Abstract:
Provided is a stent pusher assembly for positioning a ureteral stent, the stent pusher assembly having an inner and outer stent pusher. The stent pusher assembly positions the ureteral stent in a patient&#39;s kidney and bladder without a bladder fixing portion of the stent entering a ureteral passage-way, thereby minimizing irritation to the patient.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/657,238 filed Jun. 8, 2012, which is hereby incorporated herein by reference. 
     
    
     FIELD OF INVENTION 
       [0002]    The present invention relates generally to implantable medical devices, and more particularly to a stent insertion assembly for inserting a ureteral stents. 
       BACKGROUND 
       [0003]    The urinary tract has a pair of kidneys that connect to a bladder by ureteral passageways, and a urethra that extends from the bladder to the exterior of a patient. Urine is made by the kidneys, passed through the ureteral passageway, stored in the bladder and ultimately voided from the urethra. A urinary sphincter is positioned around the urethra near the base of the bladder to control the flow of urine from the bladder. 
         [0004]    The ureteral passageways normally allow urine to pass from the kidney to the bladder by peristalsis. When the bladder fills with urine, the bladder compresses a segment of the ureteral passageway that passes through a wall of the bladder to prevent urine from going backwards from the bladder into the kidney. These passageways can become blocked by tumors or kidney stones thereby preventing normal urine flow, and the resulting high pressure within the kidneys can cause pain to the patient. To reopen a blocked ureteral passageway, a ureteral stent can be positioned in the patient. The stent holds the blockage in the passageway open, for example to allow a small kidney stone to pass. This enables urine to flow from the kidney into the bladder, reduces kidney pressure, and reduces pain of the patient. 
       SUMMARY OF INVENTION 
       [0005]    The present invention provides a stent pusher assembly for positioning a ureteral stent, the stent pusher assembly having an inner and outer stent pusher. The stent pusher assembly positions the ureteral stent in a patient&#39;s kidney and bladder without a bladder fixing portion of the stent entering a ureteral passageway, thereby minimizing irritation to the patient. 
         [0006]    According to one aspect of the invention, a method for positioning a ureteral stent in a kidney, ureteral passageway and bladder of a patient using a stent pusher assembly is provided. The stent pusher assembly has an inner and outer pusher and the ureteral stent includes a bladder portion configured to be positioned in the bladder, a kidney portion configured to be positioned in the kidney and the ureteral passageway, and at least one tether coupled to the bladder portion and the kidney portion. The method includes advancing a guidewire into the bladder, the ureteral passageway and the kidney, advancing the kidney portion and bladder portion over the guidewire, advancing the outer pusher over the guidewire, advancing the outer pusher along the guidewire until a second end of the outer pusher abuts a first end of the bladder portion, advancing the outer pusher towards the kidney to advance the bladder portion and kidney portion until the kidney portion is substantially positioned in the ureteral passageway, advancing the inner pusher over the guidewire, through a lumen of the outer pusher and through a lumen of the bladder portion until a second end of the inner pusher abuts a second end of the kidney portion, and advancing the inner pusher towards the kidney to advance the kidney portion such that the second end of the kidney portion is disposed in the ureteral passageway and a first end of the kidney portion is disposed in the kidney. 
         [0007]    The kidney portion and bladder portion are in respective restrained shapes when the guidewire extends through the kidney portion and bladder portion. 
         [0008]    The method further includes withdrawing the guidewire from the first end of the kidney portion to allow the first end to move to its unrestrained shape to secure the kidney portion in the kidney, and withdrawing the guidewire, inner pusher and outer pusher from the bladder portion to allow the bladder portion to move to its unrestrained shape to prevent the bladder portion from migrating into the ureteral passageway. 
         [0009]    Advancing the outer pusher towards the kidney until the kidney portion is substantially positioned in the ureteral passageway includes advancing the outer pusher until a portion of the kidney portion is positioned in the bladder and a majority of the kidney portion is positioned in the ureteral passageway. 
         [0010]    The outer pusher has an axial length less than an axial length of the inner pusher. 
         [0011]    An outer diameter of the inner pusher is equal to or greater than an outer diameter of the kidney portion to allow the inner pusher to advance the kidney portion without entering a lumen of the kidney portion. 
         [0012]    An inner diameter of the bladder portion is greater than an outer diameter of the kidney portion to allow the inner pusher having an outer diameter equal to or greater than the outer diameter of the kidney portion to be advanced through the bladder portion. 
         [0013]    According to another aspect of the invention, a pusher assembly for positioning a ureteral stent in a kidney, ureteral passageway and bladder of a patient is provided. The pusher assembly includes an inner stent pusher including a body having a lumen and a handle member coupled to a first end of the body, and an outer stent pusher including a body having a lumen and a handle member coupler to a first end of the body, wherein the body of the inner stent pusher has an axial length greater than an axial length of the body of the outer stent pusher, and wherein the body of the inner stent pusher has an outer diameter that is less than an inner diameter of the body of the outer stent pusher to allow the inner stent pusher to move through the lumen of the outer stent pusher during placement of the ureteral stent. 
         [0014]    The handle member of the inner stent pusher acts as a stop to prevent the first end of the body of the inner stent pusher from entering the lumen of the outer stent pusher during placement of the ureteral stent. 
         [0015]    The pusher assembly further includes a guidewire configured to extend through the lumen in the inner stent pusher. 
         [0016]    The pusher assembly is provided in combination with the ureteral stent. 
         [0017]    The ureteral stent includes a bladder portion configured to be positioned in the bladder, a kidney portion configured to be positioned in the kidney and the ureteral passageway, and at least one tether coupled to the bladder portion and the kidney portion. 
         [0018]    The bladder portion is biased in an unrestrained position. 
         [0019]    The guidewire is configured to extend through the bladder portion during placement of the stent to place the bladder portion in a restrained position. 
         [0020]    The bladder portion is substantially straight when in the restrained position and curved when in the unrestrained position. 
         [0021]    The kidney portion has a resilient fixing portion configured to be positioned in the kidney and a ureter portion configured to be positioned in the kidney and the ureteral passageway to place the ureteral passageway in an open state, the resilient fixing portion being biased in an unrestrained position. 
         [0022]    The guidewire is configured to extend through the kidney portion during placement of the stent to place the resilient fixing portion in a restrained position. 
         [0023]    The resilient fixing portion is substantially straight when in the restrained position and curved when in the unrestrained position 
         [0024]    The bladder portion and the fixing portion are movable between a restrained position when being positioned in the bladder and kidney by the pusher assembly and the unrestrained position when positioned in the bladder and kidney. 
         [0025]    An outer diameter of the inner stent pusher is equal to or greater than an outer diameter of the kidney portion to allow the inner pusher to advance the kidney portion without entering a lumen of the kidney portion. 
         [0026]    An inner diameter of the bladder portion is greater than an outer diameter of the kidney portion to allow the inner pusher having an outer diameter equal to or greater than the outer diameter of the kidney portion to be advanced through the bladder portion. 
         [0027]    The foregoing and other features of the invention are hereinafter described in greater detail with reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]      FIG. 1  is a schematic view of an exemplary stent positioned in a patient; 
           [0029]      FIG. 2  is a schematic view of the exemplary stent of  FIG. 1 ; 
           [0030]      FIG. 3  is a fragmentary cross-sectional view of an exemplary stent pusher assembly and a guidewire according to the invention; 
           [0031]      FIG. 4  is a schematic view of a guidewire being inserted into the patient; 
           [0032]      FIG. 5  is a schematic view of the stent assembly being positioned in the patient by the stent pusher assembly; 
           [0033]      FIG. 6  is another schematic view of the stent assembly being positioned in the patient by the stent pusher assembly; 
           [0034]      FIG. 6A  is a schematic view of a blown-up portion of  FIG. 6 . 
           [0035]      FIG. 7  is still another schematic view of the stent assembly being positioned in the patient by the stent pusher assembly; 
           [0036]      FIG. 7A  is a schematic view of a blown-up portion of  FIG. 7 . 
           [0037]      FIG. 8  is a schematic view of a kidney with a kidney portion of the stent assembly inserted therein; and 
           [0038]      FIG. 9  is a schematic view of a ureteral passageway and bladder with a bladder portion of the stent assembly inserted therein. 
       
    
    
     DETAILED DESCRIPTION 
       [0039]    The principles of the present application have particular application to ureteral stent pusher assemblies for positioning ureteral stents and thus will be described below chiefly in this context. It will, of course, be appreciated and also understood that the principles of the application may be useful in other medical applications, for example for the placement of other stents. 
         [0040]    Referring now in detail to the drawings and initially to  FIG. 1 , a pair of kidneys  10  and  12  and a bladder  14  of a patient are shown. The kidneys  10  and  12  are connected to the bladder  14  by respective ureteral passageways  16  and  18 . The ureteral passageways  16  and  18  each include a portion extending into the bladder  14  that moves from an uncompressed state to compressed state and in a normal state only allows urine to pass from the kidneys  10  and  12  to the bladder  14  with the help of peristalsis of the ureter. When one of the passageways  16  and  18  becomes blocked, for example by swelling near one of the kidneys  10  and  12  or blockage from a kidney or ureteral stone, a ureteral stent may be positioned in the kidney  10 ,  12 , ureteral passageway  16 ,  18  and bladder  14  to assist in opening the passageway  16 ,  18  to aid in the flow of urine. The ureteral stent may be any suitable ureteral stent, such as the type disclosed in U.S. Patent Application No. 61/657,228, which is hereby incorporated herein by reference. 
         [0041]    Turning now to  FIG. 2 , the ureteral stent, referred to herein by reference numeral  50 , includes a bladder portion  52  configured to be positioned in the bladder  14 , a kidney portion  54  configured to be positioned in the kidney  10  and ureteral passageway  16 , and one or more tethers  56  coupling the bladder portion  52  to the kidney portion  54 . When in position in the bladder  14  the bladder portion  52  is in an unrestrained shape. When unrestrained the bladder portion  52  is a flexible tube in the form of a flexible loop to prevent the bladder portion  52  from migrating into the ureteral passageway. When being positioned using a pusher assembly, the bladder portion  52  is in a substantially straightened restrained shape. 
         [0042]    The bladder portion  52  includes one or more openings  60  in a wall of the bladder portion  52  that allow fluid to flow in/out of the bladder portion  52 . The bladder portion  52  also includes at least one radiopaque element, and in the Illustrated embodiment radiopaque bands  62  and  64  near first and second ends  66  and  68  of the bladder portion  52 , respectively. The bladder portion  52  additionally includes a tip or ring  70  at the first end  66  having a stiffness greater than a stiffness of the rest of the bladder portion  52  to assist in the insertion of the stent  50 , as will be discussed below. 
         [0043]    Similar to the bladder portion  52 , the kidney portion  54  has a resilient fixing portion  76  that when in position in the kidney  10  is in an unrestrained shape. When unrestrained the resilient fixing portion  76  is a flexible tube in the form of a flexible loop to secure the kidney portion  54  in the kidney  10 . When being positioned using the pusher assembly, the kidney portion  54  is in a substantially straightened restrained shape. 
         [0044]    The kidney portion  54  also has a ureter portion  78 , which may be a flexible tubular portion, configured to extend from the resilient fixing portion  76  in the kidney  10  into the ureteral passageway  16  to keep the passageway open, for example when there is swelling between the kidney and passageway. The kidney portion  54  also includes one or more openings  80  in a wall of the kidney portion that allow fluid to flow to flow in/out of the kidney portion, and at least one radiopaque element such as radiopaque bands  82  and  84  near first and second ends  86  and  88  of the kidney portion, respectively. 
         [0045]    As noted above, the bladder portion  52  and kidney portion  54  are coupled together by one or more tethers  56 . The tethers have a thin flexible cross-section such that the ureter muscles at the ureter opening  20  can clamp around the tethers and create a urine tight seal. The tethers may be any suitable tether, such as a suitable suture made of cotton, a polymer such as nylon, etc. As shown in  FIGS. 1 and 2 , the tethers  56  are coupled to the second end  68  of the bladder portion and the second end  88  of the kidney portion in any suitable manner, for example by adhesive, knotting, etc. When the stent  50  is positioned in the body of the patient, the one or more tethers  56  extend from the ureteral passageway  16 , through the ureter orifice  20  and into the bladder  14 . 
         [0046]    To position the ureteral stent  50 , an exemplary stent pusher assembly  100  is provided. As shown in  FIG. 3 , the stent pusher assembly  100  includes an inner stent pusher  102  and an outer stent pusher  104  surrounding the inner stent pusher. In the illustrated embodiment, the inner stent pusher  102  is concentric with the outer stent pusher  104 , although it will be appreciated that the inner stent pusher  102  may be disposed in the outer stent pusher  104  in any suitable manner. The inner and outer stent pushers  102  and  104  may include radiopaque elements along their length to assist an operator in positioning the stent  50 , and/or tracking markers along their length. 
         [0047]    The inner and outer stent pushers  102  and  104  each have body  103  and  105  having a lumen  106 ,  108  extending respectively through the bodies  103  and  105 . The bodies  103  and  105  of the inner and outer stent pushers  102  and  104  may be tubular members, although it will be appreciated that the bodies of the inner and outer stent pushers may have any suitable shape and may have different shapes from one another. 
         [0048]    The body  103  of the inner stent pusher  102  has an axial length greater than an axial length of the body  105  of the outer stent pusher  104 , and the body  103  is sized such that an outer diameter is less than an inner diameter of the body  105  of the outer stent pusher  104  to allow the inner stent pusher  102  to move through the outer stent pusher  104  during placement of the stent  50 . The body  103  of the inner stent pusher  102  is also sized such that its inner diameter is greater than a diameter of a guidewire  110 , which may be any suitable guidewire, to allow the guidewire  110  to move through to the inner stent pusher  102  during placement of the stent  50 . 
         [0049]    The inner stent pusher  102  also includes a handle member  112  coupled to a first end  114  of a body  103  of the inner stent pusher  102 . The handle member  112 , which remains outside the patient, acts as a stop to prevent the first end  114  of the body  103  from entering the outer stent pusher  104 . The handle member  112  is coupled to the body  103  in any suitable manner, such as adhesive, and may be made of any suitable material, such as plastic. Alternatively, the handle member  112  may be integrally formed with the body  103 . To allow the guidewire  110  to extend out of the first end  114  of the body  103  of the inner stent pusher  102 , the handle member  112  includes a through-hole  118  having a diameter equal to or greater than the inner diameter of the body  103 . 
         [0050]    Similar to the inner stent pusher  102 , the outer stent pusher  104  includes a handle member  120  coupled to a first end  122  of the body  105  of the outer stent pusher  104 . The handle member  120 , which remains outside the patient, acts as a stop to prevent the first end  122  from entering the patient. The handle member  120  is coupled to the first end  122  of the body  105  in any suitable manner, such as adhesive, and may be made of any suitable material, such as plastic. Alternatively, the handle member  120  may be integrally formed with the body  105 . To allow the guidewire  110  and inner stent pusher  102  to extend out of the first end  122  of body  105 , the handle member  120  includes a through-hole  126  having a diameter equal to or greater than the inner diameter of the body  105 . Additionally, the handle members  112  and  120  include coupling portions, such as male and female luer lock members, to allow the handle members to be coupled together. 
         [0051]    Referring now to  FIGS. 4-7A , an exemplary method of delivering the stent  50  using the pusher assembly  100  will be described in detail. As shown in  FIG. 4 , the method begins with the guidewire  110  being inserted through the bladder  14 , into the ureteral passageway  16  and into the kidney  10 . Then, the kidney portion  54  and bladder portion  52  of the stent  50  are advanced over the guidewire  110  outside the patient. It will be appreciated, however, that the kidney portion  52  and the bladder portion  54  can be advanced over the guidewire  110  prior to the guidewire  110  being positioned. Next, the outer stent pusher  104  is advanced over and along the guidewire  110  until a second end  124  of the outer stent pusher  104  abuts the tip  70  at the first end  66  of the bladder portion  52 . As the outer stent pusher  104  is advanced, the second end  124  abuts the tip  70  at the first end  66  and the second end  68  of the bladder portion  52  abuts the second end  88  of the kidney portion  54  as shown in  FIG. 5 . 
         [0052]    The outer stent pusher  104  is advanced into the patient, thereby advancing the stent  50  into the patient until the bladder portion  52  is positioned or substantially positioned in the bladder  14  and the kidney portion  54  is substantially positioned in the ureteral passageway  16 , with the second end  88  of the kidney portion  52  being positioned in the bladder  14  near the ureter orifice  20 , as shown in  FIGS. 6 and 6A . The outer stent pusher  104  and the kidney portion  54  may be guided fluoroscopically by the radiopaque elements on the stent  50  and/or one the outer stent pusher  104  and/or by the tracking markers on the outer stent pusher. Additionally or alternatively, the stent  50  may be positioned using a suitable endoscope. 
         [0053]    Next, as shown in  FIGS. 7 and 7A , the inner stent pusher  102  is advanced over the guidewire  110 , through the lumen  108  and through a lumen of the bladder portion  52  until a second end  116  of the inner stent pusher  102  abuts the second end  88  of the kidney portion  54 . To allow the inner stent pusher  102  to advance the kidney portion  54  without inadvertently entering the lumen of the kidney portion  54 , the outer diameter of the inner stent pusher  102  is equal to or greater than the outer diameter of the kidney portion  54 . Additionally, as should be appreciated, the inner diameter of the bladder portion  52  is greater than the outer diameter of the kidney portion  54  to allow the inner stent pusher  102  having an outer diameter equal to or greater than the diameter of the kidney portion  54  to be advanced through the bladder portion  52 . 
         [0054]    The inner stent pusher  102  is then advanced to advance the kidney portion  54  further into the ureteral passageway  16 . The kidney portion  54  is advanced until the second end  88  of the kidney portion  54  is positioned in the ureteral passageway  16  and the first end  86  of the kidney portion  54 , i.e. the fixing portion  76 , is disposed in the kidney  10 . As should be appreciated, while the guidewire  110  is disposed within the kidney portion  54 , the kidney portion remains in the restrained shape. After the kidney portion  54  has been positioned in the kidney  10  and ureteral passageway  16  as shown in  FIGS. 6 and 7A , the guidewire  110  is withdrawn from the first end  86  of the kidney portion  54  to allow the fixing portion  76  to return to its unrestrained shape, as shown in  FIG. 8 . When unrestrained, the fixing portion secures the kidney portion  54  in the kidney  10 , and the ureter portion  78  extends from the kidney  10  into the ureteral passageway  16  to keep the passageway open. 
         [0055]    The guidewire  110 , inner stent pusher  102 , and outer stent pusher  104  are then withdrawn from the patient, either separately, simultaneously or in any suitable order, to allow the bladder portion  52  to return to its unrestrained shape, i.e. the flexible loop as shown in  FIG. 9 . When unrestrained, the flexible loop prevents the bladder portion  52  from migrating into the ureteral passageway to reduce irritation of the ureter orifice  20 . 
         [0056]    Although described as being advance over the guidewire  110  after the outer stent pusher  104  has been used to advance the kidney portion  54 , it will be appreciated that the inner stent pusher  102  may be advanced over the guidewire  110  at the same time as the outer stent pusher  104  and advanced into the patient at the same time or later than the outer stent pusher  104 . 
         [0057]    Although the invention has been shown and described with respect to a certain embodiment or embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In particular regard to the various functions performed by the above described elements (components, assemblies, devices, compositions, etc.), the terms (including a reference to a “means”) used to describe such elements are intended to correspond, unless otherwise indicated, to any element which performs the specified function of the described element (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary embodiment or embodiments of the invention. In addition, while a particular feature of the invention may have been described above with respect to only one or more of several illustrated embodiments, such feature may be combined with one or more other features of the other embodiments, as may be desired and advantageous for any given or particular application.