Surgery – Instruments – Internal pressure applicator
Reexamination Certificate
1997-09-03
2004-08-17
Woo, Julian W. (Department: 3731)
Surgery
Instruments
Internal pressure applicator
C606S194000
Reexamination Certificate
active
06776788
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an embolization device for positioning in a blood vessel, comprising an elongated wire body which in its unloaded condition has a predetermined shape and has an elongated shape with a substantially straight center line during its insertion through a catheter to a placement site in the blood vessel and after its release from the catheter assumes a complexly curved shape which depends on the predetermined shape and on the blood vessel impact on the wire body, which wire body preferably has a coupling means at its back end.
BACKGROUND OF THE INVENTION
Embolization devices in the form of coils where the wire body is formed by a thread extending helically around the center line of the wire body are well-known within radiology, where embolization coils are used for a number of different purposes all with the common feature that it is desired to limit or stop the free flow of blood in an area of a blood vessel. One example of an endovascular field of application for embolization devices for percutaneous, transluminal insertion using minimally invasive techniques, can be mentioned occlusion of an aneurism to prevent rupture of the vessel wall with resulting bleeding. Aneurisms may occur anywhere in the vascular system, but particularly cerebral and abdominal aneurisms require treatment to avoid life-threatening conditions. Another application is occlusion of arteriovenous malformations (AVM), where short-circuiting of arteries and veins looking like skeins of wool may occur, or occlusion of arteriovenous shunts or fistulas, which are major short-circuits between the artery side and the vein side in the vascular system with resulting heavy undesired blood flow. A fourth example of an application is blocking of the blood flow to a tumor, and a fifth, closure of traumatically conditioned blood flows owing to incised wounds or other bodily injuries or gastrointestinal bleeding.
Since embolization devices can be used in many different places in the vascular system and in vessels with very differing sizes, many different coils have been specially designed with various basic designs of the predetermined shape, and each basic design is usually made in a number of different sizes. To treat emergency patients, radiologists today have to stock a large number of different coils, and in the endovascular repair normally many coils are used which are inserted individually and are placed in a pile at the site of placement to be occluded. Considerable expertise is required to select the correct coil sizes for the relevant application, and the risk of unintended migration of a coil to other vessel sites owing to insufficient fitting within the vessel cannot be disregarded.
Conventionally, the predetermined shape of the embolization devices is made so that the wire body is helical with a helix diameter of the same size or slightly larger than the relevant vessel lumen, so that the wound wire body exerts an abutment pressure against the vessel wall. If the helix diameter is too large, the pressure against the vessel wall may become injuriously high, and if it is too small, the wire body can easily be released and drift away. Embolization coils with a regular helical shape or irregular coil shape are known from, for example, U.S. Pat. Nos. 4,994,069, 5,122,136, WO094/11051 and WO94/11051; SU-1777842-A1 discloses a coil with a single helix, WO95/25480 describes a spiral coil, DE-295 18 932-U1 a spherical coil, and WO96/18343 and U.S. Pat. No. 4,994,069 coils with a random matrix shape.
Before insertion of the embolization device, a catheter is placed transluminally in the vascular system having its distal catheter end at the site of placement, whereupon a guidewire mounted with the embolization device is pushed in through the catheter. When the wire body leaves the distal end of the catheter, it seeks to assume the predetermined shape. If the size and shape of the device are deemed suitable for the vessel geometry at the site of placement, the wire body is disconnected from the guidewire. A number of applicable types of coupling means in the back end of the guidewire with associated corresponding part on the guidewire are known, see for example EP-A-720 838 disclosing a screw thread, U.S. Pat. No. 5,217,484 disclosing a prehensile claw, WO94/06503 disclosing a pin connection, WO94/06502 disclosing a clamp connection, WO96/00104 disclosing a conical thread connection and EP-A 717 969 disclosing an inflatable holder.
SUMMARY OF THE INVENTION
The object of the present invention is to provide an embolization device which is applicable for a number of different vessel geometries and sizes and which at its placement in the vessel assumes a complexly curved shape which provides effective occlusion by means of the wire body itself. It is also desirable to achieve the occlusion with a smaller number of devices than is possible in the known art in order thus to reduce the risk of travel of a device away from the site of placement and to reduce the time spent on performing the occlusion.
In view of this the embolization device according to the invention is characterized in that the wire body in its predetermined or first or unloaded shape has at least one section located between its front and back ends in which the center line has substantially no curvature or such a small curvature that along a length of at least 20 mm it follows a helix-free path, and that the front end section of the wire body is adapted to be frictionally locked to the vessel wall at its discharge from the catheter, before said helix-free section has been discharged from the catheter. Of course, while the wire body is within the catheter, it is constrained in a generally linear shape.
The distal end of the catheter is usually located immediately at or at a short distance from the site of placement when the front end section of the wire body is discharged from the catheter as the wire body is pushed at its back end. During the discharging, the end section will approach and abut the vessel wall. At the continued discharge, the end section will arrange itself along the vessel wall over a length that causes the end section to frictionally lock with the vessel wall. Frictional locking in the present context means that the frictional forces between the distal end section and the vessel wall reach a magnitude at which the column loading from the free end of the wire body located between the catheter opening and the closest point of abutment with the vessel wall is unable to move the end section in relation to the vessel wall. As the helix-free section has a length of at least 20 mm, at least part of the section will still be inside the catheter when the end section becomes frictionally locked. At the subsequent release of the helix-free section, the free portion thereof will bend sideways away from the closest point of abutment with the vessel wall and seek towards an opposite area of the vessel wall, as seen in relation to the closest point of abutment, where a frictional locking will also occur. Then discharge of a further portion of the helix-free section of the catheter will lead to renewed bending of the wire body in a new direction, etc. The length of the helix-free section can be adapted to the vessel geometry at the site of placement to be occluded, a longer helix-free section for the same vessel geometry making the embolization device arrange itself with more portions of the wire across the vessel lumen, thereby making the occlusion denser, and a shorter helix-free section producing a more open occlusion, should this be desired.
The embolization device provides the considerable advantage that the helix-free section itself automatically adapts to the vessel geometry in question, and is fastened securely to it without any risk of unintended release from the site of placement. The various fields of application of the embolization device display different specific problems, for example that the wire body should only exert a relatively limited pressure on the vessel wall at placement in an aneurism w
Klint Henrik S.
Molgaard-Nielsen Arne
Rasmussen Erik E.
Brinks Hofer Gilson & Lione
William Cook Europe A/S
Woo Julian W.
LandOfFree
Embolization device for positioning in a blood vessel does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Embolization device for positioning in a blood vessel, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Embolization device for positioning in a blood vessel will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3331897