Device for retrieving stents

Abstract: A technique for removing an implanted stent (10) and a device useful therefor. An endoscope (60) is introduced into position at the proximal end (15) of the implanted stent (10) and a cannula (70) is then introduced through the endoscope (60). A wire guide (80) is then passed through the cannula (70) and into the duct (20) through the lumen of the stent (10) which is to be removed. The cannula (70) is then removed and a stent retrieval cable (90) is advanced over the wire guide (80) and into position at the proximal end (15) of the stent (10). The stent retrieval cable (90) is torqueable, and has a tapered thread (91a) at its distal end and a rotation dial (92) at its proximal end. Once the retrieval cable (90) has been placed into position, the rotation dial (92) is turned to engage the threading (91a) into the lumen of the stent (10). After the stent (10) has been attached to the retrieval cable (90) in this manner, the stent (10) and cable (90) are removed together through the endoscope (60) and out of the body, leaving the endoscope (60) and wire guide (80) in place for use in the implantation of the replacement stent (10).

Description: BACKGROUND OF THE INVENTION It is common medical practice today to implant stents within the body to maintain openings within certain passages therein. For instance, a biliary stent might be implanted to ensure drainage through an obstructed bile duct. Stents are configured in a variety of shapes and sizes, depending upon the location and purpose of the intended implantation, and the personal preference of the attending physician. When a stent needs to be replaced or removed, prior to the present invention, the procedure for removal has been standardly performed with the use of retrieval forceps, baskets, or snares. Such devices are used to grasp the proximal end of the implanted stent. After the stent has been firmly grasped, it is pulled through the duct and out of the body. Such a device is also known from EP-A-0 364 420 forming the closest prior art with regard to the present invention. There are several attendant disadvantages with this heretofore commonly used practice for removing implanted stents from within the body. For one thing, the actual process of technically grasping and pulling the stent out of its implanted position evenly and atraumatically can sometimes be difficult to perform, particularly for the larger sized stents. Where the stent has not been and pulled out evenly, bleeding and/or scaring can result, which can cause trauma and possible aggravation of the problem of occlusion that is being treated. Yet another significant complication concerns the fact that, when grasped by a retrieving device, the stent will most often not fit within the channel of the endoscope. The endoscope must therefore be removed in order to allow for the retrieval of the stent, and then be repositioned again for the replacement procedure. The requirement of recannulation adds considerable time to the overall replacement process. Implanted stents need to be regularly removed and replaced since they, themselves, tend to become occluded after a period of time. Owing at least partially to the relative difficulty involved in replacement, much has been done in the way of attempting to extend the useful life of an implanted stent. What is needed is an improved method and apparatus for removing stents that have been implanted within the body, which would facilitate replacement in an atraumatic way. SUMMARY OF THE INVENTION Generally speaking, the present invention relates to a new and improved method for removing an implanted stent from within the body, and to a new device which is useful to accomplish this result. According to one embodiment of the method of the present invention where a biliary stent is to be removed from the common bile duct, an endoscope is first introduced into position at the papilla of vater. Then, a cannula is introduced through the endoscope and a wire guide is then passed through the cannula and into the bile duct through the lumen of the biliary stent which is to be removed. The cannula is then removed and a stent retrieval cable is advanced over the wire guide and into position at the proximal end of the stent. The stent retrieval cable is torqueable, and has a threaded portion at its distal end and a rotation dial at its proximal end. Once the retrieval cable has been placed into position, the rotation dial is turned to engage the threading into the lumen of the stent. After the stent has been attached to the retrieval cable in this manner, the stent and cable are removed together through the endoscope and out of the body, leaving both the endoscope and wire guide in place for use in the implantation of the replacement stent. BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1a through 1d illustrate a sequence of steps in the removal of an implanted stent from the common bile duct of a patient. FIG.1a is a side view of a biliary stent implanted in the common bile duct of a patient. In FIG. 1a, an endoscope has been positioned at the papilla of vater, and a cannula has been advanced through the channel of the endoscope and into axial alignment with the implanted stent. In FIG. 1b, a wire guide has been passed through the cannula and through the lumen of the implanted stent. In FIG. 1c, the cannula has been removed, and a stent retrieval cable has been advanced along the wire guide and into position for threaded engagement with the stent. FIG. 1d illustrates the stent, which has been threadedly attached to the retrieval cable, being pulled through the channel of the endoscope and out of the body of the patient. FIGS. 2a through 2c are enlarged views of the area about the proximal end of the stent and the distal end of the endoscope for FIGS. 1a through 1c respectively. FIG. 2a illustrates the axial alignment of the introduction cannula with the proximal end of the implanted stent. FIG. 2b shows the wire guide having been advanced through the cannula and into the lumen of the stent. FIG. 2c is a detailed view of the retrieval cable in position for threaded engagement with the lumen of the stent to be removed. FIGS. 3a through 3c are side elevational views of the components used in the described procedure for removing an implanted biliary stent. FIG. 3a is an illustration of stent retrieval cable 90. FIG. 3b is an illustration of wire guide 80. FIG. 3c is an illustration of introduction cannula 70. FIGS. 4a through 4c are enlarged, segmented, cross sectional views of various portions of stent retrieval cable 90 in combination with wire guide 80 and stent 10. FIG. 4a is a segmented cross sectional view of the proximal end portion of stent retrieval cable 90, as seen along line 4a-4a of FIG. 3a, and with wire guide 80 positioned within the interior passageway thereof. FIG. 4b is a cross sectional view of the shaft of stent retrieval cable 90, as seen along line 4b-4b of FIG. 3a. FIG. 4c is a segmented cross sectional view of stent retrieval cable 90, as seen along line 4c-4c of FIG. 3a, with wire guide 80 positioned within the interior passageway thereof, and where stent retrieval cable 90 has been threadedly engaged with the lumen of stent 10. DESCRIPTION OF THE PREFERRED EMBODIMENT For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates. Referring now to the drawings, FIGS. 1a through 1d illustrate the sequencing of steps whereby an implanted biliary stent 10 is removed from the common bile duct 20. Biliary stent 10 is made of radiopaque polyethylene. Stent 10 includes a distal end 11, and distal drainage holes 12, as well as a proximal flap 13 near the proximal end 15 of stent 10, and proximal drainage holes 14. The placement of biliary stent 10 facilitates the drainage of bile fluids from hepatic ducts 30, through common bile duct 20, and out through the papilla of Vater 40 towards the small intestines 50. It is to be appreciated that the biliary stent, as shown and described, is illustrative in nature as a suitable stent for use with the present invention, and that other stents of differing configurations, compositions, and locations of implantation, are contemplated to be suitable for use with the present invention as well. To begin the procedure for removal of stent 10, an endoscope 60 is first introduced into position at the papilla of Vater 40. Then, a cannula 70 is introduced through the channel of endoscope 60 and into position in axial alignment with the proximal end 15 of stent 10. FIG. 1a illustrates the stage of the procedure where endoscope 60 and cannula 70 have been so placed. As shown in FIG. 1b, a wire guide 80 is then passed through cannula 70 and into bile duct 20 through the lumen of stent 10. Cannula 70 is then removed and a stent retrieval cable 90 is advanced over wire guide 80 and into position at the proximal end 15 of stent 10. Stent retrieval cable 90 is torqueable, and has a threaded portion 91 at its distal end and a rotation dial 92 at its proximal end (see FIG. 3a). FIG. 1c illustrates the stage of the procedure where cannula 70 has been removed and stent retrieval cable 90 has been advanced along wire guide 50 and into position for threaded engagement with stent 10. Once retrieval cable 90 has been placed into position, rotation dial 92 is turned to engage threading 91 into the lumen of stent 10. After stent 10 has been attached to retrieval cable 90 in this manner, stent 10 and cable 90 are removed together through the channel of endoscope 60 and out of the body of the patient, leaving both endoscope 60 and wire guide 80 in place for use in the implantation of the replacement stent. FIG. 1d illustrates this point of the procedure where stent 10, which has been threadedly attached to retrieval cable 90, is being pulled through the channel of endoscope 60 and out of the body of the patient. FIGS. 2a through 2c are enlarged views of the area about the proximal end 15 of stent 10 and the distal end 61 of endoscope 60 at the points of the procedure above described and illustrated by FIGS. 1a through 1c respectively. From the detailed view of FIG. 2c, it can be seen that the threaded portion 91 of retrieval cable 90 includes a first tapered portion 91a, and a second cylindrical threaded portion 91b. First tapered threaded portion 91a allows for ease of initial engagement into the relatively soft lumen of stent 10, while second cylindrical threaded portion 91b provides reliable anchoring of cable 90 into the lumen of stent 10 through the continued threading of portion 91b into lumen of stent 10. FIGS. 3a through 3c are side elevational views of the components used in the above described procedure for removing an implanted biliary stent from the common bile duct. FIG. 3a is an illustration of stent retrieval cable 90, and shows, at the distal end of cable 90, threaded portion 91, which includes a first far distal tapered threaded portion 91a, and a second cylindrical threaded portion 91b proximal thereto. As shown by FIG. 3a, cable 90 further includes rotation dial 92 at its proximal end, and torqueable shaft 93 along the length thereof. FIG. 3b is an illustration of wire guide 80, which is of conventional construction suitable for introduction through the interior passageway of introduction cannula 70, and for guidance of stent 10 and stent retrieval cable 90 through the placement thereof within their respective interior passageways. FIG. 3c is an illustration of introduction cannula 70 which is also of conventional construction. FIGS. 4a through 4c are enlarged, segmented, cross sectional views of various portions of stent retrieval cable 90 in combination with wire guide 80 and stent 10. FIG. 4a is a segmented cross sectional view of the proximal end portion of stent retrieval cable 90, as seen along line 4a-4a of FIG. 3a, and with wire guide 80 positioned within the interior passageway 99 thereof. As shown in FIG. 4a, torqueable shaft 93 is constructed of spiraled stainless steel wiring 94, about which has been applied a coating of teflon material 95. Wiring 94 defines an interior passageway 99 therewithin through which is receivable wire guide 80. Rotation dial 92 is soldered to wiring 94 at the proximal end of shaft 93 and serves to facilitate the torqueing of cable 90 whereby cable 90 may be threadably engaged with stent 10. FIG. 4b is a cross sectional view of the shaft of stent retrieval cable 90, as seen along line 4b-4b of FIG. 3a. FIG. 4b shows the spiraling of wire 94 which provides for the torqueability of cable 90, and serves to transfer the rotation of rotation dial 92 at the proximal end of the cable 90 into the rotation of threaded portion 91 at the distal end of cable 90. FIG. 4b also provides a good view of teflon coating 95 about the circumference of wiring 94. By providing a smooth outer surface, teflon coating 95 serves to facilitate insertion and removal of cable 90. FIG. 4c is a segmented cross sectional view of stent retrieval cable 90, as seen along line 4c-4c of FIG. 3a, with wire guide 80 positioned within the interior passageway 99 thereof, and where stent retrieval cable 90 has been threadedly engaged with the lumen of stent 10. Threaded portion 91 is soldered to wiring 94 at the distal end of shaft 93 and serves to form the attachment with stent 10 whereby stent 10 may be removed from the body through the channel of endoscope 60. As previously mentioned, threaded portion 91 includes a far distal tapered threaded portion 91a which facilitates the initiation of threaded engagement into the lumen of stent 10, and also includes a second cylindrical threaded portion 91b which is proximal thereto. By the continued threading of threaded portion 91 into the lumen of stent 10, the threaded engagement of cylindrical threaded portion 91b into stent 10 serves to firmly anchor cable 90 into stent 10 whereby stent 10 may be reliably removed. While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiment has been shown and described and that all changes and modifications that come within the scope of the invention are desired to be protected.

Claims: A device for removing a stent that has been implanted within the body of a patient, said device characterized by: A torqueable cable (90), said cable being sized to be received through the channel of an endoscope (60) and defining a passage therewithin for receiving a wire guide (80), said cable further having a threaded portion (91) at its distal end and a rotating means (92) for rotating said cable at its proximal end whereby the rotating of the proximal end of said cable rotates the threaded portion at the distal end of said cable; said threaded portion (91) being sized to threadedly engage the lumen of an implanted stent (10) to be removed from the body of a patient when positioned proximal thereto, and whereby the rotating of said threaded portion (91) by the use of said rotating means (92) engages the threading at the distal end of said cable, when so positioned, with the lumen of the implanted stent (10) to form an attachment between said the cable and the stent to be removed such that the combined cable and stent may be removed, in tandem, out through the channel of the endoscope (80). The device for removing a stent that has been implanted within the body of a patient as recited by claim 1 in which the threaded portion (91) of said cable includes a first tapered threaded portion at the far distal end of said cable and a second cylindrical threaded portion proximal thereto. The device for removing a stent that has been implanted within the body of a patient as recited by claim 1 in which said rotating means (92) included a rotation dial located at the proximal end of said cable. The device for removing a stent that has been implanted within the body of a patient as recited by claim 1 in which the torqueability of said cable includes the shaft of said cable being made of spiralled wiring (94). The device for removing a stent that has been implanted within the body of a patient as recited by claim 4 in which said spiralled wiring (94) is made of stainless steel. The device for removing a stent that has been implanted within the body of a patient as recited by claim 4 in which the shaft of said cable is coated with teflon (95).

Inventors: GROSSE CARSTEN, SOEHENDRA NIB, GROSSE, CARSTEN, SOEHENDRA, NIB
Applicants: WILSON COOK MEDICAL INC, WILSON-COOK MEDICAL INC.
Application year: 1991
Main classification: A61F2
IPC codes: A61F2, A61M25, A61M27