CA2126623C

CA2126623C - Suction catheter system

Info

Publication number: CA2126623C
Application number: CA002126623A
Authority: CA
Inventors: Bernhard Cramer
Original assignee: Schneider Europe GmbH
Current assignee: Schneider Europe GmbH
Priority date: 1993-06-24
Filing date: 1994-06-23
Publication date: 1998-12-01
Anticipated expiration: 2014-06-23
Also published as: AU6592694A; ES2123019T3; DE59308956D1; DK0630617T3; EP0630617A1; US5569204A; CA2126623A1; AU662861B2; EP0630617B1; JPH0724058A; US5749858A; JP2925457B2; ATE170383T1

Abstract

A suction catheter system for drawing off thrombi and emboli from blood vessels has a central catheter and an outer catheter which coaxially surrounds the latter. For introducing the catheter system into a vessel and for widening the said vessel, a guide wire and a dilator are provided. A blood clot is removed by means of a vacuum which is applied to the central catheter. Should the central catheter become blocked by the blood clot as the latter is drawn off, the central catheter can be withdrawn from the outer catheter and can be replaced by a new central catheter. This new central catheter can be connected to the suction device and the procedure continued. Instead of introducing a new central catheter, the suction procedure can also be continued via the outer catheter by means of the latter being connected to the suction device after the central catheter has been removed.

Description

-- 1 -- 22725\090694P1 2i2,66~3 A SUCTION CATHETER SYSTEM

FIELD OF THE INVENTION

The present invention relates to a suction catheter system for continuous drawing-off of thrombi and emboli from blood ves-sels, having a central catheter which is designed to receive an axially displaceably dilator.
Catheter systems of the type explained above are used for re-moving thrombi and emboli, the catheter being advanced through a blood vessel as far as the blood clot which is to be removed and being connected via its proximal end to a suction device. The blood clot is then sucked up and drawn off by means of the vacuum prevailing in the catheter.
A major problem in drawing off blood clots with such suction catheter systems is that the suction catheter is easily blocked by the blood clots, especially if these have a greater diameter than the catheter itself. In order to remove such a blockage, the catheter must be removed from the blood vessel. This blocked catheter is then cleaned outside the body, or a new, unused cathe-ter is introduced into the vessel. In both cases, however, a catheter has to be introduced at least twice into the correspond-ing blood vessel.
Each time the catheter is advanced through the blood vessel, however, a strain is imposed on the vessel wall. Even if the catheter is advanced with a dilator inserted in order to reduce 22725\090694P1 the risk of damage to the vessel wall, the advance must in any case be carried out very slowly and carefully. The cleaning proce-dure, which is already time-consuming per se, is protracted still further by this. In addition, when the catheter is re-introduced, the position of the blood clot inside the vascular system has to be located all over again. If a previously unused catheter is in-troduced, this, like the first catheter used, must be completely sterile.

PRIOR ART

In order to reduce the risk of blockage of such suction catheters during drawing-off of blood clots, various catheter de-signs are known. For example, EP 0 177 782 describes an apparatus for removing thrombi through the lumen, this apparatus having a rotating shaft. This rotating shaft is intended to take up the fi-brin from the thrombus, and in so doing break the thrombus up so that the blood can flow again. A particularly rounded tip on the shaft itself and the catheter around the outside of the shaft pre-vent the shaft from damaging the vessel wall. The pressure at the treatment site can be measured via the catheter, and medicaments can be administered. Above all, fluid can also be drawn off con-tinuously via the catheter. However, the fibrin wound round the shaft must be removed from the shaft mechanically, and to do this the shaft has to be withdrawn from the catheter.
Furthermore, EP 0 367 982 discloses a catheter system which is described as a device for the percutaneous removal of thrombi 22725~090694P1 _ ~ 3 ~ 2126623 and emboli and which has, at the distal end of the catheter, a ro-tating propeller for breaking up the blood clot during suction.
The blood clots can be drawn off continuously via the catheter with the aid of a suction device.
However, both designs have a number of disadvantages. For ex-ample, the catheter cross-section available for suction is consid-erably reduced by the rotation body, as well as by the drive shaft necessary for driving the latter. In addition, catheters designed in this way are of relatively complex construction and are expen-sive to produce on account of the rotation body and the drive shaft necessary for driving the latter. Above all, however, these instruments do not have a dilator and they therefor have to be in-troduced into the blood vessel using insertion equipment which is to be kept at the ready for this purpose. Similarly, due to the absence of a dilator, there is a risk of damage being done to the vessel wall when these instruments are advanced through the ves-sel, this damage being caused by the edge of the distal catheter opening. Moreover, damage to the surrounding vessel parts cannot be ruled out completely by a rotating comminution head or a tip.
When using insertion equipment, the blood vessel is first punc-tured with a hollow puncture needle. A short and relatively stable guide wire is then advanced through the hollow puncture needle and into the blood vessel. A conical dilator is pushed over this short guide wire and receives the guide wire in a longitudinal bore in its center. The conical dilator widens the puncture point to the extent that the insertion catheter can be pushed with a closed fit over the dilator. The dilator and the insertion catheter are ~ ~ 4 - 2126623 adapted exactly to one another, and their diameters must be chosen such that the appropriate suction catheter can then be pushed into the blood vessel through the insertion catheter.
Catheter designs of this type are also very expensive for one-off use. However, if they are to be used several times, then the whole catheter system must be cleaned at great length and sterilized again. Since such a system is subject to a certain amount of wear and since repeated sterilization can lead to changes in the material, repeated use is nevertheless associated with certain risks. In addition, catheter systems with rotating bodies are still relatively susceptible to defects. Moreover, a catheter system designed in this way, with its distal end rigid because of the drive shaft, cannot be guided round tight radii of curvature. Finally, such devices have in principle a relative large external diameter, with the result that only vessels having appropriately large lumina are accessible.
A device for withdrawing blood clots from arteries and veins is known from DE GBM 8910603.2. This device has an inner catheter which is provided at its distal end with an inflatable balloon (Fogarty catheter). This inner catheter is surrounded by a sluice catheter whlch has a radially expandable end piece. The sluice catheter is in turn surrounded by an outer catheter. In order to withdraw blood clots, the device is introduced percutaneously into the blood vessel using the established Seldinger technique, with the aid of insertion equipment. The balloon arranged at the end of the inner catheter is then pushed, in the uninflated state, through the blood clot and is subsequently inflated. The thrombus 22725\0906~4P1 _ 5 - 21266~3 is then drawn mechanically into the widened end piece of the sluice catheter by pulling on the inner catheter with the inflated balloon, is crushed by the folding down of the radially expandable end piece, and is removed from the blood vessel by mechanically withdrawing the sluice catheter together with the inner catheter.
By virtue of the sluice catheter which can be radially ex-panded at the end, this device has the advantage that blood clots which are larger in diameter than the sluice catheter can be drawn into the latter and removed from the vessel. However, this device is limited to those applications where blood clots are to be re-moved from the vessel individually. Although a vacuum can be ap-plied as support to the sluice catheter, this device is neverthe-less unsuitable for continuous removal of the blood clots by suc-tion. The fibrin of the thrombus remains hanging in the expandable net at the end of the sluice catheter upon suction and can only be held there by the vacuum and cannot be drawn off further in a con-tinuous manner.
Furthermore, in the area of its distal end the sluice cathe-ter has only a very small lumen, since in this area it has to sup-port the net of the expandable end piece, and the wall thickness must be of an appropriately large dimension for transmitting the shear and tensile forces necessary for moving this net.
A further disadvantage of such a device lies in the fact that, at least in the area of their distal ends, the sluice cathe-ter and the outer catheter are designed relatively rigidly because of the expandable net. Thus, only winding vessels with appropri-ately large radii of curvature can be negotiated using this de-vice. Twisting vessels with small radii of curvature cannothowever be reached or passed through with a device designed in this way. There is also a risk of the blood vessels being damaged by improper expansion of the net arranged at the distal end of the sluice catheter.
SUMMARY OF THE IN~ENTION
The invention provides a suction catheter system for continuous drawing-off of thrombi and emboli from blood vessels, having a central catheter which is designed to receive an axially displaceable dilator, said catheter system having an outer catheter which coaxially surrounds said central catheter and whose distal end can be pushed as far as the distal end of said central catheter, the external diameter of said outer catheter is Gnly slightly greater than the external diameter of said central catheter such that the useful diameter of the central catheter for drawing-off thrombi and emboli is nearly equivalent to the inner diameter of the outer catheter.
Preferred embodiments of the invention provide a catheter system for continuous drawing-off of blood clots which can be used without separate insertion equipment, which is simple in terms of its use and uncomplicated in terms of construction, which can be produced economically, which permits a high operating speed even in the event of blockages of the suction catheter, which can additionally be used ~lithout imposing a strain on the blood vessels into which it is introduced, which also allows blood clots larger than the diameter of the suction catheter to be completely removed, which moreover offers a large cross-section of suction in ~ ~ 2 ~

~~relation to its external diameter, which can be guided flexibly even through tight curves in the vessel path r which can also be advanced even into small vessels, which nevertheless has a high degree of rigidity at the proximal end for its advance, and which has a smooth suction opening, without obstacles for the thrombus.
The suction catheter system according to the invention provides for an outer catheter whose distal end can be pushed as far as the distal end of the central catheter. By means of such a design of the suction catheter system, the latter can be introduced percutaneously, and without insertiGn equipment, through a small puncture opening into a correspond-ing blood vessel.
The distal ends of the two catheters are normally flush during insertion. However, it is also conceivable for one of the two catheters to project beyond the other at its distal end. In this way, the rigidity of the catheter system and its diameter at the distal end can be varied very simply, without thereby adversely affecting the desired high degree of rigidity in the area of the proximal end of the catheter system or the large cross-section of suction. For removing a blood clot, the outer catheter is introduced, together with the central catheter and with the fitted dilator and guide wire, in a known manner through the puncture point and into the blood vessel and is advanced further through the lat-22725\090694Pl ~ - 8 2126623 ter as far as the blood clot which is to be removed. The dilator and the guide wire are then removed.
By connecting the central catheter to a suction device, an attempt is now made to draw the blood clot off by suction. As long as the central catheter is not blocked by the blood clot which is to be drawn off, the suction procedure is not different from the conventional suction methods. However, if the blood clot blocks the central catheter, as is very likely in the case of fairly large thrombi, then at least four different solutions are possible in principle:

1. The blocked central catheter is withdrawn from the outer catheter and replaced by a new central catheter, the new central catheter is advanced through the outer catheter and the suction procedure is continued with the new central catheter.

2. The blocked central catheter is withdrawn from the outer catheter, and instead the outer catheter is connected to the suction device, and the suction procedure is continued via the outer catheter.

3. The blocked central catheter is withdrawn from the outer catheter, the blockage is removed from the central cathe-ter, the same central catheter is re-introduced and the suction procedure is continued with the same central catheter.

4. After the central catheter has become blocked, the outer catheter is advanced, while maintaining the vacuum on the central catheter, and in this way the whole blood clot is drawn into the outer catheter, and then the whole blood clot is re-moved by withdrawing the two catheters together.

This inserting and withdrawal of the central catheter, as de-scribed under points 1. to 3., can, due to the presence of an outer catheter, be repeated several times without thereby imposing an additional strain on the blood vessels. Also, the central catheter can be withdrawn and re-introduced very quickly through the outer catheter. The central catheter is guided reliably back to the same treatment point via the outer catheter which remains in the vessel. No time is taken up in relocating the treatment point. The proposed catheter is also very simple in terms of con-struction , consisting merely of two tubes which fit one into the other, with a dilator on the inside. The parts do not have to withstand high loads. The new catheter is therefore very easy to produce.
A further important advantage of such a catheter system is that, compared to catheter systems with a rotating body, it is very cost-effective to produce. In addition, no drive device for the rotation body has to be provided. Similarly, the cross-section available inside the catheter is not unnecessarily restricted. The cost-effective production further favors the one-off use of such a catheter system, and it is therefore possible to dispense with the elaborate, time-consuming and, for the materials used, sometimes ~ -- 10 --21266'~3 quite problematic re-sterilization of the used catheter system.
Reliable cleaning of the inner lumen of catheters is generally difficult.
In order also to permit the connection of the outer catheter to a suction device, it is proposed, in a further preferred em-bodiment, to provide the outer catheter in the area of its proxi-mal end with a connection part by means of which it can be con-nected to a suction device. By connecting the outer catheter to a suction device it is possible to apply a vacuum to the outer catheter itself after the central catheter has been withdrawn therefrom, and thus to draw off the blood clot or residue thereof via the outer catheter.
A further embodiment of the catheter system proposes a number of outer catheters. In this way, once the central catheter has been withdrawn, it is possible simply for the innermost of the outer catheters to be used for drawing off by suction. By means of such a design, a number of catheters can be brought into use one after the other without a new central catheter having to be used in each case for this purpose. On the other hand, high degrees of rigidity can be obtained iIl this way at the proximal end of the catheter device without compromising the flexibility, the large cross-section of suction and the small external diameter of the distal end.
In a further preferred embodiment of the invention, provision is made for the external diameter of the central catheter to cor-respond at least approximately to the internal diameter of the outer catheter, or, in the case where there are a number of outer 22725~090694P1 catheters, for the external diameter of the inside outer catheter to correspond in each case to the internal diameter of the outer catheter next outside. In this way, the external diameter of the outer catheter is only negligibly greater than that of the central catheter, and the catheter system is not thereby unnecessarily in-creased in terms of diameter. Moreover, by means of such a design, the central catheter is guided in the outer catheter. It goes without saying that the diameters are chosen here in such a way that the catheters can nevertheless be easily displaced axially with respect to one another. Furthermore, as a result of the close fit, the wall thickness of the two catheters or of the various catheters can be varied, and indeed can be chosen to be so thin that the wall thickness of the one catheter alone would not have sufficiently high rigidity for reliable introduction into a blood vessel, but that the catheters pushed one into the other together have a sufficient rigidity or resistance to buckling.
In order to promote this displaceability, in a further em-bodiment the material proposed for the catheters is TEFLO~R).
A further embodiment proposes that the tip of the dilator forms an angle to the axis of the shaft, and that the tip of the dilator can be turned in different directions by turning the dila-tor at its proximal end. The dilator is thus controllable, so that in this way even twisting vessels can be reliably reached.
Finally, in a further embodiment it is proposed that the tip of the dilator can be bent relative to the axis of the shaft. In this way, the tip can be designed to be individually controllable or straight.

227~5\0~0694P1 BRIEF DESCRIPTION OF THE DRAWINGS

An exemplary embodiment of the invention will be explained in greater detail herein below with reference to the attached draw-ings, in which:
Fig. 1 shows a perspective view of the suction cathe-ter system with inserted dilator and guide wirei Fig. 2 shows a perspective view of the suction cathe-ter system in an embodiment with two outer catheters; and Fig. 3 shows a perspective and diagrammatic view of the suction catheter system during drawing-off of a blood clot.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Fig. 1 shows the suction catheter system in a perspective view. The most important component parts of this catheter system are an outer catheter 1, a central catheter 2, a dilator 3 and a guide wire 4. The guide wire 4 is pushed into the dilator 3. Guide wires 4 are kept so flexible at their distal end that they can be relied upon not to damage the vessel wall on being advanced through the vessel. However, in addition, guide wires 4 are also as torsionally stiff as possible and their distal end can be bent permanently. By means of these properties the guide wire 4 can be directed, from its proximal end, for example into a branch of the vascular system.

~_ - 13 - 2126623 The dilator 3 for its part is tubular in design and has, at its distal end, a conically shaped tip 7 whose axis forms an angle with respect to the axis of the shaft 8. This tip 7 can be bent relative to the axis of the shaft 8 and can in this way be adapted individually to the task in hand. By turning the dilator 3 at its proximal end, the tip 7 can be turned in different directions. The central catheter 2 surrounds the dilator 3 over a large part of its longitudinal extent and has, at its proximal end, a connection part 10, for example for introducing contrast fluid, with a haemo-static valve 11. The central catheter 2 for its part is sur-rounded, also over a large part of its longitudinal extent, by the outer catheter 1, the outer catheter 1 likewise having, at its distal end, a connection part 13 and a haemostatic valve 14.
Fig. 2 shows a further embodiment of the suction catheter system, the difference in relation to the embodiment in Fig. 1 be-ing that a second outer catheter la is provided which surrounds the first outer catheter 1 over a large part of its ~ongitudinal extent. This outer catheter la likewise has, at its proximal end, a connection part 13a and a haemostatic valve 14a. Embodiments which have still further outer catheters are of course also possi-ble.
The removal of a blood clot is explained with reference to Fig. 3. In the catheter system represented in this figure, the central catheter 2 thereof is shown in longitudinal section in the frontmost distal area for the purpose of better illustration. The introduction of such a catheter system into a blood vessel is known, for which reason only the most important points are dealt 22725\090694P1 with here. First, the guide wire 4 is placed in a blood vessel 16 through a puncture in the skin and is advanced, for example as far as the vicinity of the blood clot 18, 18a which is to be removed.
The dilator 3, together with the central catheter 2 and the outer catheter 1, is then introduced into the blood vessel 16 and is ad-vanced as far as is necessary, the dilator 3 protruding slightly beyond the central catheter 2 at the distal end for the purpose of widening the puncture point. The haemostatic valves 11, 14 ar-ranged at the proximal ends of the catheters 1, 2 prevent blood from flowing out through the catheter system.
The two catheters 1, 2 can be introduced and advanced in dif-ferent ways. Thus, the catheters 1, 2 and the dilator 3 can be in-troduced together and with their distal ends flush. However, it is also possible, during introduction, for the distal end of the one catheter, preferably of the central catheter 2, to lie in front of the distal end of the other catheter. In this way the rigidity and the diameter of the catheter system in the area of its distal end can be varied.
Finally, the central catheter 2 is brought right up to the blood clot 18 which is to be removed. Only now is the dilator 3, together with the guide wire 4, withdrawn from the central cathe-ter 2 and removed. The blood clot 18, 18a is removed in a conven-tional manner by means of suction. For this purpose, the haemo-static valve 11 of the central catheter 2 is removed, and the cen-tral catheter 2 is connected to a manual suction device 20 via the connection part 10. Instead of the manual suction device 20 other solutions are of course also possible, such as, for example, an ''4_ - 15 -electrically driven pump. By means of the vacuum prevailing in the central catheter 2, the blood clot 18, 18a can now be drawn off continuously. If, during suction, the central catheter 2 is blocked by the blood clot 18 or a part 18a thereof, the central catheter 2 can be withdrawn from the outer catheter 1 and cleaned, or a new central catheter can be pushed into the outer catheter 1 and the operation continued after the new central catheter has been connected to the suction device 20. However, it is also pos-sible, after the central catheter 2 has been removed, to continue the suction procedure using the outer catheter 1, the haemostatic valve 14 thereof being removed and the proximal end being con-nected to the suction device 20.
A further alternative for removing the blood clot 18, 18a consists in attempting to draw the latter all in one piece into the outer catheter 1 by means of a vacuum applied on the central catheter 2 and a forward movement of the outer catheter 1, and then to remove the clot by simultaneously withdrawing the two catheters 1, 2, preferably while maintaining the vacuum on the central catheter 2. This is unproblematic to the extent that the blood clot 18, 18a, after it has been drawn into the outer cathe-ter 1, is not exposed to any further friction upon withdrawal of the catheter system from the blood vessel 16 and can therefore be safely removed. This method is particularly effective if, in order to secure the thrombus on or in the outer catheter 1, a vacuum is also applied to the outer catheter 1 via the connection part 13.
If a suction catheter system such as that shown in Fig. 2 is used, still further variants of this suction methods are possible.

22725\090694P1 ~ - 16 - 2126623 Thus, after the central catheter 2 has become blocked and has been removed, the suction procedure can be continued using the inner-most outer catheter 1 (Fig. 2), and should this outer catheter 1 become blocked and be removed, the procedure can be continued us-ing the outer catheter la next outside (Fig. 2).
In contrast to conventional devices for removing thrombi and emboli, a suction catheter system of this type has the great ad-vantage that, if the central catheter 2 becomes blocked, the pro-cedure can be continued after a brief interval. Blockage of the catheter previously meant that the latter had to be removed from the blood vessel. If the blood clot was not completely removed by the time the blockage occurred, then a new catheter had to be in-troduced. However, renewed introduction brings with it the usual problems. Thus, a strain is once more imposed on the blood vessels of the patient, and the catheter has to be guided carefully back to the correct point in the blood vessel. This is difficult, espe-cially in the case of blood clots which are situated far away from the puncture point. Moreover, in such a case a great deal of valu-able time is unnecessarily wasted.
In conclusion it may be stated that a blood clot can be re-moved in the shortest possible time using the suction catheter system according to the invention, and that in doing so the blood vessels of the patient are not stressed.

,. , ,;

Claims

1. A suction catheter system for continuous drawing-off of thrombi and emboli from blood vessels, having a central catheter which is designed to receive an axially displaceable dilator, said catheter system having an outer catheter which coaxially surrounds said central catheter and whose distal end can be pushed as far as the distal end of said central catheter, the external diameter of said outer catheter is only slightly greater than the external diameter of said central catheter such that the useful diameter of the central catheter for drawing-off thrombi and emboli is nearly equivalent to the inner diameter of the outer catheter.

2. A suction catheter system according to claim 1 wherein said outer catheter has, in the area of its proximal end, a connection part by means of which said outer catheter can be connected to a suction device.

3. A suction catheter system according to claim 1 or 2 wherein said outer catheter and said central catheter have, in the area of their proximal ends, in each case a haemostatic valve.

4. A suction catheter system according to claim 3 wherein said haemostatic valve is arranged detachably on said connection part.

5. A suction catheter system according to one of the preceding claims wherein a plurality of outer catheters are provided and are arranged coaxially to said central catheter.

6. A suction catheter system according to one of claims 1 to 4 wherein the external diameter of said central catheter corresponds at least approximately to the internal diameter of said outer catheter at its distal end.

7. A suction catheter system according to claim 5 wherein the external diameter of said central catheter corresponds at least approximately to the internal diameter of said outer catheter, and in that in each case the external diameter of the inside outer catheter corresponds at least approximately to the internal diameter of the outer catheter next outside.

8. A suction catheter system according to one of the preceding claims wherein said catheters consist of TEFLONR.

9. A suction catheter system according to one of the preceding claims wherein said dilator has a tip which, with its axis, forms an angle relative to the axis of said shaft, and in that said tip of said dilator can be turned by turning said dilator in different directions.

10. A suction catheter system according to one of the preceding claims wherein said tip of said dilator can be bent, with its axis remaining at an angle relative to said axis of said shaft, and in that said tip can be turned by turning said dilator in different directions.

11. A suction catheter system according to one of the preceding claims wherein a guide wire is guided in said dilator.