Patent Application
20130173016
The technical field of this invention is implantable medical devices, and in particular a stent useful for urinary drainage.
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.
Ureteral stents may be used to retain patency of the ureteral lumen and to continue normal urinary drainage following the treatment and removal of stones and calculi from kidneys and ureters. To treat this condition, several individual steps are involved. In one procedure, these steps include placing a relatively narrow guidewire through a urethra and a bladder, and then through the ureter and into the kidney. After the guidewire is placed, a catheter is run along the guidewire, dilating the body passage (the urethra and the ureter) as it moves down the guidewire. The access sheath also dilates the body passages as it moves from outside the body, through the urethra, and into the ureter, down the desired location, and into or very near the kidney.
The physician may then remove calculi and stones through the access sheath, using a grasper, a retrieval basket or other device. The access sheath protects the ureter from repeated passage of the retrieval device while the stones or calculi are removed. After the stones are removed, the ureteral stent may be placed into the ureter through the access sheath, using the catheter or a pushing tube to position the stent.
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 portion, such as a curved 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. There can be problems, however, with ureteral stents, as urine may fail to drain through the stent. This may be due to a number of reasons, such as extrinsic compression of the stent or blockage of the drainage mechanism of the stent by encrustation. Furthermore, there can be problems associated with migration of the urethral stent from the original implantation site either upward into the kidney of the patient or downward into the bladder of the patient.
The present disclosure relates to a stent for placing in a body passage of a patient. The stent has an elongated portion having a proximal end and a distal end. The elongated portion defines a lumen throughout the stent. The stent has a proximal anchoring member on the proximal end of the elongated portion and a distal anchoring member on the distal end of the elongated portion. The anchoring member comprises a wall curving outward from each end of the elongated portion of the stent.
In one aspect, the wall of the anchoring member includes a plurality of support struts. In one example, the plurality of support struts is integral with the wall of the anchoring member. The plurality of support struts may be comprised of shape memory materials. In another aspect, the wall of the anchoring member has a first opening having a first diameter and a second opening having a second diameter, forming an edge. The second diameter of the second opening is greater than the first diameter of the first opening. The wall of the anchoring member may be symmetrical along a longitudinal axis.
In another aspect of the present disclosure, an anchoring member for a stent is provided. The drainage device includes a wall having a generally concave configuration. The wall includes a first opening having a first diameter and a second opening having a second diameter defining an edge. The drainage device further includes a plurality of support struts disposed about an outer surface of the wall. The second diameter of the second opening of the wall is greater than the first diameter of the first opening of the wall. The wall of the drainage and anchoring member may be comprised of material selected from the group consisting of polyesters, fluorinated polymers, and polyurethanes.
In another aspect of the present disclosure a stent for placing in a body passage of a patient is provided. The stent includes a coiled wire. The coiled wire has an internal lumen. The internal lumen is configured to communicate outside of the coiled wire through small spaces between adjacent coils. The stent has an anchoring member on a distal end of the coiled wire. The anchoring member includes a wall curving outward from each end of the coiled wire. A plurality of support struts is disposed longitudinally about the circumference of the wall. In one aspect, the wire is selected from the group consisting of MP35N, MP159, Astroloy M, Inconel 625, 315 stainless steel, 35N LT, Bidur 108, titanium, and Hastelloy S.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.
The term “prosthesis” means any device for insertion or implantation into, or replacement, for a body part or function of that body part. It may also mean a device that enhances or adds functionality to a physiological system. The term prosthesis may include, for example and without limitation, a stent, stent-graft, filter, valve, balloon, embolization coil, and the like.
The term “endoluminal” refers to or describes the internal or inside of a lumen, duct, and other passageways or cavities located in a human or other animal body. A lumen or a body passageway may be an existing lumen or a lumen created by surgical intervention. As used in this specification, the terms “lumen” or “body passageway,” and “vessel” are intended to have a broad meaning and encompass any duct (e.g., natural or iatrogenic) or cavity within the human body and may include, without limitation, blood vessels, respiratory ducts, gastrointestinal ducts, such as the biliary duct, intestines, the esophagus, the pericardial cavity, the thoracic cavity, and the like. Accordingly, the terms “endoluminal device” or “endoluminal prosthesis” describe devices that can be placed inside or moved through any such lumen or duct.
The terms “patient,” “subject,” and “recipient” as used in this application may refer to any animal, particularly humans.
The terms “proximal” and “distal” will be used to describe opposing axial ends of the ureteral stent, as well as the axial ends of various component features. The term “proximal” is used to refer to the end of the ureteral stent (or component thereof) that is closest to the operator during use of the system. The term “distal” is used to refer to the end of the ureteral stent (or component thereof) that is initially inserted into the patient, or that is closest to the patient during use.
The term “biocompatible” refers to a material that is substantially non-toxic in the in vivo environment of its intended use, and that is not substantially rejected by the patient's physiological system (i.e., is non-antigenic). This can be gauged by the ability of a material to pass the biocompatibility tests set forth in International Standards Organization (ISO) Standard No. 10993 and/or the U.S. Pharmacopeia (USP) 23 and/or the U.S. Food and Drug Administration (FDA) blue book memorandum No. G95-1, entitled Use of International Standard ISO-10993, Biological Evaluation of Medical Devices Part-1: Evaluation and Testing.” Typically, these tests measure a material's toxicity, infectivity, pyrogenicity, irritation potential, reactivity, hemolytic activity, carcinogenicity and/or immunogenicity. A biocompatible structure or material, when introduced into a majority of patients, will not cause a significantly adverse, long-lived or escalating biological reaction or response, and is distinguished from a mild, transient inflammation which typically accompanies surgery or implantation of foreign objects into a living organism.
The term “medical device” means any object that is itself or that includes a component that is intentionally inserted into the body of a patient as part of a medical treatment, and that comprises a structure adapted for introduction into a patient. The medical device can be a tool, such as, without limitation, a catheter, a wire guide, a forceps, or a scissors used to affect a surgical procedure at and/or deliver a second medical device to a treatment site in a patient. An alternative medical device of the present invention is one that is commonly intended to be a permanent implant, such as a stent.
Materials used in the stents 12 are preferably biocompatible and corrosion-resistant. The coiled wire 16 is preferably made from alloys with minimal or low magnetic properties to avoid interference with diagnostic equipment, such as MRI machines. Alloys such as MP35N, MP 159, Astroloy M, Inconel 625, 316 stainless steel, 35N LT, Biodur 108, pure titanium, and Hastelloy S are preferred. It should be understood that embodiments of the ureteral stent 10 may be manufactured from other biocompatible materials, including, but not limited to, polyester-based biocompatible polymers, nylon-based polymers, polytetrafluoroethylene (PTFE) polymers, silicone polymers, polyurethane polymers, polyethylene polymers, and thermoplastic polymers.
Referring back to
Suitable materials for the wall 26 of the anchoring member 20 may be selected from biocompatible materials. Examples of biocompatible materials from which the wall of the ureteral stent can be formed include, without limitation, polyesters, such as polyethylene terephthalate; fluorinated polymers, such as PTFE and expanded PTFE, and polyurethanes. For example, the wall 26 may be constructed from polyester, for example and without limitation, Dacron™, produced by DuPont. Dacron™ is known to be sufficiently biologically inert, non-biodegradable, and durable to permit safe insertion inside the human body.
The anchoring member 20 includes a plurality of support struts 28. The support struts 28 may be integral with the wall 26 of the anchoring member 20 or, alternatively, separately attached to the wall 26. The support struts 28 may either be positioned on an outer surface of the wall 26 of the anchoring member 20, or within the inner surface of the wall 26 of the anchoring member 20. In some embodiments, the support struts 28 are disposed longitudinally about the circumference of the wall 26 of the anchoring member 20. In other embodiments, the support struts 28 may have other configurations including, but not limited to, circumferentially disposed about the surface of the wall 26 and helically disposed about the surface of the wall 26. The plurality of support struts 28 are configured to maintain the patency of the anchoring member 20 when the distal and proximal ends 22, 24 of the ureteral stent 12 are deployed within the ureter and the bladder of the patient, respectively, and reinforce the wall 26 of the anchoring member 20.
The support struts 28 may be manufactured from numerous metals and alloys. In one example, the support struts comprise a shape-memory material such as a nickel-titanium alloy (“Nitinol”). In another example, the support struts 28 comprise metal alloy, such as stainless steel. Moreover, the structure of the support struts 28 may be formed in a variety of ways to provide a suitable support structure. For example, one or more of the support struts 28 may be made from a woven wire structure, a laser-cut cannula, individual interconnected rings, or another pattern or design. While one exemplary arrangement is shown in
Table 1 shows the percentage of reduction of side-port cross sectional area for a 5 Fr stent and an 8 Fr stent with side drainage ports having a diameter of 0.8 mm and a side drainage port of 1.25 mm, respectively, as a result of an increase in encrustation thickness. Table 2 shows the percentage of reduction of cross sectional area for a 5 Fr stent and an 8 Fr stent, each stent having an anchoring member with a first opening having a diameter of 1.1 mm and 1.78 mm, respectively, as a result of an increase in encrustation thickness. The percentage of reduction of cross sectional area was calculated using the following formula:
where CSA is the cross sectional area, D is the diameter, and E is the thickness of encrustation. These calculations assume a uniform encrustation thickness over the entire surface of the stent.
As shown, the effect of an identical amount of encrustation on the flow rate through the first opening of the anchoring member is reduced as compared to a similarly sized stent having side drainage ports. The first opening of the anchoring member of the ureteral stent provides a greater cross-sectional area for the drainage of urine as the thickness of encrustation increases. As a result, the first opening of the anchoring member of the ureteral stent minimizes the effects of encrustation on the stent over time. This provides a great benefit to a patient, as the ureteral stent could be used for a longer period of time. Furthermore, the improved drainage characteristics of the ureteral stent reduce the need for repeated procedures to remedy problems with blockage, which can cause added trauma to the patient.
A method of introducing the prosthesis 10 is shown in
The distal opening of the access sheath 40 is generally positioned at or near the ureteropelvic junction of the patient. The prosthesis 10 is inserted into the access sheath 40 and the catheter 42 is used to advance the prosthesis 10 through the inner lumen of the access sheath 40. The catheter 42 is advanced through the access sheath 40 until the distal end 22 of the prosthesis 10 exits the distal opening of the access sheath 40, which results in an expansion of the distal anchoring member 20 into the ureteropelvic junction of the kidney. The position of the catheter 42 is maintained by the physician while withdrawing the access sheath 40. This continual withdrawal of the access sheath 40 allows the proximal anchoring member 20 to be expanded and deployed in the bladder of the patient. Following the deployment of the proximal anchoring member 20, the physician can remove the catheter 42 and the access sheath 40 from the patient.
In addition to the method shown in
An embodiment of a kit useful in the above procedure is depicted in
Catheter 42 may interface with one or more connectors 52 for mating with syringe adapter 58 (such as a female Luer lock adapter) so that a syringe (not shown) can inject the radiopaque fluid. Connector 52 may include a male Luer lock fitting 54 on a distal end of connector 52 and internal threads 56 on its proximal end. Male Luer lock connection 54 may be used to connect first connector 52 to second connector 44. Threads 56 may interface with matching external threads 60 of a syringe adapted for delivery of a fluid through lumen 62. Flared end 49 of the catheter 42 helps to seal the connection between connector 52, catheter 42, and syringe adapter 58. While the Luer lock and threaded connections depicted and described are preferred, other connectors may be used instead. For example, quick-release connectors could be used to secure the catheter or sheath to their proximal fittings. When connectors 52 and 58 are joined with flared end 49, a leak-tight connection is formed, and the catheter may reliably deliver fluid without undesirable leakage.
Access sheath 40 includes a proximal portion 41 and an end portion with a flared tip 43. The access sheath also includes a distal end 45. The distal end 45 may be atraumatic, soft and rounded or tapered for ease of introduction into the patient. Distal end 45 of the access sheath 40 is also preferably more highly radiopaque than the remainder of the access sheath, so that the end may be observed with x-ray or fluoroscopic detection device during the implantation procedure. Flared tip 43 helps to seal an interface between access sheath 40 and connector 44. Access sheaths are preferably made from low friction polymers (e.g. PTFE, FEP etc.) with reasonable radial compressive strength-wire reinforcement added to the sheath for extra radial strength. Suitable access sheaths sold under the name of Check-Flo® II Introducer sheaths sold by Cook Incorporated, Bloomington, Ind. may be used. Also Flexor® sheaths available from Cook Urological Incorporated of Spencer, Ind. may be used. In this application the sheath is typically 70 cm long so to extend from the ureteral meatus to the ureteropelvic junction. The access sheath is generally just slightly larger in inner diameter than the outer diameter of the catheter. Connector 44 may include internal threads 46 for connecting to Luer lock connector 48 having female Luer lock connection 50. While Luer lock connections and connectors are preferred, other types of medically acceptable connectors may be used. At least a distal portion of sheath 40 may also include a hydrophilic coating.
The fittings described above may be used to connect access sheath 40 with catheter 42. To help insure that access sheath 40 seals securely, connector 44 may be temporarily joined to connector 48 with an adhesive. Other methods may also be used, such as securely tightening connectors 44, 48 together. Joining the female Luer lock connection 50 to male Luer lock connection 54 reliably secures access sheath 40 to catheter 42 for insertion or for removal. By breaking the connection between connectors 48, 52 after insertion, catheter 42 may be removed and the access sheath 40 may be used for other purposes. These other purposes may include diagnostic purposes, such as insertion of an endoscope, or therapeutic procedures, such as breaking up stones or calculi, using a holmium laser or other type of lithotripter. A grasper or basket may then be inserted into the working channel of the endoscope to remove the fragments. In the same manner, connectors 52, 58 may also be temporarily joined with an adhesive to prevent easily breaking the connection. By adhering connector pairs 44, 48 and 52, 58, it is easier for the surgeon to make and break the Luer lock connection between connectors 48, 52.
In the assembled view of
Throughout this specification various indications have been given as to preferred and alternative embodiments of the invention. However, the foregoing detailed description is to be regarded as illustrative rather than limiting and the invention is not limited to any one of the provided embodiments. It should be understood that it is the appended claims, including all equivalents, that are intended to define the spirit and scope of this invention.
The present application claims priority to U.S. Provisional Patent Application Ser. No. 61/580,935 filed Dec. 28, 2011, the entirety of which is hereby incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61580935 | Dec 2011 | US |
