Strengthened implant for bodily ducts

Details Strengthened implant for bodily ducts Strengthened implant for bodily ducts

1999-01-22

2002-01-15

Reip, David O. (Department: 3731)

Surgery

Instruments

Internal pressure applicator

C606S194000, C623S001220

Reexamination Certificate

active

06338736

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an implant for closing passages in organs, comprising a primary coil of a resilient material, where the implant, in an operational state, forms a secondary structure of greater diameter compared to the primary coil, where the implant can be converted by a guide element from the shape of the secondary structure into a transporting state in which the implant adopts an elongate shape, and the implant, after separation from the guide element, once again assumes the operational state, and also a set containing the implant and an insertion device for the implant.
2. Description of the Currently Available Technology
For many years now, in invasive surgery, such implants for closing vessels have been implanted by means of catheters. DD-A-158,084 discloses a wire coil for intraarterial and intravenous closure of blood vessels. Here, a wire coil is shaped to give a helical spring body such that, on application of an external force, it can be deformed elastically to a straight wire coil and, after the force is released, assumes a knot-shaped configuration.
EP-B1-0,571,422 describes various forms of implants and a device of the type mentioned in the introduction. Accordingly, the primary coil can be made from a suitable wire material or an elastic polymeric tube. A particular embodiment of the implants of the type described at the outset is proposed in EP-B1-0,571,422 in which the proximal end of such an implant is designed in a specific way so as to solve, with an appropriate applicator, the problem of, on the one hand, being able to push the primary coil off from a guide wire and, on the other hand, maintaining a sufficiently secure connection between primary coil and guide wire when the primary coil has almost completely formed the secondary coil. This is of particular importance in order to correct possible dislocations caused by the opening-out of the secondary coil, and, if need be, to pull the primary coil back at least partially onto the guide wire
10
again. At the same time, however, the connection between primary coil and guide wire must be designed such that the primary coil can also be finally pushed off from the guide wire without excessive forces being required.
U.S. Pat. No. 5,382,259 discloses implants for closing passages in organs, which implants have, at both ends, short coil pieces which are connected to one another via a cylindrical fibrous fabric or mesh. In one embodiment, the two coil pieces located at the ends are additionally coupled to one another via a wire. This wire can consist of a memory metal such as, for example, the alloy nitinol. It is in this case described as an advantage if the wire has a secondary structure which forms after implantation. Thus, on account of the soft fabric or mesh which adapts to the structure of the wire, a second configuration of the implant with an increased diameter is formed. The configuration of the coil pieces located at the ends thereby remains unaltered.
In a further embodiment disclosed in U.S. Pat. No. 5,382,259, a continuous wire coil is enclosed by a fabric of silk or by a synthetic fibre in order to form a thrombotically active surface. This fabric has no supporting function whatsoever.
A problem of the known implants is, however, the closure of larger openings. When the conventional primary coils are used to form larger secondary coils, there is the problem that the forces sufficient to hold the implant securely in the desired position are no longer available in the outer turns of the secondary coil. This problem can be avoided by increasing the rigidity of the primary coil, for example by using stronger wire. However, the result of this is that, in the centre of the secondary coil, it is no longer possible to have such small radii of the secondary coil as when using softer primary coils. This has the effect that a fairly large hole remains in the centre of such a secondary coil. Since in practice this hole can only be closed by thrombosis, going beyond certain minimum values means that a tight closure of the vessel can no longer be achieved. Thus, implants with complex secondary structures in particular, in which both small and large radii of curvature are formed, and which thereby ensure a particularly tight closure, cannot be used for closing larger openings.
Also in the case of the implants disclosed in U.S. Pat. No. 5,382,259 and described above, the closure of larger openings leads to problems. Said specification discloses a fabric which encloses the wire, has no supporting functions whatsoever, and serves only to create a thrombotic surface. The dimensional stability of the secondary configuration of the implant has to be provided solely by the central wire. If the dimensional stability sufficient for secure closure of large openings is to be achieved in the outer areas too, then the wire must have very great rigidity, and this makes it very difficult to stretch the wire out for the purpose of inserting the implant into a catheter, or indeed makes this impossible. For this reason, these implants are also only suitable for closing small openings. In addition, U.S. Pat. No. 5,382,259 discloses only very simple secondary structures with large radii, and in particular without any great differences in the radii. This results in a very open structure whose closure can be achieved only by virtue of the thrombotic action of the fabric.
SUMMARY OF THE INVENTION
The invention is therefore based on the object to provide an implant of the type mentioned at the outset, in particular with a complex secondary structure with different radii of curvature, and with which implant it is possible to reliably close even larger vessel defects, for example in the central circulatory system, where there is a strong blood flow and also a high blood pressure. A further object of the present invention is to provide a suitably adapted device for application of such an implant.
This object is achieved by means of an implant of the type mentioned at the outset, which implant is characterized in that the primary coil has areas of different bending rigidity along its longitudinal extent. In the case of an implant having a secondary structure with different radii of curvature, it is particularly advantageous if the primary coil has, in the areas of large radii of curvature of the secondary structure, a greater transverse spring rate than in the areas of smaller radii of curvature of the secondary structure.
With such a primary coil, it is possible for very complex secondary structures having different radii of curvature to be constructed. The areas of lower transverse spring rate are in this case formed into turns with small radii, and the areas of greater transverse spring rate are formed into turns with large radii. This ensures that in areas of small radii of the turns of the secondary structure, the primary coil is sufficiently soft to enable the secondary structure to be simply stretched out again, for example for inserting the implant into a catheter, and at the same time, in areas of greater radii of the turns of the secondary structure, the primary coil is sufficiently rigid to reliably guarantee the dimensional stability necessary for tight closure of a vessel defect, even in the case of large openings and the associated large radii of curvature of the secondary structure.
In accordance with the present invention, secondary structures can be developed by twisting the primary coil, which assumes the shape of a cylinder, a cone, a double cone with greater radii at the ends, a double cone with different radii at the ends, a cylinder in which turns of the secondary structure with different radii alternate with each other, two spirals connected by a cylindrical section, a double rosette, a double cone, where the turns of the second cone are wound onto the turns of the first cone, or assumes the shape of a plurality of eight shapes. By appropriate adjustment of the bending rigidity in different areas of the primary coil, cone or spiral structures can b

Affiliated with

Also associated with

Rating

Strengthened implant for bodily ducts does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Strengthened implant for bodily ducts, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Strengthened implant for bodily ducts will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2856029