WO2009083688A2

WO2009083688A2 - Device intended for heat administration into a human or animal tissue, vessel or cavity

Info

Publication number: WO2009083688A2
Application number: PCT/FR2008/052381
Authority: WO
Inventors: Henri Mehier
Original assignee: Henri Mehier
Priority date: 2007-12-28
Filing date: 2008-12-19
Publication date: 2009-07-09
Also published as: CA2709335A1; FR2925837A1; FR2925837B1; WO2009083688A3

Abstract

A completely or partly implantable microresistor (9) intended for heat administration into a cavity, tissue or vessel, taking the form of a metal tube (11) of resistivity R1 surrounding an electrically conductive material (12) of resistivity R2 at least 5 times greater than R1, and having: a proximal and median portion coated with a layer (15) of an electrically conductive material and then with a second, insulating, layer, and a distal portion coated only with an insulating layer (16). A completely or partly implantable device intended for the administration of steam into a tissue or vessel provided with said microresistor.

Description

DEVICE FOR ADMINISTERING CALORIES IN HUMAN OR ANIMAL TISSUE, VESSEL OR CAVITY

The invention relates to a new device for the administration of calories, for example in the form of water vapor in a cavity (bladder etc.), a human or animal tissue or vessel.

The device of the invention can be used for the treatment of tumors by the so-called "thermoablation" technique. Depending on the nature of the tumor, particularly its water content, calories can be generated to heat the water that the tumor contains, or to vaporize water brought from outside the body (in the body). hypothesis or water content is too low to effect efficient thermoablation). In a particular embodiment, the device is adapted to eliminate excess subcutaneous fat by the so-called "liposuction" technique.

The device of the invention is also intended, when it is used endoluminally, for the treatment of venous or arteriovenous pathologies, in particular varicose veins, hemorrhoids, arteriovenous shunts and other vascular malformations. In this case, since the blood contains a certain proportion of water, it may be preferable to use the calories to heat the water contained in the blood at a temperature of the order of 95 ° C, rather than the water brought from outside the body.

Until now, the Applicant has developed a number of devices for injecting water vapor into tissues or vessels. The general principle common to all these devices is to maintain the water before release, in pressurized form, that is to say liquid at a temperature above 100 ⁰ C, which allows to have a transfer optimized calories between the heat source and pressurized water. To do this, in all the solutions proposed by the Applicant until now, the water circulates in a restricted space, in practice in the light of a micro tube of diameter between 100 and 250 microns.

The document WO 00/29055 thus describes a thermoablation by heat technique of injecting continuously, by means of a microtube, directly into the tissues of the body, pressurized water or hydrogen peroxide. a temperature of 200 to 400 ^° C.

In the document WO 03/070302, the Applicant proposes an improved thermoablation method in that it plans to inject the heat transfer fluid into the microtube no longer continuously, but in pulsed form, which makes it possible to avoid the diffusion of heat outside the area to be treated by quickly bringing the calories into the area to be treated. In both cases, the heating system is outside the body and remains unchanged. It consists, essentially, in a metal coil incorporating an electrical resistance around which is surrounded the stainless microtube in which circulates the coolant. In other words, these methods involve heating the water through the wall of the tube. This approach may have certain drawbacks and in particular that of causing necrosis of tissues or vessels by "dry" heat to the extent that the temperature of the tube may exceed 400 to 500 ^° C. The phenomenon of "dry" heat necrosis, at very high temperatures, causes the formation of CO ₂ , responsible for air embolism, as well as the formation of toxins.

To solve this problem, the Applicant proposed in WO 2006/108974, to heat the tube exclusively at its distal end, through an electric current flowing through the microtube and constituting the source of calories. This avoids heating parts of the tube not in contact with the tumor to be treated. To limit the heating of the distal portion of the tube, said tube is covered with a sheath made of an electrolytic coating of gold approximately 1 μm thick.

If this solution provides calories only in the area to be treated, it does not limit the phenomenon of dry heat. It also remains very expensive since it requires the deposition, under vacuum, of insulating layers, requiring a delicate polishing of the tube, as well as the deposition of very thin conductive materials of the order of 200 to 500 nanometers inherent in vacuum deposition, necessarily limiting the supply of electric current and therefore the available energy in the area to be treated. In addition, the deposition in thin layer, under the effect of heat can crack and therefore spread in the tissues of the body, especially in pulsed injection regimes, with alternating hot or cold.

US2007 / 0032785A1 discloses an implantable device capable of diffusing water vapor into a tissue. The device consists of two concentric tubes between the walls of which circulates water. The water is pressurized at the distal end for injection into the tissues through orifices. The pressurized water is heated along the entire length of the peripheral tube via electrodes. More specifically, the peripheral tube is traversed by a current generated by an electrode, towards the distal end of the device, then the current returns to the proximal portion by traversing the inner tube. Although such a system can significantly reduce the temperature of the peripheral wall, it remains relatively high and is likely to cause thermonecrosis phenomena, thermofibrosis but also dry heat necrosis outside the area to be treated. As mentioned in the preamble, there may also be an interest in directly heating the tissue or vessel by generating a sufficient amount of calories to increase the temperature of the water contained in the tissue or vessel at a temperature of about 95 ° C. This is particularly the case for the treatment of varicose veins. However, the heating must remain elective and applied only at the level of the varix and not around. To the knowledge of the Applicant, no device fulfilling this purpose has been described, with the exception of the laser. Nevertheless, laser technology is not optimal. Indeed the laser generates a point heat, causing the formation of micro-hematoma in the venous wall.

In other words, the problem is to develop implantable devices capable of generating calories exclusively in the area to be treated, that these calories can either heat the water contained in the area to be treated, or spray the water. water brought from outside the body. Another object of the invention is to develop a device whose implanted part is of the smallest possible size, so as to be introduced into any type of cavity (bladder etc.), fabric or human or animal vessel.

To do this, the Applicant has managed to develop a micro-resistance in all or part implantable for the delivery of calories in a cavity, a tissue or a vessel, the heating of which is offset at the distal end of said micro-resistance. In other words, the micro-resistance of the invention has only a distal heating zone, which makes it possible to avoid any heating of the tissues outside this zone. More specifically, the subject of the invention is a micro-resistance in whole or in part implantable intended for the administration of calories in a cavity, a tissue or a vessel in the form of a resistivity metal tube R1 having ends proximal and distal and enveloping an electrically conductive material (in the form of a wire or a tube) of resistivity R2 at least 5 times, advantageously at least 15 times greater than R1, said electrically conductive material being connected at the distal closed end of the resistivity metal tube R1 at its end end and having, upstream of said terminal end, two distinct portions, a medial and proximal portion covered with: a first layer of a conductive material; resistivity electricity

R3 less than R2 having means for connection to one of the terminals of a current generator and ensuring the arrival of the current or vice versa, o then, a second insulating layer, a distal portion covered only with said second insulating layer, the resistivity metal tube Rl having connection means to the other terminal of the current generator and thus ensuring the return of the current or vice versa. In practice, the diameter of the micro-resistor, when it is implanted as such, is between 0.2 and 0.8 mm.

Moreover, said "second insulating layer" is advantageously resistant to a temperature of 200 ^° C. and made from a material chosen from the group comprising teflon®, polyimide and alumina.

Insofar as the conductive material is wrapped with the resistivity metal tube R1, the insulating layer is trapped in the peripheral tube and is not likely to diffuse into the body in case of cracking.

In other words, the current flows in practice from the + pole of the generator to the pole - passing successively by the resistivity layer R3 at the proximal and median portions of the conductive material and then in the electrically conductive material of R2 resistance on the distal portion. The current then passes into the wall of the resistivity metal tube R1 at the end end without insulating layer, the electrically conductive material resistivity R2, to return to the generator.

Insofar as the distal end of the electrically conductive material has a resistivity R2, at least 5 times greater than the resistivity R3, it follows a warming of the micro-resistance exclusively at the distal portion of the tube, at a temperature in practice of about 200 ^° C.

In an advantageous embodiment, the value of the resistivity R1 is substantially equal to the value of the resistivity R3.

Advantageously and according to another characteristic, the resistivity metal tube R1 and the first layer of a resistivity-conducting electrically conductive material R3 are made of copper, in particular by electrolytic deposition or by crimping, the resistivity of the copper being 1.7 μΩcm. The copper layer applied to the resistivity material R2 has, in practice, a thickness of between 10 and 40 microns, advantageously of the order of 30 microns.

Advantageously, and in a first embodiment, the electrically conductive material of resistivity R2 is in the form of a constantan wire, that is to say a copper / nickel alloy whose resistance is independent of temperature or a wire made of a nickel / chromium alloy. In practice, the constantan resistivity is 50 μΩcm while the nickel / chromium alloy has a resistivity of 110 μΩcm. The constantan or the nickel / chromium alloy may possibly be replaced by stainless steel. However, the deposit of copper on the stainless steel remains delicate. Associated with the metal resistivity tube R1, made in practice of copper, the constantan or the nickel / chromium alloy gives the micro-resistance a certain flexibility. To stiffen the system, the electrically conductive material resistivity R2 is not in the form of a wire but in the form of a tube possibly closed at its distal portion and into which is introduced a removable stainless steel needle, conferring on the system a certain rigidity. In this case, the constantan or nickel / chromium alloy tube replacing the constantan or nickel / chromium alloy wire, coated with the first and second insulating layers as previously described, is placed in the metal resistivity tube. apply. The end end of the resistivity conductive material tube R2 in contact with the distal end of the resistivity metal tube R1 is devoid of an insulating layer thereby allowing the passage of the current from one tube to the other.

As already mentioned, the micro-resistance of the invention as just described can be used as such, that is to say without external water supply, particularly for the treatment of varicose veins according to a process which will be described later.

In a second embodiment, the micro-resistance of the invention can be used as a heating means for vaporizing water brought from outside the body, like the systems described in the state. of the technique.

In this hypothesis, the subject of the invention is a device that is wholly or partially implantable for the administration of water vapor in a tissue or vessel, which is characterized in that:

- It is in the form of a peripheral tube consisting of distal, medial and proximal parts, said tube containing in its light, throughout its length, a micro-resistance of the type described above, the water being intended for circulating in the dead space separating the wall of the tube from the micro-resistance, the proximal portion of the tube has a Y end, one outlet of which is intended to be connected directly to a water inlet, and the other of which is partially closed to allow passage of the connection means of the micro-resistance to the terminals of the current generator.

In other words, the water is no longer heated through the wall of the tube, but by means of an electrical resistance incorporated in the tube lumen, at the distal end thereof. In this way, the temperature gradient is reversed compared to the system of the prior art, that is to say that it decreases from the center to the periphery of the tube and not the opposite. The second condition for transforming water into steam at the time of release thus remains its transfer into the tube in pressurized form, which is made possible by the implementation of a restricted volume in which the water circulates. One of the advantages of the newly proposed solution is that there is no longer any dimensional constraint for the realization of the tube ensuring the transfer of water, since it is sufficient to defining a sufficiently small volume between the wall of the tube and the central micro-resistance so that the water is in the pressurized state at the distal end of the tube. The wall therefore reaches a temperature lower than that of the water vapor, thus limiting the effect of the heating produced to a phenomenon of thermonecrosis or thermofibrosis but in no case to a necrosis phenomenon by dry heat.

In other words, the difference in resistivity between the peripheral tube enveloping the micro-resistance (at its distal portion) and the microresistance itself being very high, this makes it possible to selectively heat the liquid in pressurized form, exclusively at the level of the distal end of the tube.

According to a first feature, the difference in diameter between the internal diameter of the tube and the diameter of the micro-resistance is between 50 and 100 microns. In practice, the outer diameter of the tube is between 0.3 and 1 mm, and the internal diameter is between 0.2 and 0.8 mm. The fact of being able to implement microresistances of diameter close to 0.8 mm, while maintaining a reduced dead space, makes it possible to generate a larger heating surface, improving the transfer of calories. It is thus possible to reduce the length of the micro-resistor in its distal part, which makes it possible to concentrate the heating in the zone to be treated.

The peripheral tube is divided into three distinct parts respectively a distal portion, a medial portion and a proximal portion.

As indicated above, the micro-resistance remains relatively flexible because of its structure associating, advantageously, copper and constantan or nickel / chromium. To stiffen the system, the distal and median portions of the peripheral tube may be in the form of a needle, preferably selected from stainless steel.

When the rigidity is improved by using a needle in a constantan or nickel / chromium tube instead of a constantan or nickel / chromium wire, the peripheral tube may be in the form of a catheter. In this case, the distal and medial parts are made of a material selected from the group comprising PEEK, PTFE and polyphenylsulfone or a super-soft alloy of the nickel / titanium type marketed under the trade name Ritinol®.

The distal portion of the peripheral tube may be open or closed. In this second case, it is laterally provided with perforations having a size of between 50 μm and 150 μm, advantageously equal to 70 μm.

As regards the proximal part, this may be made of a flexible material, such as, for example, silicone, the junction between the silicone part and the needle or the catheter being performed by any connection means known to those skilled in the art, and in particular by screwing or gluing.

In practice, this connection is secured by the establishment of a gripping sleeve covering the junction between the middle portion and the proximal portion of the tube.

The proximal portion is in the form of a Y-shaped part, an outlet of which is connected sealingly, for example by means of a luer, to a water supply and the other outlet is electrically isolated and partially closed to allow passage of the connection means of the micro-resistance to the terminals of the current generator.

The device as just described has the further advantage of being inexpensive in terms of manufacturing. Therefore, it is a consumable device and thus completely eliminate the problem of contamination.

As already said, the device can be used for the treatment of tumors by inserting the micro-resistance associated or not with a peripheral catheter or needle directly into the tissue. This is a function of the content of the tumor in water, being reminded that if this content is sufficient, micro-resistance alone can heat the water contained in the tumor at a temperature of about 95 ° C. In the same way, the device can also be used endoluminally, for the treatment of other pathologies, such as for example the treatment of varicose veins. All of these techniques are described in the aforementioned documents of the Applicant.

The invention therefore also relates to a method for treating tumors by administering calories comprising: incising the skin and then introducing into the target tissue the distal and medial portions of the micro-resistance or the device (microresistance + peripheral tube ), then, supplying the micro-resistance with electricity and if necessary simultaneously and continuously, the tube with water, so as to heat the water by maintaining it in the pressurized state at the distal end of the tube before injection into the tissue, remove the device at the end of treatment.

When the micro-resistance is used in combination with a peripheral tube, the distal and middle portions of said tube are in the form of a needle, the needle is directly stitched into the tissue to be treated.

When the distal and median portions of said tube are in the form of a catheter, it is introduced directly into the body, the rigidity of the catheter being obtained by the implementation of a tube of constantan or nickel / chrome provided with a removable stainless steel rod, instead of constantan wire or nickel / chrome.

The invention also relates to a method for treating arteriovenous pathologies by injecting endoluminal calories into the vessels, consisting of:

- To incise the skin, then to introduce in the vessels the distal and medial parts of the micro-resistance or the device (micro-resistance + peripheral tube), - then, to feed the micro-resistance in electricity and if necessary simultaneously, and continuously , the tube in water, so as to heat the water by maintaining it in the pressurized state at the distal end of the tube before injection into the vessels, to remove the device at the end of treatment.

In a particular embodiment, the subject of the invention is a method for treating varicose veins by endoluminal injection of calories, under local or general anesthesia, consisting in: performing a tracing of the vein to be treated, by marking on the skin the path of the vein and the introduction orifice of the device,

to incise the skin, then to introduce into the vein to treat the distal and medial portions of the micro-resistance or the device (microresistance + peripheral tube), then, to supply the micro-resistance with electricity and if necessary simultaneously, and continuously, the tube in water, so as to heat the water by maintaining it in the pressurized state at the distal end of the tube before injection into the vein, to gradually remove the device.

The subject of the invention is also, in the particular case where there is water vapor injection, an installation for implementing said endoluminal variceal treatment method, comprising the device previously described, the end of which is Y of the proximal part is connected by its first branch to a water injection system and by its second branch to a current source.

In an advantageous embodiment, the water injection system is in the form of a flexible tube directly sealingly connected to the Y, the tube being compressed, at its proximal end, between two fixed rollers. rotated at the same speed by means of a motor, in the opposite direction to that of the vein to be treated. The movement of the rollers thus causes the injection of the actual water into the device of the invention and simultaneously the regular retreat and thus the removal of the device from the vein. The present device can also be adapted to eliminate excess fat by the so-called "liposuction" technique.

Currently, cellulite reduction can be achieved essentially by two methods.

The first is to introduce, subcutaneously, a cannula whose distal end is provided with an ultrasound system whose function is to break the membrane of adipocytes. This device has the essential disadvantage of being very expensive since manufactured from non-consumable materials. This leads to potential risks of contamination.

Another technique consists in treating cellulite by destroying the adipocytes by heat by means of a laser beam. This technique has the main disadvantage of generating a point heat that can cause tissue necrosis by dry heat.

The Applicant has found that its device could be used to reduce cellulite with some adaptations, including providing a peripheral sheath provided with lateral perforations arranged around the tube at least in its distal portion and connected to a suction system.

The advantage of the treatment of cellulite by steam injection makes it possible, compared to the other techniques, to provide a complementary effect of thermofibrosis, that is to say the retraction of the collagen fibers (heating at 85.degree. minus 15 seconds) thus allowing to retension the skin. In addition, there is no risk of necrosis of the subcutaneous tissue by dry heat.

In other words, the invention also relates to a method for removing excess fat from the human body implementing the device described above.

More precisely, the method consists in: - incising the skin, then introducing subcutaneously into the adipose tissue the distal and medial parts of the device (microresistance + peripheral tube), then, simultaneously, and continuously, feeding the tube in water and means of heating electricity, so as to heat the water by maintaining it in the pressurized state at the distal end of the tube before injection into the tissue, to suck the fat cells destroyed by the steam water, - remove the device at the end of treatment. The invention and the advantages which result therefrom will emerge more clearly from the following exemplary embodiments, in support of the appended figures.

Figure 1 is a schematic sectional representation of a device of the invention used directly in tissues or endoluminally.

Figure 2 is a schematic sectional representation of the device of the invention adapted for the removal of excess fat.

Figure 3 is a detailed sectional representation of the microresistor of the invention according to a first embodiment. Figure 4 is a detailed sectional representation of the micro-resistor according to a second embodiment.

Figure 5 is a schematic representation of an installation for treating varicose veins.

According to FIGS. 1 and 2, the device of the invention consists of a peripheral tube (1) which can be divided into two parts, respectively: distal and medial implantable parts (2), and a non-implanted part (3) corresponding to the proximal portion of the device.

In Figure 1, the implantable portion is in the form of a beveled needle made of stainless steel whose internal diameter is for example equal to 0.8 mm while the outer diameter is 1 mm. Of course and as already said, this needle can be replaced by a catheter of equivalent dimensions made for example PEEK. This implantable portion is connected to the proximal portion (3) not implanted sealingly for example by gluing (4). The non-implanted portion is in the form of a Y, made of silicone, one of the branches (5) is intended to be connected to a water inlet (6), and the other branch (7) is partially closed to allow passage of the connection means (8) of the microresistor (9) to the terminals of the current generator (10).

To facilitate the gripping of the device, said device is provided with a sleeve (11) of silicone covering the tube (1) at the junction of the medial and proximal parts.

According to an essential characteristic, the peripheral tube (1) comprises, in its light, a microresistor designated by the general reference (9), the distal end of which is aligned with the distal end of the peripheral tube. In an embodiment not shown, the distal end of the microresistor has a rounded shape and extends beyond the distal end of the peripheral tube. This embodiment is more particularly suitable for the treatment of varicose veins because it is necessary not to alter the wall of the vein to be treated by an angular end. The micro-resistance presents, in this example, an outer diameter of 0.75 mm leaving a reduced dead space of 50 microns between said microresistor (9) and the inner surface of the tube (1).

FIG. 3 shows the microresistor (9) of the invention.

Essentially, this micro-resistance is in the form of a casing tube (11) made of copper, with a diameter of 0.750 mm. The constituent copper of the tube has a resistivity R1 of 1.7 μΩcm.

The tube (11) contains in its lumen a current-conducting wire (12), whose end end (13 ') of the distal portion (13) is connected by laser welding or crimping to the distal end (14) of the tube (11). This wire is a constantan wire, with a diameter of 0.3 mm or a wire of a nickel / chromium alloy with a diameter of 0.26 mm having two distinct portions.

Thus, the medial and proximal portions of the wire (12) are covered with a first layer of electrolytic copper (15) of a thickness of 30 microns, then a second layer (16) of an electrical insulator. At its distal end, the constantan wire is free of electrolytic copper coating (15), but is electrically insulated (16) with the exception of the terminal end itself, which is crimped or soldered to the resistivity tube. Rl.

As shown diagrammatically in FIG. 3, the copper coating (15) applied to the wire (12) is connected (8) to the + terminal of the current generator (10) while the peripheral wrapping tube (11) is connected ( 8) to the - terminal of the same generator (10). In this way, the electric current flows to the distal end of the microresistor in the copper coating (15) applied around the wire. Near the end of the tube, the electricity passes into the distal portion of the wire (12) to return thereafter to the generator (10) while traveling in the wall of the peripheral tube (11).

The presence of a copper coating (15) applied to the medial and proximal portions of the wire (12) prevents heating of the wrapping tube (11) over the entire length of the device (due to the difference in resistivity between the wire and the constituent copper of the enveloping tube). In practice, the resistivity of the constantan wire R2 is about 50 μΩcm or the nickel / chromium alloy wire is about 110 μΩcm, while the resistivity of the electrolytic copper R3 is of the order of 1.7 Ωcm . This difference in resistivity allows heating of the water circulating between the inner wall of the tube of the device and the outer wall of the wrapping tube, exclusively at the distal portion of the microresistor (9), to a value of approximately 400 ^° C. C. At this temperature, the water causes the wall of the tube (1) to be heated at a temperature below 200 ^° C. FIG. 4 shows another embodiment of the microresistor more particularly adapted to the case in which the implantable portion is in the form of a flexible catheter (20). The principle is to compensate for the flexibility of the catheter added to that of the micro-resistance, by implementing the constantan or the nickel / chromium alloy not in the form of a wire but in the form of a hollow tube (25). in which is inserted removably a stainless steel rod (21). In practice, the stainless steel rod is removed once the implanted tube.

The device of the invention can be implanted directly into the tissues or vessels endoluminally.

Depending on the case, the needle or the implantable catheter are inserted into the body to reach the tumor or the vessel to be treated. In some cases, the micro-resistance is introduced alone, without peripheral tube.

In a second step, the current generator is actuated so as to route the current in the microresistor. At the same time, the water is injected into the reduced dead space, thus making it possible to heat the water gradually to reach, at the distal end, a temperature of 200 ^° C., the water then being in pressurized form, that is to say liquid at a temperature above 100 ^° C. The water, in this zone, being at a temperature of about 200 ^° C., is propelled continuously or discontinuously outside the catheter or of the needle through its open distal end, and immediately turns into vapor after release.

In a particular embodiment, shown in Figure 2, the device is adapted to allow its use for the extraction of grease, and in particular cellulite. This technique, known by the term "liposuction", may advantageously be implemented by means of the device of the invention when it is covered, at its periphery, with a sheath (17) connected to a vacuum system. suction (18) of the adipocytes, the sheath being provided with a number of lateral perforations (19).

After making an incision of the skin, the implantable tube which, in practice, has a length of about 30 cm, is introduced into the subcutaneous adipose tissue, the microresistance is then supplied with current so as to heat the tube enveloping at its distal end. At the same time, the water is propelled into the dead space and then heated and pressurized at the distal end. At the outlet, the water is transformed into vapor and allows not only the removal of adipocytes, but also thermofibrosis, that is to say the retraction of collagen. At the same time, the excess fat is sucked into the sheath by suction means. In a particular embodiment, shown in Figure 5, the device of the invention is combined with a specific system of water injection, in the context of treatment varicose veins.

According to this diagram, the device of the invention designated by the general reference (1) is connected at its proximal end to a water injection system in the form of a flexible tube (22), pressed between two rollers (23.24), said roll being rotated about their axis, at identical speed, by means of a motor not shown. In practice, the size and the volume of the flexible tube are determined to contain the entire volume of water necessary for the treatment of the targeted vein. The movement of the rollers thus causes the injection of the actual water into the device of the invention and simultaneously the regular retreat and thus the removal of the device from the vein.

The invention and the advantages derived therefrom are apparent from the foregoing description.

In particular, the implementation of a system avoiding any risk of necrosis of tissues or vessels by dry heat, that the system consists solely of microresistance or combination microresistance + peripheral tube.

Another advantage of the invention remains the low cost that can lead to the marketing of a consumable device, thus avoiding any risk of infection that is known with the means currently implemented on the market.

Claims

1/ Micro-resistance (9) in whole or in part implantable intended for the administration of calories in a cavity, a tissue or a vessel in the form of a metal tube of resistivity Rl (11) having proximal ends and distal and enveloping an electrically conductive material of resistivity R2 (12) at least 5 times greater than Rl, said electrically conductive material (12) being connected to the closed distal end (14) of the metal tube of resistivity Rl ( 11) by its terminal end and having, upstream of said terminal end, two distinct portions: - a middle and proximal portion covered: o with a first layer (15) of an electrically conductive material of resistivity R3 less than R2 having means of connection to one of the terminals of the current generator (10) and ensuring the arrival of the current or vice versa, o then, a second insulating layer, a distal part covered only with an insulating layer (16), the metal tube of resistivity Rl (11) presenting connection means to the other terminal of the current generator (10) and thus ensuring the return of the current or vice and versa.

2/ Micro-resistance according to claim 1, characterized in that Rl is substantially equal to R3.

3/ Micro-resistance according to claim 1, characterized in that it has a diameter of between 0.2 and 0.8 mm.

4/ Micro-resistor according to claim 1, characterized in that that metal tube of resistivity Rl and the first layer of an electrically conductive material of resistivity R3 are made of copper.

5/ Micro-resistor according to claim 1, characterized in that the electrically conductive material of resistivity R2 is in the form of a constantan wire or a nickel/chromium alloy (12) or a tube of constantan or a nickel/chromium alloy (25) into which a removable rod (21) is introduced.

6/ Device in whole or in part implantable intended for the administration of water vapor into a tissue or vessel, which is characterized in that: it is in the form of a peripheral tube (1) made up of distal parts ( 2), median (2) and proximal (3), said tube (1) containing in its lumen, over its entire length, the micro-resistance object of one of claims 1-5, the water being intended to circulate in the dead space separating the wall of the tube (1) from the micro-resistance (9), the proximal part (3) of the tube has a Y-shaped end, one outlet (5) of which is intended to be connected directly to a water inlet (6), and the other outlet of which

(7) is partially closed to allow the passage of the connection means

(8) of the micro-resistance (9) to the terminals of the current generator (10).

11 Device according to claim 6, characterized in that the difference in diameter between the internal diameter of the peripheral tube (1) and the diameter of the micro-resistance (9) is between 50 and 100 micrometers.

8/ Device according to claim 6, characterized in that: the internal diameter of the peripheral tube (1) is between 0.2 and 0.8 mm, the external diameter of the peripheral tube (1) is between 0.3 and 1 mm.

9/ Device according to claim 6, characterized in that the distal (2) and middle (2) parts of the peripheral tube (1) are in the form of a stainless steel needle.

10/ Device according to claim 6, characterized in that the distal (2) and middle (2) parts of the peripheral tube (1) are in the form of a catheter made of a material chosen from the group of PEEK, PTFE , polyphenylsulfone.

11/ Device according to claim 6, characterized in that the proximal part of the tube is made of silicone.

12/ Device according to claim 6, characterized in that it is provided with a gripping device in the form of a sleeve (11) made of silicone covering the junction between the middle part and the proximal part.

13/ Device according to claim 6, characterized in that it is covered with a sheath (17) provided with lateral perforations (19) connected to a suction system.

14/ Device according to claim 13, characterized in that the water inlet is in the form of a flexible tube (22) directly connected in a sealed manner to the Y, the tube being compressed at its end proximal, between two fixed rollers (23,24) rotated at the same speed by means of a motor.