United States Patent
`
`[19]
`
`[11}
`
`4,307,723
`
`
`Finney
`[45]
`Dec. 29, 1981
`
`[54] EXTERNALLY GROOVED URETERAL
`STENT -
`
`[75]
`Inventor:
`Roy F. Finney, Tampa, Fla.
`[731 Assignee Medical Engineering Corporation,
`Raeme, Wis.
`-
`[21] Appl. No“ 119365
`[22] Filed:
`Feb. 8, 1980
`
`'
`Related US. Application Data
`_
`‘
`.
`Contmuation-m-part 0f Ser. No. 894’273’ AP“ 7’ 1978’
`Pat, No' 4’212’304'
`'
`Int. (21.3 ............................................. A61M 25/00
`
`128/350 v, 348 R, 419 P
`,
`References Cited
`U.S. PATENT DOCUMENTS
`
`[631
`
`[51}
`[52]
`[58]
`
`[56]
`
`5/1913
`1,060,665
`2,043,630 6/ 1936
`2,118,631
`5/1938
`2,221,138 11/1940
`
`Beil ................................. 128/349 R
`Raiche .......
`128/349 B
`
`Wappler ........
`128/349 R
`Hendrickson ................... 128/349 R
`
`5/1943 Raiche ............................. 128/349 B
`2,320,157
`3,419,010 12/1968 Williamson .
`..... 128/350
`
`3,630,206 12/1971 Gingold ......
`. 128/349 B
`
`3,890,977
`6/1975 Wilson
`. 123/349 R
`2:13:31 132313 33:15:51..::._..........._.....::::: 153212
`‘ h d J A 1
`_
`,Primary Examiner—Ric ar
`.
`p ey
`Assistant Examiner—T. Brown
`Attorney, Agent, or Firm—Quarles & Brady
`[57]
`ABSTRACT
`_
`_
`.
`.
`The stent 15 an elongated, flexrble generally cylindrical
`member. One of the ends of the stent is closed and set in
`the form of a hook and the other end is set in the form
`of a hook with a long intermediate portion connecting
`the hook ends. The stent is provided with at least one
`longitudinally extending groove to provide a passage
`for fluid and a wire stylet. The stylet
`is used to
`straighten the curved ends so that the stent can be cys-
`toscopically inserted within the patient, the stylet being
`removed when the stent is properly positioned so that '
`upon removal the hooks will reform and prevent the
`stent from migrating.
`
`14 Claims, 8 Drawing Figures
`
`
`
`
`
`
`
`Lombard Exhibit 1011, p. 1
`
`Lombard Exhibit 1011, p. 1
`
`

`

`US. Patent
`
`Dec. 29, 1981
`
`4,307,723
`
` .
`
`Lombard Exhibit 1011, p. 2
`
`Lombard Exhibit 1011, p. 2
`
`

`

`1
`
`4,307,723
`
`EXTERNALLY GROOVED URETERAL STENT
`
`The present application is a continuation-impart of
`my earlier patent application Ser. No. 894,278 filed Apr.
`7, 1978 (Pat. No. 4,212,304) entitled “Ureteral Catheter
`Stent”.
`
`5
`
`2
`ureteral stents in that it does not migrate and it resists
`encrustation extremely well in noninfected urine, espe-
`cially when the stent is formed of a silicone elastomer.
`However, even such stents of silicone elastomer can
`become encrusted with various materials found in urine
`in the presence of infections.
`Certain bacteria which commonly cause urinary tract
`infections (proteus and pseudomonas) can cause severe
`encrustation. These organisms produce an enzyme
`which can break down urea, a normal component of all
`urine into ammonia. Therefore, they are called “urea
`'splitting” bacteria. Ammonia makes the normally acid
`urine highly alkaline. As the calcium salts in the urine
`are much more soluble and are often near saturation in
`the normal acid urine, these salts, especially calcium
`phosphate, precipitate out in the alkaline urine caused
`by the urea splitting organisms. In the face of a urinary
`tract infection, the stents may have calcium phosphate
`encrusted within, which completely obstructs the
`lumen of the stent thus interfering with urinary drain—
`age.
`
`SUMMARY OF THE INVENTION
`
`It is the general object of the present invention to
`disclose a ureteral catheter stent which is easily intro-'
`duced both cystoscopically and during open surgery,
`and which once in place both resists migration and
`resists plugging due to encrustation.
`_
`It is a still further object to disclose a stent which ha
`at least one longitudinal groove on its external surface
`through which fluid can drain.
`I have now discovered that a ureteral stent which has
`at least one external longitudinal extending groove to
`promote urine drainage around the stent will resist plug-
`ging due to encrustation and maintain flow even in the
`presence of urinary infection. The reason that the exter-
`nal groove does not become encrusted is that the ureter
`transports urine in an active fashion from the kidney to
`the bladder by peristalsis. Successive constrictive rings
`of peristaltic moVement propel successive boluses of
`urine to the bladder. The peristaltic contraction rings
`moving down over the outer surface of the stent when
`it is in place keep the outer surface of the stent, includ-
`ing the external groove, swept clean of encrustation.
`The first microscopic crystals whih tend to form are
`swept off by the peristaltic movement.
`_
`In a preferred embodiment, the stent comprises an
`elongated flexible cylindrical member of substantially
`uniform outside diameter throughout its length which
`has proximal and distal ends which are set in the form of
`hooks. There is at least one external longitudinally ex-
`tending groove which provides a passage for fluid along
`the outside of the member. The stent has an internal
`lumen which is large enough to allow the passage of a
`small wire stylet for the purpose of straightening the
`hooks so that the stent can be inserted cystoscopically.
`To pass the grooved stent in open surgery, it also is
`advisable to have several small radial passages through
`the side wall that permit the wire stylet to be inserted
`through the radial passage into the lumen to straighten
`one hook so that the stent can be passed in one direc—
`tion; the other hook can be straightened and passed in
`the other direction in the same manner.
`The groove itself can serve as the indicating means to
`show which direction the proximal hook will take when
`the stylet
`is removed. However,
`it may be desired
`where more than one groove is employed to have a
`separate indicating means such as an index strip. The
`
`Lombard Exhibit 1011, p. 3
`
`10
`
`15
`
`20
`
`25
`
`30
`
`'
`
`35
`
`45
`
`50
`
`55
`
`The present invention relates to ureteral catheter
`stents. More particularly,
`it relates to an externally
`grooved ureteral stent which can be introduced both
`cystoscopically or during open surgery and which once
`in place resists migration and encrustation.
`BACKGROUND OF THE INVENTION
`
`Indwelling ureteral catheter stents or drainage tubes
`have been used to bypass ureteral obstructions or ure-
`terovaginal fistulas and maintain urinary drainage. In
`the past, stents made of open end silicone tubing have
`been used for this purpose and have provided good
`drainage for sustained periods of time. However, the
`use of such open end tubing has not been completely
`satisfactory. For example, in some instances, the tubing
`has migrated and in others it has been expelled. In still
`other instances, the lumen of the tubing has become
`encrusted greatly reducing urinary drainage.
`Various attempts have been made to produce stents
`which do not have the problems which accompany the
`use of open end tubing. For example, stents have been
`designed which are closed at one end to facilitate pas-
`sage into a body passage and which have radial passage-
`ways in the wall connecting the lumen to the outside
`and a flange at the other end to make upward migration
`of the stent less likely. Another approach to prevent
`migration has been to provide the body of the stent with
`sharply pointed barbs which are designed to prevent
`downward migration and explusion. However, such
`barbs increase the diameter of the stent making it more
`difficult to insert and in some instances can cause the
`stent to migrate outside the bladder to create medical or
`other problems for the urologist. Recently, a stent has
`been introduced which is made of stiff polyethylene. It
`has a relatively small flange on the distal end which is
`intended to prevent upward migration, and the proxi-
`mal end is formed in the shape of a pigtail. Unfortu-
`nately, this stent must be introduced by the relatively
`complex Seldinger technique. Furthermore, the rela-
`tively small flange has not always prevented the stent
`from passing above the bladder making removal uncer-
`tain.
`
`All the prior art stents have one feature in common;
`they are primarily designed to be passed endoscopically
`in a retrograde fashion and not during open surgery.
`The ideal ureteral stent should have at least the fol-
`lowing desirable characteristics: (1) The stent should be
`made of a material which is soft, quite flexible and re-
`sists tissue reaction and encrustation; (2) it should be
`radiopaque; (3) to facilitate its passage it should be of a .
`uniform diameter throughout without barbs or flanges;
`(4) it should be easily passed during open surgery as
`well as endoscopically;
`(5) it should have means to
`prevent migration in either direction; and (6) it should
`be able to withstand repeated sterilization. It also would
`be desirable if the stent would be of a design which
`resists plugging of flow due to encrustation.
`In my earlier patent application, Ser. No. 844,278,
`filed Apr. 7, 1978, I disclosed an improved ureteral stent
`having a hook at each end to prevent migration. This
`stent has proven to be a significant advance in the art of
`
`60
`
`65
`
`Lombard Exhibit 1011, p. 3
`
`

`

`3
`preferred stent will also have measurement markings
`every five centimeters along the straight intermediate
`section.
`
`4
`11 of the stent 10 to the other end 12 and is used with the
`wire stylet 21 to straighten the stent 10 for insertion.
`In FIGS. 5a to So can be seen the cross sectional
`
`4,307,723
`
`5
`
`The two gently formed opposed hooks of the stent
`prevent it from migrating either upwardly or down-
`wardly once it is in place. Means for increasing the
`rigidity of the proximal and distal hooks may be incor-
`porated. Plastic, fabric, metal, or other suitable material,
`may be incorporated into the hooks to make them less
`flexible and therefore make them more resistant to mi- 10
`gration. The hooks extend in opposite directions so that
`when used as an indwelling ureteral stent the proximal
`end can hook into the lower calix or renal pelvis while
`the distal end curves out into the bladder. This design
`also prevents the tip of the stent from impinging di- 15
`rectly into the bladder mucosa thereby decreasing dis-
`comfort and inflammation.
`
`These and still other objects and advantages of the
`invention will be apparent from the description which
`follows.
`
`20
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a perspective view of the preferred stent of
`the present invention and means for inserting the stent; 25
`FIG. 2 is a back elevational view of the stent of FIG.
`
`1;
`
`FIG. 3 is an enlarged view of a section of the stent of
`FIG. 1;
`
`FIG. 4 is a sectional view taken along lines 4—4 of 30
`FIG. 3; and
`FIGS. 5a to 5d are views similar to FIG. 3 of altema—
`
`tive designs of externally grooved stents.
`DESCRIPTION OF THE PREFERRED
`EMBODIMENT
`
`35
`
`In the preferred embodiment shown in FIGS. 1 to 4,
`the stent 10 is seen to be an elongated tubular member
`which is closed at both ends 11 and 12. Portions adja-
`cent each end are formed and set in the shape of gently 40
`curved hooks 13 and 14 which extend in opposite direc-
`tions. A relatively straight intermediate section 15 ex-
`tends between the opposed hooks 13 and 14. The sec-
`tion 15 is provided with measurement markings 16,
`which are preferably spaced 5 centimeters apart. The 45
`stent 10 is supplied in 7 French and 8.5 French O.D.
`sizes in 16, 24, 26, 28 and 30 cm lengths. The listed
`length of the stent 10 is the length of the section 15 and
`does not include the hooked ends 13 and 14. This allows
`the user to radiographically estimate the ureteral length 50
`and select the proper stent for passage.
`Referring now to FIGS. 1 and 2, it can be seen that
`there are four longitudinal grooves 17 in the external
`surface of the stent 10 (as best seen in FIG. 4). The
`grooves 17 extent substantially the entire length of the 55
`stent 10 from a point 18 adjacent the proximal end 11 to
`a point 19 adjacent the distal end 12. Wire stylet open-
`ings 20 are located adjacent each of the hooks 13 and 14
`and intermediate the length of the stent 10. The grooves
`17 also can serve as indicating means which can be seen 60
`through the optics of the cystoscope so that the user can
`see the direction that the proximal hook 13 and distal
`hook 14 will form when the straightening metal stylet
`21 is removed from the stent 10. If desired, other indi-
`cating means can be included such as an index stripe 22 65
`in one of the grooves 17.
`As seen in FIGS. 3 and 4, the stent 10 has a wire stylet
`receiving lumen 23. The lumen 23 extends from one end
`
`shapes of alternative embodiments of the stent having 2,
`3 and 5 external grooves, respectively. Embodiments of
`other shapes can, of course, also be used, if desired.
`Referring to FIG 511, there can be seen the cross-sec-
`tional shape of an embodiment that does not have a
`central wire stylet receiving lumen. Instead, groove 24
`is provided with lips 24a, 2417 which will retain a wire
`stylet press fit into the groove. A stent having the cross-
`sectional shape shown in FIG. 5d may also be provided
`with a stylet tip receiving pocket (not shown) at the
`proximal end to help retain the stylet in place.
`Returning to FIG. 1, there also can be seen a stent
`pusher 25 and the wire stylet 21 which may be used to
`help position the stent 10 in a body passage.
`The preferred stent 10 is supplied with both ends 11
`and 12 closed. As seen in FIG. 1, the proximal end 11 is
`preferably closed with a colored or opaque material and
`the distal end 12 with a clear material. When used for
`endoscopic or cystoscopic insertion, the distal end 12 is
`clipped and the wire stylet 21 is introduced into the
`lumen 23 of the stent 10 and passed through substan-
`tially the full length of the stent 10 to straighten both
`hooks 13 and 14.
`
`The stent pusher 25 will normally be supplied as a
`component of a ureteral catheter stent kit. However, a
`satisfactory stent pusher 25 may be made from a half
`length of a standard 5 F ureteral catheter.
`In use, the stent pusher 25 is threaded over the wire
`stylet 21 and inserted 102 mm into the open end of the
`stent 10. This allows the partial withdrawal and redirec-
`tion of the stent, if necessary, during standard retro-
`grade catheterization. If necessary, the obstructed ure-
`ter is dilated with a standard catheter before inserting
`the stent 10. Once the stent 10 is properly positioned,
`the stylet 21 and stent pusher 25 are removed by with—
`drawing the stent pusher 25 while holding the wire
`stylet 21 causing the stent 10 and stent pusher 25 to
`disengage after which the wire stylet 21 and then the
`stent pusher 25 are withdrawn.
`As the stent is of a substantially uniform diameter
`with both ends smoothly closed and without flanges or
`barbs or other protrusions, it also may be passed easily
`during open surgery through a pyelotomy, ureterotomy
`or transvesically as indicated. When the stent 10 is thus
`used, the distal end 12 is not clipped. Instead, the stylet
`21 is inserted through an opening 20 into the lumen 23
`and used to straighten an appropriate length of the stent
`10 and a hook 13' or 14. The stent 10 is then easily
`passed. Once the stylet 21 is withdrawn, the hook once
`again forms to prevent migration. This same techinque
`is used to pass the stent 10 into the opposite viscus.
`When it is desired to remove the stent 10, it may be
`removed endoscopically on an outpatient basis using
`either a foreign body or biopsy forceps or by using a
`stylet wire with a small hook formed at its end. In any
`case, once the stent is engaged, it is best removed by
`withdrawing the entire cystoscope.
`The ureteral catheter stent 10 of the present invention
`is preferably made of silicone elastomer, preferably of
`the addition-reaction type, which when cured has a
`durometer of about 70 Shore ‘A’. A suitable material is
`
`Dow Corning Silicone No. 4772 to which 10% barium
`sulfate has been added as a radiopaque material. Other
`plastic materials which resiist encrustation with urine
`salts can also be used.
`
`Lombard Exhibit 1011, p. 4
`
`Lombard Exhibit 1011, p. 4
`
`

`

`4,307,723
`
`5
`The stent is preferably formed by extruding uncured
`tubing of the desired size and cross-sectional shape of a
`suitable silicone elastomer having the desired durome-
`ter. A suitable length of the tubing is then placed in a
`form to retain the end portions in the shape of gently
`curved hooks. The thus formed tubing is then cured by
`heating and the ends closed with silicone. The measure-
`ment markings 16 and an index strip 22 may be painted
`on or otherwise applied and, if desired, then covered
`with silicone to lock them in place. The openings 20
`may be formed by piercing the wall of the tubing with
`a flattened, sharpened hole cutter of the desired size or
`by use of a laser or any other conventional means.
`The ureteral catheter stent may be supplied in a kit
`which contains one or an assortment of stents of differ—
`ent sizes and types and which also includes a wire stylet
`and a stent pusher. In addition, if desired, an open end
`stent could be included for endoscopic use eliminating
`the need for the user to clip the distal end.
`In the preferred embodiment described and shown in
`the drawing, the proximal and distal end portions of the
`catheter stent are both in the form of a gently curved
`hook. However, it is to be understood that the term
`“hook” is intended to include other functionally equiva-
`lent shapes which prevent migration and do not in-
`crease the effective outer diameter of the stent, or com-
`plicate its method of introduction. It is also to be under-
`stood that externally grooved stents with other means
`of retention, such as the conventional barbs and flanges
`in place of the hooks, may be employed with advantage
`where migration is not a problem and that the shape of
`the grooves is not critical provided they permit ade-
`quate drainage.
`It will be readily apparent to those skilled in the art
`that a number of modifications and changes can be
`made without departing from the spirit of the invention.
`For example, if desired, the stent could be equipped at
`the distal end with a reflux valve such as a flapper valve
`or the like. Obviously, the stent, although described as
`ureteral stent, also can be used in other applications than
`those described in the specification. Therefore, it is to
`be understood that the scope of the invention is not to
`be measured by the description, but only the claims that
`follow.
`'
`I claim:
`1. A ureteral stent for use in maintaining urinary
`drainage in a patient, which stent comprises an elon—
`gated, flexible, generally cylindrical member of substan-
`tially uniform outside diameter throughout its entire
`length, said member having a proximal end which is
`closed and set in the form of a hook, a relatively long
`straight intermediate section and a distal end which is
`also set in the form of a hook, said member having at
`least one longitudinally extending external groove to
`provide a passage for fluid and wire stylet retaining
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`45
`
`50
`
`55
`
`60
`
`65
`
`6
`to
`the use of a wire stylet
`means which permit
`straighten the member, including the hooks, so that the
`member can be cystoscopically inserted and positioned
`within the patient and which permit the stylet to be
`removed when the stent is properly positioned so that
`upon removal the hooks will reform and prevent the
`member from migrating.
`2. A ureteral stent comprises an elongated relatively
`flexible member having at least one longitudinally ex—
`tending external groove to provide a passage for fluid
`flow along the outer surface of the member, the end
`portions of said member being set in the form of hooks,
`at least one of which has a rounded end, said member
`including wire stylet retaining means which enable the
`user to forcibly straighten the hooks to facilitate the
`placement of the stent in a body passageway.
`3. The stent of claim 2 in which the member is of
`substantially uniform outer diameter throughout
`its
`length.
`4. The stent of claim 2'in which the member is of a
`silicone elastomer material.
`5. The stent of claim 2 in which both end portions
`have rounded ends.
`' 6. The stent of claim 2 in which the member is of an
`unreinforced silicone elastomer having a durometer of -
`about 70 Shore ‘A’.
`7. The stent of claim 2 in which the hook portions
`extend in opposite directions.
`8. The stent of claim 2 in which the wire stylet retain-
`ing means is a pair of lips on the groove which once the
`stylet is in the groove prevents the stylet from being
`accidentally dislodged therefrom.
`9. The stent of claim 2 in which the wire stylet retain-
`ing means is a longitudinal extending lumen in the mem-
`ber.
`
`10. A kit for providing urinary drainage comprising:
`(a) a wire stylet, and
`(b) a ureteral catheter stent comprising an elongated
`relatively flexible member having at least one lon-
`gitudinally extending external groove to provide a
`passage for fluid flow, said member having end
`portions set in the form of hooks at least one of
`which has a rounded end, and wire stylet retaining
`means which enable the user to forcibly straighten
`the hooks to facilitate the placement of the stent in
`a body passageway.
`11. The kit of claim 9 in which the stent is comprised
`of silicone elastomer having a durometer of. about 70.
`12. The kit of claim 9 in which both hook portions of
`the stent have rounded ends.
`13. The kit of claim 9 in which the hook portions of
`the stent extend in opposite directions.
`14. The kit of claim 9 in which the stent is of a mate-
`rial which is radiopaque to x-rays.
`a
`a
`x:
`. a
`e
`
`Lombard Exhibit 1011, p. 5
`
`Lombard Exhibit 1011, p. 5
`
`