JPH1071148A - Catheter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lessen transmission loss and to improve mechanical characteristics while reducing the diameter of a signal cable in order to reduce the diameter of a catheter. SOLUTION: The signal cable of the catheter having a transducer for converting signals and the signal cable for leading the electrical contacts of this transducer outside is constituted by intertwining three pieces of conductors 201 to form a conductor core 202, coating the circumference thereof with an insulator 203 to constitute a core cable 204 and intertwining two pieces of these core cables 204.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catheter, and more particularly to a catheter having a built-in transducer for converting a signal.

[0002]

2. Description of the Related Art Heretofore, one type of a biological measurement catheter which is inserted into a coronary artery or other small blood vessels of the heart or a blood vessel such as a bile duct to display a cross-sectional image of a body cavity or to measure blood flow. Thus, an ultrasonic imaging catheter is known.

FIG. 1 is a longitudinal sectional view showing the structure of a conventional ultrasonic catheter. The ultrasonic transducer 3 is disposed at the distal end of the hollow catheter shaft 2 inserted into the body cavity, and receives a driving force (for example, rotation and translation) from an external driving source 8 via the driving force transmission shaft 6. Is transmitted. A signal cable 7 that connects the ultrasonic vibrator 3 and an electric circuit in the external device 5 is passed through the driving force transmission shaft 6. In this configuration, a desired body cavity cross-sectional view can be obtained by scanning an ultrasonic wave while rotating or translating the ultrasonic transducer 3 via the driving force transmission shaft 6 by the external driving source 8.

The conventional ultrasonic catheter 1 shown in FIG.
It has an outer diameter of 1 mm or more, and the signal cable 7 is 0.2 m
It is composed of a coaxial cable having an outer diameter of at least m. Under such dimensions, the conductor resistance of the coaxial cable is 10Ω / m
Hereinafter, since the capacitance is 150 pF / m or less, the signal transmission loss does not cause a problem in characteristics.

[0005]

In recent years, it has been required to reduce the diameter of a catheter. This is because the catheter can be inserted into a thin blood vessel or a blood vessel and can be combined with a treatment device. However, as shown in FIGS. 2 and 3, the coaxial cable has a structure in which a conductor 23 for a signal line is covered with an insulator 24, the outside thereof is covered with a conductor 22 for shielding, and further covered with an insulator 21. Therefore, it is difficult to reduce the outer diameter to 0.2 mm or less in manufacturing, and the reduction in the diameter causes transmission loss due to an increase in capacitance and conductor resistance. Furthermore, since the coaxial cable has a large diameter and is hard to bend due to its structure, it cannot be used as a signal cable in the drive transmission shaft.
This is a major cause of instability of the operation of the drive transmission shaft for transmitting rotational or translational drive force.

Therefore, a structure in which a cable having a coaxial structure is replaced with a cable having a twisted pair structure is considered. But,
Since the conventional twisted pair cable has a structure in which one conductor 25 is covered with an insulator 26 as shown in FIG. 4, for example, in order to reduce the conductor resistance of the conductor 25 to 10 Ω / m or less, The diameter needs to be 70 μm or more. Therefore, when the twisted pair cable is passed through a drive transmission shaft having an outer diameter of 0.6 mm or less, the operation of the drive transmission shaft becomes unstable as in the case of the coaxial cable.

[0007] The above-mentioned problem of transmission loss is caused by a signal cable used in a catheter without a drive transmission shaft, that is, a catheter for measuring a living body for measuring blood pressure, blood flow velocity, blood component, temperature, PH and the like. The same is true for

In particular, when a twisted cable is used for transmitting a high-frequency signal or a high-speed signal of 1 MHz or more, the conductor resistance and the characteristic impedance greatly affect the characteristics of the catheter, and are insufficient when the diameter of the catheter is reduced. It was difficult to obtain the properties.

The present invention has been made in view of the above problems, and has as its object to reduce the diameter of a signal cable and thereby reduce the diameter of a catheter, and more specifically, to reduce the diameter of a catheter. Therefore, an object of the present invention is to reduce the transmission loss while reducing the diameter of the signal cable and improve the mechanical characteristics of the signal cable.

[0010]

According to the present invention, there is provided a catheter having a transducer for converting a signal and a signal cable for leading an electrical contact of the transducer to the outside, wherein the signal cable is electrically connected. A signal line covered with an insulating material is bundled around at least two connected conductors.

In the catheter according to the present invention, it is preferable that the signal line is formed by twisting the at least two conductors.

[0012] In the catheter according to the present invention, it is preferable that the signal cable is formed by twisting the signal line.

In the cartel according to the present invention, it is preferable that the signal cable is formed by horizontally winding the signal line.

[0014] In the catheter according to the present invention, it is preferable that the signal line has the at least two conductors arranged in a plane, and the signal cable is formed by horizontally winding the signal line.

[0015] The catheter according to the present invention further comprises a hollow shaft for transmitting an external mechanical driving force to the transducer, and the signal cable is drawn out through a hollow portion of the shaft. Is preferred.

In the catheter according to the present invention, the transducer generates an ultrasonic wave based on an electric signal provided through the signal cable, converts a reflected wave from the subject into an electric signal, and connects the signal cable. It is preferable to use an ultrasonic transducer that outputs the signal to the outside.

In the catheter according to the present invention, it is preferable that a part of the at least two conductors is fixed to the electrical contact of the transducer.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

<First Embodiment> FIG. 5 is a longitudinal sectional view showing the configuration of a biometric catheter according to a first embodiment. Inside the vicinity of the distal end of the catheter 100, there is provided a transducer 101 for converting, for example, blood pressure, blood flow velocity, blood component, temperature, PH, etc. into an electric signal. The electric signal output from the transducer 101 is transmitted to the proximal side (rear end side) of the catheter 100 via the signal cable 103 and is extracted from the electric contact 104.

FIG. 6 is a sectional view showing a first configuration example of the signal cable 103. The signal cable 103 in FIG.
Two core cables 204 are twisted.
One core cable 204 is obtained by covering a conductor core 202 formed by twisting three conductors 201 with an insulator 203. The number of core cables 204 constituting the signal cable 102 may be determined according to the number of electrical contacts of the transducer 101.

The material constituting the conductor 201 is C
Metals or alloys such as u, Au, Ag, and Fe are suitable. The outer diameter of the conductor 201 is preferably as large as possible as long as the operability of the catheter 100 is not impaired.
And more preferably 16 to 50 μm. The number of twists of the conductor 201 is
It is sufficient that the number is two or more, but it is preferable that the number is an odd number in which the twist shape is stable, and it is preferable that the number is three to five in terms of production.

As a material constituting the insulator 203, a high insulating resin such as urethane, polyimide, or fluorine is suitable. The coating thickness may be thin as long as a desired withstand voltage is obtained. It is preferably at least 5 μm,
More preferably, it is 0 to 30 μm.

The signal cable 103 may be configured by twisting the core cable 204 as described above, or may be configured by winding the core cable 204 horizontally, for example.

FIG. 7 is a diagram showing a method of manufacturing the signal cable 103 according to the second configuration example, that is, the signal cable 103 in which the core cable 204 is wound horizontally. The signal cable 102 according to the second configuration example is, for example, SUS,
A desired number (for example, two) of core cables 204 are wound around a core metal 301 made of a metal wire such as Cu, and then the core metal 301 is pulled out and wound until a desired outer diameter is reached. It can be manufactured by extending the cable 204 (pulling in the left-right direction in the figure).

As described above, the core cable 204 is formed by twisting a plurality of conductors 201, and the signal cable 103 is formed by bundling a desired number of core cables 204, whereby the signal cable 103 (catheter) is formed. The transmission loss in the signal cable 103 can be reduced while the bending is facilitated. Reduction of the transmission loss is particularly effective when the frequency of the signal transmitted through the signal cable 103 is high. At a high frequency, the current flowing through the conductor is concentrated on the surface due to the skin effect, but the surface area of the conductor can be increased by forming one signal line by the plurality of conductors 201.

FIG. 8 is a sectional view showing a third configuration example of the signal cable 103. The signal cable 103 in FIG.
Conductor core 202 formed by bundling three conductors 201 in a plane
Is covered with an insulator 203, which is horizontally wound like a signal cable 103 shown in FIG.

The signal cable 103 shown in FIG. 8 can be easily bent, reduce transmission loss, and can be made smaller in diameter than the signal cable 103 shown in FIG.

As described above, according to the present embodiment, it is possible to obtain a signal cable having excellent mechanical characteristics and a small transmission loss even if the diameter is reduced, and as a result, the catheter can be reduced in diameter. Can be.

<Second Embodiment> In this embodiment, the above-described signal cable 102 is applied to a biological measurement catheter for obtaining a cross-sectional image of a body cavity such as a blood vessel or a vessel, that is, an ultrasonic imaging catheter. Is what you do.

FIG. 9 is a longitudinal sectional view showing an example of the configuration of the catheter for measuring a living body according to the present embodiment. In this example, an ultrasonic transducer 901 is used as a transducer. The ultrasonic transducer 901 is connected to the drive transmission shaft 9.
03 is fixed to a housing 902 connected to the tip of the same.

Two electrodes 901a of the ultrasonic transducer 901
And 901b are connected to the respective core cables 204 in the signal cable 103 in which the two core cables 204 are bundled. The signal cable 103 passes through the inside of the hollow drive transmission shaft 903, reaches the proximal side (rear end side) of the catheter 900, and is connected to the electrical contact 904. The electric contact 904 is electrically connected to the contact of the external drive source 905, and serves as a signal processing unit (a drive circuit of the ultrasonic vibrator 901 and a detection circuit of an output signal from the ultrasonic vibrator 901) in the external device 906. Is included).

The housing 902 to which the ultrasonic transducer 901 is fixed is driven (for example, rotated and translated) by an external drive source 905 via a drive transmission shaft 903. The drive transmission shaft 903 is preferably formed of a hollow coil made of, for example, a corrosive metal wire such as SUS.

FIG. 6, FIG. 7, FIG.
The structure shown in any of the above. For example, the drive transmission shaft 903 has an inner diameter of 0.22 mm / outer diameter of 0.46 mm.
When a hollow coil is used, the signal cable 103 is formed by winding two core cables 204 in each of which a conductor 201 having a diameter of 25 μm is twisted into three to cover a conductor core 202 with a urethane resin of about 20 to 25 μm. Are preferred (see FIG. 7).

As described above, the transmission loss of the signal cable is reduced by applying the signal cable 103 described in the first embodiment to a biological measurement catheter having a drive transmission shaft such as an ultrasonic imaging catheter. In addition to making the catheter thinner,
The bending of the signal cable can be facilitated, and the mechanical stability when driving a transducer such as an ultrasonic transducer can be improved.

Next, the operation of the ultrasonic imaging catheter will be described. First, a blood vessel is secured from outside the body using an introducer or the like, and a guiding catheter for inserting a catheter for imaging, inspection and treatment is selected and inserted into the blood vessel using a guide wire. . After the guiding catheter reaches a target site to be examined or treated, a cross-sectional image of a blood vessel can be obtained by inserting the above-described ultrasonic imaging catheter into the guiding catheter.
When inserting the ultrasonic imaging catheter, a so-called over-the-wire or rapid exchange method for inserting a guide wire into the ultrasonic imaging catheter may be used, or a method for inserting the ultrasonic imaging catheter alone may be used. Further, an ultrasonic imaging catheter may be inserted into a guide wire lumen of a treatment catheter such as a balloon catheter. In this case, the outer diameter of the ultrasound imaging catheter is preferably at least about 1 mm or less,
More preferably, it is 0.5 mm or less.

<Third Embodiment> This embodiment relates to a method of electrically connecting a signal cable and a transducer. Here, a case where an ultrasonic transducer is used as a transducer will be described as an example.

FIG. 10 is a diagram showing a method of electrically connecting the signal cable and the ultrasonic vibrator. In the illustrated example, three conductors 20 pulled out of the core cable 204 are used.
Only one of the electrodes 901a of the ultrasonic transducer 901 is used.
(901b) by soldering. Thus, the plurality of conductors 2 included in the core cable 204
By connecting only a part of 01 to the electrode of the ultrasonic transducer 901, the mechanical load applied to the ultrasonic transducer 901 by the conductor 201 can be reduced.

That is, when all the conductors 201 are connected to the electrodes 901a (901b) of the ultrasonic vibrator 901, the electrodes 901a (901b) drive all the conductors 201 related to the connection as a mechanical load. Become bound by vibration. Therefore, by limiting the number of conductors 201 connected to the electrodes 901a (901b), unnecessary load applied to the ultrasonic vibrator 901 can be reduced, and good ultrasonic waves can be generated. For the same reason, it is possible to shorten the pulse of the ultrasonic signal to be transmitted, and to make the shape of the transmitted and received ultrasonic beam uniform.

The present invention is not limited to the above specific embodiments, and various modifications can be made without departing from the scope of the technical idea.

[0040]

According to the present invention, the diameter of the signal cable can be reduced, and the diameter of the catheter can be reduced.

Specifically, for example, transmission loss is reduced,
By reducing the diameter of the signal cable while improving its mechanical characteristics, the diameter of the catheter can be reduced.

[0042]

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a configuration of a conventional ultrasonic catheter.

FIG. 2 is a longitudinal sectional view of a coaxial cable.

FIG. 3 is a cross-sectional view of the coaxial cable.

FIG. 4 is a cross-sectional view of the twisted pair cable.

FIG. 5 is a longitudinal sectional view showing the configuration of the biological measurement catheter according to the first embodiment.

FIG. 6 is a cross-sectional view of the signal cable according to the first configuration example.

FIG. 7 is a diagram illustrating a method of manufacturing a signal cable according to a second configuration example.

FIG. 8 is a cross-sectional view of a signal cable according to a third configuration example.

FIG. 9 is a longitudinal sectional view showing a configuration example of a biological measurement catheter according to a second embodiment.

FIG. 10 is a diagram illustrating a method of electrically connecting a signal cable and an ultrasonic transducer.

[Description of Signs] 1,100,900 Ultrasound catheter 2,102,908 Exterior shaft 3,101,901 Ultrasonic transducer 5,906 External device 6,903 Drive transmission shaft 7,12,103 Signal cable 8,905 External drive source 9,907 Ultrasonic transmission liquid 21,24,26,203 Insulator 22,23,25,201 Conductor 104,904 Electrical contact 105,909 Hand operation unit 202 Conductor core 204 Core cable 301 Core metal 901a, 901b Electrode 902 housing

Claims (8)

[Claims] 1. A catheter comprising a transducer for converting a signal and a signal cable for leading electrical contacts of said transducer to the outside, said signal cable being wrapped around at least two electrically connected wires. A catheter comprising a bundle of signal lines coated with an insulating material. 2. The catheter according to claim 1, wherein the signal line is formed by twisting the at least two conductors. 3. The catheter according to claim 2, wherein the signal cable is formed by twisting the signal line. 4. The catheter according to claim 1, wherein the signal cable is formed by horizontally winding the signal line. 5. The signal line according to claim 1, wherein the at least two conductors are arranged in a plane, and the signal cable is formed by horizontally winding the signal line.
A catheter according to claim 1. 6. The apparatus according to claim 1, further comprising a hollow shaft for transmitting an external mechanical driving force to the transducer, wherein the signal cable extends to the outside through a hollow portion of the shaft. Claim 1
The catheter according to any one of claims 1 to 5. 7. The transducer generates an ultrasonic wave based on an electric signal supplied through the signal cable, converts a reflected wave from the subject into an electric signal, and outputs the electric signal to the outside through the signal cable. The catheter according to claim 6, wherein the catheter is an ultrasonic vibrator. 8. The electrical contacts of the transducer include:
The catheter according to claim 1, wherein a part of the at least two conductors is fixed.