WO2002019927A1

WO2002019927A1 - Method and device for chemical dispersion of a gel in an organic structure

Info

Publication number: WO2002019927A1
Application number: PCT/SE2001/001892
Authority: WO
Inventors: Lennart STENSTRÖM; Hugo STENSTRÖM
Original assignee: Calluna Ide Ab; William Cook Europe Aps; Cook Incorporated
Priority date: 2000-09-05
Filing date: 2001-09-05
Publication date: 2002-03-14
Also published as: SE522810C2; AU2001284592A1; SE0003116D0; SE0003116L

Abstract

Method and arrangement for chemical dispersion of a gel. In a chamber (8), which is held filled with an aqueous solution, free radicals contaning oxygen are produced. The chamber has an opeing (9) which is brought forward towards the gel (10). The aqueous solution is supplied under pressure through a throttled down nozzle (6). Whirls arise which carry newly created free radicals in contact with the gel which is hereby dispersed to a colloid and exits from the chamber throught a narrow clearance (11) along the edge of the opening of the chamber. The nozzle is aimed in such a way that the flow form there cannot hit the gel directly and fragmentate it mechanically. The free radicals may be produced in the chamber in alot of ways. The most simple measure for this is to raise the pressure before the nozzle (6) so much that a strong turbulence with accompanying cavitation arises. For dispersion of a blood-clot the chamber is built into a spool formed body equipped with an organ for guiding it through bent blood vessels.

Description

METHOD AND DEVICE FOR CHEMICAL DISPERSION OF A GEL IN AN ORGANIC STRUCTURE

Technical sphere The present invention concerns a method and a related device for being able to disperse an unwanted gel, for instance a blood-clot in an organic structure, so this clot may be removed without any negative effects. An example of a negative effect may be when fragments of gel revert to a continuous gel in a place where this means a disadvantage or when the dispersion effect is spreading to a gel which is to be left untouched.

Background of the invention

The area of application where the efforts to meet the mentioned need have been the most extensive is the medical field. Especially, one has worked with the problem to eliminate blood-clots or to widen stopped up blood vessels or constrictions in these. The problem is difficult because both the blood-clot and the surrounding tissues have a gel structure. Persons devoted to the task have started with the assumption that disintegration is to be done mechanically ("thrombec- tomy") and they build their devices accordingly. A known device has at the end of a flow supported catheter a fast running turbine which at the same time functions roughly like a milling cutter.

Another known device works with ultrasound which is focused towards the blood-clot in approximately the same way as when ultrasound is focused for dividing into pieces of stones in the kidneys (Dagens medicin, 1998, No. 35). The au- thor talks about "cleaving" a simulated blood-clot and to "breaking off' the fibrin threads which are building up the blood-clot and to utilize the energy of the ultrasound "to do a mechanical work which is able to decompose the blood-clot".

A third known device (Radiology 1997; 205; 675-681 ) works with a catheter equipped with a nozzle part, which delivers radial jet streams, which streams "fragmentate the thrombotic material". The device also has backwards aimed jet streams which, like water stream pumps, take fragmented material away.

The mentioned three examples of mechanical fragmentation all have the drawback that fragments of the treated blood-clot may get lost in the circulation of the blood and create new blood-clots there. In the third example one tries to dimin- ish the risk for this by forcing the major part of these fragments out through an aspiration channel in the catheter.

The largest drawback with the above mentioned mechanical methods is however that they are only effective only upon fresh blood-clots. Older parts of the blood-clot, which has a solid connection to the vessel wall and a more stable structure, they do not manage to attack.

In this situation it is not astonishing that one has also tried to decompose blood-clots chemically. This method has also shown problematic because such compounds that have been supplied in order to disperse a blood-clot also may at- tack healthy tissue so that this tissue is weakened or gets lasting injuries.

The treatment of a blood-clot with a laser has also been tried but has also failed partly because it is hard to avoid damage to the surrounding tissues and partly because the result in the best case will be fragments of blood-clot material as in connection with the mechanical methods. Also burned substance may be created which should not get out into the blood circulation.

Description of the invention

Tests have, however, shown that blood-clots and other gels may be dispersed according to the process and with the device which are taught by the in- vention and this is without any of the mentioned drawbacks occurring. The invention is possible to realize in most organic structures, even in curved vessels, for instance blood vessels.

The method according to the invention presumes a supply of energy as well as of an aqueous solution. The supply is for example arranged via one or several tubular connections such as catheters. In addition to water the solution may contain salt and dissolved gases, for instance CO_2, N₂ or air. The method is built upon the fact that the gel is dispersed chemically and this is done when the gel is brought into contact with a liquid stream containing a dispersant (dispersing agent). According to the invention the liquid is supplied as an aqueous solution and the dispersant is manufactured in the aqueous solution just before or as soon as this comes into contact with the gel. The dispersant is preferably free radicals, especially free radicals containing oxygen. Also acids, such as HCI, HNO₂ and HNO₃ are utilized, where appropriate, as dispersant. The liquid is preferably fed through a pipe, for instance a catheter, and is transported, via a whirl and reaction chamber, out into a blood vessel (or equivalent) next to the gel, which is to be dispersed. In the chamber so much kinetic energy is consumed in whirls that the velocity of the liquid stream in the proximity of the surface of the gel is at most half of its mean velocity in the rest of the chamber. Hereby the gel is spared from mechanical damage.

Through the chemical dispersing and through the just mentioned velocity restriction next to the gel the treatment of the gel with liquid from the mentioned chamber results in a pure colloid - without gel fragments. Since also old stable gels in tests have shown to be dispersed with the described method the mentioned liquid flow from the mentioned chamber may successfully be used in connection with blood-clots which are more than 10 days old.

According to the invention energy and solution are met next to the surface of the gel, which is to be dispersed. This is done in a confined reaction chamber with an opening, which is advanced up to the surface of the gel, so that this forms one of the walls of the chamber. The energy is given such a form and intensity that it, at meeting the mentioned solution, creates from this free radicals which are containing oxygen, radicals such as »HOO and *OH and *O₂ ^" divalent and secondarily - present within the solution of salt and air -also acids such as HCI, HNO₂ and HNO_3. The flow of the solution, which is delivered to the mentioned chamber is throttled down at its entry thereinto so that a stream of whirls is created. This flow with its contents of whirls is given a substantially larger flow area within the chamber whereby the whole surface of the gel is swept by a quiet flow bringing whirls of different sizes with the result that the mentioned newly created substances within the solution are brought into contact with the gel and disperse this gel in the solution which after that without delay is led away as a colloid from the surface of the gel preferably through a narrow clearance which appears between the gel and the opening of the chamber. The chamber with its opening is moved in relation to the gel so that new parts of this successively are exposed in the opening of the cham- ber and are dispersed.

In a simple variant of the described method the energy which is delivered into the chamber has the form of chemical energy carried by an additive in the solution which additive after its arrival into the reaction chamber at contact with a catalyst installed there, inorganic or organic, creates hydroxyl radical, OH, which disperses the gel. A good combination is H₂O₂ as an additive and divalent iron as a catalyst.

In another variant of the described method the energy which is delivered into the chamber is electromagnetic with such a quantum energy that it is able to activate an ingredient in the solution to free radicals which disperse the gel whereas measures are taken which prevent the electromagnetic energy from directly reaching and influencing the gel.

In a third variant of the described method the energy which is delivered into the chamber is mechanical and of such a kind and intensity that cavitation arises within the chamber whereby one or several of the mentioned free radicals are created and disperse the gel and whereas measure/measures is/are taken which prevents/prevent the mechanical energy from directly reaching and frag- mentating the gel.

In an example of the last mentioned variant of the method the mechanical energy which is delivered in the confined chamber is ultrasound of a frequency in the area of 20 kHz-2MHz. The ultrasound beam which is coming into the chamber is then directed in such a way that it does not directly hit the gel.

In another example which gives an especially simple, effective and at the same time preferred method the mechanical energy is pressure energy within the supplied aqueous solution and the velocity with which the solution is pressed into the confined reaction chamber is given such a size that cavitation arises in the chamber and such a direction that the gel cannot be hit directly and fragmented mechanically.

Whilst it is preferred to use an aqueous solution, it is not essential to only use such a material. Solutions containing other material, such as hydrogen peroxide, could alternatively be used. The energy added to the solution disperses the gel, such as a blood clot, into colloidal form, which can harmlessly be removed. The apparatus can be provided with an arrangement for sucking out the colloid, or the colloid can be allowed to harmlessly enter the patient's blood flow system.

Description of figures

The invention is described in more detail below in the form of examples of modes of execution with references to the accompanying drawings where Figure 1 schematically shows a device in which the method according to the invention may be realized. Figure 2 shows in a double scale a view in the direction A in figure 1 which in a simplified manner shows the flow within the chamber and over its edge.

Figure 3 shows a device according to the invention where the supplied energy is chemical. Figure 4 shows a device according to the invention where the supplied energy is electromagnetic. Figure 5 shows a device according to the invention where the supplied energy is acoustic. Figure 6 shows a device according to the invention where the supplied energy is pressure energy. Figure 7 shows a device according to the invention for spontaneous clearing of somewhat curved blood vessels.

Figure 8 shows an unsymmetrical device according to the invention for one- dimensionally guided clearing of curved tubular organic structures. Figure 9 shows in principle a device according to the invention for two- dimensionally guided clearing of curved tubular organic structures. The invention builds further upon the experience that a gel is dispersed chemically also when the energy, which is necessary, is provided in a mechanical way. A mechanical device may cut out fragments of the gel but a true dispersion (to colloid) is possible only with chemical dispersants. Blood-clots have a gel structure. They are especially quickly dispersed by oxidation with free radicals which contain oxygen, radicals such as »O₂ ^", »HOO and *OH (hydroxyl radical) irrespective of whether the mentioned radicals are produced via mechanical energy (through cavitation), light quanta or catalysis. Of the mentioned radicals especially the hydroxyl radical is known as a very effective oxidant and dispersant.

The dispersion of a gel containing chains and membranes of molecules is mainly happening within the gel even if the contact of the gel with the dispersant just happens over its surface. Crosslinkings are broken up, the gel swells, takes up water, becomes soft and turns into a colloid which successively is removed. If the colloid is not removed it may further on revert to a gel. The functions which are needed in a device 1 according to the invention for successive dispersion of a gel are shown schematically in figure 1. From a source of water under pressure, for instance a pump 2 and a water pipe 3, an aqueous solution 14 is transported through a throttled down nozzle 6 into a con- fined reaction chamber 8 so that it fills this up. Free radicals containing oxygen are created there with energy which is made available at an energy emitter 13 and which energy emanates from an energy source 4 and a transport device 5 for supplying and transporting energy respectively. The jet from the nozzle 6 with solution 14 is aimed in such a way that it brings dispersant newly created at the energy emitter 13, out into the chamber 8. The chamber has an opening 9, preferably round or rounded, but is limited by walls for the rest.

The chamber 8 is so placed next to the gel 10 that this gel covers the opening of the chamber except for a narrow clearance 11 between the gel and the rounded edge 12 of the chamber. In that way the gel becomes exposed to the dis- persant. As gel is dispersed, solution with created colloid is pressed out through the clearance 11. The device with its chamber is transported forward ly so that the position of its edge 12 remains close to the surface of the gel. In that way the chamber stays confined into all directions and filled with solution. The movement of the chamber 8 is done by a special movement aid 7. This may be provided with a resilience so that the clearance automatically sets in a position where the spring force is as large as the pressure drop within the clearance multiplied by the area of the opening 9.

The flow pattern within the chamber 8 is very decisive for the velocity and the evenness along the exposed surface of the gel with which the gel is dispersed. A large velocity gradient next to the surface of the gel gives a large exposure for free radicals and in this way a rapid dispersion. It is preferable to arrange the nozzle 6 excentrically within the chamber 8 and to let the inner walls of the chamber be rotation surfaces or at least rounded. The first measure causes, the second promotes the creation of a large whirl around the center of the opening 9, the ve- locity of which whirl close to the clearance 11 is many times larger than the exit velocity through the clearance 11. This suppresses a tendency of the dispersing to create radial ditches in the gel in the clearance 11 which would make the velocity of the exit flow and as a consequence also the dispersion rate along the edge 12 of the chamber 8 uneven. It has been practically shown that the flow pattern and as a consequence the distribution over the surface of the gel of created free radicals becomes smoothest and most effective if in the chamber 8 a number of nozzles 6 are used with a spread placing and different exit flow directions. The drawing has however not been complicated with this. The larger the volume of the chamber 8, the longer the dwelling time of the solution in the chamber 8 and the larger part of the created dispersant is consumed for irrelevant reactions in the chamber 8, because such reactions occur rapidly. However the flow situation may be best trimmed if the volume is not too small. In any case space must be reserved for the nozzle 6 which is asymmetrically placed or directed and further on arranged in such a way that the jet from there cannot hit the gel directly and fragmentate it.

Figure 2 shows the chamber seen in the direction A in figure 1 whereby the scale has been doubled. Three important types of flow are indicated in the figure. The solution 14 which leaves the throttled down nozzle 6 in the direction of the arrow and at the energy emitter 13 takes with it newly created free radicals out into the chamber 8, creates a main whirl 15 which comprises practically the whole contents of the chamber 8. The solution from the nozzle also excites a series of pairs 16 of whirls, which pairs accompany the main stream. The small curved arrows around the edge 12 of the chamber 8 finally show the flow with dispersed substance which in a quiet flow is led away from the chamber 8 via the clearance 11. The main whirl 15, which mainly is a spiral with a small pitch and many turns has as an aim to transport *OH etc. to the whole surface of the gel and outwardly to transport dispersed materials left by the gel which materia may then exit around the edge 12 of the chamber 8. The small whirls 16 function as brushes which in circling movements transport *OH etc through the boundary layer at the gel which the large whirl 15 creates until attaining intimate contact with the gel surface.

The transformation gel <->colloid is reversible. In principle, therefore, the escaping colloidal solution may create a new gel. This tendency is suppressed by arranging in such a way that the flow of this solution after passage of the clear- ance 11 is quiet and free from whirls.

The energy which is utilised according to the invention is used for the creation of free radicals may be of many forms. The device according to the invention is adapted to the choice of energy form. Figure 3 shows a device adapted to the case when the delivered energy is chemical. This is for example delivered in the form of hydrogen peroxide, which is dosed in the aqueous solution 14 by the energy source 4, the aqueous solution being transported to the nozzle 6 by the pump 2. This nozzle is formed in such a way that it gives a flow of solution along a structure 17, which carries a catalyst. This may be inorganic and contain divalent iron. Hereby «OH is created (Fentons reagens) which *OH at the same time is mixed into the solution in the chamber 8 whereafter the gel is dispersed according to the above. The catalyst may also be organic (enzymes like for example peroxidases). The structure 17 is in a known way created with its area with catalyst large in relation to the flowing through area. Certain organic gels themselves contain catalyzing compounds of the mentioned type and arranged in a convenient structure. If these are present in a sufficient amount and within reach via the exposed surface of the gel in the front of the chamber 8 the arrangement of a special structure 17 is unnecessary. The device in figure 3 is quite suitable for medical applications since aqueous solution and energy are brought to the chamber 8 with one and the same organ 3, conveniently a simple catheter.

Also electromagnetical energy may be utilized for the process according to the invention. Figure 4 shows a device for this. In this case the energy source 4 is a laser with such a short wavelength that its quantum energy is enough for producing free radicals out of the water. The laser beam is transported with the transport device 5, in this case a light wave guide to the chamber 8, where it is directed in such way that it cannot hit and burn the gel 10. The wave guide is conveniently entered in a pipe, for instance a catheter 3, the outlet of which, the nozzle 6, leads the flow of the aqueous solution according to what has been earlier described. The laser beam is reflected via a mirror system 18 forth and back through the solution so it does not hit the gel. The method becomes especially fast if the solution has an additive of hydrogen peroxide, which by the laser beam is divided into *OH. Also the device in figure 4 has the advantage that the connections between the pump 2 and the energy source 4 for the supply of aqueous solution and energy respectively and the chamber 8 may be realised within one and the same catheter 3. In a similar way the cavitation which ultra sound can provide may be used for carrying out the process according to the invention. Where cavitation arises •OH etc. is created in the solution. Figure 5 shows a device for this. The energy source 4 is constituted by an ultrasonic generator from which ultra sound is transported to the chamber 8 via a acoustic transmitter 5. The sound mirror 19 prevents the main lobe of the sound emission from directly influencing the gel and further on increases the creation of free radicals by creating standing waves. The solution is supplied via the pipe 3. In comparison with the devices of today for gel fragmentation with ultra sound the described device has the advantage that it disperses the gel evenly over the whole front of the chamber 8 and that it takes away dispersed substance as a colloid from the gel and not as fragments and that it takes away the risk of ultra sound radiation going astray. If the ultra sound generator works with magnetostriction the frequency is in the area of 20-200 kHz and the acoustic transmitter is conveniently a metal wire. This may be enclosed in the catheter 3 in analogy with the arrangement in figure 4. If the ultra sound generator is piezoelectric it is conveniently placed as a plate at the outside of and in direct contact with a plane wall of the chamber. The outside of the plate, which is made conductive, is fed from the energy source 4 which is then a high frequency generator with a frequency in the area of approximately 200 kHz -2 MHz. Its input wires may be built into the catheter 3 in analogy with the arrangement in figure 4.

Another way of creating »OH etc. with mechanical energy is to utilize cavi- tation created by turbulence. It has been shown in tests that this way is practically possible with a very simple variant of the device according to the invention. Figure 6 shows this variant. Means for supplying the aqueous solution is a pump 2, which delivers the solution via the pipe (the catheter) 3 under a high pressure (in the area of 3-30 Mpa). The necessary energy for the process is delivered as pressure energy which in one or more throttled down nozzles 6 is transformed to kinetic energy. The obtained velocity, up to a couple of hundred m/s, is enough for producing cavitation and with this »OH etc. in sufficient amount for dispersing of the gel. The nozzle 6 is aimed in such a way that the hard stream from it cannot hit and fragmentate the gel. When a very high pressure is utilized also a turbulence damp- ing net 40 may be arranged in the chamber between the nozzle 6 and the opening 9 of the chamber. Hereby the velocity of the solution is further reduced close to the gel and consequently also the danger of mechanical fragmentation. Higher pressure in combination with a small outlet area in the nozzle gives the advantage of an increased «OH production and a colloid is achieved also at minor flow. If it is desired to decrease the flow of the solution further it is suitable to let the pressure through in pulses. By choosing a high pressure and short pulses it is possible to get a good production of free radicals in spite of the flow being minor. In the de- scribed variant the need for special organs to supply and transport energy disappears. The simpleness of the device gives a low cost, simple utilization, good reliability and small dimensions - important in treating for instance narrow blood vessels.

The described method and device give above what is already said the following advantages in comparison with the prior art:

The gel turns directly into a colloid, which is led away in such a quiet flow that it does not recreate any gel. The treatment cannot lead to fragments of gel being cut loose and going astray. The treatment is very fast because it acts directly upon the depth of the gel, which thereby successively takes up a lot of water and turns into a colloid.

The transformation of the gel to colloid goes slowly where it consists of a well organised tissue, for instance in the walls of the vessels. Hereby these are spared. They are also protected in that the supplied energy is consistently prevented from directly influencing them. A consequence of the present invention is also that the device gets a tendency to be self centering and thereby easier to guide through curves and branchings of the vessel system.

For applications where a leader, i.e. metal wire, is considered as essential as a guiding aid the installation of such a leader is simple. The leader is simply drawn through the catheter 3 of the device and further centrally through its cham- ber 8. Alternative or additional guiding aids are shown in figures 7, 8 and 9.

Figure 7 shows in a section a mode of execution of the device according to the invention which spontaneously seeks its way through somewhat curved structures. The chamber 8 here constitutes a part of an elongated spool shaped body 20 outwardly mainly limited by a surface of revolution. The connection 21 of the catheter 3 to the body 20 at the bottom of the chamber 8 is articulated or at least so weak that the body 20 easily can be leaned somewhat in relation to the catheter. The connection part may for instance contain a crank hose which has been wound with a thin metal wire 22 in order to sustain the overpressure which the process needs. The front part of the body 20 is at the outside equipped with longitudinal grooves 23, however not in the edge 12 of the chamber, which has the form of a smooth ring with a rounded cross-section. When this device is moved forwards towards a curved part of a blood vessel 33 a contact arises at the outer curve between the edge 12 of the chamber and the inside of the blood vessel whereby the discharge of the created colloid is suppressed in this place. At the inner curve the edge 12 of the chamber is not close to the inside of the blood vessel. The discharge is there easily led via the clearance 11 from the chamber passing its edge and then flows without any particular pressure drop further out through the open grooves. The outflowing solution has left unconsumed *OH etc. in small con- centration. Its dispersing ability depends on how much solution passes. Therefore much less gel is dispersed at the outer curve where the flow is small than at the inner curve to which the main part of the flow is directed. This phenomenon acts centering upon the front part of the body whereby the body seeks its way through the gel in the bent, occluded blood vessel. In order to be able to follow narrower curves or choose the right way at a branching the body must have aids that facilitate active operation from outside. For this purpose the body 20 is provided with aids for X-ray observation of its place and attitude in the blood vessel and also with externally controllable means for the movement and turning of the body 20. The word attitude has reference to three angles deciding the direction of the body (compare the "roll", "pitch" and "heading" of the airplanes). The observation aids are implemented according to prior art, for instance with radiopaque small markers which may constitute part of the surface of the body 20 and which together with the X-ray shadow of the body 20 itself give the desired information. When needed the information may be translated with the aid of a computer so that the three attitude angles are possible to read directly. The place in the blood vessel of the body is mainly one-dimensional and may therefore be controlled (and also read from outside) via the position of the catheter 3. The roll angle of the body may likewise be controlled directly with the catheter 3 if this has been made sufficiently stiff for torsion. The body 20 may also be equipped for guiding of the "head- ing" and/or "pitch". In the most simple case it is enough to arrange an asymmetry in the front part of the chamber 8, in its opening or in the field of flow in its opening. Figure 8 shows in a vertical cross-section a simple mode of execution with an asymmetry. The body 24 is hollow and essentially defined by surfaces of revolution except that at least the front part of its chamber 8 has an oblique design. The catheter 3 has an attachment 25 in the bottom of the chamber which attachment is stiff for turning around the longitudinal axis of the catheter 3 but articulated around an axis 26 which is perpendicular to the symmetry plane of the body (the plane of the paper). Due to the fact that the front of the chamber 8 is oblique also the large whirl 15 is oblique inside its edge 12. Hereby also the surface of the gel 10 becomes oblique. This results in the course of the body 24 being turned downwards. If it is desired that the course of the body through the gel 10 instead is bent upwards one lets the body roll 180° with the aid of the catheter 3. If, on the other hand it is desired to guide the body laterally one rolls the body 90° etc. The de- scribed device always follows a curved path. If it is desired to let it move straight ahead one has to parry by turning the body 24 with the catheter 3 forwards and backwards or by giving it a constant rotation. This may be done manually or by a motor. The device is simple but does not manage sharply curved vessels. For that purpose more guiding means must be established. Figure 9 shows in a horizontal cross section an example of a mode of execution of the invention where, with the aid of the catheter 3, the attitude angles of the body are guided, not only by rolling it in said manner but also by manoeu- vering a certain kind of rudder so that for instance also its "heading" may be guided directly. In the hollow spool formed body 27 the catheter 3 has the same type of attachment 25 with an axis 26, which has just been described. The axis is perpendicular to the cross section in the figure. Except with the chamber 8 the catheter 3 is in connection with two oval small balloons 28, 29 laid into the body each on one side of the catheter. Its connection 30 with the balloon 28 is very narrow. Its connection 31 with a balloon 29 is wide. As guiding means serves a mar- ginal change of the pressure with which the catheter 3 is supplied. At a constant pressure in the catheter 3 the same pressure prevails in both the balloons. If the pressure suddenly increases, balloon 29 at once takes the new pressure while the balloon 28 keeps the old lower pressure for a time. This leads to the body 27 with its chamber 8 being guided in the direction of the arrow 32 (to the right). By a sud- den decrease of the pressure it is possible to guide to the left in a corresponding way. If it instead is desired to guide upwards or downwards the catheter is turned 90° and a pressure increase is applied etc. If the described method is not sufficient for the wanted heading correction the same is repeated periodically while rolling the body 27 180° between every change of pressure. Since the changes of pressure are marginal they have no noticeable influence upon the velocity or the quality of the dispersing of the gel - which dispersing however of course increases with the pressure in the catheter. With the aid of modern mecatronics many guiding principles and modes of execution may be possible to realize. For instance one may, for transferring of a guiding signal via the catheter 3, in principal use a marginal change of the temperature of the solution instead of its pressure. However, a borderline for what is today possible and economically defendable is set by the small physical dimen- sions of the blood vessels.

The process and devices according to the invention are supposed to find many uses. Beyond the clearing of occluded anatomical tubular structures such as arteries and veins one may imagine application within the dental care, above all removal of infected or otherwise sick parts in and in the neighbourhood of teeth, for instance plaque. Since almost all body tissue has the character of a gel certain tumours and enlarged organs, such as prostate, should be able to be reduced or eliminated. The process can attack healthy tissue but acts faster upon unhealthy, less well structured tissue. This quality may in itself motivate a number of applications. The situation that not only free radicals but also hydrochloric acid may be created in the process explains further that this process may be useful for dissolving for instance stones in the kidneys and calcified parts of blood vessels.

Also outside the purely mechanical applications the invention may be useful, for instance within cosmetics, food technology and surface sterilization (the process is according to tests heavily germicidal). The last mentioned application concerns all kinds of surfaces where germs cause a covering, for instance skin or surfaces with germ contamination in hospitals, dairies, ships, pipes and pools, also in a radioactive environment. The invention may further be utilized at clearing of heat exchangers and evaporators. The present invention concerns all applications where the process leads to an advantage.

Claims

1. Apparatus for dispersing an organic gel within a patient, said apparatus comprising means for causing liquid to flow adjacent to the gel, and means for ap- plying energy to the liquid to enable the latter to disperse the gel into colloidal form.

2. Apparatus according to claim 1 , wherein the means for causing the liquid to flow comprises a reaction chamber which, when introduced within the patient, has an opening designed to face or surround at least part of the gel.

3. Apparatus according to claim 2, wherein said liquid is an aqueous solution with or without additives, and wherein the liquid is to be applied to at least one nozzle within said chamber.

4. Apparatus according to claim 3, wherein the nozzle or nozzles are orientated within the chamber in such a manner to avoid fragmentation of the gel.

5. Apparatus according to claim 3 or 4, wherein the energy applying means has a part thereof placed adjacent to the nozzle or nozzles to assist the dispersion.

6. Apparatus according to claim 3, 4 or 5, wherein the energy is in the form of light such as produced by a laser.

7. Apparatus according to claim 3, 4 or 5, wherein the energy is in chemical form.

8. Apparatus according to claim 3, 4 or 5, wherein the energy is ultrasonic energy.

9. Apparatus according to claim 3, 4 or 5, wherein the energy is in the form of mechanical energy.

10. Method for dispersion of an organic gel, such as a blood-clot in a bloodvessel, in a liquid flow containing a dispersant, characterized in that the liquid is supplied as an aqueous solution and that the dispersant is manufactured in the aqueous solution just before or when the same comes into contact with the gel.

11. Method according to claim 10, characterized in that free radicals, preferably free radicals containing oxygen, are used as dispersant.

12. Method according to claim 11 , characterized in that also an acid such as HCI, HNO₂ and HNO₃ is used as dispersant.

13. Method according to any of the claims 10-12, characterized in that the liquid is supplied through a pipe, for instance a catheter, and via a whirl and reaction chamber is brought to enter a blood vessel or equivalent next to the gel which will be dispersed.

14. Method according to any of the claims 10-13, characterized in that the liquid flow is given a velocity along the surface of the gel which velocity is at the most half its mean velocity in the rest of the chamber.

15. Method according to any of the claims 10-14, characterized in that a flow of liquid is given from the mentioned chamber, which flow at contact with the gel, turns it into a colloid.

16. Method according to any of the claims 10-15, characterized in that the liquid flow is given at a blood-clot which is more than 10 days old.

17. Method according to any of the claims 10-16, characterized in that energy and an aqueous solution containing a salt are delivered into a confined reaction chamber next to the gel that will be dispersed, the chamber having an opening which is forwarded towards the gel surface so that this surface creates one of the walls of the chamber, the energy being given such a form and intensity that it in the mentioned solution can create a dispersant mainly in the form of free radicals containing oxygen, radicals such as #0₂ ^", *HOO and «OH and secondarily also acids such as HCI, HNO₂ and HNO₃.

18. Method according to claim 17, characterized in that the flow of solution which reaches the mentioned chamber is throttled down at its entry therein so that a flow of whirls is created and that this flow with its contents of whirls is then within the chamber given a substantially larger flow area, whereby the surface of the gel which is exposed in the opening of the chamber in its entirety is swept by a flow which is containing whirls of different sizes with the result that the mentioned newly created substances within the solution are brought into contact with the gel and successively disperses this in the solution which after that is led away from the surface of the gel as a colloid.

19. Method according to claim 17 or 18, characterized in that the aqueous solution contains dissolved gases, for instance CO₂, N₂ or air.

20. Method according to any of the claims 17-19, characterized in that the mentioned energy is supplied to the chamber in the form of a chemical energy carried by an additive in the solution which additive after its arrival in the whirling flow into the reaction chamber is brought into contact with a catalyst, inorganic or organic, which is present there and thereby creates a hydroxyl radical, *OH, which disperses the gel.

21. Method according to claim 20, characterized in that the additive is hydro- gen peroxide and that the catalyst contains divalent iron.

22. Method according to any of the claims 17-19, characterized in that the mentioned energy is supplied to the chamber in the form of an electromagnetic energy with such a quantum energy that it is able to activate a substance within the solution to free radicals and that the electromagnetic energy is prevented from directly reaching and influencing the gel.

23. Method according to any of the claims 17-19, characterized in that the mentioned energy is supplied to the chamber in the form of mechanical energy and of such a kind and intensity that cavitation arises within the chamber whereby one or more of the mentioned free radicals is/are created and the gel dispersed and that the mechanical energy is prevented from directly reaching and fragmen- tating the gel.

24. Method according to claim 23, characterized in that the mentioned energy is supplied to the chamber in the form of acoustical energy with a frequency within the ultrasound area and that the supplied ultrasound is directed in such a direction within the chamber that the direct sound beam does not hit and cut the gel.

25. Method according to claim 23, characterized in that the mentioned energy is supplied in the chamber in the form of pressure energy in the supplied solution which pressure energy is transferred to velocity energy and that the velocity with which the solution is forced within the confined reaction chamber is given such a size that cavitation arises within the chamber and such a direction that the gel is not hit directly and fragmentated.

26. Method according to any of the claims 17-25, characterized in that created dispersion is led away from the chamber via a narrow clearance, which is created, between the gel and the opening of the chamber.

27. Method according to any of the claims 17-26, applied at a gel in anatomical pipe formed tissue, such as a blood-clot in a blood vessel, whereat the chamber or its opening shows an asymmetry, characterized in that the angular position of the chamber in relation to the gel is adjusted by rotation around an axis which substantially coincides with the local center axis of the pipe formed tissue, whereby the gel is fastest dispersed within the sector where it is thickest leading to the feature that also curved blood vessels may be treated.

28. Arrangement (1 ) for implementing the method according to any of the claims 1-18 for dispersion of an organic gel, such as a blood-clot in a blood vessel, in a liquid flow containing a dispersant, characterized in that it contains a confined reaction chamber (8) with an opening (9), which in its service position is covered by the gel (10) and whereat the mentioned reaction chamber is in connection with primary means (2, 3) for the supply and the transport respectively of the aqueous solution (14) under pressure.

29. Arrangement according to claim 28, characterized in that it comprises secondary means (4, 5) for the supply and the transport respectively of energy.

30. Arrangement according to claim 28 or 29, characterized in that it comprises energy giving means (13) in order to lead energy into the chamber in such a form and intensity that free radicals containing oxygen and, where appropriate, also other dispersing substances are created within the chamber (8) and that the energy giving means are placed nearby a nozzle (6) from which the aqueous solution is flowing out into the chamber so that jets from the nozzle (6) with the aqueous solution (14) directly pass the energy giving means (13) and thereby bring the newly created dispersant out into the chamber (8).

31. Arrangement according to any of the claims 28-30, characterized in that the mentioned nozzle (6) and mentioned energy giving means (13) are placed somewhat eccentrically within the chamber whereby the momentum of the solution (14) supplied via the nozzle (6) creates pairs of whirls (16) which puts the surface of the gel into contact with the dispersant in the solution and which pairs of whirls are carried by a helical macro flow (15) the outlet of which is a clearance (11) along the periphery of the chamber.

32. Arrangement according to any of the claims 28-31 , characterized in that the secondary means comprise an energy creating means (4) in order to supply energy which means is constituted by an apparatus which in a known way doses energy carrier, preferably H₂O₂, which is forwarded to the aqueous solution which is supplied and fed respectively by the primary means (2, 3) to the nozzle (6), and a structure (17) the surface of which is the carrier of a catalyst, in this case diva- lent iron or an enzyme, for the creation of »OH in the chamber which structure the mixture passes.

33. Arrangement according to any of the claims 28-31 , characterized in that the secondary means comprise an energy creating means (4) in order to supply light energy, preferably a laser, and as well as an arrangement (5) for transporting energy quanta with a potential to make radicals out of the solution, which arrangement is constituted by a light guide, for instance of glassfibre, being arranged to deliver the mentioned quanta to the solution.

34. Arrangement according to claim 33, characterized in that it comprises a system of mirrors (18) which is arranged for deviation of the light beam in such a way that it cannot hit and influence the gel directly.

35. Arrangement according to any of the claims 28-31 , characterized in that it comprises an arrangement (5) for supplying energy in form of ultrasound to the chamber, the arrangement having the form of a thread of for example metal, the energy creating means (4) in order to supply energy being an ultrasound generator for a frequency of between 30 and 1000 kHz and with such an effect that is causes cavitation in the aqueous solution within the chamber.

36. Arrangement according to claim 35, characterized in that it comprises an acoustic mirror (19) which is arranged both to give standing sound waves, which increase cavitation, and to prevent the acoustic energy from directly hitting and fragmentating the gel.

37. Arrangement according to claim 31 , characterized in that the primary means (2, 3) for supplying and transport respectively of the aqueous solution are dimensioned for giving a pressure drop within the nozzle (6) of over 3 MPa.

38. Arrangement according to claim 37, characterized in that the mentioned pressure is pulsed.

39. Arrangement according to any of the claims 28-38, for applying to a gel in an anatomic pipe formed tissue, characterized in that the chamber constitutes a part of an elongated body (20), that the support of the chamber (8) with aqueous solution under pressure is done with a catheter (3) connected to the chamber (8) and that means for guiding the body through the gel also in a curved channel are contemplated.

40. Arrangement according to claim 39, characterized in that the connection (21 ) of the catheter (3) to the body is articulated, that the elongated body is spool shaped and externally provided with longitudinal grooves (23) and that the surface of the annular edge (12) of the chamber (8) is smooth and its cross section mainly circular.

41. Arrangement according to any of the claims 28-40, characterized in that the body (20) is provided with means, for instance radiopaque markers with the aid of which the orientation of the body may be seen upon an X-ray picture.