Patent Publication Number: US-2021169520-A1

Title: Endoscopic ultrasound guided access needle

Description:
PRIORITY CLAIM 
     The present disclosure claims priority to U.S. Provisional Patent Application Ser. No. 62/944,725 filed Dec. 6, 2019; the disclosure of which is incorporated herewith by reference. 
    
    
     FIELD 
     The present disclosure relates to an endoscopic needle and, in particular, an endoscopic ultrasound (EUS) guided access needle. 
     BACKGROUND 
     A hollow needle may be used in an EUS-guided procedure to access target anatomy, e.g. an intestinal lumen, and introduce a guidewire through the needle lumen into the target anatomy to, e.g., guide a stenting procedure. The guidewire, when it is extended distally from the needle tip, may be bent in multiple directions and at different points such that, when the physician attempts to retract the guidewire into the needle, the guidewire may catch on the sharp edge or tip of the needle, potentially stripping the guidewire. The stripped material may be left behind in the anatomy and/or may expose the metal wire core of the guidewire and create an electrical safety hazard. 
     SUMMARY 
     The present disclosure relates to an access needle which includes a hollow shaft having a lumen sized and shaped to slidably receive a guidewire therein and having a distal end including an angled surface extending proximally and transversely from a sharpened distal-most tip of the shaft to a beveled smoothed area of the shaft proximal and transverse to the sharpened tip, the beveled smoothed area being positioned to slidably engage a guidewire extended distally out the distal end of the needle so that, as the guidewire is retracted proximally into the needle, the beveled smoothed area slidably engages the guidewire to minimize abrasion to the guidewire. 
     In an embodiment, the distal end of the shaft includes sharp cutting surfaces extending proximally from the sharpened tip, the beveled smoothed area being positioned so that, as a guidewire extending out of the distal end of the needle along a curve is retracted into the needle in a desired orientation relative to the needle, a surface of the guidewire which forms a radially inner surface along the curve contacts the beveled smoothed area of the needle. 
     In an embodiment, wherein the distal end of the shaft includes a first sharp cutting surface extending from the distal-most tip to a first transition and a second sharp cutting surface extending from the first transition to a second transition, the first sharp cutting surface extending at a first angle relative to a longitudinal plane of the shaft at the distal-most tip and curving to a second angle relative to the longitudinal plane of the shaft at the first transition, the second cutting surface having a third angle relative to the longitudinal plane of the shaft. 
     In an embodiment, the distal end of the shaft includes a third sharp cutting surface extending from the distal-most tip to a third transition and a fourth sharp cutting surface extending from the third transition to a fourth transition, the third sharp cutting surface extending at a fourth angle relative to a longitudinal plane of the shaft at the distal-most tip and curving to a fifth angle relative to the longitudinal plane of the shaft at the third transition, the fourth sharp cutting surface extending at a sixth angle relative to the longitudinal plane of the shaft. 
     In an embodiment, the first and second sharp cutting surfaces are substantially symmetric relative to a midplane of the needle with respect to the third and fourth sharp cutting surfaces. 
     In an embodiment, the first angle is in a first range of 0-10 degrees, the second angle is in a second range of 20-50 degrees and the third angle is in a third range of 10-30 degrees. 
     In an embodiment, the beveled smoothed area is defined by a U-shaped surface having a midpoint proximal and transverse to the sharpened tip, the U-shaped surface having a curvature at the midpoint parallel to a transverse plane of the shaft. 
     In an embodiment, the beveled smoothed area includes an outer bevel on an outer surface of the shaft and an inner bevel on an inner surface of the shaft. 
     In an embodiment, the shaft includes a feature extending along a distal portion thereof configured to mechanically engage a corresponding feature of a guidewire inserted therein to maintain the guidewire in a desired rotational orientation relative to the needle. 
     In an embodiment, the feature of the shaft includes a slot extending along a portion of a length of the needle configured to receive a tab extending radially from the guidewire. 
     The present disclosure also relates to an access needle assembly which includes an anchoring guidewire including a first orienting feature; and an access needle including a hollow shaft having a lumen sized and shaped to slidably receive the guidewire therein and having a distal end including a cut surface extending proximally and transversely from a sharpened distal-most tip of the shaft to a beveled smoothed area of the shaft proximal and transverse to the sharpened tip, the beveled smoothed area being positioned to slidably engage the guidewire extended distally out the distal end of the needle so that, as the guidewire is retracted proximally into the needle, the beveled smoothed area slidably engages the guidewire to minimize abrasion to the guidewire, the access needle further including a second orienting feature extending along a distal portion thereof configured to mechanically engage the first orienting feature to maintain the guidewire in a desired rotational orientation relative to the access needle. 
     In an embodiment, the second orienting feature includes a slot extending along a portion of a length of the needle and the first orienting feature includes a tab projecting outward from the guidewire. 
     In an embodiment, the tab has a ramped section to facilitate engagement of the shaft and the tab so that, when the needle is retracted proximally over the guidewire, the ramp engages a distal end of the slot so that the tab is folded over and passes through the needle until the tab has emerged from the distal end of the needle. 
     In an embodiment, the second orienting feature includes a slot extending along a portion of a length of the needle and the first orienting feature includes a tab projecting outward from the guidewire, the tab being configured to be severed from the guidewire as the needle is withdrawn proximally over the guidewire. 
     In an embodiment, the guidewire has a nitinol core with a polymer coating. 
     The present disclosure further relates to a method which includes extending a guidewire distally out of a distal end of an access needle, the access needle including a hollow shaft having a lumen sized and shaped to slidably receive the guidewire therein, the distal end of the needle including a cut surface extending proximally and transversely from a sharpened distal-most tip of the shaft to a beveled smoothed area of the shaft proximal and transverse to the sharpened tip; retracting the guidewire proximally back into the needle so that the beveled smoothed area slidably engages the guidewire to minimize abrasion to the guidewire. 
     In an embodiment, the method further includes rotating the guidewire relative to a longitudinal axis of the access needle to position a curve of the guidewire so that a portion of the guidewire surface forming a radially inner part of the curve contacts the beveled smooth area as the guidewire is retracted into the needle. 
     In an embodiment, the guidewire is rotated under ultrasound guidance so that the curved distal end curves away from a side of the needle on which the distal tip of the needle is formed. 
     In an embodiment, the distal end of the shaft includes sharp cutting surfaces extending proximally from the sharpened tip, the beveled smoothed area being positioned so that, as a guidewire extending out of the distal end of the needle along a curve is retracted into the needle in a desired orientation relative to the needle, a surface of the guidewire which forms a radially inner surface along the curve contacts the beveled smoothed area of the needle. 
     In an embodiment, the beveled smoothed area is defined by a U-shaped surface having a midpoint proximal and transverse to the sharpened tip, the U-shaped surface having a curvature at the midpoint parallel to a transverse plane of the shaft. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows an access needle having a distal end with a sharp distal tip for puncturing a target anatomy and a plurality of machined surfaces shaped for a smooth advancement and retraction of a guidewire. 
         FIG. 2  shows the access needle of  FIG. 1  with a needle coordinate system. 
         FIG. 3  shows a cross section of the distal end of the access needle of  FIG. 1  at a first transition. 
         FIG. 4  shows a cross section of the distal end of the access needle of  FIG. 1  at a second transition. 
         FIG. 5  shows an exemplary guidewire for use with the access needle of  FIG. 1 . 
         FIG. 6  shows a beveled portion of the distal end of the access needle of  FIG. 1 . 
         FIG. 7  shows the access needle of  FIG. 1  with the exemplary guidewire of  FIG. 5  extended therefrom. 
         FIG. 8  shows a side view of the access needle and guidewire of  FIG. 7  where the guidewire engages the inner bevel of the access needle. 
         FIG. 9  shows a section view of the access needle and guidewire of  FIG. 8 . 
         FIG. 10  shows a side view of the access needle and guidewire of  FIG. 7  where the guidewire engages the outer bevel of the access needle. 
         FIG. 11  shows an access needle with a longitudinal slot and a guidewire with an alignment tab according to a second exemplary embodiment. 
         FIG. 12  shows a slanted edge of the alignment tab of  FIG. 11 . 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure 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 exemplary embodiments describe devices having a needle with smoothed surfaces for ease of advancing or retracting a guidewire without damaging the guidewire. The exemplary devices may include means for aligning the guidewire within the needle so that the guidewire is caused to interact with the smoothly ground surfaces instead of sharper edges defined in the needle tip. 
       FIG. 1  shows a distal end of an access needle  100  having a distal end  102  with a sharp distal tip  104  for puncturing target anatomy and a plurality of machined surfaces shaped to facilitate smooth advancement and retraction of a guidewire  150  out of and back into the distal end  102 . The needle  100  is formed as a hollow shaft  124  sized and shaped to slidably receive a guidewire  150  so that it may pass therethrough to be extended distally from the distal tip  102  as would be understood by those skilled in the art. The needle  100  may be formed from any suitable material, such as a nitinol alloy, a cobalt-chromium alloy, stainless steel, etc. The guidewire  150  may be configured to bend multiple times over a tortuous path which an insertion device such as an endoscope has traversed via, for example, a natural body lumen to access a target tissue structure. Additionally, the guidewire may be an anchoring guidewire having a shaped distal end that enables anchoring of tissue. 
     In the present embodiment, as shown in  FIG. 5 , the guidewire  150 , in its unconstrained state, has a curved end  152  pre-formed to assume a curved shape having two curved sections  154 , each curving through an angle of up to approximately ˜135 degrees in the same curvature direction such that, when unconstrained, a distal tip  156  of the guidewire  150  points in a direction angled up to approximately ˜270 degrees relative to the longitudinal axis of a portion of the guidewire  150  proximal to the curved end  152 . However, guidewires having other curvatures may be used. As would be understood by those skilled in the art, the guidewire  150  is sufficiently flexible so that the curved end  152  can conform to the path along which the interior of the hollow shaft  124  extends when one or both of the curved sections  154  are withdrawn into the shaft  124 . The guidewire  150  may have, for example, a nitinol core covered in a polymer coating. 
     When the curved end  152  of the wire  150  is extended distally out the distal tip  102  of the needle  100 , i.e., when the curved end  152  is not constrained by the inner diameter of the shaft  124 , the distal tip  156  of the guidewire  150  reverts to its unconstrained state. However, the guidewire  150  as described herein is used for exemplary purposes only, and any guidewire may be used with the access needle  100 . For example, the guidewire may be curved at different points in different curvature directions and/or have more or fewer curves. Those skilled in the art will understand that guidewires with significant curvature at their distal ends are the most likely to be damaged upon withdrawal into a conventional needle as a radially inner side of the curved end is dragged over the sharp end of the needle to re-enter the lumen of the needle. As would be understood by those skilled in the art, guidewires with pre-formed curved distal ends are often used as anchoring guidewires. That is, this type of guidewire may be inserted into a target structure via a needle or other insertion device that holds the curved distal end substantially straight. Furthermore, the guidewire may be of any desired construction. 
     When the target structure has been accessed, the guidewire  150  may be advanced distally out of the needle  100  (or the needle  100  may be withdrawn proximally over the guidewire  150 ) to free the curved end  152  to assume its curved configuration. In this curved state, the guidewire  150  is no longer able to pass proximally out of the aperture through which it entered the target tissue structure and so is anchored within the target structure. The needle  100  may then be withdrawn proximally over the guidewire  150  which may then be used to provide a pathway for the insertion of other treatment devices (e.g., stents, etc.) over the guidewire  150  into the target structure. 
     When the procedure is completed, the needle  100  is again advanced distally over the guidewire  150  into the target structure. At this point, the guidewire  150  is withdrawn proximally into the needle  100  during which operation, contact between the walls of the lumen of the needle  100  and the guidewire  150  constrain the guidewire to return to the path of the lumen of the needle  100 . The needle  100  with the guidewire received therein may then be withdrawn from the body. The needles of the present embodiments are directed to minimizing or eliminating damage to guidewires during their withdrawal proximally into the lumen of the needle. 
     The opening at the distal end  102  of the needle  100  is defined by a plurality of machined surfaces cut into the hollow shaft  118 . The opening is defined by a first segment  106 , a second segment  110  and a third segment  116 . The segments are defined in the manner described below, relative to a needle coordinate system with a longitudinal axis A, a first transverse axis B and a second transverse axis C, the axes defining a first longitudinal plane AC, a second longitudinal plane BC and a transverse plane AB, as shown in  FIG. 2 . 
     The distal end  102  has a sharp, tissue-penetrating, distal tip  104  at the origin of the needle coordinate system, i.e. the distal-most point of the access needle  100 . In this embodiment, the opening at the distal end  102  of the needle  100  is substantially symmetrical with respect to the distal tip  104  so that the first, second and third segments on either side of the AC plane are mirror images of one another. The first segment  106  is defined by a first cut extending proximally and transversely from the distal tip  104  into the cylindrical wall of the needle  100 . 
     The first cut begins at the distal tip  104  at a first angle relative to the BC plane, the first angle being between approximately 0 degrees and 10 degrees, i.e., substantially parallel or nearly parallel to the BC plane, and gradually steepens to a second angle relative to the BC plane at a first transition  108 , as may be seen in  FIG. 1  and more clearly in  FIG. 8 . For example, the second angle, i.e. the angle of the cut of the first segment  106  relative to the BC plane at the first transition  108 , may be between approximately 20 degrees and 50 degrees. Thus, the first cut results in a curved first segment  106  that progresses from a shallow distal-most angle nearly parallel to a longitudinal axis of the needle  100  to a deeper angle relative to the longitudinal axis at the first transition  108 . As noted above, the first cut of this embodiment is substantially symmetrical on both sides of the distal tip  104 . 
     The second segment  110  is defined by a second cut extending proximally and transversely from the first transition  108  to a second transition  112  and a third cut extending only proximally, i.e., substantially parallel to the BC plane, from the second transition  112  to a third transition  114 . The second cut is at a third angle relative to the BC plane, the third angle remaining substantially constant from the first transition  108  to the second transition  112 . For example, the third angle, i.e. the angle of the second cut relative to the BC plane, may be between approximately 10 degrees and 30 degrees. It is noted that the second and third cuts are reflected on both sides of the needle  100 . The cross section of the needle  100  at the first transition  108  is shown in  FIG. 3 , and the cross section of the needle  100  at the second transition  112  is shown in  FIG. 4 , which is the same as the cross section of the needle  100  at the third transition  114 . 
     As those skilled in the art would understand, the first, second and third angles may differ from the exemplary angles provided above without departing from the scope of the invention. The shape of the first and second segments  106 ,  110  is configured for the puncturing and/or acquisition of tissue from a target site in a living body. Thus, the edges of the needle  100  resulting from the first, second and third cuts are left sharp. 
     The third segment  116  is defined by a fourth cut extending proximally and transversely from the third transition  114 . The fourth cut is parallel to the A axis throughout the cut, with a varying angle relative to the AC plane, forming a substantially U-shaped cavity in the third segment  116 . The fourth cut begins at the third transition  114  at a fourth angle relative to the AC plane, which may begin at approximately ˜0 degrees, with the angle gradually increasing to ˜90 degrees until the fourth cut reaches a midpoint  118 , i.e. the furthest proximal point in the cut distal end  102 . The angle of the fourth cut at the midpoint is substantially parallel to the AB plane and orthogonal to the AC plane. It is noted that the fourth cut is substantially symmetrical with respect to the AC plane. The fourth cut, in the absence of any further machining, would result in sharp edges on the inner and outer surfaces of the shaft  124 . 
     During an endoscopic procedure, such as a procedure to insert a stent or a rendezvous procedure, a guidewire such as the guidewire  150  shown in  FIG. 5  may be introduced into a target anatomical space and advanced distally out of the needle  100 . This allows the guidewire  150  to revert to its unconstrained bent configuration anchoring it in the target space. After the procedure has been completed and it is desired to withdraw the guidewire  150  from the body, the user inserts the needle  100  over the guidewire  150  until the distal tip  104  of the needle  100  enters the target space. The user then withdraw the curved end  152  of the guidewire  150  proximally back into the distal end  102  of the needle  100 . As indicated above, if the guidewire  150  was drawn back into the needle  100  in such a manner that the guidewire  150  was dragged over a sharp tissue cutting surface the guidewire  150  may be damaged. 
     To mitigate the aforementioned risk, in an exemplary embodiment the needle  100  is machined further after the first, second, third and fourth cuts are made. As shown in  FIG. 6 , the distal end  102  has an outer bevel  120 , smoothing the sharp edge on the outer surface of the third segment  116 , and an inner bevel  122 , smoothing the sharp edge on the inner surface of the third segment  116  to minimize the effects of contact between these surfaces and the guidewire  150 . A radius of curvature for both the outer bevel  120  and the inner bevel  122  may range from approximately 0″ to 0.010″. Furthermore, the outer bevel  120  and the inner bevel  122  each has a degree of curvature of approximately 45 degrees to avoid creating a new sharp edge. In another embodiment, the outer and inner bevel  120 ,  122  may be an outer radius and inner radius, an outer chamfer and inner chamfer, or an outer fillet and an inner fillet. Moreover, the third segment  116  may have a combination of a bevel, radius, chamfer, and fillet (e.g. the sharp edge of the outer surface is a fillet and the sharp edge of the inner surface is a bevel). 
       FIG. 7  shows the needle  100  of  FIG. 1  with the guidewire  150 , the curved end  152  of the guidewire  150 , extending distally out the distal end  102 .  FIGS. 8-10  show an exemplary interaction of the guidewire  150  with the distal end  102  during retraction thereof. The guidewire  150  in this embodiment is curved around the B axis of the needle, ensuring that, as the guidewire  150  is withdrawn into the needle  100 , it is drawn across the surface defined in the third segment  116  of the distal end  102  and not over the sharper surfaces of the first and second segments  106 ,  110 , respectively. As may be seen in  FIG. 9 , the guidewire  150  is drawn over the smoothed inner bevel  122 , thus mitigating the risk of the guidewire  150  being stripped during the retraction. As may be seen in  FIG. 10 , when the radius of curvature of the guidewire  150  is small, the interaction between the guidewire  150  and the bevels  120 ,  122  increases, such that the guidewire  150  may also be drawn over the outer bevel  120 . 
     To bring a guidewire into contact only with beveled third segment  116 , rather than the sharp first or second segments  106 ,  110 , it must be ensured that the guidewire is properly aligned rotationally within the needle  100 . In other words, the curvature of the guidewire  150  during refraction must be oriented so that the curvature of the guidewire  150  extends generally within the AC plane and the guidewire  150  curves away from the side of the needle  100  on which the distal tip  104  is formed. If a guidewire has a more complex curvature (e.g., a curvature extending in more than one plane), the user may rotate the guidewire  150  or the needle  100  relative to the other under Ultrasonic visualization so that the segment that is currently entering the needle  100  is oriented in the AC plane as described above. Thus, the guidewire  150  will always contact the third segment  116  as it enters the needle  100 . 
     The needle  100  and the guidewire  150  may have features for enhancing their visualization under ultrasound guidance, such that the operating physician may ensure that the proper alignment of the needle  100  and guidewire  150  is achieved by monitoring the orientations of the elements. For example, the needle  100  and the guidewire  150  may be formed from echogenic materials. However, it is possible that refraction may occur without direct visualization. Thus, proper alignment of the elements may be ensured in an alternate manner. 
       FIGS. 11-12  show an access needle  200  having a longitudinal slot  204  in its hollow shaft  202 . The access needle  200  may be used in conjunction with a guidewire  250  having a tab  252  projecting radially outward (e.g., welded or coated onto the wire  250 ) that is sized and shaped to travel in the longitudinal slot  204  during distal advancement and proximal retraction of the guidewire  250  out of and into the needle  200 . The tab  252  is restricted from transverse motion by the slot  204 . In other words, interaction between the tab  252  and the slot  204  maintains the guidewire  250  in a selected rotational alignment relative to the access needle  200  throughout the procedure. 
     The slot  204 , in this embodiment, is closed at a distal end  206  of the needle  200 . However, in another embodiment, the slot  204  may be open at the distal end  206 . Thus, it may be ensured that the curvature of the guidewire  250  interacts only with the beveled portions of the needle  200 . Those skilled in the art will understand that this slot may be curved in a manner corresponding to the curvature of more complex guidewire shapes to ensure that a distal end of the guidewire  250  rotates into the desired alignment relative to the needle  200  at all times during the withdrawal of the guidewire  250  into the needle  200 . 
     In some procedures, the needle  200  is pulled proximally off the guidewire  250  after the guidewire  250  has been anchored in the target anatomy. The existence of the tab  252  could prevent such a withdrawal of the needle  200  if it is not designed to allow the needle  200  to pass thereover. As would be understood by those skilled in the art, the tab  252  may be designed so that it will snap off as the needle  200  is pulled proximally off the guidewire  250 . In another embodiment, the tab  252  may be designed to compress and pass through the distal end of the lumen of the needle  200  until it exits the distal end  206  of the needle  200 . The needle  200  may then be slid proximally off of the guidewire  250  and removed from the body. For example, the tab  252  may have a ramped section  254  that facilitates the folding over of a leading edge of the tab  252  as it reaches the distal end of the slot  204  so that the tab  252  folds over and is compressed into the lumen of the needle  200  as the tab  252  passes under the portion of the needle  200  distal to the distal end of the slot  204  as the needle  200  is drawn proximally over the guidewire  250 . 
     It will be appreciated by those skilled in the art that changes may be made to the embodiments described above without departing from the inventive concept thereof. It should further be appreciated that structural features and methods associated with one of the embodiments can be incorporated into other embodiments. It is understood, therefore, that this invention is not limited to the particular embodiment disclosed, but rather modifications are also covered within the scope of the present invention as defined by the appended claims.