Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Implantable prosthesis – Hollow or tubular part or organ
Reexamination Certificate
2000-04-07
2001-11-20
Milano, Michael J. (Department: 3738)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Implantable prosthesis
Hollow or tubular part or organ
C623S001110, C623S001230
Reexamination Certificate
active
06319287
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a stent assembly for keeping open body channels, especially the bile duct.
For draining body cavities, it is known to use a stent assembly, wherein a stent acting as a draining tube is introduced in a patient's body on a guiding string. U.S. Pat. No. 4,963,129 describes a stent assembly with a tubular stent for draining the cavity system of the kidneys. This stent is introduced via a guiding string which is withdrawn when the stent has been positioned. Moreover, a so-called pusher hose is pushed over the guiding string. The proximal end of the stent is supported at the distal end of the pusher hose. A coupling means is provided for transmitting not only thrust forces, but also tensile forces from the pusher hose to the stent. The coupling means consists of two complementary parts at the stent and at the pusher hose that mutually embrace each other and are locked by the guiding string passed therethrough such that they cannot be disengaged with the guiding string inserted. Thus, it is possible to position the stent very accurately, it being possible to pull back the stent over some distance before the disengagement.
German Patent DE 42 33 514 C1 describes a ureter catheter also placed over a guiding string, a pusher hose being provided in addition. The catheter and the pusher hose are connected through a disengageable coupling device locked by the guiding string.
A body channel that is especially hard to access is the bile duct. The bile duct leads the bile produced in the liver into the duodenum. At the mouth of the bile duct, a constriction is located that is called papilla or sphincter and functions as a valve. Liquid bile produced in the liver is introduced into the intestines through the bile duct. When the bile duct is clogged, a stent is introduced for keeping it open, the stent being a tubular prosthesis through which the liquid bile is introduced into the intestines. Inserting the stent is generally done with the help of a special endoscope from the distal end of which the stent is pushed out laterally. In doing so, it may happen that the stent is introduced to deep into the bile duct or is displaced after insertion and disappears in the bile duct. Further, it may happen that the stent becomes obstructed after having been placed. In such cases, it is necessary to remove the stent endoscopically or the correct its position.
SUMMARY OF THE INVENTION
It is the object of the invention to provide a stent assembly that is suitable for placement of the stent in a body channel, on the one hand,.and that, on the other hand, allows for later repositioning or extraction of the stent.
In the stent assembly of the present invention, the coupling device comprises a filament making the connection to the pusher hose. The coupling device is locked by means of the guiding string and unlocked when the guiding string is pulled out. In this context, a guiding string is a guiding wire or, in general, a guiding probe of plastic material, for example. In the unlocked state, the pusher hose may be withdrawn while the stent remains in the body channel. The filament is still located at the proximal end of the stent. Should it be found that the stent is positioned too far in the body channel, it may be pulled back by pulling at the filament. Thus, positional corrections can be made easily either immediately after the positioning of the stent or at a later time, using an instrument, e.g. having a pair of tongs for pulling at the filament, introduced into the body. It is also possible to remove the stent at a later time without any problems.
The present stent assembly is particularly suited for a bile duct stent. The bile duct is a body channel that is very difficult to access invasively. The filament at the proximal end of the stent is readily accessible from the duodenum after the placement of the stent and can thus be reached well from the intestines using a gripping instrument such as tongs.
The stent forms an elongated draining tube with a length of about 4-18 cm for bridging constrictions (stenoses) or occlusions, preferably in a bile duct. Suitably, the stent is provided with barbs to fix it. Such a barb and/or a sleeve carrying the barbs is suitably used as retaining elements for the filament. The filament has a typical length of about 2-10 cm.
Preferably, the filament forms a filament loop. This enables a simple and strong coupling with the pusher hose and a simple gripping for positional corrections with an instrument, e.g., having a hook.
REFERENCES:
patent: 4963129 (1990-10-01), Rusch
patent: 5713948 (1998-02-01), Uflacker
patent: 6019779 (2000-02-01), Thorud
patent: 6068654 (2000-05-01), Berg
patent: 6132450 (2000-10-01), Hanson
patent: 6132471 (2000-10-01), Johlin
patent: 6214036 (2001-04-01), Letendre
patent: 6221096 (2001-04-01), Aiba
patent: 6241738 (2001-06-01), Dereume
patent: 42 33 514 C (1994-04-01), None
B. Braun Melsungen AG
Diller Ramik & Wight
Milano Michael J.
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