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United States Patent  [li] Patent Number: 4,931,037
Wetterman  Date of Patent: Jun. 5, 1990
 IN-DWELLING URETERAL STENT AND INJECTION STENT ASSEMBLY, AND METHOD OF USING SAME
 Inventor: Peter H. Wetterman, Pomfret, Conn.
 Assignee: International Medical, Inc., Danielson, Conn.
 Appl. No.: 257,087
 Filed: Oct. 13,1988
 Int. C1.5 ,A61M 37/00; A61M 25/00
 U.S. CI 604/8; 604/280
 Field of Search 604/8, 14, 53, 280,
 References Cited
U.S. PATENT DOCUMENTS
2,212,334 8/1940 Wallerich .
2,393,003 1/1946 Smith .
3,419,010 12/1968 Williamson .
3,633,585 1/1972 McDonald, Jr 604/8
3,726,269 4/1973 Webster, Jr. .
3,890,977 6/1975 Wilson .
3,938,529 2/1976 Gibbons .
4,117,838 10/1978 Hasson .
4,212,304 7/1980 Finney .
4,307,723 12/1981 Finney .
4,469,483 9/1984 Becker et al. .
4,531,933 7/1985 Norton et al. .
4,568,338 2/1986 Todd .
4,610,657 9/1986 Densow 604/8
4,643,716 2/1987 Drach .
4,671,795 6/1987 Mulchin .
4,713,049 12/1987 Carter 604/8
4.790.809 12/1988 Kuntz 604/8
4.790.810 12/1988 Pugh, Jr. et al 604/8
Primary Examiner—Robert A. Hafer
Assistant Examiner—Kerry Owens
A stent has a first tubular portion with a straight section and a curled section at the proximal end thereof, a second tubular portion curl providing a curled section at the distal end. The second portion has a larger diameter than the first portion and receives the straight section therein which is bonded thereton. The end of the straight section within the second portion forms a shoulder for abutment by an injection catheter to inject the stent into a patient. The outer surface of the distal portion is relatively soft to avoid bladder irritation.
17 Claims, 2 Drawing Sheets
IN-DWELLING URETERAL STENT AND INJECTION STENT ASSEMBLY, AND METHOD OF USING SAME
BACKGROUND OF THE INVENTION
The present invention relates to in-dwelling ureteral catheter stents and to the method of using the same.
In-dwelling ureteral catheter stents or drainage tubes 10 have been used to bypass ureteral obstructions or uretero-vaginal fistulas and maintain urinary drainage. Stents made of straight lengths of open-ended tubing are widely used for this purpose and have provided drainage for sustained periods of time. However, the use of 15 such open-ended tubing has not been completely satisfactory in that, in some instances, the tubing has migrated, and, in other cases, it has been expelled.
To combat the problem of migration or expulsion, stents have been designed which are closed at the proxi- 20 mal end to facilitate passage into the ureter, and which have a flange or other formation at the distal end to preclude upward migration of the stent. U.S. Pat. Nos. 4,212,304 and 4,307,723 disclose ureteral stents with ends having portions with hooks or curls which have 25 been effective in preventing migration and expulsion. Such stents can be introduced both endoscopically and during open surgery.
Other stents having formed proximal and distal ends to combat migration and expulsion are disclosed in U.S. 30 Pat. Nos. 4,643,716; 4,610,657; and 4,713,049.
At the present time, there are two general types of ureteral stents available. One type is made of a soft material, and the other is made of a stiff material. Each requires a different method of placement within the 35 ureter and each has its advantages and disadvantages. A ureteral stent made from a soft material has a closed proximal tip which is inserted into the kidney. This type of stent is placed in the ureter by inserting a stiff stylet through the distal end until it abuts against the proximal tip. The stent stiffened by the stylet is guided into the bladder with the use of a standard cystoscope. Once the ureteral orifice is located, the stent is advanced up the ureter by pushing the stylet against the closed proximal end.
The disadvantage of using a stent of soft material is that it must be stiffened and guided by a stylet. This increases the possibility for the stent to migrate and perforate the ureteral wall, especially if the ureter is 5Q partially obstructed or tortuous. After placement, soft stents have a greater tendency to migrate distally and proximally because soft curls formed therein will straighten easily.
A ureteral stent made from a stiff material has open 55 distal and proximal ends. The stent is inserted by first inserting the guide wire through the ureter into the kidney and the stent is fed over the guide wire which straightens its curls as it travels thereover. A push rod is slid over the guide wire until it abuts the distal end of 60 the stent. Because the material is stiff, this stent may be advanced along the guide wire with the push rod without collapsing the stent and with less chance of perforating the ureteral wall. Once the stent is in place, both the push rod and guide wire are removed and the distal 65 and proximal ends curl to prevent the stent from migrating or being expelled. The major disadvantage of using the stiff material stent is patient discomfort, because the
distal curl tends to irritate the bladder wall when the bladder is empty.
With the development of the extracorporeal shockwave lithotriptor (ESWL) which provides a non-invasive method of breaking kidney stones using shock waves, the use of stents has greatly increased, and most patients with large kidney stones are stented prior to ESWL procedures. This is to aid in the migration of sediment from the kidney to the bladder as well as to prevent the possible formation of steinstrasse (stone street) which occur when a large fragment of the disintegrated stone blocks the ureter. By stenting a patient prior to ESWL, large fragments cannot enter the ureter and cause urinary blockage.
It is an object of the present invention to provide a new and improved in-dwelling ureteral stent with curled end portions for anchoring the stent in the kidney and bladder.
It is also an object to provide such a stent which affords greater comfort to the patient.
Another object is to provide a catheter assembly permitting facile and accurate placement of the stent and facilitating irrigation of the kidney.
A further objection is to provide an improved method for placement of a ureteral stent and irrigating the kidney.
SUMMARY OF THE INVENTION
It has now been found that the foregoing and related objects may be readily attained in an in-dwelling ureteral stent comprising a first flexible tubular portion with a straight section and a curled section at the proximal end, and a second flexible portion providing a tubular curled section at the distal end. The second portion has a larger diameter than the outer diameter of the first portion and seats therein the end of the straight section of the first portion which is bonded thereto. The end of the straight section within the second portion forms a shoulder against which an injection push catheter may abut. Both portions of the stent are fabricated from synthetic resin, and the second portion has a surface which is softer than that of the first portion.
In the preferred embodiments, the tubular portions are radio-opaque and the second portion is formed of two layers of differing durometer resin, the outer layer being softer than the inner. The curled sections of the first and second portions have drainage holes therein.
The stent is used in an injection push ureteral catheter assembly which additionally includes a guide wire of a lesser diameter extending in the passage through the stent and having a stiffness sufficient to straighten the curled portions thereof. Also included is a tubular push catheter having a passage therethrough in which is received the guide wire. The wall of the push catheter has a diameter so that it seats within the passage of the second portion of the stent and abuts the shoulder to permit the stent to be pushed along the guide wire as the push catheter is pushed therealong. Desirably, the push catheter has markings along its length adjacent the end external to the stent.
Preferably, the assembly also includes a tubular stent positioner with a passage slidably seating the push catheter therein and the end of the stent positioner abuts the distal end of the wall of the second portion of the stent. The push catheter and stent positioner are fabricated from synthetic resin.
In the method of inserting the ureteral stent into the ureter of a patient, the guide wire is inserted through