Note: Descriptions are shown in the official language in which they were submitted.
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1 FIELD OF THE INVENTION
The invention relates to an apparatus for the transcutaneousor
percutaneous removal of thrombi and emboli by means of an
embolectomy catheter suitable for insertion into a duct in
a human body, such as a vein or an artery.
BACKGROUND INFORMATION
Embolectomy catheters are known. Such catheters are equipped
with a rotatable wire supported in a hollow conduit. The
wire and conduit are flexible for insertion into a vein or ~
artery, hereafter referred to simply as ducts. The distal - -
end of the wire is equipped with a surgical tool in the form
of a rotational body.
It is also known to combine a catheter with a vacuum bell
for the extraction of lung emboli by means of simple suction.
However, such techniques are rather cumbersome and time con-
suming so that the respective equipment has not generally
proved itself. However, the use of suction thrombilectomy
has had satisfactory results in its application to peripheral -
arteries. Even for this limited application rather large
interior clearances or cross-sectional areas are required ` --
for the hollow catheter conduit.
For clearing out ducts in humans it is also known to use
devices with rotating tool means, however, without any suc-
tion. Such devices are part of arterial angioplastic systems,
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1 such as the Kensey catheter, the Kaltenbach catheter, and
the so-called atherolytic wire or the Ritchie catheter. The
first catheter with a rotatable tool was disclosed by Ritchle
in 1986 for the treatment of acute thrombic occlusions in
peripheral arteries. This initial Ritchie catheter was
equipped with a dull tip rotating at 600 rpm and being non-
permeable to radiation. Such a rotating nonpermeable tip was
capable of resolving of acute thrombi by winding fibrin around
the shaft. While thus extracting the fibrin, the nonfibrous
cell elements of the clotting were released into the blood-
stream. It has been found that this type of device is not
effective in blood clots that are two to eight days old.
A further development resulted in a cutting tip comparable
to a grinding head made of diamonds having a diameter of
30 to 40 micrometer. The grinding head was driven to rotate
at 40,000 rpm and advanced by means of a guide wire having
a diameter of lmm. In animal tests it was found that this
device is suitable and effective for the removal of subacute
thrombic occlusions, however, with the disadvantage that
about 30% of the tests showed perforations of the artery
wall.
Another device of the type described above was disclosed
by Beck et al. in 1988, comprising a rotational body in the
form of a spiral drill bit rotating inside the hollow con-
duit of the catheter. The spiral drill bit is supposed to
comminute parts of a thrombus or embolus. The device of
Beck et al. is also equipped with a suction means for the
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1 removal of the comminuted particles of a thrombus or embolus.
The device according to Beck et al. has the disadvantage
that the spiral drill bit forming the rotational body takes
up substantially all of the inner cross-section of the
catheter's conduit so that for the suction flow of the par-
ticles, there is only that cross-section available in the
zone of the spiral drill bit which is provided by the sprially
extending grooves of the drill bit. These spirally extending
grooves have a natural tendency to clog so that the rotational
body or spiral drill bit with its clogged grooves has a ten-
dency to completely prevent or interrupt the effective -
removal by suction. ;
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OBJECTS OF THE INVENTION
In view of the foregoing it is the aim of the invention to - `-~
achieve the following objects singly or in combination~
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to construct an apparatus of the type mentioned -
above in which the percutaneous removal of a substantial
number of thrombi and emboli is possible, especially from
the veinous system and from the pulmonary arteries;
such an apparatus shall also be capable to provide ~;~
an improved cleaning of intravenous filters by a thorough
comminution of the clogging and a simultaneous efficient -~
removal of the comminuted particles by suction; and -
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1 to construct such an apparatus in such a way that
it can accomplish its purpose during treatment durations
which are as short as possible.
SUMMARY OF THE INVENTION
The above objects have been achieved according to the inven-
tion by equipping the flexible rotatable shaft at its distal
end in a hollow conduit of a catheter with a propeller tool.
Preferably, the propeller tool has two wings and its advantage
is the fact that the inner clearance or free cross-sectional
area inside the hollow conduit where the rotating tool body
is located, is substantially unobstructed, except for the
wing cross-section. As a result, the reduced pressure pro-
duced by a suction device inside the hollow catheter conduit
is effective substantially without any throttling throughout
the distal catheter end so that the reduced pressure,or rather
suction, can be effectively applied to a thrombus that needs
to be removed. Thus, in operation the present catheter first
sucks a portion of the thrombus into the catheter and the
propeller then comminutes the sucked-in portion and the re-
sulting particles are directly sucked away. As the catheter ~;
is advanced, one portion of the thrombus after another is
sucked into the free end of the catheter and comminuted until
in this manner the entire thrombus has been destroyed and
its particles have been removed by suction.
According to a further embodiment of the invention the sur-
face of the propeller facing axially out of the distal end `-
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1 of the hollow catheter conduit extends in the same plane
or flush with the plane defined by the distal end of the
hollow catheter conduit. This feature makes sure that the
rotating propeller which preferably may have an S-configur-
ation with a twist in the axial direction for an improved
feed advance capacity, is safely supported along its entire
axial length inside the hollow catheter conduit. Yet another
important advantage of this feature is seen in that the rota-
tion of the propeller cannot damage the walls of the ducts
to be cleaned. It has been found that the flush arrangement
of the propeller at the distal end of the hollow catheter
conduit is effective for the intended purpose even if the
portion of a thrombus sucked into the distal end of the hollow
conduit,is rather small. The rotation of the propeller can
comminute portions of a thrombus or embolus sucked into the
distal end independently of the size of such portion.
An optimal supporting and mounting of the propeller inside
the hollow flexible catheter conduit is achieved by making
the outer circumferential rim of the propeller wings as part
of a cylinder surface having a diameter somewhat smaller
than the inner diameter of the hollow catheter conduit.
.
According to a further embodiment of the invention, the pro- ~
peller is soldered or brazed to the rotatable shaft. The `
shaft itself is made of an elastic rust-free solid wire or
of a rust-free solid wire wound into a helical shaft.
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1 In order to safely drive the propeller the invention connects
the rotatable shaft at its proximal end to the shaft of a
d.c. motor which is mounted, for example, in a handle o~
the catheter. A shaft seal is provided in a coupling adapter
so as to prevent any fluid communication between the driven
end of the shaft and the distal shaft end.
Preferably, a suction pump is connected to the flexible con-
duit of the catheter by means of a manifold. Preferably,
the manifold should be rotatable relative to the flexible
hollow conduit of the catheter. Proper seals are provided
between the manifold and the coupling adapter. This feature
enables a substantially free handling and arrangement of
the present catheter since the rotatable manifold for the
suction device can be tilted into any position required for
the particular handling or motion of the catheter.
BRIEF DESCRIPTION OF THE DRAWINGS ~ -
In order that the invention may be clearly understood, it
will now be described, by way of example, with reference
to the accompanying drawings, wherein~
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20 Fig. 1 is a side view of a flexible shaft equipped
with a propeller according to the invention,
whereby the shaft is a solid flexible wire;
Fig. 2 is a view in the direction of the arrow A
in Fig. 1, thereby showing the distal end
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1 of the present catheter on a relatively
enlarged scale;
Fig. 3 is an axial sectional view through a catheter
according to the invention, however, without
the drive shaft and without the propeller -
tool;
Fig. 4 is a view similar to that of Fig. 3, but
additionally showing the support of the flex-
ible shaft in the hollow catheter conduit
including the suction means and the handle
with the drive motor; and
Fig. 5 shows a flexible shaft in the form of a helic-
ally wound wire.
DETAILED DESCRIPTION OF PREFERRED EXAMPLE EMBODIMENTS AND OF
THE BEST MODE OF THE INVENTION
Fig. 1 shows a flexible shaft 2 suitable for the present
purposes. The shaft 2 has a proximal end 2c connectable to
; a drive pcwar and a stal end to which the propeller tool 3 is `-`~
secured, for example, by a soldered connection as shown at 2a.
Near the proximal end 2c the shaft 2 is provided with a larger
diameter shaft section 2b for improving the rotatable mounting
and sealing of the shaft 2 in an adapter housing 8 shown
in Figs. 3 and 4. The propeller3 may be made of "vitallium"
and the hollow casing 4 shown in Figs. 2, 3, and 4 may, for I ~
example, be made of Teflon (RrM). - -
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1 Fig. 2 shows a view in the direction of the arrow A in Fig. 1
against the end surface 5 of the casing 4 illustrating the
position of the tool propeller 3 with its two wing~ 3a an~ 3b
soldered to the wire 2 at 2a. The radially outer circumferen-
tial edges 3c and 3d are preferably parts of a cylinder sur-
face having a diameter slightly smaller than the internal
clearance diameter of the casing 4. As best seen in Fig. 4,
the facing surface of the propeller 3 is flush with the plane
defined by the end surface 5 of the casing 4.
Fig. 3 shows the catheter proper having a tubular flange mem-
ber 6 connected to a coupling adapter housing 8 which in turn
is connected to an intermediate section 8a connected to a
rotatable manifold section 9 which in turn is connected to ~ -~
the flexible casing 4, if necessary through an adapter 4a. A
shaft seal 7 is located in the coupling adapter housing 8 to
properly support the thicker section 2b of the rotatable
shaft 2 in a sealed manner. Shaft bearings 7a are arranged ~-~
in the manifold 9. Rotatable couplings 7b are provided between
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the manifold 9 at the section 8a and between the manifold 9 - - -
and the adapter 4a. ~ ~ -
Fig. 4 shows the proximal shaft end 2c of the shaft 2 connected
to the shaft 1 of a d.c. motor la, for example, mounted in a
shell-type handle. The motor la may, for example, be a 25V
d.c. motor which is provided with a conventional power supply,
not shown. The coupling between the proximal shaft end 2c and
the motor shaft 1 is conventional. The shaft seal 7 provides
a fluid-tight seal between the proximal shaft end 2c
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1 and the remainder of the shaft. The motor la is preferably
encapsulated in the handle in a water-tight manner. Fur-
ther, the motor operates at an rpm of up to 1,000 revolu-
tions per minute for driving the flexible shaft 2.
Fig. 4 further shows the connection of a side flange 9a of
the rotatable manifold 9 to a suction pump 10. The suction
pump 10 also provides the required rinsing fluid. Since
the bearings 7a in the rotatable manifold 9 also permit a
rotation of the shaft 2 relative to the manifold 9, and since
the rotatable couplings 7b permit relative rotation between
the manifold 9 and the section 8a as well as between the
manifold 9 and the casing 4, it is possible to rotate the -
catheter during a surgical operation into any desired posi-
tion relative to the manifold 9, thereby preventing the mani-
fold 9 from interfering with the proper handling of the
catheter. The propeller 3 may be soldered to the shaft 11.
Fig. 5 shows a shaft 11 constructed as a helically wound
flexible wire.
In operation, prior to switching on the suction pump, the
distal facing end 5 of the flexible casing 4 is pushed direct-
ly into a thrombus. Thereafter, the suction is switched
on while the propeller 3 keeps rotating at an rpm within
the range of about 500 to 1,000 revolutions per minute. As
a result, the thrombus is continuously sucked into the
catheter and comminuted by the propeller 3, whereby the par-
ticles are sucked out of the catheter through the manifold 9.
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1 Although the invention has been described with reference
to specific example embodiments, it will be Appreciated
that it is intended to cover all modifications and equivalents
within the scope of the appended claims.
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