Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Method for Connecting a Catheter Balloon rnrith a Catheter
Shaft of a Balloon Catheter
Description
The invention relates to a method for connecting a catheter
balloon with a catheter shaft of a balloon catheter according
to claim 1.
In a known method this connection is carried out by local
welding, fox example by means of laser welding: This local
welding requires locating the light beam on the connection
site_ In order to do so, for carrying out the known method the
machine has to be adjusted exactly or the welding site has to
be positioned exactly, respectively. However, this adjustment
is very complicated, prone to errors and often requires manual
correction of the apparatus. In addition to that, laser
welding involves the problem that the total technical effort
is very high and that examinations carried out in the context
of the invention have shown that poor uniformity of the weld
is often the result. In addition to that, in this method the
material must be adapted to the radiation source.
It is thus the object of the present invention to provide a
method for connecting a catheter balloon with a catheter shaft
of a balloon catheter the technical effort of which is lower
and the welding results of which are improved compared to
prior art..
This object i.s achieved by the features of claim 1.
One advantage of the method according to the invention is that
any desired materials may be used for the catheter balloon and
the catheter shaft or catheter tube, respectively, since an
adaptation to the radiation source to be used may be carried
out by the welding energy absorbing device. During assembly
the welding energy absorbing device defines the exact position
at which welding is carried out afterwards or energy is
injected, respectively. Consequently, no complex machine
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adjustment has to be carried out, since the required
localization of the light beam is achieved by this external
welding energy absorbing device which may be arranged exactly
in the area of the desired weld in the area of the fixation
site. A higher degree of automatian of the welding apparatus
is thus possible, involving at the same time higher accuracy
and thus higher quality of the weld.
In addition to this, a distinction may be made between energy
injection and fixation or sealing, respectively, of the
welding site in the given arrangement, which makes an
intensive flow of material possible. A displacement of
material during the welding process and/or an intensive
mixture of material are thus possible.
Furthermore, another advantage is that the method according to
the invention is independent of the energy source, so that a
variety of different radiation sources may be used.
The subclaims include advantageous developments of the
invention.
As a particularly simple pre-fixation a heat shrink tubing can
be used, which is applied to the pre-fixation site and is
capable of fixing and sealing the fastening portion to be
welded with the catheter shaft.
There are also several embodiments of welding energy absorbing
devices possible. A particularly simple embodiment is a
coloured tubing which may be applied via the pre-fixation
exactly to the site at which the welding between balloon
catheter and catheter shaft is to be carried out. In a further
embodiment the pre-fixation is already locally coloured and
thus serves both as pre-fixation and welding energy absorbing
device. In addition to this, a coloured marking on the pre-
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fixation, for example a marking with- a felt-tip pencil
{Edding), can serve as welding energy absorbing device.
An alternative is a stiletto which may be inserted into the
catheter shaft'. On the stiletto a coloured area may be
attached which may be positioned exactly at the site where the
welding is desired. In this case, the welding is carried out
"from within".
As has been explained above, a variety of different radiation
sources are possible, such as laser sources, monochromatic or
polychromatic light sources or other electromagnetic radiation
sources. In this context it is important to bear in mind that
the welding substrate and the focussing device have to differ
in their absorption behaviour to a high degree.
Further details, features and advantages of the invention
result from the following description and from the drawing,
wherein:
Fig. 1 is a schematically considerably simplified
representation of a balloon catheter to explain a
first embodiment of the inventive method, and
Fig. 2 is a representation of the balloon catheter
corresponding to Fig. 1 to explain a second
embodiment of the inventive method.
In Fig. 1 the proximal area of a balloon catheter 3 is shown.
In this area a catheter balloon 1 is to be fastened on a
catheter shaft 2 at two fixation sites V or V' , respectively,
via fastening portions 8 or 8', respectively. In order to
explain the inventive method reference is made below to the
schematically considerably simplified representation of the
area of the fixation site V, the principles of which may also
be used at the site V'.
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In Fig. 1 an embodiment of the inventive method is shown, in
which a pre-fixation 4, in this case in the form of a heat
shrink tubing, is applied at the beginning, which
fastens/connects the fastening portion 8 on the desired area
of the catheter shaft 2. In the embodiment shown in Fig_ 1 a
coloured tubing 5 is then applied to the pre-fixation 4, which
constitutes a welding energy absorbing device whose absorption
is adapted to the light source whose course of beam is
symbolised by the wavy arrow L.
After arrangement of the pre-fixation 4 and tubing 5, the
fixation site V is irradiated with homogenous radiation. This
results in welding of the fastening portion 8 of the catheter
balloon 1 with the desired portion of the catheter tubing 2.
The advantage of this method is that the assembly of the
welding energy absorbing device already defines the
localization of the welding site. The welding is carried out
in an automated manner in a homogenously excited area without
precise requirements with regard to the position of weld
metal. In doing so, the irradiated area may also be
considerably larger than the welding site itself.
After the welding has been carried out both the welding energy
absorbing device and the pre-fixation 4 are removed.
In Fig. 2 an alternative embodiment is shown in which in the
area of the fixation site V a stiletto 6 having a coloured
area 7 is inserted into the catheter shaft 2 on the distal
side for welding with the fastening portion 9 of the catheter
tubing 1 or with the fastening portion 9', respectively. In
this embodiment the stiletto 6 and the coloured area 7 form
the welding energy absorbing device 5'.
After pre-fixation, for example by means of a heat shrink
tubing 4 according to the embodiment of Fig. l, another
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irradiation with the help of the radiation source L may be
carried out, so that the welding explained above in connection
with the method according to Fig. 1 by injection of the
radiation energy is achieved exactly in the area of the
desired site of connection.
It should also be noted that the weld metal or the light
source has to be turned during the welding process or the
light source has to be ring-shaped. The pre-fixation or the
heat shrink tubing, respectively, also serves as welding
protection tube to ensure an even distribution of heat.
