OF THE INVENTION 
       [0003]    The present invention is directed to an endoscopic instrument comprising a first flexible insertion member sized for insertion through a body lumen to a target site and a needle coupled to the insertion member for penetration of tissue, the needle including a plurality of flexibility enhancing grooves formed therein along at least a first portion of the length of the needle. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]      FIG. 1  shows a side view of an exemplary embodiment of a needle within a catheter according to the present invention; 
           [0005]      FIG. 2  shows a detail view of the needle according to the present invention; 
           [0006]      FIG. 3   a  shows a side view of an exemplary embodiment of a needle according to the present invention; 
           [0007]      FIG. 3   b  shows a perspective view of the embodiment of the needle shown in  FIG. 3   a;    
           [0008]      FIG. 4   a  shows a side view of a further exemplary embodiment of a needle according to the present invention; 
           [0009]      FIG. 4   b  shows a perspective view of the embodiment of the needle shown in  FIG. 4   a;    
           [0010]      FIG. 5   a  shows a side view of another exemplary embodiment of a needle according to the present invention; 
           [0011]      FIG. 5   b  shows a perspective view of the embodiment of the needle shown in  FIG. 5   a ; and 
           [0012]      FIG. 6  shows a perspective view of an exemplary embodiment of a system according to the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    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. Although the present invention is described herein in reference to sclerotherapy, those skilled in the art will understand that a flexible needle constructed in accord with the present invention may be employed in any procedure which requires a needle with enhanced flexibility (e.g., for bending around a tight radius). Furthermore, although the present invention is described herein with specific reference to needles, those skilled in the art will understand that the teachings of the invention may be applied in the same manner to a wide range of items formed of rigid materials which are inserted through endoscopes. For example, hemaclips, Enteryx® needles, fine needles, aspiration needles, and coring needles for tissue acquisition may be made more flexible using the same processes described herein for the needle  35 . Further, all gastrointestinal instruments and other medical instruments which are often formed of rigid materials to achieve a desired column strength but which are required to pass through a tortuous path to reach target tissue may be made more flexible using the teachings of the present invention. 
         [0014]    As shown in  FIG. 1 , a catheter  5  includes an outer sheath  10  and an inner sheath  15 . Both the inner sheath  15  and the outer sheath  10  may, for example, be formed of a plastic polymer tubing, although other materials having similar characteristics (e.g., flexibility, biocompatibility, etc.) may be used. A needle  35  is attached to inner sheath  15  by, for example, mechanically crimping a proximal end of the needle  35  to a distal end of the inner sheath  15 . Alternatively or additionally, an adhesive  18  may be applied to the proximal end of the needle  35  to bond it to the inner sheath  15 . A first predetermined length  32  of the needle  35  is inserted proximally into the inner sheath  15  leaving a second predetermined length  34  extending distally from the distal end of the inner sheath  15 . In one embodiment, the first predetermined length  32  is approximately 3 to 4 mm, and the second predetermined length  34  is approximately 5 to 6 mm. 
         [0015]    The inner sheath  15  is slidably received within a lumen of the outer sheath  10  so that a position of the outer sheath  10  relative to the inner sheath  15  may be manipulated by a user. During insertion and retraction of the catheter  5  through an endoscope, the outer sheath  10  is advanced distally relative to the inner sheath  15  until the distal end of the outer sheath  10  extends past a distal end of the needle  35  to protect the needle  35  and the endoscope by preventing the needle  35  from scraping, puncturing, or otherwise damaging a wall of the endoscope. 
         [0016]    After the endoscope has been positioned in a desired location relative to the target tissue, the outer sheath  10  and the inner sheath  15  are advanced together to project distally from a distal end of the endoscope. The needle  35  is then exposed by withdrawing the outer sheath  10  proximally. Those skilled in the art will understand that alternatively, the needle  35  may be exposed by moving the outer sheath  10  and the inner sheath  15  together to the distal end of the endoscope and then extending the inner sheath  15  distally relative to the outer sheath  10 . The inner sheath  15  and the outer sheath  10  are preferably moved relative to one another via an actuator which, during use, remains outside the body. The actuator may be any standard actuator, but may preferably be a one-hand operable device, such as a spool or finger loop handle as would be understood by those skilled in the art. Once exposed, the needle  35  is inserted into the target tissue by advancing the inner sheath  15  further distally. At this point, a therapeutic agent (e.g., a sclerosing agent) may be injected into the target tissue. 
         [0017]    Successful insertion of the needle  35  into the target tissue may require the second predetermined length  34  of the needle  35  to be at least approximately 3 or 10 mm. Taking into account the 2 to 5 mm of needle length required for attachment to the inner sheath  15 , a total length of the needle  35  is approximately 1.5 cm. 
         [0018]    According to the present invention, a plurality of slots  20  are formed at predetermined locations on the needle  35  to enhance its flexibility. The slots  20  may preferably be formed by removing segments of the material comprising the needle  35  as described in more detail below. The slots  20  may be formed along the length of the needle  35  at regular intervals or may be spaced by variable distances, thereby increasing the flexibility of selected areas while leaving others relatively rigid. In addition, the slots  20  may be formed around an entire circumference of the needle  35  to achieve a substantially equal amount of flexibility in all directions or may be formed on one side only to allow greater flexibility in one direction than another. However, an embodiment where the slots  20  are formed circumferentially around the needle  35  may be preferable to achieve a substantially flexibility which is substantially uniform in all directions. This increased flexibility of the needle  35  facilitates navigation around tight bends in the endoscope, minimizing the risk of the needle  35  scraping or penetrating the wall of the endoscope. 
         [0019]    The size and spacing of the slots  20  are selected to maintain a predetermined degree of axial strength sufficient to allow the needle  35  to be pushed through the turns required to navigate target pathways in the body and to penetrate the target tissue. Those skilled in the art will understand that the outer sheath  10  adds a degree of support to the needle  35  when the inner sheath  15  and the outer sheath  10  are advanced together. Thus the flexibility of the needle  35  may be increased to a level greater than would be feasible without the outer sheath  10 . 
         [0020]    The slots  20  in the first predetermined length  32  of the needle  35  may also receive the adhesive  18 . The slots  20  act as a mechanical lock for the adhesive  18  to grip and hold, thereby providing a stronger attachment to inner sheath  15 . Accordingly, the inner sheath  15  may be more securely bonded to the proximal end of a needle  35  with slots  20  than it would be to a typical medical needle. The slots  20  will retain flexibility where there is no adhesive or crimp. Consequently, however, the flexibility of the needle  35  may be decreased in the first predetermined length  32  relative to the second predetermined length  34  which is exposed. As this portion is only necessarily 2 to 5 mm in length, its decreased flexibility should not present a problem. Alternatively, the adhesive, crimp, or other attachment means may be made flexible, and thus even this portion of the needle  35  may be slotted so that this portion too will exhibit an increased degree of flexibility. However, those skilled in the art will understand that even in an embodiment where the attachment means is relatively stiff, the portion at which it is coupled to the inner sheath  15  is short enough to pass through even the tightest bends in a narrow lumen with relative ease. 
         [0021]    The recommended method for creating the slots  20  is by using a computer-controlled slot grinding technology. The grinding technology utilizes a computer to control a length of a cut made in the needle  35 . Preferably, this process is used to grind the slots  20  at a predetermined width (e.g., 0.003″ to 0.004″, which converts to approximately 0.075 mm to 0.10 mm). This process is described in detail in U.S. Pat. No. 6,766,720 the entire disclosure of which is hereby incorporated in its entirety by reference herein. 
         [0022]    The slots allow a rigid material to exhibit flexible characteristics in a controlled manner. That is, portions of the rigid material can be selectively ground away, thereby creating slots, which may be sized and spaced to achieve a desired degree of flexibility while other areas are left relatively stiff or are made more or less flexible. In addition, by grinding on one side only, the material may be made flexible in one direction and relatively stiff in other directions. By locating slots only in selected areas along the axis of the needle  35 , a desired flexibility may be obtained in those preselected sections of the needle  35  while maintaining rigidity in other areas of the needle  35 . The grinding process may be performed on tubing of a relatively small diameter, as well as tubing of a much larger diameter. Furthermore, those skilled in the art will understand that, depending on the properties desired for the needle  35  or other instrument being formed, slots may be formed along helical paths, or substantially parallel to a longitudinal axis of the needle  35  or other instrument. In addition, the geometry of the slots may vary from slot to slot. 
         [0023]    Although the computer controlled slot grinding may be used to create the slots  20  in the needle  35 , other methods may be used. For example, in one embodiment, a laser may be used to make the slots  20 . The laser may be employed to cut more intricate, complex shapes with precision and minimal damage (e.g. fracture) or distortion (e.g. compression) to the needle  35 . Other methods which may be used to create the slots  20  in the needle  35  include drilling, high pressure water cutting, photo-etching, etc. In another embodiment of the present invention, the needle  35  and the slots  20  may be created by a molding process (e.g., injection molding, blow molding, etc.). That is, the needle  35  may be made of a strong and/or reinforced polymer. Thus, the slots  20  would be positioned, sized, and shaped in accordance with a pattern defined by the molding process. 
         [0024]    In a preferred embodiment, the needle  35  is made of a shape-memory alloy (e.g. nitinol hypodermic tubing) or of a similar material that has a high tensile strength. The high tensile grade of nitinol makes this type of needle  35  easier to work with than one composed of other materials, because nitinol can withstand high amounts of flexing without fracture or permanent flexion under normal working conditions. Although nitinol is the preferred material for composition of the needle  35 , other materials are suitable and compatible with the computer controlled grinding process. For example the grinding process may be performed on stiff polymers (e.g. plastic polyimids), reinforced materials, stainless steel braided reinforced tubing, etc. 
         [0025]    As would be understood by those skilled in the art, the flexibility of the needle  35  may be manipulated through variation of the shape and position of the slots  20 .  FIG. 2  depicts a pattern formed by grinding a plurality of slots  20  along the needle  35 , thereby excising partial circumferential sections of the needle  35 . These partially circumferential excisions are placed at predetermined intervals along the length of the needle in such a way as to increase flexibility while maintaining a high degree of strength. Regarding  FIG. 2 , narrow circumferential sections  55  are removed from the needle  35  so that a segment  50  is left intact to keep the distal end of the needle  35  from being completely severed from the proximal end. In the adjacent excision  60 , the segment left intact is located approximately directly opposite the original remaining segment  50  with respect to a longitudinal axis of the needle  35 . The next adjacent partial circumferential excision  65  is positioned such that the remaining segment  70  is roughly even with the original remaining segment  50 , but slightly vertically displaced therefrom. As shown in  FIG. 2 , a pattern is formed in the needle  35  by the slots  20  such that the remaining segments are substantially evenly distributed along the axis and wrapping around the body of the needle  35 , along a substantially helical path. This pattern produces a degree of flexure that is suitable for navigating through an endoscope and a body lumen and which is substantially equal in all directions. 
         [0026]    The slots  20  as described above with respect to  FIGS. 1 and 2  may optionally penetrate all way to the bore  22  of the needle  35 . Alternatively, the depth of the slots  20  may be less than a thickness of a wall of a hollow needle  35 . When the depth of the slots  20  is less than a thickness of the wall of the needle  35 , the wall of the needle  35  is substantially thinned at the slots  20  relative to other sections of the needle  35  and therefore increases a degree of flexibility of these portions of the needle  35  while maintaining the integrity of the inner lumen of the needle  35 . This allows a more precise control of the locations at which a fluid supplied to the inner lumen of such a needle  35  would be delivered. Furthermore, as the thinner section still connects the distal end of the needle  35  to the proximal end, such slots  20  may if desired be formed fully circumferentially. This embodiment therefore provides increased flexibility without creating porosity in the needle  35 . Those skilled in the art will understand that the depth of the slots may be varied along the length of the needle  35  to achieve any desired flexibility and/or fluid delivery characteristics along the length of the needle  35 . 
         [0027]    As illustrated in  FIG. 2 , the slots are created in a substantially rectangular shape that extends over a substantial portion of the circumference of the needle  35 . However, the slots may take alternative forms (e.g. elliptical, polygonal, etc.) and may be sized to extend over varying portions of the circumference of the needle  35 . Variations in the size or shape of the slots may have a corresponding effect on the flexibility of the needle  35 . 
         [0028]    As the size and shape of the slots  20  may affect the flexibility characteristics of a needle  35 , the placement and separation between the slots  20  may also have a substantial effect. For instance, a plurality of slots  20  concentrated in one portion of the needle  35  may substantially increase the flexibility of the needle  35  in that portion. However, that portion of the needle  35  will also lose a degree of longitudinal rigidity. Conversely, if the same number of slots  20  are positioned at a greater distance from one another along a longer section of the needle  35 . However, the entire needle  35  will have a level of flexibility higher than that of the areas of this needle  35  outside the area of dense slot concentration. The needle  35  will not have any section as flexible as the area of dense slot concentration described above. 
         [0029]    The slots  20  illustrated in  FIGS. 1 and 2  are positioned in planes substantially perpendicular with respect to the longitudinal axis of the needle  35 . In an alternative embodiment, the slots  20  may extend in planes orientated at various angles with respect to the longitudinal axis. A preferred range of angles with respect to the longitudinal axis of the needle  35  may be between approximately 45° and 90°. 
         [0030]    Referring back to  FIG. 1 , the needle  35  has a distal tip  30  which facilitates penetration into target tissue. The needle  35  also includes a hollow bore  22 , through which a fluid may pass proximally or distally. In sclerotherapy, for example, fluid exits the needle  35  at an outlet near the tip  30 . Accordingly, once the needle  35  has been inserted into target tissue, an agent is injected thereinto from the distal end of the needle  35 . Due to the nature of its release, the stream of injected fluid immediately comes into contact with the portion of target area toward which the needle  35  is pointing. From there it spreads to the rest of the target tissue. An advantage of the flexible needle of the present invention is that fluid may also exit through the slots  20  formed along the length of the needle  35 , dispersing the fluid more widely throughout the target tissue. 
         [0031]    If it is desired to have a needle  35  which is flexible but not porous, any slots  20  which penetrate to the bore  22  may be sealed. In one embodiment of the present invention, the slots  20  may be sealed by dipping the needle  35  in a soft polymer. The polymer preferably covers the slots  20  without obstructing the bore  22 . As a result, a needle  35  sealed with a thin polymer coating and having an outlet at the distal end will possess substantially the same flexibility characteristics as the porous needle  35  described above. In another exemplary embodiment, a thin sheath may be slidably received around the needle  35 , thereby sealing the slots  20 . As would be understood by those skilled in the art, the sheath may be formed to impart a selected degree of rigidity to the needle  35  so that the needle  35  will retain a desired degree of flexibility. 
         [0032]    As shown in  FIGS. 3 ,  4 , and  5 , the distal end of the needle  35  may be contoured to take a form most suitable for a desired application.  FIG. 3  depicts a needle  82  having a regular medical point, or a “lancet point.” The distal end of the needle  82  is shaped to form a sharp point  90 . As shown in  FIG. 3 , a sharp cutting edge  85  is formed at an angle (e.g. approximately 15 degrees) with respect to a longitudinal axis of the needle  82 . Preferably, the angle of the sharp cutting edge  85  may be approximately equivalent to a diameter of the needle  35  divided by a length of the sharp cutting edge  85 . The sharp cutting edge  85  meets a heel  80  of the lancet point. The heel  80  may be formed at an angle, with respect to the longitudinal axis of the needle  35 , that is smaller than the angle formed by the sharp cutting edge  85  as per standard needle specifications in the industry. 
         [0033]      FIG. 4  depicts a needle  102  having a deflected point  105  reducing possibility of puncturing a lumen wall of an endoscope as the needle  102  is advanced therethrough. The deflected point  105  also aids in keeping the bore  110  of the needle  102  unobstructed. For example, when injecting a lancet point needle  82  such as that shown in  FIG. 3  into target tissue, the large diameter of the outlet in connection with the sharp cutting edge  85  may cause a section of tissue approximately the diameter of the needle  82  to be removed. The removed tissue section may then become lodged in the needle bore  95  leaving a hole in the target tissue. The deflection of the point  105  in  FIG. 4  displaces the point  105  toward the sharp cutting edge  100 . Accordingly, the outlet of the hollow bore  110  is more closely aligned with the longitudinal shape of the needle  102 . As the point  105  lies nearly on the same plane as an opposite surface of the needle  102 , and the sharp cutting edge  100  does not directly abut a surface of the target tissue, the needle  102  penetrates tissue more smoothly. The diameter of the hole created in the tissue by the puncture gradually increases to the diameter of the needle  102  as the needle  102  is inserted without removing a section of tissue. Thus, the hole will close and the tissue will heal more readily. 
         [0034]      FIG. 5  portrays a needle  122  with a deflected guide tip  125 . This needle  122  retains all the benefits of the needle  102  of  FIG. 4 . For example, the outlet of a hollow bore  130  is more closely aligned with a longitudinal shape of the needle  122 , and therefore a sharp cutting edge  120  does not directly abut a surface of the target tissue, enabling smooth penetration of the needle  122 . Additionally, the tip  125  of this needle  122  is curved towards axis of the needle  122  reducing risk of damaging the lumen wall as the needle  122  is passed through the endoscope. 
         [0035]    In an alternative embodiment shown in  FIG. 6 , an injection catheter  5  is slid through the working channel  165  of an endoscope  170  which may be, for example, a standard endoscope including, for example, devices such as an irrigation system  164  and at least one optical system  162  to facilitate insertion of the endoscope  170 , positioning, and performance of the procedure. The endoscope  170  may be a single use endoscope or a conventional multi-use endoscope. The endoscope  170  is placed within a body lumen (e.g., through a naturally occurring orifice) and positioned proximate to a target area. The optical system  162 , the irrigation system  164 , and a syringe  175  are connected to the endoscope  170  through a medical luer adaptor  180 , as would be understood by those skilled in the art. The injection catheter  5  includes a needle  35  attached to an inner sheath  15 , within an outer sheath  10 . As with conventional sclerotherapy needles, the needle  35  is extended and retracted as necessary via a manipulator  185  located at the proximal end of the endoscope  170 . The manipulator  185  may be a one-hand or two-hand operable device. Additionally or alternatively, the manipulator  185  may be automatic and/or computer controlled. When in the retracted position, the needle  35  is housed within the outer sheath  10 . As the needle  35  is extended and exposed from the distal end of the outer sheath  10 , the user may insert the needle  35  into the target tissue and inject fluid from syringe  175  into the target tissue. After the fluid has been administered to the target tissue, the needle  35  is retracted and withdrawn through the endoscope  170 . 
         [0036]    In another exemplary embodiment of the present invention, the needle  35  and/or the injection catheter  5  may be part of the endoscope  170 . That is, the needle  35  and/or the injection catheter  5  may be a permanent fixture of the endoscope  170 . This embodiment may be practical with respect to incorporating the present invention into a single-use endoscope. 
         [0037]    In another exemplary embodiment of the present invention, the needle  35  may be part of an endoscopic accessory. For example, the needle  35  may be part of a cup attached to a distal end of an endoscope (e.g., via a snap-on linkage) with a generic device connection linking the needle  35  to an actuator or controller of the endoscope. For example, the needle  35  may be connected to a control wire extending between a distal end of the endoscope and a proximal actuator of the endoscope. 
         [0038]    The present invention has been described with reference to specific exemplary embodiments. Those skilled in the art will understand that changes may be made in details, particularly in matters of shape, size, material and arrangement of parts without departing from the teaching of the invention. Accordingly, various modifications and changes may be made to the embodiments without departing from the broadest scope of the invention as set forth in the claims that follow. The specifications and drawings are, therefore, to be regarded in an illustrative rather than a restrictive sense.