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.
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, 20~0621 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 ` 2(~C~06Xl .` ,`
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. ;
~:, 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 -:~' - 4 - "`
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 `-- 5 - -~
ZO~(~621 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.
~:0~0621 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 -0~0621 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). - -r~r~
'` ~ ' `' , .~ , ` 2C)~:)06Zl 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 :- - ..: - ~ ,-.
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 ~ ~ -_ g _ 2~ 621 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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2~)~0621 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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