JP2003144452A - Catheter for thermocautery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a catheter for thermocautery capable of eliminating only a lesion part by thermocautery without excessively heating other parts than the lesion part, having high cooling efficiency and cooling speed without the leakage of cooling water, and allowing temperature control of a tip electrode without using a temperature sensor. SOLUTION: This catheter for thermocautery has a catheter tube 4 insertable in the body; the tip electrode 10 provided at the distal end part of the catheter tube 4 and capable of cauterizing the interior of a contact part by allowing a high frequency current to flow to the contact part; and a heat pipe 20 having a heat absorbing part 24 integrated with the tip electrode 10, a heat radiating part 22a provided at the opposite side end part to the heat absorbing part 24, and a conduit part 21 axially extending in the catheter tube 4 and communicating the heat absorbing part 24 with the heat radiating part 22a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cautery catheter that can be removed by cauterizing a lesion site in a body cavity, and more specifically, to a lesion site without excessively heating a portion other than the lesion site. The present invention relates to a cautery catheter capable of being removed by cauterization.

[0002]

2. Description of the Related Art An ablation catheter can be cauterized and removed only from a lesion site without requiring a large-scale operation for the patient, and thus it is expected that demand will increase more and more in the future. Cautery catheters typically have a tip electrode on the distal end of the catheter.

When using a catheter for ablation, the distal end of the catheter is inserted into the body cavity where the lesion site is present, and the tip electrode is brought into contact with the inner wall of the body cavity where the lesion site is present. A high-frequency voltage is applied to the tip electrode through the lead wire. As a result, a high-frequency current flows through the inner wall of the body cavity where the tip electrode contacts, and the lesion site is heated and cauterized.

In the conventional cautery catheter, when a lesion site is present in the immediate vicinity of the inner wall surface of the body cavity where the tip electrode contacts, only the lesion site is adjusted by adjusting the high-frequency power supplied to the tip electrode. Can be easily cauterized and removed. However, when the lesion site is located near the outer wall surface of the body cavity, apart from the inner wall surface of the body cavity, there are the following problems.

That is, if the high frequency power supplied to the tip electrode is increased in order to cauterize the lesion site existing near the outer wall of the body cavity, there is a problem that the temperature of the tip electrode becomes too high. There is. Therefore, the blood and the like near the tip chip electrode are altered, and the altered blood adheres to the electrode surface, increasing the impedance,
It becomes difficult to apply high-frequency current. Further, even a portion other than the lesion site may be removed by cauterization, which may open a through hole in the body cavity wall.

Therefore, as disclosed in Japanese Patent No. 2562861, there has been proposed an ablation catheter in which a cooling saline solution or the like is caused to flow inside the tip tip electrode so that the tip tip electrode can be cooled.

[0007]

However, in the ablation catheter disclosed in this publication, cooling water such as cooling saline is circulated in the tip electrode of the tip, so that the cooling water may leak. Have.
Further, since the outer diameter of the catheter is usually as small as about 3 mm or less, if the cooling water is circulated through the inside of the catheter, the flow resistance of the tube is large and the cooling water may not flow well. Further, since the inner diameter of the tube for flowing the cooling water is small, it is difficult to obtain a large amount of circulating water, the cooling efficiency is poor, and the cooling rate is slow. In addition, since the cooling rate is slow, in order to control the temperature of the tip electrode, it is necessary to provide a temperature sensor near the tip electrode so that the temperature of the tip electrode cannot be accurately controlled. is there.

The present invention has been made in view of such circumstances, and an object of the present invention is to remove only a lesion site by cauterization without excessively heating a part other than the lesion site, and to cool the lesion site. It is an object of the present invention to provide a catheter for ablation which does not leak water, has a high cooling efficiency and a high cooling rate, and can control the temperature of a tip electrode without using a temperature sensor.

[0009]

In order to achieve the above object, an ablation catheter according to the present invention is provided in a catheter tube which can be inserted into the body and a distal end portion of the catheter tube. A tip electrode capable of cauterizing the inside of the contact portion by applying a high-frequency current to the contact portion, a heat absorbing portion integrated with the tip electrode, and a heat radiating portion provided at an end opposite to the heat absorbing portion. And a heat pipe having a conduit portion that connects the heat absorbing portion and the heat radiating portion and that extends in the axial direction inside the catheter tube.

In the ablation catheter according to the present invention, since the tip electrode to which high-frequency power is supplied is cooled by the heat pipe, even when the lesion site is separated from the inner wall surface of the body cavity and near the outer wall surface of the body cavity, It is possible to control the heating temperature so that it is close to the peak at the lesion site.
Therefore, it becomes easy to cauterize and remove only the lesion site. Moreover, in the present invention, since the tip electrode is cooled by the heat pipe and the cooling system is a closed system, there is no risk of leakage of cooling water. Further, the heat pipe has advantages of high cooling efficiency and high cooling rate. further,
Due to the characteristics of the heat pipe, the temperature of the heat absorbing portion of the heat pipe is immediately transferred to the heat radiating portion, and if the temperature of the heat radiating portion is managed, the temperature of the heat absorbing portion can be easily controlled. Therefore, it is possible to easily control the temperature of the chip electrode integrated with the heat absorbing portion without providing the chip electrode with a temperature sensor or the like.

In the present invention, preferably, the heat absorbing portion of the heat pipe is formed of a hollow metal electrode and also serves as the chip electrode. Alternatively, the heat absorbing portion of the heat pipe may be formed in a coil shape, and the heat absorbing portion formed in the coil shape may be covered with a conductive metal to form the chip electrode. By adopting such means, the heat absorbing portion of the heat pipe can be easily integrated with the chip electrode.

Preferably, the heat radiating portion of the heat pipe is arranged in a pipe connector, and the pipe connector is
It is detachably attached to the temperature control device. In this case, the heat dissipation portion of the heat pipe is formed in a meandering shape,
It is preferably arranged on the inner circumference of the pipe connector. Alternatively, the heat radiating portion of the heat pipe may be formed in a coil shape and arranged on the inner circumference of the pipe connector. By configuring the heat absorbing portion of the heat pipe in this manner, it becomes possible to easily and detachably connect to the temperature control device via the connector. Examples of the temperature control device include an electronic cooling device using a Peltier element or the like, a cooling device using a normal refrigeration cycle, and the like. Since the temperature control device is placed outside the patient's body, temperature control is easy.

[0013] Preferably, the conduit portion of the heat pipe is a flexible conduit. It is preferable that the flexible conduit has a metal film formed on the outer peripheral surface of a synthetic resin tube. By configuring the conduit part of the heat pipe with such a flexible conduit,
The tip electrode can be cooled without impairing the flexibility of the catheter tube.

Preferably, the conduit portion of the heat pipe may be used as a part of the electrical wiring of the tip electrode.
That is, the conduit may be used as a part of the wiring by making it conductive. In that case, the number of wires arranged inside the catheter tube can be reduced.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on the embodiments shown in the drawings. 1 is a schematic view showing a partial cross section of an ablation catheter according to an embodiment of the present invention, FIG. 2 is a development view showing a heat radiating portion of the heat pipe shown in FIG. 1, and FIG. 3 is an ablation catheter shown in FIG. FIG. 4 is a schematic diagram showing a method of using the same, FIG. 4 is a graph showing a temperature distribution in the depth direction near the lesion site shown in FIG. 3, and FIG. 5 is a heat pipe used for an ablation catheter according to another embodiment of the present invention. It is a schematic diagram of a heat absorption part.

As shown in FIG. 1, an ablation catheter 2 according to one embodiment of the present invention is used to ablate and remove an arrhythmogenic lesion in a wall of a body cavity of a heart. A distal tip electrode 10 and a plurality of intermediate ring electrodes 12 are attached to the distal end of the catheter tube 4. Note that, in FIG. 1, only a single ring-shaped electrode 12 is shown for simplification of the illustration, but the number of ring-shaped electrodes 12 is usually about 1 to 20,
It is formed on the distal end of the catheter tube 4 at predetermined intervals.

The tip electrode 10 is, in this embodiment,
It has a hemispherical tip and a shape similar to a bullet, and is fixed to the most distal end of the catheter tube 4. The ring-shaped electrode 12 is fixed to the outer circumference of the catheter tube 4 axially rearward of the distal tip electrode 10 at predetermined intervals in the axial direction.

The tip electrode 10 is, in this embodiment,
Endothermic portion 24 formed at the distal end of the heat tube 20
And the inside is hollow, and the hollow is
It communicates with the conduit portion 21 of the heat pipe 20.
The conduit portion 21 of the heat pipe 20 extends along the axial direction inside the lumen formed inside the catheter tube 4, and is fixed to the proximal end portion of the catheter tube 4 for operation. 6 is projected from the rear end portion and connected to the pipe connector 22.

Inside the pipe connector 22, for example, a heat radiating portion 22a of the heat pipe 20 shown in FIG. 2 is arranged. As shown in FIG. 2, the heat radiating portion 22 a is formed in, for example, a meandering shape in order to increase a heat radiating area, and the meandering shaped heat radiating portion 22 a is the inner circumference of the concave pin hole of the pipe connector 22. It is mounted circumferentially along the surface. A convex connection connector of the cooling device is detachably fitted into the concave pin hole of the pipe connector 22.

Therefore, by cooling the convex connection connector fitted in the concave pin hole of the pipe connector 22 with the cooling device, the heat is absorbed by the heat absorbing portion 24 of the heat pipe and transmitted to the heat radiating portion 22a through the conduit portion 21. The heat is quickly dissipated.

From the operating connector 6 attached to the proximal end of the catheter tube 4, various wires 30 and 40 are drawn out in addition to the conduit portion 21 of the heat pipe 20. At the rear end of the wiring 30, a tip chip electrode connector 32 for connecting to a high frequency power supply device is connected. The wiring 30 is electrically connected to the tip electrode 10 through a wiring (not shown) inside the catheter tube 4. The conduit portion 21 of the heat pipe 20 may be used as a part of the electrical wiring between the tip electrode 10 and the electrode connector 22. As will be described later, the conduit portion 21 has a metal film and has conductivity, and thus may be used as a part of wiring. In that case, the number of wires arranged inside the catheter tube 4 can be reduced.

A ring-shaped electrode connector 42 for connecting to a measuring device such as an electrogram recorder is connected to the rear end of the wiring 40. The wiring 40 is electrically connected to the ring-shaped electrode 12 through a wiring (not shown) inside the catheter tube 4. A knob 7 is attached to the operation connector 6. By rotating the knob 7, the direction of the distal end portion of the catheter tube 4 can be bent and changed as shown by an arrow X, for example.

The catheter tube 4 is made of, for example, a synthetic resin such as polyolefin, polyamide, polyether polyamide or polyurethane. The outer diameter of the catheter tube 4 is generally about 0.6 to 3 mm, and the inner diameter thereof is about 0.5 to 2.5 mm.

The outer diameter of the tip electrode 10 constituting the heat absorbing portion 24 of the heat pipe 20 is about the same as the outer diameter of the catheter tube 4, and the rear end portion of the tip electrode 10 is the most distal end of the catheter tube 4. Glued or heat fused to the end openings. The tip chip electrode 10 that constitutes the heat absorbing portion 24 is formed integrally with the conduit portion 21 of the heat pipe 20, and is made of a metal having good thermal conductivity, such as aluminum, copper, stainless steel, gold, or platinum. The tip electrode 10 is preferably made of platinum or the like in order to have good contrast to X-rays.

The outer diameter of the conduit portion 21 of the heat pipe 20 is designed so that it can be inserted into the lumen of the catheter tube 4, and is, for example, about 0.3 to 1.0 mm. The conduit part 21 is made of a gas-permeable flexible tube, and has a single or a plurality of lumens formed therein along the axial direction, and a gas for forming a heat pipe is enclosed therein. The gas for forming the heat pipe is not particularly limited, butane gas, freon gas,
Carbon dioxide gas, chlorofluorocarbon gas and the like are used, and among them, butane gas is preferable from the use temperature range of the present invention. Conduit part 2
The lumen formed in the inside of 1 along the axial direction communicates with the inside of the heat absorbing portion 24 and the heat radiating portion 22a of the heat pipe 20, and the gas sealed inside the heat pipe 20 is Does not leak outside.

The gas impermeability-resistant flexible tube forming the conduit portion 21 of the heat pipe 20 has, for example, a metal film, preferably the same metal as the metal forming the tip electrode 10 such as aluminum, on the outer periphery of the synthetic resin tube. It can be obtained by vapor deposition, plating, or sputtering. The thickness of the metal film is not particularly limited, but is preferably about 5 to 50 μm.

The flexibility of the conduit portion 21 is required because the conduit portion 21 is inserted into the body cavity such as a tortuous blood vessel together with the catheter tube 4 and the flexibility is required. Further, the gas impermeable resistance of the conduit portion 21 is required so that the gas sealed inside the conduit does not permeate to the outside and escape.

The material of the synthetic resin tube which is the base material tube of the flexible tube is not particularly limited, but may be polyamide resin, fluororesin, polyester resin,
Examples include polyamide resins.

The heat radiating portion 22a of the heat pipe 20 is made of a metal having good thermal conductivity like the heat absorbing portion 24 of the tip electrode 10. The shape of the heat radiating portion 22a is not limited to the meandering shape as shown in FIG. 2, but may be a coil shape as shown in FIG. 5, for example.

In the ablation catheter 2 according to this embodiment, the tip electrode 10 to which high frequency power is supplied is cooled by the heat pipe 20. Therefore, as shown in FIG. 3, even when the lesioned part 52 exists near the outer wall surface of the body cavity away from the inner wall surface 50 of the body cavity, as shown by the solid line B in FIG. 4, the tip electrode 10 shown in FIG. It is possible to control the heating temperature so that the heating temperature is near the peak at the position Lm of the lesion site 52 at the distance L in the depth direction from the contact position.
Therefore, it becomes easy to cauterize and remove only the lesion site 52. An ablation catheter that does not include the heat pipe 20 has the disadvantage that the temperature becomes too high at the position where the tip electrode 10 is in contact, as indicated by the chain double-dashed line A in FIG. The present invention does not have such an inconvenience.

Further, in the present invention, since the tip pipe electrode 10 is cooled by the heat pipe 20 and the cooling system is a closed system, there is no risk of leakage of cooling water. Further, the heat pipe 20 has advantages of high cooling efficiency and high cooling rate. Further, due to the characteristics of the heat pipe 20, the temperature of the heat absorbing portion 24 of the heat pipe is immediately transferred to the heat radiating portion 22a, and if the temperature of the heat radiating portion 22a is controlled, the heat absorbing portion 24a can be controlled.
The temperature control can be done easily. Therefore, it is possible to easily control the temperature of the tip chip electrode 10 integrated with the heat absorbing portion 24 without providing the tip chip electrode 10 with a temperature sensor or the like.

The present invention is not limited to the above-mentioned embodiment, but can be variously modified within the scope of the present invention.

For example, the structure of the heat absorbing portion of the heat pipe 20 is not limited to that of the embodiment shown in FIG. 1, and other structures may be used. In the embodiment shown in FIG. 5, the heat absorbing portion 24a of the heat pipe 20 is formed into a coil shape, and the outer peripheral portion thereof is completely covered with a conductive metal such as platinum to form the tip electrode 10a. The coating method is not limited to the plating method, and the vapor deposition method, the sputtering method and the like are exemplified.

[0034]

As described above, according to the present invention, it is possible to cauterize only the lesioned part without excessively heating the part other than the lesioned part, and to prevent the cooling water from leaking. It is possible to provide a catheter for ablation which has high cooling efficiency and high cooling rate and which can control the temperature of the tip electrode without using a temperature sensor.

[Brief description of drawings]

FIG. 1 is a schematic view showing a partial cross section of an ablation catheter according to an embodiment of the present invention.

FIG. 2 is a development view showing a heat radiating portion of the heat pipe shown in FIG.

FIG. 3 is a schematic view showing a method of using the ablation catheter shown in FIG. 1.

FIG. 4 is a graph showing a temperature distribution in the depth direction near the lesion site shown in FIG.

FIG. 5 is a schematic view of a heat absorbing part of a heat pipe used for an ablation catheter according to another embodiment of the present invention.

[Explanation of symbols]

2… Cautery catheter 4 ... Catheter tube 10 ... Tip electrode 12 ... Ring-shaped electrode 20 ... Heat pipe 22 ... Piping connector 22a ... Heat dissipation part 24 ... Heat absorption part

Claims (9)

[Claims] 1. A catheter tube that can be inserted into the body, and a tip electrode that is provided at the distal end of the catheter tube and that can cauterize the inside of the contact site by passing a high-frequency current through the contact site. A heat-absorbing part integrated with the tip electrode, a heat-dissipating part provided at an end opposite to the heat-absorbing part, the heat-absorbing part and the heat-dissipating part are connected to each other, and the inside of the catheter tube is axially connected. A heat pipe having a conduit portion extending in the direction,
An ablation catheter having: 2. The ablation catheter according to claim 1, wherein the heat absorbing portion of the heat pipe is formed of a hollow metal electrode and also serves as the tip electrode. 3. The heat absorbing portion of the heat pipe is formed in a coil shape, and the heat absorbing portion formed in the coil shape is covered with a conductive metal to form the chip electrode.
The catheter for cauterization according to 1. 4. The ablation catheter according to claim 1, wherein the heat radiating portion of the heat pipe is arranged in a pipe connector, and the pipe connector is detachably attached to a temperature control device. 5. The ablation catheter according to claim 4, wherein the heat radiating portion of the heat pipe is formed in a meandering shape and arranged on the inner circumference of the pipe connector. 6. The ablation catheter according to claim 4, wherein the heat radiating portion of the heat pipe is formed in a coil shape and is arranged on the inner circumference of the pipe connector. 7. The ablation catheter according to claim 1, wherein the conduit portion of the heat pipe is a flexible conduit. 8. The ablation catheter according to claim 7, wherein the flexible conduit has a metal film formed on an outer peripheral surface of a synthetic resin tube. 9. The ablation device according to claim 1, wherein a conduit portion of a heat pipe having conductivity is used as a part of electrical wiring for supplying electric power to the tip electrode. catheter.