Patent Application
20090105719
The invention relates to medical devices, particularly those used in conjunction with positioning stents.
Indwelling ureteral stents have been widely used for years. Such stents are placed in the ureter, which is the duct between the kidney and the bladder, for the purpose of establishing and/or maintaining an open, patent flow of urine from the kidney to the bladder. Some reasons for placing a ureteral stent include extrinsic compression occlusions, ureteral injury due to trauma, and obstructive uropathy.
The typical ureteral stent can be composed of various radiopaque polymers, including polyethylene, silicone, polyurethane, and thermoplastic elastomer. These stents are retained in the ureter by a retentive anchoring means, such as a curve shape, pigtail, coil, J-shape, or hook configuration, at either end of the stent that engages the walls of the bladder and the kidney, respectively. The stent is resilient to allow it to be straightened for insertion into a body passageway and returned to its predetermined retentive anchoring shape when in situ.
Indwelling ureteral stents are positioned in the ureter by antegrade (percutaneous) placement, retrograde (cystoscopic) placement through the urethra, as well as by open ureterotomy or surgical placement in the ureter by direct manipulative control. Ureteral stent positioning has heretofore been accomplished by two basic methods.
In one method, a wire guide is introduced into the ureteral orifice in the bladder via a cystourethroscope under direct vision. The wire guide is advanced up the ureter until the advancing flexible tip of the guide is confirmed by X-ray or fluoroscopy to be in the renal pelvis of the kidney. A tubular stent with both ends open is fed onto the exposed external segment of the wire guide and advanced over the wire guide by hand until a short segment of the stent is visible outside the cystoscope. A pusher catheter (usually a length of tubing) is then fed onto the exposed external end of the wire guide and advanced over the wire guide by hand until it butts against the stent. With the wire guide held stationary, the positioner is advanced over the wire guide to push the tubular stent up the ureter to the renal pelvis. With the anatomically proximal end of the stent in the renal pelvis, the positioner is held stationary while the wire guide is gradually extracted from the stent and the positioner. It is desired that as the wire guide leaves the distal end of the tubular stent, the retentive hook or curve of the distal end of the stent is formed to retain the stent in the pelvis of the kidney, and as the wire guide is withdrawn past the proximal, or intravesicle, end of the stent, the retentive hook or curve of the proximal end is formed so that the stent end is retained within the bladder. However, often times the stent is placed too far into the kidney or not far enough due to physician inexperience, anatomical challenges, the inability to properly visualize the stent's progression through the bodily passage, etc. Improper placement leads to poor stent drainage and often the need to reposition the stent subjecting the patient to the possibility of further bodily injury and infection from multiple invasive procedures. Accordingly, proper stent placement is difficult to achieve.
In another method of ureteral stent placement, a ureteral stent having one end closed is backloaded onto a wire guide. In this “push-up” method, the tip of the wire guide contacts the closed end of the ureteral stent, which is then introduced into the ureteral orifice in the bladder via a cystourethroscope under direct vision. The stent is advanced up the ureter under fluoroscopic control until the tip of the stent lies within the renal pelvis. A positioner catheter or length of tubing is fed onto the external end of the wire guide and advanced over the wire guide by hand until it butts against the open, distal end of the stent. The positioner is held steady while the wire guide is removed in a fashion similar to that described above. Like the previous method described, this method, too, suffers from the same drawbacks and often results in a poorly positioned stent.
What is needed is a device for insuring the proper placement of a stent that overcomes the limitations known in the art.
A medical device is provided that includes an elongated tubular body having a proximal portion, a distal portion, and a lumen extending therethrough, a taper configured near the distal portion of the elongated tubular body, wherein an outer diameter of the taper is larger than an anatomical landmark, and a stent-stop configured near the distal portion of the elongated tubular body, wherein the stent-stop is configured to receive a proximal portion of a stent.
In addition, an insertion device is provided that includes a bit having a proximal and distal portion, a hand collet, wherein the hand collet is adapted to receive the proximal portion of the bit, and further wherein the distal portion of the bit is adapted to receive a sent-stop.
Furthermore, a method for deploying a stent that includes inserting a wire guide to the location of a stent deployment, placing a stent, having a first anchor at the proximal portion and a second anchor at the distal portion, onto the wire guide, providing a positioner having a stent-stop and a taper, wherein the taper has a diameter larger than an anatomical landmark, abutting the proximal portion of the stent to the stent-stop, pushing the positioner until the taper reaches the anatomical landmark, withdrawing the wire guide to deploy the second anchor, and withdrawing the wire guide and positioner to deploy the first anchor.
The embodiments will be further described in connection with the attached drawing figures. Throughout the specification, like reference numerals and letters refer to like elements. It is intended that the drawings included as a part of this specification be illustrative of the embodiments and should in no way be considered as a limitation on the scope of the invention.
The embodiments provide an apparatus that is able to properly position a stent within a kidney and a bladder. However, it is contemplated that which is disclosed herein can be used to place stents in other parts of the body, including but not limited to, the urethra, the vascular system, and the pancreatic-biliary system. Moreover, that which is disclosed herein in not limited to use in human beings.
A more detailed description of the embodiments will now be given with reference to
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Positioner 20 has taper 25 located at the distal portion 20B of elongated tubular body 21 and is a blunt tip formed using a heated glass mold, heated metal alloy mold, or by other methods known in the art, such as buffing, grinding, or using a heat shrinkable tubing as a means to form a taper. Taper 25 is larger than ureteral orifice 13 but small enough to fit through urethra 11. Taper 25 is approximately 3-5 mm long, although other sizes are contemplated depending upon the needs of the patient. Thus, taper 25 can be sized to fit an average patient or any particular patient. Ureteral orifice is able to stretch; thus, it is desired that no more than a minimal portion of taper 25 enter ureteral orifice, because otherwise, the anatomical landmark used to position stent 26 could inadvertently be passed.
Elongated tubular body 21 is an 18 Fr. polyurethane tube that is approximately 30-40 cm long, although other sizes are contemplated depending upon the needs of the patient. In addition, elongated tubular body 21 can be made from other materials, including but not limited to polytetrafluoroethelyne (PTFE), common medical polymers such as polyethylene, polypropylene, silicone, stainless steel, tungsten, Titanium, PEEK, brass, aluminum, nylons, vinyls (such as PVC), and other medically acceptable metal materials. Moreover, elongated tubular body 21 may be covered with a coating to ease friction; such coatings include but are not limited to a hydrophilic coating, poly vinyl alcohol, poly vinyl pyrrolidone, hydrophobic coating (such as parylene), anti-microbial or antiseptic coating, Teflon, and other medically acceptable coatings.
Additionally, elongated tubular body 21 may be coated with a bioactive agent. As used herein, “bioactive agent” refers to any substance that can be used for therapeutic, prophylactic, or diagnostic purposes. A therapeutic purpose refers to the treatment of an on-going disease or disorder—the goal being to cure it or at least ameliorate its symptoms. A prophylactic purpose refers to the administration of a bioactive agent before any disease or disorder has manifested itself or to administration after the disease or disorder has been subjected to therapeutic treatment to prevent recurrence of the disease or disorder or of symptoms of the disease or disorder. Elongated tubular body 21 may be coated with, formed with, or impregnated with a fluoropolymer or other protective, lubricious coating and/or a bioactive agent selected to mitigate or eliminate encrustation with long-term implantation of medical devices. Heparin or other drug-containing coatings may be applied to elongated tubular body 21 by any suitable means, including spraying, dipping, solvent casting, and the like. Fluoropolymers, such as PTFE, help to enable the bonding of certain drugs, such as heparin, to the surface of elongated tubular body 21. Other drugs useful for mitigating or preventing encrustation include heparin, covalent heparin, dexamethazone, dexamethasone sodium phosphate, dexamethasone acetate, and other dexamethasone derivatives, triclosan, silver nitrate, ofloxacin, ciproflaxin, phosphorylcholine, and triemethoprim. In addition, one or more bioactive agents may be placed on the surface of, or contained within, elongated tubular body 21 in order to assist in patient care and comfort. For instance, an antimicrobial drug, such as a combination of rifampin and minocycline, may help to reduce inflammation and microbial activity in the vicinity of the stent. Antimicrobial coatings applied to elongated tubular body 21 may include the following drugs or their salts or derivatives: rifampin, minocycline, a mixture of rifampin and minocycline, a non-steroidal anti-inflammatory agent, a penicillin, a cephalosporin, a carbepenem, a beta-lactam, an antibiotic, an aminoglycoside, a macrolide, a lincosamide, a glycopeptide, a tetracyline, a chloramphenicol, a quinolone, a fucidin, a sulfonamide, a trimethoprim, a rifamycin, an oxaline, a streptogramin, a lipopeptide, a ketolide, a polyene, an azole, an echinocandin, alpha-terpineol, methylisothiazolone, cetylpyridinium chloride, chloroxyleneol, hexachlorophene, chlorhexidine and other cationic biguanides, methylene chloride, iodine and iodophores, triclosan, taurinamides, nitrofurantoin, methenamine, aldehydes, azylic acid, rifampycin, silver, benzyl peroxide, alcohols, and carboxylic acids and salts, and silver sulfadiazine. Also useful as antimicrobials are anthracyclines, such as doxorubicin or mitoxantrone, fluoropyrimidines such as 5-fluoroacil, and also podophylotoxins, such as etoposide. The salts and the derivatives of all of these are meant to be included as examples of antimicrobial drugs. Analgesics, such as aspirin or other non-steroidal anti-inflammatory drugs, may also be applied to elongated tubular body 21 to reduce pain and swelling upon implantation. These drugs or their salts or derivatives may include aspirin and non-steroidal anti-inflammatory drugs, including naproxen, choline, diflunisal, salsalate, fenoprofen, flurbiprofen, ketoprofen, ibuprofen, oxaprozin, diclofenac, indomethacin, sulindac, acetoaminophen, tolmetin, meloxicam, piroxicam, meclofenamate, mefanimic acid, nabumetone, etodelac, keterolac, celecoxib, valdecoxib, and rofecoxib, mixtures thereof, and derivatives thereof. Other analgesics or anesthetics that may be coated onto the surface of elongated tubular body 21 include opioids, synthetic drugs with narcotic properties, and local anesthetics to include at least paracetamol, bupivacaine, ropivacaine, lidocaine, and novacaine, alfentanil, buprenorphine, carfentanil, codeine, codeinone, dextropropoxyphene, dihydrocodeine, endorphin, fentanyl, hydrocodone, hydromorphone, methadone, morphine, morphinone, oxycodone, oxymorphone, pethidine, remifantanil, sulfentanil, thebaine, and tramadol, mixtures thereof, and derivatives thereof. Any of these bioactive agent coatings can be applied in a time-release manner should there be a need for positioner to dwell within the patient for an extended period of time. Other bioactives include but are not limited to those discussed in U.S. patent application Ser. No. 10/410,587, filed Apr. 8, 2003 and incorporated herein by reference in its entirety.
It is desired, although not required, that positioner 20 be long enough to reach ureteral orifice 13. Elongated tubular body 21 has lumen 22 extending throughout that has an inner diameter of approximately 0.115-0.119 inches, although other sizes are contemplated depending upon the needs of the patient. Disposed within elongated tubular body 21 is retention disk 23.
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Furthermore, positioner 20 may further include any number of markers (not shown) that are visible under fluoroscopy means, X-Ray means, ultrasonic means, or other means known in the art, to aid in the placement of the stent. Markers can be made from Platinum-Iridium alloy or any other radiopaque material, such as gold or tungsten, or echogenic material. An echogenic material includes surface irregularities that reflect ultrasonic waves and thus, allow the material to be seen with ultrasonic imaging devices. Echogenic techniques are described in U.S. Pat. No. 5,081,997 and U.S. Pat. No. 5,289,831, assigned to the assignee of the present invention, and they are hereby incorporated by reference in their entirety.
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To use positioner 50, stent 26 is placed over wire guide 27. Wire guide 27 and proximal portion 26A of stent 26 are placed into positioner 50 such that proximal portion 26A of stent 26 abuts against smaller lumen 52A of elongated tubular body 51. Positioner 50, along with stent 26, are pushed up through urethra and bladder 12 until taper 53 of positioner 50 abuts ureteral orifice 13. Stent 26 is then deployed as previously described.
As is evident, the embodiments provide a very effective solution for positioning a stent. The foregoing description and drawings are provided for illustrative purposes only and are not intended to limit the scope of the invention described herein or with regard to the details of its construction and manner of operation. In addition, the dimensions and sizes described herein are not intended to be limiting as they can be altered to fit the needs of the patient or medical professional. Moreover, the positioner is not limited for use with a ureteral stent or the use of the ureteral orifice as an anatomical landmark. It will be evident to one skilled in the art that modifications and variations may be made without departing from the spirit and scope of the invention. Changes in form and in the proportion of parts, as well as the substitution of equivalents, are contemplated as circumstances may suggest and render expedience; although specific terms have been employed, they are intended in a generic and descriptive sense only and not for the purpose of limiting the scope of the invention set forth in the following claims.
