NL1004655C2 - Ablation catheter and device. - Google Patents

Abstract

The signal conduit extends through the basic body from the electrodes to the proximal end. Cooling devices are provided for the internal cooling next to the electrodes of the end part which is heat-conductive. The cooling devices are of the adiabatic-expansion type, comprising a pressure conduit extending in the basic body from the proximal end to the end part. The pressure conduit at the location of the end part is provided with a restriction and an outlet channel extending from the end part to the proximal end. The cooling device can give rise to a heat flow from outside the end part to the inside. Connected to the signal conduit is an electromagnetic energy-generating device.

Description

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ABLATION CATHETER AND DEVICE

The invention relates to an ablation catheter comprising a tubular basic body with a proximal and distal end. At the distal end, the catheter has a catheter end portion to which a number of external electrodes are mounted. Connected to the electrodes is a signal lead extending through the base body from the electrodes to the proximal end.

Such a per se known catheter is intended to be used, for example, for the treatment of tachycardia. The catheter is then inserted into the patient's body and manipulated so that the end portion with the electrodes engages an internal wall of the heart. By connecting the signal line to an electromagnetic energy generating device, the tissue in contact with the electrodes can be agitated, thereby eliminating the electrical conductivity of this tissue.

In this context, electromagnetic energy is understood to mean all energy propagating as electromagnetic vibrations with which tissue can be heated in order to ablate it. It is known to use radio frequency energy with a frequency in the order of magnitude of 500 kHz for an application such as the one described here.

When ablating with a known ablation catheter and device, the depth of action is limited. When the energy supply is too high, the active end part of the catheter obtains a too high temperature, as a result of which coagulated tissue deposits thereon.

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The object of the invention is now to provide a catheter of the type described in the preamble with which tissue can be ablated at great depth.

This object is achieved with the catheter according to the invention as characterized in claim 1.

By cooling the end part with the cooling means, the direct heating effect of the tissue in contact with the electrode can be greatly reduced and in principle even eliminated. However, the electromagnetic energy penetrates the tissue, so that the intended damage to the tissue takes place at a greater depth. This makes it possible to achieve a large operating depth without the end section of the catheter getting too high a temperature.

The measure of claim 2 is preferably applied. Despite the limited space available in the end part, a sufficiently large cooling capacity can still be obtained in this way.

The invention also relates to and provides an ablation device comprising a catheter according to the invention as described above, wherein the cooling means can generate a heat flow from outside the end part and an electromagnetic energy generating device is connected to the signal line . Furthermore, the electromagnetic energy generating device and the cooling means are connected to a control device for controlling the heat flow and the generated electromagnetic energy. By suitable control of the generated heating energy and cooling energy, a suitable shape of the tissue region affected by the ablation can be achieved.

A very favorable additional advantage is that with a sufficiently large capacity of the cooling means, these can be regulated such that the end part cools down to such an extent that ablation also takes place. This makes it possible to ablate the surface of the fabric by cooling and to ablate the deeper tissue 1004655 3 by heating. A great freedom of adjustment of the shape of the area to be ablated is thus attainable.

A further favorable development of the ablation device according to the invention is characterized in claim 4. With the aid of the electrical voltage detection means, the end part of the catheter can be used to map the electrical conductivity situation of the tissue .

After obtaining a clear picture of the areas of the tissue to be treated, the signal line is connected to the electromagnetic energy generating device for ablating the detected areas.

Before the definitive ablation, a so-called "ice mapping" or "cold mapping" can be performed with the device according to the invention. The tissue is locally cooled and the electrical conductivity of the underlying tissue is temporarily slowed or stopped, without the tissue actually being damaged. The result of a possible ablation in that place can thus be assessed. This can greatly increase the effectiveness of the actual ablation treatments performed and avoid unnecessary ablations.

The invention will be further elucidated in the following description with reference to the attached figures.

Figure 1 shows in partial schematic perspective view an ablation device according to a preferred embodiment of the invention.

Figure 2 shows a cross-section of the end part of the ablation catheter according to the invention indicated in arrow 1 indicated by arrow II.

The ablation device 35 according to the invention shown in figure 1 comprises an ablation catheter 1 which is formed by a tube-like basic body 2 with an end part 3 shown further in figure 2 at the distal end.

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At the proximal end of the catheter 2, a reusable handle 4 is provided, with which the catheter 1 can be manipulated during insertion into a patient.

Although not shown in the figures, the catheter 1 is preferably designed such that the end part 3 thereof can be bent in a controlled manner. The handle 4 then comprises the operating means for effecting the desired bending of the end part 3. Controlled bendable catheters are known per se and a suitable construction is described, for example, in Dutch patent application 1002254.

As Figure 2 shows, the end portion 3 of the catheter 1 comprises a tip 15 received in the distal end of the base body 2, which is of good heat-conducting material, for example metal, and itself forms an electrode.

A number of grooves are formed in the periphery of the tip 15, in which annular electrodes 16 are received. The annular electrodes 16 are embedded in insulating material 17, so that there is no direct electrical contact between the electrodes 16 and the tip 15.

A signal line 7 is connected to the electrode 16, which, in this case, comprises one conductor for each of the electrodes 16. It is also possible to connect the electrodes to a known multiplexer, a single signal line of which is led to the proximal end of the catheter.

Furthermore, a pressure pipe 6 of an adiabatic expansion cooling device opens into the tip piece 15 to be further described. A restriction 18 is included in this pressure line 6.

The pressure line 6 and the signal line 7 have been passed through the central lumen 20 of the catheter 1 to the proximal end. At the location of a Y-piece 5 incorporated in the basic body 2, the lines 6, 7 are led out in a sealed manner. The pressure line 6 is connected to the cooling device 8 and the signal line 7 is connected to the measuring device 10 to be further described.

The cooling means may, for example, be designed in the manner described in European patent application 0 655 225. In a manner not further shown in detail, a coolant is pressurized or kept in the device 8 and via the line 6 to the distal end. from the catheter. There, the coolant leaves the line 6 via restriction 18 and ends up in an expansion space 19 which is recessed in the interior of the metal tip 15. This expansion space 19 communicates via the central lumen in the handle 4 with a discharge pipe 9, which in turn is connected to the cooling device 8 and with which suction of expanded coolant is sucked off. As a result, there is a considerably lower pressure in the expansion space 19 than in the pressure pipe 6, so that the coolant exiting through the restriction 18 expands adiabatically and thereby extracts heat from its surroundings. As a result, the tip piece 15 is cooled and because the tip piece 15 is conductive of heat, a heat flow is created from outside the end part 3 inwards, so that material in contact with the end part 3 is cooled.

The cooling energy can be adjusted by varying the difference in the pressure of the fluid in the pressure pipe 6 and in the expansion space 9. By providing the cooling device 8 with, for example, an adjustable pump or a controlled valve, the cooling effect can be varied.

As already described, the electrodes 16 are connected via the signal line 7 to the device 10. In this preferred embodiment, this device 10 comprises electrical voltage detecting means. With these electrical voltage detecting means, which are known per se, the electrical activity or the electrical conductivity of the tissue in contact with the electrodes 16 can be determined.

In order to map the electrical activity or the electrical conductivity of the tissue of, for example, a ventricle, the end part 3 is brought into contact with the heart wall at various locations and a measurement is carried out.

After mapping the electrical activity and electrical conductivity, it can be determined where tissue has to be ablated to remedy the tachycardia. The end part 3 can then be maneuvered at the desired position against the wall of the heart, whereby an indication of the correct position is obtained with the aid of the measuring device 10. When the correct position is reached, the refrigerants are activated to temporarily cool the tissue and shut down its electricity. In this way it can be assessed whether an ablation at the location in question will lead to the desired result.

If it has indeed been determined that an ablation treatment is required at the location in question, switching means (not shown) which connect the electromagnetic energy generating device 11 instead of the measuring device 10 to the signal line 7 are activated. By activating the electromagnetic energy generating device 11, electromagnetic energy will be applied to the electrodes 15, 16 and dissipate into the tissue in contact therewith, thereby damaging this tissue by heating in order to definitively reduce the electrical conductivity .

At the same time, the cooling device 8 has been put into operation, whereby the metal tip 15 is cooled and overheating is prevented. The electromagnetic energy easily penetrates the tissue with a high energy density and dissipates at a greater depth, so that a greater temperature rise is achieved at a greater depth.

Control means 7 integrated in cooling device 8, measuring device 10 and electromagnetic energy generating device 11, which are not shown in more detail, control the electromagnetic energy and heat energy supplied in such a way that a desired shape of the area damaged by the ablation is achieved. . The achievable variation possibilities can be determined experimentally by a skilled person skilled in the art.

In addition to variation of the energy supplied and extracted, a variation in time is also possible. The control means can thus be designed such that the cooling means are first activated for a certain time before the electromagnetic energy generating device is activated. Fluctuating and / or pulsating activation is also possible.

The desired result can thus be achieved by a suitable control of the cooling means and the electromagnetic energy generating device.

It is noted that the invention is not limited to the use of adiabatic expansion refrigerants. Coolants based on other effects, such as 20 Peltier elements, can also be used. The electrodes do not necessarily have to be inserted into the tip of thermally conductive material. It is thus possible to arrange a number of electrodes at a distance from the point piece.

All such variations are considered to be within the scope of the appended claims.

1004655

Claims (5)

An ablation catheter comprising a tubular base body having a proximal and distal end, a catheter end section at the distal end, a plurality of external electrodes at the end section, a signal lead 5 connected to the plurality of electrodes and extending through the base body from the electrodes to the proximal end, cooling means for internally cooling the end portion near the electrodes and wherein the end portion is heat conductive. Ablation catheter as claimed in claim 1, wherein the cooling means are adiabatic expansion cooling means comprising a pressure pipe extending in the basic body from the proximal end to the end part and provided with a restriction and a discharge channel at the location of the end part. the end portion extends to the proximal end. 3. Ablation device comprising an ablation catheter comprising a tubular base body having a proximal and distal end, a catheter end portion at the distal end, a plurality of external electrodes at the end portion, a signal lead connected to the plurality of electrodes and passing through the base body extends from the electrodes to the proximal end and cooling means for cooling the end section internally near the electrodes wherein the end section is heat conducting and the cooling means can generate a heat flow from outside the end section, an electromagnetic energy generating means connected to the signal line and means for controlling the heat flow and the electromagnetic energy generated connected to the cooling means and the electromagnetic energy generating device. , 1 Ablation device according to claim 3, further comprising electrical voltage detecting means and switching means for optionally connecting the plurality of electrodes to the electromagnetic energy generating device or the electrical voltage detecting means. Ablation device according to claim 3, wherein the cooling means are adiabatic expansion cooling means comprising a pressure pipe which extends in the basic body from the proximal end to the end part and is provided with a restriction at the location of the end part, a discharge channel which extending from the end portion to the proximal end, a source of pressurized cooling medium connected to the pressure line and a coolant discharge means connected to the drain. -V Λ 5 "S v"