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Vessel implant for the treatment of an aneurysm

Vessel implant for the treatment of an aneurysm description/claims

This application claims priority to German Patent Application Number 10 2007 019 058.3, filed Apr. 23, 2007, which is hereby incorporated by reference as if set forth herein.

1. Field of the Invention

The present invention relates to a vessel implant for the treatment of an aneurysm, comprising an elongate body which has an inlet opening, an outlet opening as well as a passage connecting the inlet opening with the outlet opening for blood flowing through the blood vessel, with the passage being bounded in the peripheral direction by a blood-impermeable wall.

An aneurysm is a pathological, spatially restricted dilatation, swelling or expansion of a flood vessel, in particular of an artery. Aneurysms can occur at any section of an artery. Abdominal aortic aneurysms or aneurysms at the popliteal artery occur particularly frequently. Dilated blood vessels are subject to a high risk of rupture so that there is a risk of fatal bleeding. Furthermore, dilated blood vessels tend to become larger. The risk of rupture increases as the diameter of the aneurysm increases since the pressure exerted on the vessel wall of the blood vessel by the blood flowing through the blood vessel increases as the vessel width increases (Bernoulli's Law).

2. The Prior Art

It is known to treat such dilated blood vessels using tubular or hose-shaped implants which are also called stents. In this connection, a stent having a blood-impermeable wall is inserted into the affected blood vessel such that the aneurysm can be bridged by means of the stent. In this connection, the two ends of the stent are fixed in as shape matched a manner as possible at the non-dilated regions of the blood vessel adjoining the dilated region at both sides, whereby a seal of the dilatation should be achieved to prevent blood from continuing to flow into the dilatation. The diameter of such a stent approximately corresponds to the normal diameter of a vessel.

There is, however, the problem with these solutions that small leaks can frequently occur, due to insufficient adaptation to the vessel, between the stent and that region of the vessel wall of the blood vessel at which the stent is fixed. Blood can continue to flow into the aneurysm, in particular due to leaks present at the inlet opening side or due to collateral vessels so that the risk of rupture of the vessel wall in the region of the aneurysm is not eliminated.

It is therefore the underlying object of the invention to provide a vessel implant of the initially named kind which reduces the risk of a rupture of the vessel wall in the region of an aneurysm.

This object is satisfied by a vessel implant having the features of claim 1 and in particular in that the inlet opening has a larger cross-sectional area than the outlet opening.

The vessel implant is preferably fixed at its end having the inlet opening and/or at a section directly adjoining the inlet opening to the non-dilated region of the blood vessel disposed upstream of the aneurysm. The vessel implant preferably has a length which can extend over the total length of the aneurysm.

In accordance with the continuity law for non-compressible fluids, the same blood volume exits the outlet opening of the body that has flown into the body at the inlet opening of the body, i.e. the volume flow or the volume moving through a cross-section of the body within a unit of time is the same at the inlet opening and at the outlet opening. It results from this that the blood flowing through the blood vessel and thus through the body passes through the outlet opening at a higher speed than through the inlet opening. An underpressure by which the blood located in an aneurysm is sucked out arises at the end of the body having the outlet opening—as with a water jet pump—due to the higher speed. In this way, a corresponding underpressure also arises inside the aneurysm so that the dilated vessel wall is relieved.

This effect even occurs when the vessel implant is not completely sealed at the inlet opening side. The risk of a rupture of the vessel wall of the aneurysm can thus be effectively reduced using the vessel implant made in accordance with the invention.

Since a seal of the aneurysm at the downstream side by the vessel implant is not required and does not even have to be 100% upstream of the seal, the vessel implant can also be used in those cases in which a sealing fixing at the blood vessel is not possible upstream and/or downstream of the aneurysm. Since a seal is not necessary downstream of the aneurysm, the vessel implant in accordance with the invention can also be used with an abdominal aortic aneurysm which starts directly at the branch to the two femoral arteries. A fixation downstream of the aneurysm can either be dispensed with or a blood-permeable fixation can be used. For an abdominal aortic aneurysm starting directly at the branches to the two renal arteries, the vessel implant can be provided with a fixation section which in particular adjoins the inlet opening of the body directly and which is made blood-permeable in order not to close the branches to the renal arteries.

In accordance with an embodiment of the invention, the body, a section of the body located between the inlet opening and the outlet opening and/or the passage from the inlet opening to the outlet opening converges and/or converge. A gradual reduction of the cross-sectional area from the inlet opening to the outlet opening can hereby be achieved over the total length of the body to avoid turbulence in the blood flow, for example. The convergence is preferably made uniformly, continuously and/or conically.

The body is preferably made for contact at the vessel wall of the blood vessel in the region of the inlet opening and/or at a section of the body adjoining the inlet opening. The outer cross-sectional area of the body is in particular dimensioned in the region of the inlet opening and/or of the section adjoining the inlet opening such that the body contacts the vessel wall of the blood vessel in the region of the inlet opening and/or at the section adjoining the inlet opening in the implanted state. A fixation of the body in the blood vessel can hereby be achieved.

To achieve a particularly good fixation of the vessel implant in the blood vessel, it can be advantageous for the section of the body adjoining the inlet opening to be cylindrical. The body can thus be adapted to the internal diameter of the blood vessel over a larger region.

It is particularly preferred for the section of the body adjoining the inlet opening to have a wall made permeable to blood. The section adjoining the inlet opening can be made as a mesh, for example. An ingrowth of the cells of the vessel wall of the blood vessel into the body of the implant is hereby promoted and thus a particularly firm fixation achieved.

In accordance with a further embodiment of the invention, the outer dimension of the body is dimensioned in the region of the outlet opening such that the body is spaced apart from the vessel wall of the blood vessel in the region of the outlet opening. This can in particular be the case when the outer dimension of the body also converges toward the side having the outlet opening in addition to the cross-sectional area of the passage.

The body is preferably provided with blood-permeable fixation means for the end of the body at the outlet opening side, said means being made for contact with the vessel wall of the blood vessel. A lateral migration of the end of the body having the outlet opening to and fro in the blood flow can hereby be prevented so that a radial fixation is achieved within the blood vessel. The fixing means are made blood-permeable to impede a sucking of the blood out of the aneurysm effected by the generated underpressure as little as possible.

The fixing means can be made to keep the body spaced apart from the vessel wall of the blood vessel in the region of the outlet opening. It is hereby ensured that the end of the body having the outlet opening does not contact the vessel wall of the blood vessel so that the previously explained water jet pump effect can occur over the full peripheral area around the outlet opening. The fixing means can in particular be made such that the outlet opening or the end of the body having the outlet opening is held in centered form inside the blood vessel.

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