DE29620088U1 - Implantable stent - Google Patents

Description

Implantable stent with honeycomb stent design in expanded state to optimize stent function, especially in the coronary vessel area

Description:

4. Generic implantable sleeves ("stents") are used in many medical disciplines (cardiology, internal medicine, cardiac surgery, urology, radiology, etc.). Stents are required when narrowed vessels or tubes need to be kept open, for example in the case of a narrowed coronary artery, where after prior or simultaneous dilation, a stent can be placed in the stenotic area to prevent the vessel from closing off, thus avoiding a bypass operation, for example.

2. The stents known from the literature or already introduced on the market are manufactured using different production methods from different approved materials, e.g.

a) wires are used that are either artistically twisted or wound into a sleeve shape (similar to a compression spring)

b) sleeves are used which are cut with a laser

c) you punch the shape out of a sheet of metal, bend it into a sleeve and weld it d)

What all of these stents have in common is that they have a smaller diameter when inserted into the human body than in their final state. In order to bring the stents to their final diameter, they are expanded (with a balloon catheter or a mechanical tool) or are made of a thermometal so that the stent reaches its maximum diameter at the point of placement under the influence of body temperature.

3. Stents are currently used which, after expansion, show the following structures: spirals (similar to a compression spring); diamond-shaped grids; square or rectangular grids; distorted diamond-shaped grids; rings extending from a long bar (bar in the longitudinal direction); etc.

When used in humans, particularly in the area of coronary vessels, it has been shown that the distorted diamond-shaped structure has proven to be very effective. It comes closest to the requirements of many users, although the web cut surfaces of these stents are rectangular and therefore least favorable for flow, since the edges, which are in the flow path, lead to turbulence and thus to deposits of blood particles with the risk of renewed stenosis.

The user’s ideal stent should meet the following requirements:

A structure that, in its final state, has the same strength in the longitudinal and transverse directions. Its webs cover as little of a coronary vessel wall as possible, so that as few side branches of the vessel as possible are covered and thus closed.

The greatest possible flexibility so that the stent, for example in the coronary vessel, optimally adapts to the twists and turns of this vessel.

A design of the stent surface on the inner side that offers as little resistance as possible to the flowing medium, e.g. blood, and is so smooth that, for example, no blood particles can settle there.

A design of the stent surface on the outside that allows the stent to exert as little uniform pressure as possible on the vessel wall in order to reduce or prevent increased cell growth of the vessel wall cells and thus a renewed narrowing or closure of the vessel or tube.

Based on this, the invention is based on the object of creating a stent which achieves the required strength with as little material as possible.

This task is solved with a stent with the features of claim 1. This stent has a honeycomb structure when expanded and thus the required equal strength in the longitudinal and transverse directions. The webs that form the "honeycombs" can be designed so thinly that as little of the vessel wall or tube as possible is covered; a blockage of any vessel side branches is thus minimized. This automatically achieves the required flexibility so that the stent can optimally adapt to the course of the vessel, for example in the coronary vessel.

The rounded (lens-like, convex) web design optimizes the flow of the stent according to claim 2, achieving better laminar medium flow (e.g. blood flow). This is further improved by a special polishing or coating process for the stent, whereby the polished and smooth surface in the inner lumen of the stent reduces the possibility of deposits of, for example, blood particles.

The rounded (lens-like, convex) design of the outside of the bar according to claim 3 reduces the probability that one or more bars will stand up when the stent is expanded (this often happens with previous sleeve stents) and penetrate the vessel wall with the sharp, raised edge. The rounded design of the outside of the bar results in the stent being placed more gently against the vessel wall, combined with a more even (and therefore less localized) pressure load on the vessel wall, so that the risk of increased cell growth (as previously described) is reduced.

The invention is explained in more detail below using an exemplary embodiment shown in the drawings. They show:

Fig.l a part of an expanded stent,

Fig.2 a honeycomb with webs,

Fig.3 a section through a web according to line A-B of Fig.2 on the inside of the sleeve, Fig.4 a section through a stent in the area where it is placed on the vessel wall.

The implantable stent 11 has a honeycomb-shaped stent design in the expanded state to optimize the stent function, especially in the coronary vessel area. The honeycomb structure thus leads to the same strength in the longitudinal and transverse directions. The webs 10 can be designed so thin that, when used in the area of the coronary vessels, the risk of occlusion of coronary side branches by stent material is minimized and better flexibility for adaptation to the course of the vessel is achieved.

The rounded bridge design according to Fig.3 achieves better laminar blood flow. This is further improved by a special polishing and coating process inside the lumen and the possibility of blood particles depositing is reduced. The outer rounded bridge design according to Fig.4 enables a more even and thus locally lower pressure load on the vessel wall 12 and thus reduces the risk of increased cell growth and the resulting re-formation of stenosis.

Advantages of the method:

- equal strength in longitudinal and transverse directions

- the webs (between the "honeycomb" openings) can be made thinner so that

- less vessel wall surface is covered by the stent material in the coronary vessel; thus, fewer vessel side branches are closed

- greater flexibility of the stent is achieved and thus a better adaptation to the course of the coronary artery

- the blood flow becomes more laminar and thus the possibility of blood particles settling is reduced. This reduces the risk of new stenosis forming

- the lower, more even pressure load of the struts on the vessel wall reduces the risk of increased cell growth and thus the risk of new stenosis formation

Claims (3)

• · Protection claims 1. Implantable stent (10) which, in the implanted state, i.e. expanded, has a honeycomb lattice structure. 2. Implantable stent according to claim 1, characterized in that its webs (11) have been optimized under flow aspects. 3. Implantable stent according to claim 1 or 2, characterized in that its webs (11) are rounded on the outer surface of the sleeve.