MXPA99005979A - Catheter for radiofrequency ablation of tumors - Google Patents

Abstract

A catheter for the treatment of tumors by hyperthermia induced by radiofrequency or other energy comprises a tubular body (1) having a proximal end (2) connected to a handle member and near the other end a cooled metal plate (5) capable to act as active electrode provided with an electric cable (8) for connection to the energy generator and with thermistors (9, 10) to be connected to the display of said generator, the tubular body (1) having at least a longitudinal channel (11, 12) for the passage of tissual thermistors, a longitudinal channel (11, 12) for the passage of electric cables and a pair of longitudinal channels for inflow and outflow pipes of the liquid cooling the metal plate (5). The metal plate can be built in a ring-like form, wherein the body of the ring has an empty space intended for the circulation of the cooling fluid.

Description

CATHETER DEVICE FOR THE THERMAL EXTRACTION OF TUMORS FIELD OF THE INVENTION The present invention relates to a device for the treatment of tumors by hyperthermia induced by radiofrequency or other forms of energy, and in particular to a catheter that will be introduced into the human body through obvious or obvious natural pathways through its dilatation. It is known that tumors of the parenchymal organs or penetrating tumors in internal hollow organs are treatable by hyperthermia induced by radiofrequency. Such treatment is carried out with suitable radiofrequency generators that have a passive electrode that is applied outside the patient's body and with an active electrode that is inserted inside the body of the patient and directly in contact with the tumor. The known active electrodes consist of needles of various sizes that are inserted into the body of the patient, passing them through various layers of body tissue. This results in losses, because it passes through tissues different from the one to be treated, some of which are not perceptible by large catheters. A transurethral device of WO 9428809 is already known, which does not require it to penetrate the different tissues to which it will be treated, but is limited to the treatment of prosthetic hyperplasia and does not have means that allow a real time monitoring of the temperature of the treated tissue. WO 96/34570 describes a system for removing body tissue by hyperthermia using an active electrode that has the shape of a bulb to focus heat on the terminal capsule of the bulb-shaped electrode. While the shape of the electrode is suitable for the treatment of cardiac tissues, it is not suitable for the treatment of prosthetic hyperplasia where large areas of body tissue must be excised. EP 0 629 382 A1 discloses a catheter assembly for the treatment of prosthetic hyperplasia where the active electrode has the shape of a needle that will be led into the tissue, with the losses of the devices mentioned above, using needles as active electrodes. The object of the present invention is, therefore, to provide a device suitable for use in the thermal extirpation of tumors, which does not have the losses mentioned above. Such an objective is achieved by a device having the characteristics specified in claim 1, which can be contacted or very close to the tumor by passing it through obvious or obvious natural pathways. The device according to the present invention has the advantage of being useful in the treatment by hyperthermia of the tumors that are close to the internal hollow organs, or passed through the internal hollow organs, as well as penetrating tumors in the internal hollow organs . For example, the device according to the present invention can be used advantageously in the treatment of prosthetic tumors by passing it through the urethra, tumors of the uterus, through the uterine channel, cholangiocalcinoma passing it through the bile ducts and through pancreatic tumors passing it through the main pancreatic duct. Another advantage of the device according to the present invention is the fact that it allows to locate the energy even in very small tissue areas to be treated, while the known devices with active needle-shaped electrodes operate at 360 ° C. Other advantages and features of the device in accordance with the present invention will be apparent to those skilled in the art from the following detailed description of one embodiment, with reference to the accompanying drawings, wherein: Figure 1 shows a plan view of a catheter in accordance with the present invention. Figure 2 shows an enlarged view of the detail between lines A and B of Figure 1. Figure 3 shows a catheter cooling system in accordance with the present invention.

Figure 4 shows a plan view in elongated cross-section taken along the line C-C of Figure 1. Figure 5 shows an embodiment of the handle member to be fixed to the catheter in accordance with the present invention; and Figure 6 shows another embodiment of the handle member to be fixed in accordance with the present invention. With reference to Figure 1, the catheter in accordance with the present invention may be in the form of a common balloon catheter, which comprises, in a known manner, a tubular body 1 having an open end 2 and the opposite end 3 it can be inflated in a known manner to form the anchor balloon to adhere within the bladder. As seen in the figure, next to the portion 3, created to inflate like a balloon, the tubular body 1 can advantageously be provided with a terminal end 4, usually solid, which favors the introduction of the catheter through a natural path in the patient's organ, for example inside the urethra. The diameter of the tubular body 1 is chosen according to the diameter of the obvious natural track to be followed. In the case of the urethra it can be approximately 7 mm while in the case of the esophagus it is approximately 3 cm. Close to the balloon portion 3, the tubular body 1 has a metal plate 5, which acts as the actual active electrode of the radiofrequency generator. When the generator is operated, such an electrode induces the hyperthermia of the tissue in its vicinity and, therefore, the necrosis of the tumor that is there. The plate 5 can be copper, steel or any other suitable metal. The metal plate 5 can be extended to 360 ° C, that is to say to the entire circumference of the tubular body 1, but it can also extend only for a portion thereof, for example from 1 to 5 degrees. Its position with respect to the opening of the portion of the balloon 3 must correspond exactly to the distance between the cervix of the bladder and the prostate. In this way, when the balloon is inflated and expanded within the bladder, the plate 5 will exactly correspond to the cancerous prostate to be treated. To allow the balloon 3 to inflate, inside the tubular body 1 there is a channel for a tube 6 connected to an air pump to pass. The length of the plate 5 is approximately between 1 mm and 20 cm. Its thickness is approximately between 0.01 mm and 5 mm. The shape of plate 5 can be chosen taking into account that the catheter must easily pass through the pathways and possibly allow the flow of organic fluids. The metal plate 5 can be electrically connected to a radiofrequency generator by means of the cable 8 passing through a longitudinal channel inside the tubular body 1. With reference to Figure 2, the plate 5 suitably has thermistors 9 and 10, which they allow the monitoring of the temperature inside the plate itself during use. If necessary, additional thermistors (not shown in the figure) can be placed in other points of the plate 5. The thermistors 9 and 10 can be electrically connected to a screen of the radio frequency generator by means of wires passing through another longitudinal channel of the radio frequency generator. tubular body 1. Close to plate 5, tubular body 1 has openings 11 and 12 for the passage of other thermistors (not shown), acting in such a way as to monitor the temperature in the tissues of the treated body. The number of said thermistors, called tissue thermistors can vary from 1 to 4. The tissue thermistors are passed through other longitudinal channels of the tubular body 1 and are extracted through openings 11 and 12 to be placed at the chosen points of the tissues that will be treated. Thermistors are well known, so a detailed description is not needed. The preferred thermistors are those that are available in the market that already have a very thin electrical cable for the connection that is required with the power generator. The thermistor is fixed on the tip of a metal needle with shape memory, and the wire is passed through the cavity of said needle. The length of the metal needle mentioned will be chosen in such a way that the portion that is extracted from the relevant openings 1 1 and 12 has a length of at least 1 cm, preferably 2 to 4 cm. The thermistors can eventually be replaced by other similar sensors, such as thermocouples, resistive wires, optical fibers and the like.

As the effective temperature for the treatment of the tumor can cause adjacent burns in healthy tissues, such as the urethra, the catheter according to the present invention adequately has a cooling system. In its simplest form, such a system consists of water flowing into plate 1 with a pump acting suitably connected to the plate. With reference to Figure 3, the cooling system of the plate 5, in its simplest form, consists of a cavity 7 located inside the same plate. A cooling fluid, preferably water, flows through the cavity 7 which is provided with an inlet tube and an outlet tube for respectively supplying and discharging the cooling fluid. These tubes preferably pass through the longitudinal channels within the material forming the tubular body 1 of the catheter in accordance with the present invention. The cooling water, by directly contacting the metal of the plate 5, ensures a constant transfer outward of the heat that is produced by the treated fabric towards the plate 5. In the embodiment illustrated in figure 3, the plate 5 has been obtained by folding a sheet of metal to give it the shape of a closed semicircular box provided with an inlet and outlet for the cooling liquid. According to another preferred embodiment, the plate 5 has the shape of a semi-cylindrical closed box having a diameter almost corresponding to that of the tubular body 1.

Figure 4 shows the structure of the tubular body 1 which is preferably made of plastic material and has a central channel 15 for the passage of a tube that provides water that is used to fill the bladder. Channels 11 and 12 were created for the passage of tissue thermistors, while channels 13 and 14 were created for the cooling liquid inlet and outlet tubes. The channel 16 was created for the air that is used to inflate the balloon 3 and the channel 17 was created for the passage of the cable 8 as well as the cable 32 connects the thermistors 9 and 10 to the radio frequency generator screen. The plate 5, instead of consisting of a simple metal sheet folded suitably to define the cavity 7, is made of two joined sheets, whereby, when they are coupled, they form a type of tube or bovine nest, improving the efficiency Cooling of the liquid circulating inside the same plate. The plate 5 may also consist of a thin tube elicoidally bent with the bovines adjacent to each other. In order to better locate the energy in the tissues to be treated without damaging the surrounding healthy tissues, the metal plate 5 is sized to surround only the predetermined fraction of the circumference of the tubular body 1. To further improve the location of the radiofrequency in the tissues to be treated only, a part of the outer surface of the plate 5 may be covered by a thin layer of an insulating material. The shape of the insulating layer can be chosen in accordance with the shape of the tumor to be treated. This is a substantial advantage of the catheter device in accordance with the present invention, which allows a perfectly dimensioned active electrode, with size and shape in accordance with the desired location of the energy in the tissue to be treated. The position of the plate 5 along the tubular body with respect to the proximal end (2) is chosen in accordance with the position of the tissue to be treated and the length of the obvious natural path available for treatment. With reference to Figure 5, the handle member 20 for the catheter device according to the present invention is fixed to the tubular body 1 by means of a connecting body 22. The connecting body 22 has the opposite opposite that to which a hollow arrow 23 is connected to the tubular body 1 having a piston 24 slidable within the hollow arrow 23. The piston 24 has at its proximal end a head 25 which can be easily moved by the operator with the same hand holding the limb of handle 20. At its distal end, the piston 24 is provided, at least, with a tissue thermistor that passes through the longitudinal channel inside the tubular body 1 and can exit through the holes 11 and / or 12 so that the tips make contact with the areas more distant from the tissue to which the thermal necrosis will reach. The piston 24 is preferably marked with a millimeter scale that allows to accurately monitor the sliding movement of the piston 24 within the hollow arrow 23, and the resulting movement of the thermistor point with respect to the tissue to be treated. The piston 24 is provided with an electric cable 18 for connecting the tissue thermistors to the screen in the power generator. The connecting body 22 has an outlet 26 of an internal channel for the passage of the cooling liquid tubes 27 and 28; the tube 29 for the water that is used to fill the bladder and the tube 30 for the air that is used to inflate the balloon 3. The handle member 22 is provided with a second outlet 31 of an internal passage for the electric cable 8, as well as for the cable 32 connecting the thermistor 9 and 10 to the radio frequency generator, Figure 6 shows another embodiment 21 of the handle member for a different embodiment of the catheter device according to with the present invention, that is, a catheter without balloon 3 will be used with the aid of a guidewire or a stylet. In this embodiment the connecting body 22 is still connected to the tubular body 1 and provided with a hollow arrow 23 with its sliding piston 24 located on the opposite side of the head 25 at least one tissue thermistor that can be pushed through the longitudinal channel 11 or 12 inside the tubular body 1. The connecting body 22 has a lateral outlet 33 for the cables 8 and 32 connecting the active electrode and its thermistors to the radio frequency generator. A central outlet 34 is for the passage of the guide wire, while the lateral passages 35 and 36 are created for the inlet and outlet of the cooling liquid.

When a prosthetic tumor is treated by hyperthermia, the passive electrode of the radiofrequency generator is placed on the patient's back. The catheter according to the present invention is inserted into the urethra until the highest part is inside the bladder. Then the balloon 3 is inflated by pumping air into the tube 30, which runs along the channel 16 inside the tubular body 1 and has outlet inside the balloon 3. To keep the bladder obvious, it is finally filled with water that is injected through of the tube 29 running along the central channel 15 of the catheter. Traction is exerted and possibly also twisting from the outside on the handle member 29 of the catheter, such that the plate 5 is made to be positioned in the desired position within the prostate. The proper position of the plate 5 within the prostate can be controlled by the usual means available such as rectal ultrasound, computed tomography or magnetic resonance imaging. By pushing the head 25 of the piston 24 the tissue thermistors pass inside the tubular body 1 thus causing them to come out of the holes 11 and 12 to place their tips exactly on the distal areas of the organ to be reached for the desired hyperthermia treatment and the subsequent necrosis. After having connected the tissue thermistors to the radiofrequency generator, the ends of the tubes passing through the channels 13 and 14 are connected to a pump to circulate the cooling water. For that moment, the radiofrequency generator is operated by providing such energy to achieve and maintain a temperature higher than 60 ° C in the area of the organ that surrounds the tip of the tissue thermistors. Under such conditions, the temperature of the tissue between the plate 5 and the tips of the thermistors exceed 100 ° C resulting in the necrosis of the same tissue. These temperatures should be maintained for more than one minute. Then the radio frequency generator is turned off, the thermistors are removed inside the catheter, an intravesical balloon is deflated and finally the catheter is removed from the urethra. In cases where the catheter, in accordance with the present invention, should be used in the treatment of other tumors, such as cholangiocarcinoma, it may not have a balloon 3, which in fact acts only as an anchor for the catheter in the cervix of the bladder. In such a case, the catheter according to the present invention may also not have the tip 4, since the catheter can be introduced into the body with the help of a guide wire already inserted in the body. For this specific use, the embodiment of Figure 6 is suitably connected to the tubular body 1 and the plate 5 with its thermistors, tissue thermistors and cooling system. In such cases, it is not necessary to remove the catheter after each treatment; in fact, it can remain inside the patient's body, then it will be connected to the radiofrequency generator and the cooling pump for each subsequent treatment. Such a catheter can also be used for the treatment of pancreatic tumors by introducing it through the main pancreatic duct by endoscopy or during surgery.

The catheter according to the present invention can be used with a radiofrequency generator or with a generator of any other suitable energy, such as lasers, microwaves and the like. In addition to the thermal excision of tumors, the catheter according to the present invention can also be used for other treatments such as endovascular treatment of atherosclerotic plaques.

Claims (10)

NOVELTY OF THE INVENTION CLAIMS

1. - A catheter for the treatment of tumors by radiofrequency-induced hyperthermia or other energy, consisting of a tubular body (1) having a proximal end (2) connected to a handle member (20, 21) and a distance from it , a cooled active electrode provided with an electric cable (8) for connection to the power generator and with the thermistors (9, 10) that will be connected to the screen of said generator, further characterized in that the tubular body (1) has a internal passage for the longitudinal channels, and the cold active electrode is a tubular metal plate (5) located along the tubular body (1).

2. A catheter according to claim 1, further characterized in that the internal passage of the tubular body (1) lies within at least one longitudinal channel (11, 12) for tissue thermistors, a channel longitudinal (17) for the electric cables and a pair of longitudinal channels (13, 14) for the inlet and outlet tubes of the fluid that is used to cool the tubular electrode (5).

3. A catheter according to claim 2, further characterized in that the tubular body (1) has near its distal end an inflatable balloon portion (3) and a relevant longitudinal channel (16) for the inflating air tube (30) is inside the tubular body (1).

4. - A catheter according to claim 3, further characterized in that the tubular body (1) has a further longitudinal channel (15) for the water that is used to fill a bladder.

5. A catheter according to any of claims 1 to 4, further characterized in that the tubular electrode (5) extends around the tubular body (1) from 1 to 360 °.

6. A catheter according to any of claims 1 to 5, further characterized in that the tubular electrode (5) is covered with an insulating material from 1 to 98% of its external surface.

7. A catheter according to claim 6, further characterized in that the tubular electrode (5) has an internal cavity (7) connected to the tubes that supply the cooling fluid.

8. A catheter according to claim 6, further characterized in that the tubular electrode (5) consists of two sheets of metal joined, coupled to form a cooling coil.

9. A catheter according to any of claims 1 to 8, further characterized in that the handle member (20) consists of a hollow arrow (23) having at one end the output of a slide piston (24). ) containing at its proximal end an electric cable (18) and at its distal end a tissue thermistor, and at the opposite end a connecting body (22) having internal passages communicating on one side with the hollow arrow (23) and on the opposite side with the tubular body (1), said connecting body (22) provided with internal passages, a first outlet (26) for the tubes (27, 28) of the cooling fluid for the tube (29) for water that is used to fill a bladder, and for a tube (30) for air to inflate the portion of the balloon (3), and a second outlet (31) for the electric cables (8,32).

10. A catheter according to any of claims 1 to 9, further characterized in that the handle member (21) consists of a hollow arrow (23) having at one end the output of a slide piston (24) , which has at its proximal end with an electric cable (18) and at its distal end with at least one tissue thermistor, and at the opposite end, a connecting body (22) communicating on one side with the arrow hollow (23) and on the opposite side with the tubular body (1), said connecting body (22) is provided with internal passages and with an outlet (33) for the electric cables (8, 32), the outlet (34) ) for a stylus or a guide wire, outputs (35 and 36) to circulate the cooling liquid.