WO2011105979A1

WO2011105979A1 - Stent- balloon assembly

Info

Publication number: WO2011105979A1
Application number: PCT/TR2011/000053
Authority: WO
Inventors: Ebru Cataltarla Sirali; Pinar Nebol Yilmaz; Ahmet Reha Basaran
Original assignee: Alvimedica Tibbi Urunler Sanayi Ve Dis Ticaret A.S.
Priority date: 2010-02-24
Filing date: 2011-02-23
Publication date: 2011-09-01
Also published as: TW201136574A; TR201001355A2

Abstract

The present invention relates to an assembly comprising at least one expandable stent (2) for use in affected vessels, at least one balloon (1) in said stent providing the required expansion, and a graft (3) enveloped around said stent, characterized in that said balloon (1) can be inflated from an initial state (1) to an inflated state (1a) with a larger diameter, said stent (2) surrounding said balloon is expanded to a diameter (2a) that is larger than that of the original stent (2), this expanded state is a stable state not restoring to the original state of the stent, the extent of expansion is adjusted by the amount the balloon is inflated, and said graft (3) enveloped around said stent (2) expands in line with the amount the stent (2) is expanded to a state with a larger diameter (3a).

Description

STENT-BALLOON ASSEMBLY

DESCRIPTION

Field of Invention

This invention relates to a balloon-expandable stent assembly, enveloped with a textile or polymer material, and maintaining its state after becoming expanded, particularly for use in treating aneurysm.

Prior Art

Aneurysm is a vascular disease occurring with the diameter of arteries of the abdomen exceeding 2 cm. Typically in this area, vessel walls expand and indications of tear/split formation are encountered. When this disease advances, vascular dissection and rupture events as well as excessive increases of the vascular diameter are seen. Vascular diameter reaching 5 cm and rupture events lead to massive hemorrhage and resultantly to death risk.

The conventional method in treating aneurysm is surgical intervention. The part involved in this disease is cut open in an attempt of repairing it. The repair operation is either in the form of sewing, or in the form of implanting tubular biocompatible elements. Whilst this method is one of the mostly-applied operations worldwide, the length of this treatment period and the risks associated with subjecting elderly patients to surgical interventions have increased the use of stent applications. With respect to stent implantations, many various application procedures have been developed to place a stent at the bulged region of a site of aneurysm. As disclosed in the patent application EP712614, as one of such approaches, a stent of an expandable design is implanted into the bulged region of a site of aneurysm, together with a balloon in said stent. Whilst basically a desired embodiment is designed according to that disclosure, not much mention is given on the configuration at the exterior of the stent cage. In addition to the lack of disclosures about the inner and outer walls of the stent in said patent, it has some drawbacks in that the stent is attached to an affected vessel by means of hooks. The most important disadvantages there are the difficulty of application and the risk of damaging the vessel structure. Furthermore, there aren't any descriptions available in that patent on the flexible structure and stability of the stent. It only mentions on attaching a stent to an affected vessel region by means of a hook. Another method of stent implantation against aneurysm is the use of a self-expandable stent. This embodiment involves many patented technologies. The basic feature of this type of stent embodiment is introducing the stent in a contracted manner into an affected vessel region and releasing the flexible stent to result in a self-expansion event there. Whilst such a structure may be considered theoretically easy, introducing a contracted stent within a tube into a vessel, and then letting it expand in practice, both requires a complex device, and leads to difficulty in application. Thus, it both causes implementation difficulties and increases the costs.

Object of Invention The object of this invention is to design and embody a stent particularly for use in aneurysm, which can be expanded in a controlled manner by means of a balloon, and is enveloped by a biocompatible and flexible textile, Teflon®, or any other material.

It has been aimed with this invention to minimize the complex designs and application- related difficulties of either self-expandable or balloon-expandable stent configurations. A great advantage of the stent, preferably fabricated from steel, is that once it is expanded with a balloon to a desired extent, it maintains this expanded state. Following the implantation of the balloon-stent assembly into a vessel, the outer diameter of this assembly is expanded until it completely leans against the inner diameter of the respective vessel so as to provide a proper immobilization there. This feature is particularly ensured based on the fact that the material used in the stent is preferably steel or any other material with similar features, maintaining the expanded state once inflated to a certain extent. Additionally, the use of a flexible textile or similar biocompatible material, enveloping the stent and moving together with the stent cage, eliminates the drawbacks encountered in the prior art. What is particularly preferred in terms of ease of application is the stability of the stent material in its expanded or inflated state and the flexibility of the textile or similar biocompatible material enveloping the stent and expanding together with the stent as it is inflated with a balloon. Another advantage here is that no complex hooks or clamps are required for fixing the stent in the vessel. Description of Figures

Figure 1 is an overall illustration of the present invention together with the device for application. Figure 2 is an illustration of the stent-graft assembly according to the present invention in a vessel prior to inflation.

Figure 2 is an illustration of the stent-graft assembly according to the present invention in an inflated state. Reference Numbers

1- balloon

1a- inflated balloon

2- stent

2a- inflated stent 3- greft enveloping the stent

3a- inflated graft enveloping the stent

4- marker

5- distal shaft

6- proximal shaft 7- guide wire

8- connector

9- aorta

10- renal arteries

11- catheter 12- site of aneurysm 13- iliac arteries

Detailed Description of Invention

The stent-graft assembly according to the present invention consists of an expandable stent (2), a graft (3) enveloping the stent, and a balloon (1) insertable into and inflated in the stent. The stent (2) is preferably made of a steel material and is structured so that it expands together with an inflating balloon (1) therein to an extent of expansion adjustable in line with the amount of inflating the balloon and in line with the diameter of the respective vessel in which it is present. The stent (2) is not restored to its original state when the balloon (1) in itself is deflated/removed. It is possible to use biocompatible alloys, polymers, and other materials in place of steel, provided that these materials guarantee the features stated above.

The graft (3) surrounding the flexible stent (2) is made of a flexible textile material which is expandable in compliance with the stent expanding in itself. The basic characteristics of the graft (3) structure is its flexibility and is covered around the stent by any mesh patterns or is directly wrapped around the former. In this context, a graft (3) can be made either from a biocompatible textile material, or from other biocompatible materials such as Teflon^® or some polymers. As illustrated in Figure 1 , the stent (2) and graft (3) are connected to a stent support. The stent support is basically of a three-component configuration serving to place a balloon stent-graft assembly (1 , 2, 3) into a vessel. This configuration is composed of a proximal shaft (5), a distal shaft (6), and a connector (8), to which a guide wire (7) serving to define the pathway in the vessel, a balloon (1) advanced following the guide wire, a stent-graft structure (2, 3) around the balloon, and a marker (4) in the balloon for localization under x- rays monitoring are connected. The balloon stent-graft assembly (1 , 2, 3) introduced into a vessel is advanced to the site of aneurysm by means of the guide wire (7).

In practice, the balloon stent-graft assembly (1 , 2, 3) advanced to a site of aneurysm (12) is placed at an optimal region in this site (12), as illustrated in Figure 2. The aorta (9) and just laterally underneath it are illustrated the renal arteries (10) in the top part of this Figure. At the inferior of the site of aneurysm (12), according to this figure, ,are illustrated the iliac arteries (13). The location of the balloon stent-graft assembly (1 , 2, 3) is checked by means of markers (4) under X-ray monitoring. Figure 2 depicts the balloon stent-graft assembly (1 , 2, 3) in the state prior to inflation. Figure 3, in turn, illustrates the case in which the balloon (1) is inflated at the aneurysm site (12) so much so as to comply with the unaffected vessel diameter at both ends of this site, and the stent (2) is expanded accordingly due to its flexibility together with the flexible graft (3) enveloping it. The diameters (1a, 2a, 3c) of the inflated balloon (1), the expanded stent (2), and of the expanded graft (3), respectively, become naturally enlarged as compared to their initial sizes. The expansion amount (2a, 3a) is adjusted with the amount by which the balloon (1) is inflated so that the assembly leans against the respective vessel wall. The balloon (1), stent (2), and graft (3) according to the present invention are embodied on the same axis. There is no axial misalignment there. Axial misalignment, however, can be provided according to the way the balloon (1) inflates, the morphology of aneurysm, and the intended geometry.

The coating layer applied over the material of the stent according to the present invention, which is preferably steel or any other biocompatible material, should likewise be flexible. Thus, the feature of this coating layer is kept unchanged or its function is maintained when the stent is expanded.

No complex arrangements are required to fix a flexible stent (2) and a flexible graft (3) surrounding the stent, which are expanded and thus situated by inflating the respective balloon (1) according to the present invention. Furthermore, since the extent of expansion can be adjusted during placement into a vessel, no separate adjustment means or no hook or catch mechanisms are required for ensuring the intravenous fixation.

The protection scope of this application is set forth in the following claims and should not be restricted to the disclosures given above for illustrative purposes only. It is obvious that a person skilled in the relevant art can produce the currently-disclosed novelty by making use of similar embodiments and/or can apply the disclosure to other fields with similar purposes in the relevant technique. Therefore such embodiments shall obviously lack the novelty criterion.

Claims

An assembly comprising at least one expandable stent (2) for coaxial use in affected vessels, at least one balloon (1) in said stent providing the required expansion, and a graft (3) enveloped around said stent, characterized in that said balloon (1) is disposed in the interior of the stent in an inflatable manner from an initial state (1) to an inflated state (1a) having a larger diameter, said stent (2) is coaxial with the balloon (1) and surrounded by the latter (1), said stent (2) is expanded by means of inflating the balloon (1) to a diameter (2a) that is larger than that of the original stent (2), this expanded state of the flexible stent (2) is a stable state not restoring to the original state of the stent, the extent of expansion of said stent (2) is adjusted by the amount the balloon is inflated, said graft (3) of a biocompatible textile or other material is enveloped around said stent (2), said graft (3) is expandable in line with the amount the stent (2) is expanded to a state with a larger diameter (3a), and after said stent (2) and graft (3) are expanded, they lean against the vessel wall so as to provide a smooth blood flow there through.

The balloon-expandable stent according to Claim 1 , characterized in that said balloon (1), stent (2), and the graft (3) enveloping said stent can be expanded in compliance with the amount said balloon (1) is inflated and once the balloon (1) is deflated, they maintain the current expanded state and do not become contracted.

The flexible stent according to claims 1 and 2, characterized in that it is capable to expand from a low-diameter state enabling it to insert into a vessel, to a state (2a) leaning against the vessel wall by inflating the balloon (1) it includes, and in that this expansion, not restorable to the original unexpanded state upon deflating the balloon, is ensured by means of a structure made of biocompatible steel, polymer or similar materials, which is flexible as it is expanded and becomes rigid and does not restore to its unexpanded state when it is released.

The stent-enveloping flexible graft according to clams 1 , 2, and 3, characterized in that the internal diameter of said graft envelopes the stent (2) all around in a mesh pattern, the outer diameter thereof leans against the inner diameter of a vessel, and in that said graft is made from a biocompatible textile, polymer or similar material expanding (3a) together when the stent (2) is expanded (2a).

The balloon-stent-graft (1 , 2, 3) assembly according to Claim 1 , characterized in that

1 the stent (2) and the greft (3) are placed immovably in an affected site of the respective vessel interior, and in that both ends of said stent (2) and graft (3) lean against unaffected or slightly-affected inner walls of the respective vessel.

2