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Description  |
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The invention relates to a device for the widening of blood vessels.
Dilation catheters with an inflatable balloon, called balloon catheters,
which are inserted into blood vessels with the balloon uninflated and the
balloon then widened at the desired position, are known in principle in a
wide variety of embodiments. Resilient metallic meshes have also
previously been used for dilating, being inserted into the vessel in
compressed form and enlarged to the desired diameter after removal of the
insertion catheter (cf. Martine Mazieres in Panorama du Medecin - No.
2517, April 1987).
However, these endoprostheses for vessels are not satisfactory to a
sufficient extent.
The object of the present invention is to provide an improved device for
the widening of blood vessels which, in the event of stenoses or
occlusions, once more guarantees the bloodflow so that the downstream
extremity or the succeeding organ remains supplied with circulating oxygen
and thus remains healthy.
This object is achieved by a device for the widening of blood vessels with
a catheter in whose front end area an elongate, inflatable balloon is
present, and wherein the outside of the uninflated balloon is wound round
with a woven material of such a length that its end edges, provided with a
border, overlap.
The end edges and the woven material overlap so far around the outer
surface of the uninflated balloon that, after inflating the balloon, the
end edges abut flush and even. That is, the extent of the overlapping
depends on the desired final diameter of the endoprosthesis and can amount
to a multiple of the outer periphery of the uninflated balloon.
The woven material preferably also has borders at the side edges. In the
case of synthetic woven materials, the borders are also of synthetic
material. However, they may contain a metal wire for reinforcement. In
order to stabilize the shape of the endoprosthesis, reinforcements may be
present running, at a distance from and parallel to the bordered side
edges, from end edge to end edge. In the case of synthetic woven
materials, the reinforcements may be of synthetic material or of metal or
of metal wires encased in synthetic material whose ends are anchored in
the borders of the end edges. When using metal wires as reinforcements,
the first reinforcements are preferably arranged directly alongside, ie.
at a short distance from, the bordered side edges. The combination of
synthetic woven material with metallic reinforcements and metallic insets
in the borders has the advantage that the metal fibers or wires act as
X-ray contrast agent and facilitate visualization of the position of the
endoprosthesis.
In the case of metallic woven materials, the borders and reinforcements are
also of metal. The number of reinforcements depends on the length in the
widened state of the cylindrical woven material bodies. The preferred
distance of reinforcements from each other is 10 to 20 mm, preferably,
depending on the length of the prosthesis, in each case after 1/3 of the
length, e.g. with a length of woven material of 3 cm, two reinforcements
after 1 cm in each case.
The woven material arranged on the balloon is preferably a fabric or mesh
with from 20 to 150 filaments per cm and filament diameters of 0.032 mm to
0.15 mm. Very particularly preferred filament diameters are 0.1 mm to 0.15
mm and fabric with filament numbers of 25 to 50 filaments per cm. The
fabric is preferably arranged on the balloon so that the filaments of the
fabric run parallel to the end edges and the side edges. If, on the other
hand, the mesh is arranged such that the filaments run oblique to the end
edges, then, in the case of non-bordered side edges and no reinforcements
and no firm connections at the cross-over points of the filaments, it is
possible for the distance of the bordered end edges of the woven material
from each other to be reduced by compression, and thus the overlapping of
the end edges required when winding around the balloon is made shorter.
When widening, the angle of the filaments of the gauze relative to each
other changes and at the same time leads to a reduction in the length of
the hollow cylindrical woven material. In order to avoid this, it is
preferred also to provide the side edges of the woven material with
borders and to provide reinforcements running from end edge to end edge,
so as to avoid a compression of the woven material and a change in the
position of the filaments of the gauze relative to each other.
Most medically tolerated plastics, such as medically tolerated polyvinyl
chloride, polyethylene, polyamide, polyester and polycarbonates, have
proven to be suitable plastic woven materials.
The particularly preferred metals for woven materials or reinforcements are
noble metals and/or base metals with noble-metal coating.
In order to stabilize the meshes of the woven material, thermal treatments
and pressing can be carried out on plastic woven materials.
In the case of metallic woven materials, a pressing is preferably carried
out before the winding onto the uninflated balloon of a balloon catheter,
in order to achieve as level a woven material structure as possible.
The rectangular woven material sections or parts are wound onto the outside
of a balloon of so-called balloon catheters. Coaxial catheters of this
type are known. Rubbers reinforced with nylon fiber materials have proven
to be suitable balloon material. In order to reduce the friction at the
face of the balloon catheters, the surfaces are coated with polyurethane.
Such balloons resist a pressure of up to 12 atm. In the inflated state,
the elongate balloons can have outer diameters of 4 to 10, preferably 5 to
8 mm. The balloon length is between 20 and 50 mm. Preferred balloon
lengths are 25 to 40 mm. This permits the winding of woven materials of
corresponding length onto the uninflated balloon with varying lengths.
The use of fabric in the preferred arrangement of the filaments, in which
the filaments run parallel or perpendicular to the borders, and of the
fixing of the outer periphery of the woven material by bordering the side
edges and applying reinforcements, has the advantage that the length of
the endoprosthesis does not change on expansion of the vessel stent
located in a blood vessel. The desired size can thus already be set before
use. The high dilation pressure which is possible with the preferred
balloon catheters means that the vessel is opened optimally on use of the
device according to the invention, and redilatation is in many cases
avoided.
The device according to the invention serves for the widening of blood
vessels, in which connection the widened woven material body remains in
the blood vessel as a so-called vessel stent or endoprosthesis.
The procedure for the use according to the invention of the device is as
follows:
The woven materials which are wound around a commercially available Olbert
balloon catheter from Maedox Surgimed A.S. with catheter diameters of 1.5
mm to 2.1 mm and balloon diameters in the non-widened state of 2.0 to 2.6
mm, and which, in the widened state, are intended to serve as
endoprostheses for blood vessels, are guided along with the balloon
catheter, using the transfemoral technique, via an access of about 2.7 mm
as far as the stenosis to be widened and then widened in the stenosis by
expanding the balloon. The stenoses are first passed through by the guide
wire of the catheter, and then the balloon and the woven material arranged
thereon are introduced into the stenosis itself. Then, with radiological
monitoring, the balloon of the catheter is charged with X-ray contrast
fluid at a pressure of up to 10.13 bar and is dilated to the desired final
diameter. After removal of the hydrostatic pressure, the balloon catheter
is removed again, and the widened woven material remains as endoprosthesis
in the blood vessel. The endoprostheses are preferably used in the femoral
artery and in blood vessels in the pelvic region and in the artery of the
knee, in the renal artery and in vessels in the neck/head area.
The invention will now be illustrated in greater detail with reference to
the figures.
FIG. 1 shows a rectangular piece of woven material in the unrolled state.
FIG. 2 shows the same woven material in rolled form, but without the
balloon catheter for support.
FIG. 3 shows the woven material widened into a hollow cylinder with
abutting end edges.
FIGS. 4 and 4a show the balloon catheter in the non-dilated and dilated
states, but without the woven material wound on.
FIG. 5 shows the device according to the invention with the as yet
uninflated balloon, and the woven material on its surface.
FIG. 6 shows the device according to the invention with the balloon
inflated and the correspondingly expanded woven material on its surface.
The rectangular piece of woven material (1) shown in FIG. 1 has bordered
end edges (2) and bordered side edges (3), and reinforcements (4) running
parallel to the side edges. In this case the woven material is cut out
from a larger piece of woven material such that the filaments of the gauze
run parallel and perpendicular to the bordered edges.
FIG. 2 shows the woven material (1) in the form in which it is wound onto
the unexpanded balloon catheter (not shown). The woven material is rolled
up so far that the end edges (2) and (2b) overlap considerably. The
bordered side edges are designated (3) and the reinforcements are
designated (4). Increasing the diameter of the cylindrically wound-on
metallic woven material (1) results in the design, shown in FIG. 3, of the
cylindrical woven material or woven material body, acting as an
endoprosthesis, with abutting end edges (2). In analogy to the previous
figures, the side edges are designated (3) and the reinforcements are
designated (4).
FIG. 4a shows a balloon catheter (5) with a balloon (6) in the uninflated
state arranged on the outer surface. FIG. 4b shows the balloon (6) in the
inflated state on the catheter (5).
FIG. 5 shows the device according to the invention with a balloon catheter
(5), with a balloon (6), on whose outer surface the woven material (1) is
wound. The bordered side edges of the woven material (1) are designated
(3).
FIG. 6 shows the inflated balloon (6) and the woven material (1) widened to
the final size. The abutting reinforced edges of the woven material
stabilize the cylindrical shape of the woven material serving as
endoprosthesis.
EXAMPLE 1
A piece 2.5 cm.times.7 cm in size is cut out from a mesh of gold-plated
brass wire with a diameter of 0.032 mm and with 124 filaments per cm in
such a way that the filaments run parallel and perpendicular to the edges
and the woven material is bordered at the edges with gold solder. At a
distance of in each case about 2 cm from the narrow edges of the
rectangular piece of woven material, in each case two wires running
parallel between the longitudinal edges are filled in with gold solder by
filling in the intermediate meshes, in order to strengthen the woven
material. The woven material is wound onto the balloon of a balloon
catheter in the way shown in FIGS. 2 and 5 so that the outer diameter is 4
mm.
EXAMPLE 2
A piece 0.5 cm.times.2 cm in size is cut out from a fabric of platinum wire
with a wire diameter of 0.063 mm with 56 filaments per cm in such a way
that the filaments run parallel and perpendicular to the edges and the
woven material is bordered at the edges with platinum solder. In the
middle, between the narrow edges of the rectangular piece of woven
material, in each case the meshes between two wires running parallel to
the longitudinal edges are filled in with platinum solder as
reinforcement. The woven material is wound onto the balloon of a
commercially available balloon catheter in the way shown in FIGS. 2 and 5
so that the outer diameter is about 2 mm.
EXAMPLE 3
A piece 1.0 cm.times.4 cm in size is cut out from a gauze of gold-plated
brass wire with a wire diameter of 0.125 mm and a filament number of 125
filaments per cm in such a way that the filaments run parallel and
perpendicular to the edges. The edges are bordered with gold solder and,
for reinforcement, meshes between two wires running parallel between the
longitudinal edges are filled in with solder. The woven material thus
prepared is wound onto the balloon of a balloon catheter in the way shown
in FIGS. 2 and 5, with the longitudinal edges, provided with a border,
overlapping and the outer diameter being about 3.5 mm.
EXAMPLE 4
A fabric of polyester filaments with a filament diameter of 0.15 mm and 23
filaments per cm is cut to a size of 2 cm.times.5 cm so that the filaments
run parallel and perpendicular to the edges. One gold-plated brass wire
running between the edges and having a diameter of 0.15 mm is in each case
drawn into the last mesh before the edges, and the edges of the woven
material are reinforced by heating the thermoplastic material to a
temperature at which the cross-over points of the filaments bond firmly to
each other. Any protruding filament ends are removed so that in each case
a filament running in the direction of the edge forms the edge. For
reinforcement between the longitudinal sides, gold-plated brass wires were
also, before heating, introduced, into the woven material at a distance of
1 cm from the narrow sides and from each other. The woven material thus
strengthened is wound onto the balloon of a balloon catheter so that the
bordered longitudinal edges overlap, as shown in FIGS. 2 and 5.
EXAMPLE 5
A piece of mesh 3 cm.times.7 cm in size is cut from a nylon woven material
with monofilaments of a diameter of 0.105 mm and a filament number of
about 40 filaments per cm, and the edges are reinforced and bordered as
indicated in Example 4. In the same way, reinforcement wires are also
drawn in between the longitudinal edges, and the ends of the gold-plated
wire are integrated into the edge border and reinforcement. In order to
eliminate projections, the edges are pressed together between heated metal
frames. The woven material thus finished is wound onto the balloon of a
balloon catheter for insertion to be used as a vessel prosthesis.
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