JP2016086969A - Nerve stimulation device and control method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nerve stimulation device capable of acquiring an electrocardiographic signal with a high degree of precision even with a simple configuration.SOLUTION: A nerve stimulation device 1 includes: stimulation electrodes 34A and 34B; a pulse generation circuit part 44 for generating electric stimulation; electrocardiographic signal detection electrodes 17A and 17B for detecting an electrocardiographic signal; an electrocardiographic signal processing part 42 having a reference potential part shared by the pulse generation circuit part 44 for acquiring the electrocardiographic signal; a change-over switch part 45 for switching the state between a first state in which the pulse generation circuit part 44 is closed and the electric stimulation is generated, and a second state in which the pulse generation circuit part 44 is blocked, and the stimulation electrodes 34A and 34B are conducted to the reference potential part; and a control part 49 for generating the electric stimulation when the change-over switch part 45 is switched to the first state, and acquiring a waveform of the electrocardiographic signal on the basis of the electrocardiographic signal acquired by the electrocardiographic signal processing part 42 when it is switched to the second state.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a nerve stimulation device and a control method thereof.

2. Description of the Related Art Conventionally, nerve stimulation apparatuses that perform treatment by applying electrical stimulation to biological tissue such as nerve tissue or muscle are known. For example, an apparatus that treats arrhythmia by suppressing an increase in heart rate and sympathetic excitement by applying electrical stimulation to the vagus nerve via an electrode connected to the vagus nerve is known.
For example, a percutaneous nerve stimulation apparatus described in Patent Document 1 is a nerve stimulation apparatus for adjusting cardiovascular functions, and performs treatment by performing nerve stimulation percutaneously. The apparatus includes a stimulation electrode disposed on a body surface, an external nerve stimulation apparatus that generates a stimulation pulse to perform nerve stimulation, and an external sensor.
The external sensor is, for example, a heart rate sensor, and controls the stimulation pulse by measuring the heart rate and feeding it back.

Special table 2010-506618 gazette

However, the conventional nerve stimulation apparatus as described above has the following problems.
The percutaneous nerve stimulation apparatus described in Patent Document 1 describes that a heart rate sensor is used as an external sensor, but the specific configuration of the heart rate sensor is not specified.
A heart rate sensor used for feedback of stimulation output needs to be measured with high accuracy. Therefore, it is preferable to acquire an electrocardiogram signal and analyze the waveform of the electrocardiogram signal. However, since the electrocardiographic signal is detected as a weak current flowing through the living body, there is a problem that noise is likely to be mixed.
For example, in an electrocardiograph, in addition to at least two electrodes for measuring an electrocardiogram signal (electrocardiogram signal detection electrode), a one-electrode reference electrode serving as a measurement reference is provided. The reference electrode is arranged on the patient's body surface together with the electrocardiogram signal detection electrode.
As described above, in the configuration including the electrocardiogram signal detection electrode and the reference electrode, it is possible to suppress the mixing of noise and obtain a favorable waveform of the electrocardiogram signal.
However, in such a device configuration, since the reference electrode is provided, there is a problem that the number of parts is increased and the configuration becomes complicated as compared with the case where the reference electrode is not provided. In addition, handling of the apparatus becomes complicated. Furthermore, in addition to the electrocardiogram signal detection electrode, the patient receiving electrical stimulation must also wear the reference electrode, which takes time and effort. In addition, since the reference electrode is also attached, the patient is less likely to move after being attached, and the patient is likely to be stressed.

  The present invention has been made in view of the above problems, and it is an object of the present invention to provide a nerve stimulation apparatus and a control method thereof that can accurately acquire an electrocardiographic signal even with a simple configuration. And

  In order to solve the above problems, a nerve stimulation device according to a first aspect of the present invention generates a stimulation electrode connected to the stimulation electrode for applying electrical stimulation to a nerve of a living body, and generates the electrical stimulation. A stimulus generator including a first electric circuit, an electrocardiogram signal detection electrode that is attached to the living body and detects an electrocardiogram signal of the living body, and a second common to the first electric circuit and the reference potential unit. An electrocardiogram signal acquisition unit that acquires the electrocardiogram signal detected by the electrocardiogram signal detection electrode by the second electric circuit, and closes the first electric circuit to perform the electrical stimulation. A changeover switch unit that selectively switches between a first state in which the first electrical circuit is generated and a second state in which the first electrical circuit is cut off and the stimulation electrode is conducted to the reference potential unit, and the changeover switch Switch the part to either the first state or the second state In other words, the electrocardiogram signal acquired by the electrocardiogram signal acquisition unit when the electrical stimulation is generated by the stimulus generation unit when switched to the first state and is switched to the second state. And a control unit that acquires the waveform of the electrocardiographic signal.

  In the nerve stimulation apparatus, it is preferable that the control unit always obtains the waveform of the electrocardiogram signal when the changeover switch unit is switched to the second state.

  In the nerve stimulation apparatus, the control unit causes the stimulation generation unit to periodically generate the electrical stimulation a plurality of times, and the electrical stimulation during the stimulation group generation operation. Only when the stimulus stop operation for stopping the electrical stimulation is alternately repeated for a time longer than the interval, and the changeover switch unit is switched to the second state during the stimulus stop operation. The waveform of the electrocardiogram signal is preferably acquired.

  The nerve stimulation device preferably includes an electrocardiogram signal analysis unit that analyzes a waveform of the electrocardiogram signal acquired by the control unit and acquires information on a heart function of the living body.

  In the above nerve stimulation apparatus, the electrocardiogram signal analysis unit analyzes the waveform after a predetermined time has elapsed since the changeover switch unit was switched to the second state in the waveform of the electrocardiogram signal. It is preferable to acquire the information on the cardiac function of the living body by performing the above.

  In the above nerve stimulation apparatus, it is preferable that the control unit acquires the waveform of the electrocardiogram signal after a predetermined time has elapsed since the changeover switch unit was switched to the second state.

  The nerve stimulation apparatus control method according to the second aspect of the present invention includes a stimulation electrode for applying electrical stimulation to nerves in a living body, and an electrocardiogram signal detection electrode for detecting an electrocardiographic signal of the living body. A control method for an apparatus, wherein the stimulation electrode and the electrocardiogram signal detection electrode are arranged on the living body, and the stimulation electrode arranged on the living body generates the electrical stimulation. And applying the electrical stimulation from the stimulation electrode, conducting the stimulation electrode to a reference potential portion of the first electrical circuit, and stopping the generation of the electrical stimulation; When the stimulation electrode is conducted to the reference potential portion, the electrocardiogram signal is acquired from the electrocardiogram signal detection electrode attached to the living body using a second electric circuit having a common reference potential portion. And the reference potential portion Based on the electrocardiographic signal obtained when intense electrode is conductive, and a method of and an obtaining a waveform of the electrocardiographic signal.

  In the control method of the nerve stimulation apparatus, it is preferable that the waveform of the electrocardiographic signal is always acquired when the stimulation electrode is conducted to the reference potential portion.

  In the control method of the nerve stimulation device, when applying the electrical stimulation from the stimulation electrode, a stimulation group generation operation for periodically generating the electrical stimulation a plurality of times, and the stimulation group generation operation during the stimulation group generation operation Only when the stimulation electrode is electrically connected to the reference potential portion in the stimulation stopping operation, the stimulation stopping operation for stopping the electrical stimulation for a time longer than the generation interval of the electrical stimulation is alternately repeated. The waveform of the electrocardiogram signal is preferably acquired.

  In the method for controlling the nerve stimulation apparatus, it is preferable that after obtaining the waveform of the electrocardiogram signal, the waveform of the electrocardiogram signal is analyzed to obtain information on the heart function of the living body.

  In the control method of the nerve stimulation device, when analyzing the waveform of the electrocardiogram signal, the analysis is performed using a waveform after a predetermined time has elapsed since the stimulation electrode is conducted to the reference potential portion. Is preferred.

  According to the nerve stimulation apparatus and the control method thereof of the present invention, when the electrocardiogram signal is acquired, the stimulation electrode is connected to the reference potential portion common to the first and second electric circuits, so that the stimulation electrode becomes the heart. Since it becomes a reference electrode at the time of electric signal acquisition, even if it is a simple structure, there exists an effect that an electrocardiogram signal can be acquired accurately.

It is a typical lineblock diagram showing the whole nerve stimulation device composition of a 1st embodiment of the present invention. It is a typical block diagram which shows the structure of the electrode unit of the nerve stimulation apparatus of the 1st Embodiment of this invention. FIG. 3 is a detailed view of part A in FIG. 2. It is a typical perspective view which shows the structure of the principal part of the nerve stimulation apparatus of the 1st Embodiment of this invention. It is a functional block diagram which shows the function structure of the nerve stimulation apparatus of the 1st Embodiment of this invention. It is a functional block diagram which shows the function structure of the electrocardiogram signal process part of the nerve stimulation apparatus of the 1st Embodiment of this invention. It is a typical circuit diagram which shows the structure of the pulse generation circuit part of the nerve stimulation apparatus of the 1st Embodiment of this invention. It is a typical circuit diagram which shows a mode that the pulse generation circuit part of the nerve stimulation apparatus of the 1st Embodiment of this invention is interrupted | blocked, and a stimulation electrode is conduct | electrically_connected to a reference electric potential part. It is a timing chart explaining the operation | movement which produces | generates the pulse signal of the nerve stimulation apparatus of the 1st Embodiment of this invention. It is a typical graph which shows the application pattern of the pulse signal in the stimulus application mode of the nerve stimulation apparatus of the 1st Embodiment of this invention. It is a typical graph which shows an example of a patient's electrocardiogram signal. It is a typical graph which shows an example of the pulse signal which the nerve stimulation apparatus of the 1st Embodiment of this invention applies. 12 is a timing chart showing an operation of acquiring an electrocardiogram signal during a period B in FIGS. It is a typical circuit diagram which shows the structure of the pulse generation circuit part and switch part of the nerve stimulation apparatus of the 2nd Embodiment of this invention. It is a functional block diagram which shows the function structure of the electrocardiogram signal process part of the nerve stimulation apparatus of the 2nd Embodiment of this invention. It is a timing chart which shows operation | movement of the nerve stimulation apparatus of the 2nd Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. In all the drawings, even if the embodiments are different, the same or corresponding members are denoted by the same reference numerals, and common description is omitted.

[First Embodiment]
A nerve stimulation apparatus according to a first embodiment of the present invention will be described.
FIG. 1 is a schematic configuration diagram showing the overall configuration of the nerve stimulation apparatus according to the first embodiment of the present invention. FIG. 2 is a schematic configuration diagram showing the configuration of the electrode unit of the nerve stimulation apparatus according to the first embodiment of the present invention. FIG. 3 is a detailed view of part A in FIG. FIG. 4 is a schematic perspective view showing the configuration of the main part of the nerve stimulation apparatus according to the first embodiment of the present invention. FIG. 5 is a functional block diagram showing a functional configuration of the nerve stimulation apparatus according to the first embodiment of the present invention. FIG. 6 is a functional block diagram illustrating a functional configuration of the electrocardiogram signal processing unit of the nerve stimulation apparatus according to the first embodiment of the present invention.

As shown in FIG. 1, the nerve stimulation apparatus 1 of the present embodiment can electrically stimulate a vagus nerve Vn (nerve) such as a patient P that is a living body, for example. In this case, the nerve stimulation apparatus 1 can be used for treatment of, for example, tachycardia and chronic heart failure.
In the nerve stimulation apparatus 1, an electrode unit 20 placed in the blood vessel Bv, electrocardiogram signal detection electrodes 17A and 17B for acquiring an electrocardiogram signal, and the electrode unit 20 and the electrocardiogram signal detection electrodes 17A and 17B are connected. The apparatus main body 10 is provided.

The electrode unit 20 is an apparatus part that is placed in a blood vessel of a patient or the like and applies a pulse signal for performing nerve stimulation generated in the apparatus main body 10 to be described later to a living tissue to perform electrical stimulation to the nerve.
The electrode unit 20 includes an electrode holding part 30 and a lead part 21.
The electrode holding portion 30 is a device portion that is provided to be locked to the inner wall of the blood vessel, elastically deforms in the blood vessel, and presses the inner wall of the blood vessel.
As shown in FIG. 2, the electrode holding portion 30 is connected to the distal end coupling portion 31 and the proximal end coupling portion 32 that are spaced apart from each other, and the end portions are connected to the distal end coupling portion 31 and the proximal end coupling portion 32, respectively. It has four wire portions 33 and a pair of stimulation electrodes 34A and 34B provided on one wire portion 33A of the four wire portions 33.
Each wire portion 33 uses an unillustrated wire having elasticity as a core material. As shown in FIG. 3, the outer peripheral surface of each wire portion 33 is covered with an external coating 39. The external coating 39 is made of a resin such as polyurethane, for example.
In particular, the outer coating 39 of the wire portion 33A, which is one of the wire portions 33, has a pair of openings 39a penetrating in the middle portion in the longitudinal direction. Stimulation electrodes 34A and 34B made of a metal having biocompatibility such as a platinum iridium alloy are exposed inside the opening.

  As shown in FIG. 2, the wire portion 33 having such a configuration is formed, for example, by curving into an arc shape having a center angle of about 180 °. Each wire portion 33 is disposed at a position rotated by 90 ° around the axis C 1, and the distal end portion and the proximal end portion are fixed by the distal end coupling portion 31 and the proximal end coupling portion 32. For this reason, the wire portion 33 between the distal end coupling portion 31 and the proximal end coupling portion 32 is disposed so as to be substantially aligned on a spherical surface having the axis C1 as a central axis in a natural state.

The stimulation electrodes 34A and 34B in the wire portion 33A are device portions for applying electrical stimulation to nerves. The stimulation electrodes 34A and 34B are formed in, for example, an annular shape, and electrical wirings 35a and 35b are electrically connected to the inner peripheral surfaces thereof as shown in FIG. In the present embodiment, as an example, the stimulation electrode 34A is a negative electrode, and the stimulation electrode 34B is a positive electrode.
The electrical wirings 35 a and 35 b are arranged in the outer coating 39 and extend along the outer coating 39. The electrical wirings 35 a and 35 b are combined into a single wiring part 35 (see FIG. 2) in a state of being insulated from each other at the base end coupling part 32, and further extend to the base end side of the lead part 21.

The lead portion 21 covers the wiring portion 35 electrically connected to the stimulation electrodes 34A and 34B provided on the electrode holding portion 30 and is inserted into the blood vessel, thereby the end portion of the wiring portion 35 serving as a proximal end. Is a linear device part that guides the patient P outside the body.
The outer peripheral surface of the lead portion 21 is covered with a flexible synthetic resin having biocompatibility and electrical insulation and capable of being inserted into a blood vessel, such as a polyurethane resin, a polyamide resin, a fluorine resin, or the like. Yes.
A connector 38 that is electrically connected to the apparatus main body 10 is provided at the proximal end portion of the lead portion 21.

The connector 38 includes a negative electrode connector pin 38a and a positive electrode connector pin 38b, and a pair of rubber rings 38c. Electrical wires 35a and 35b (not shown in FIG. 2) included in the wiring portion 35 are connected to the negative electrode connector pin 38a and the positive electrode connector pin 38b, respectively.
The rubber ring 38 c is provided to insulate the negative electrode connector pin 38 a and the positive electrode connector pin 38 b from each other and to maintain water tightness when connected to the apparatus main body 10.
As an example of such a connector 38, a well-known IS1 type connector can be mentioned, for example. However, as the connector 38, other than the IS1 type, an appropriate waterproof connector used when the apparatus main body 10 is installed outside the body can be used.

As shown in FIGS. 1 and 4, the electrocardiogram signal detection electrodes 17 </ b> A and 17 </ b> B are electrodes for detecting an electrocardiogram signal of the patient P. In the present embodiment, as an example, the electrocardiogram signal detection electrode 17A is a negative electrode, and the electrocardiogram signal detection electrode 17B is a positive electrode.
As the configuration of the electrocardiogram signal detection electrodes 17A and 17B, for example, an electrode of a type that is placed inside the patient P to acquire an electrocardiogram signal, or a type that is placed outside the body of the patient P and acquires an electrocardiogram signal. An electrode can be employed.
In the present embodiment, as an example of the electrocardiogram signal detection electrodes 17A and 17B, an electrode of a type arranged outside the patient's body is provided. The adhesive electroconductive gel for fixing to the body surface of the patient P is apply | coated to the surface of the electrocardiogram signal detection electrodes 17A and 17B.
The electrocardiogram signal detection electrodes 17A and 17B are electrically connected to the apparatus main body 10 to be described later via wiring 17a.

As illustrated in FIG. 4, the apparatus main body 10 includes a display unit 11 that displays various information and an operation unit 12 that performs various operations of the apparatus main body 10 on the outer surface.
As the display unit 11, for example, an appropriate display device using a display element such as a liquid crystal or LED can be adopted. Below, as an example, the display unit 11 has a plurality of LED elements. The display unit 11 can display a message based on character information or a mark or icon based on an image by combining these LED elements.

  As shown in FIG. 5, the apparatus body 10 includes a battery 40, a power supply circuit 41, a pulse generation circuit unit 44 (stimulus generation unit), a changeover switch unit 45, and an electrocardiogram signal processing unit 42 (electrocardiogram signal acquisition unit). ), An electrocardiogram signal analysis unit 43, a buzzer 13, and a control unit 49.

The battery 40 is a power source that supplies power for driving the entire nerve stimulation apparatus 1 and is disposed on a circuit board (not shown).
Although the kind of battery 40 is not specifically limited, For example, it is preferable to use small lithium coin batteries, such as CR2450. In this case, the apparatus size of the apparatus main body 10 can be reduced.

  The power supply circuit 41 generates a voltage to be applied to each device portion of the nerve stimulation device 1 from the voltage of the battery 40, and electrically connects each device portion that requires voltage application through a circuit board or wiring not shown. It is connected to the. For example, +12 V is applied to a pulse generation circuit unit 44 described later, and +2.1 V is applied to generate other signals.

The pulse generation circuit unit 44 generates a pulse signal for performing nerve stimulation and applies the pulse signal to the stimulation electrodes 34A and 34B. The pulse generation circuit unit 44 is communicably connected to the control unit 49, and generates a pulse signal in accordance with a control signal from the control unit 49.
The pulse generation circuit unit 44 is connected to the stimulation electrodes 34A and 34B, and constitutes a stimulation generation unit including a first electric circuit that generates electrical stimulation.
As the waveform of the pulse signal, various waveforms can be adopted depending on the purpose of the electrical stimulation. For example, examples of a constant current method or a constant voltage method, such as a biphasic waveform or a rectangular pulse waveform can be given.
In the present embodiment, the pulse generation circuit unit 44 is communicably connected to the control unit 49, and can change the waveform of the pulse signal based on the waveform control signal sent from the control unit 49. .

  The pulse generation circuit unit 44 can be configured by combining appropriate hardware in accordance with the signal waveform of the pulse signal. A specific configuration example will be described collectively after the entire configuration of the apparatus main body 10 is described.

The changeover switch unit 45 is a switch for closing or blocking the pulse generation circuit unit 44 based on the control of the control unit 49. When the changeover switch unit 45 closes the pulse generation circuit unit 44, a first state in which electrical stimulation is generated is obtained. When the changeover switch unit 45 shuts off the pulse generation circuit unit 44, a second state in which the stimulation electrodes 34A and 34B are electrically connected to the reference potential unit of the pulse generation circuit unit 44 is obtained.
The specific configuration of the changeover switch unit 45 will be described later together with the configuration of the pulse generation circuit unit 44.

The electrocardiogram signal processing unit 42 is connected to the electrocardiogram signal detection electrodes 17A and 17B, and is a device part that performs signal processing by acquiring and amplifying an electrocardiogram signal due to a heartbeat from a potential difference between these electrodes. Thereby, the electrocardiogram signal processing unit 42 acquires an electrocardiogram signal from the electrocardiogram signal detection electrodes 17A and 17B. The electrocardiogram signal processing unit 42 is communicably connected to the control unit 49 and sends the acquired electrocardiogram signal to the control unit 49.
As shown in FIG. 6, the electrocardiogram signal processing unit 42 includes a differential amplifier 60, a high-pass filter 61, an amplifier circuit 62, and a low-pass filter 63.

The differential amplifier 60 is a device part that constitutes a differential amplifier circuit that amplifies the potential difference between the ECG signal detection electrodes 17A and 17B. An electrocardiogram signal detection electrode 17 </ b> A is connected to the inverting input terminal (−) of the differential amplifier 60. An electrocardiogram signal detection electrode 17B is connected to the non-inverting input terminal (+) of the differential amplifier.
Since the signal level of the ECG signal detected by the ECG signal detection electrodes 17A and 17B arranged on the body surface of the patient P is generally about 1 mV to 1.5 mV, the acquired signal needs to be amplified.
The differential amplifier 60 amplifies the differential voltage of the electrocardiogram signal detection electrode 17B with respect to the electrocardiogram signal detection electrode 17A and outputs it to the output terminal. The output potential of the differential amplifier 60 uses the ground of the circuit board on which the electrocardiogram signal processing unit 42 is formed as a reference potential. Here, the ground to which the differential amplifier 60 is connected is a signal ground, which is a reference potential portion of the circuit board on which the electrocardiogram signal processing portion 42 is formed.
In the present embodiment, at least the electrocardiogram signal processing unit 42 and the pulse generation circuit unit 44 are formed on the same circuit board. The reference potential parts of the electrocardiogram signal processing unit 42 and the pulse generation circuit unit 44 are common to each other.

  The high-pass filter 61 is connected to the output terminal of the differential amplifier 60 and is a device part that removes low-frequency noise of an electrocardiogram signal that is an output signal of the differential amplifier 60. Examples of the low-frequency noise removed by the high-pass filter 61 include an example of baseline fluctuation caused by the breathing of the patient P.

The amplifying circuit 62 amplifies the output of the high-pass filter 61 to a signal level at which sufficient measurement resolution can be obtained at the time of A / D conversion when analyzing an electrocardiogram signal described later.
The low-pass filter 63 is a device part that removes high-frequency noise such as hum noise from the output of the amplifier circuit 62.
The electrocardiogram signal from which the high frequency noise has been removed by the low pass filter 63 is sent to the control unit 49.

As shown in FIG. 5, the electrocardiogram signal analysis unit 43 is a device part that analyzes the waveform of the electrocardiogram signal and acquires information on the cardiac function of the patient P. The electrocardiogram signal analysis unit 43 is connected to the control unit 49 so as to be communicable. The electrocardiogram signal analyzed by the electrocardiogram signal analysis unit 43 is transmitted from the control unit 49. As will be described later, the electrocardiogram signal transmitted by the control unit 49 is a waveform obtained by A / D-converting the electrocardiogram signal acquired by the electrocardiogram signal processing unit 42 using an AD converter included in the control unit 49.
The information on the cardiac function is not particularly limited as long as it is information obtained by analyzing the electrocardiogram signal. For example, information on cardiac function for determining the therapeutic effect of nerve stimulation may be used, or information on cardiac function for monitoring a change in patient P due to nerve stimulation may be used. Examples of cardiac function information acquired by the electrocardiogram signal analysis unit 43 include, for example, information such as a heart rate, an appropriate time interval that can be acquired from the electrocardiogram signal waveform, a repetition period, and a change in the electrocardiogram waveform. it can.
The electrocardiogram signal analysis unit 43 can analyze the electrocardiogram signal and send information on cardiac function to the control unit 49.
Hereinafter, as an example, an example in which the electrocardiogram signal analysis unit 43 analyzes a heart rate will be described.
The heart rate can be obtained, for example, by detecting the arrival of an R wave and counting the number of R waves per unit time or by measuring the period of the R wave and calculating from the reciprocal thereof.

The buzzer 13 is a device portion that generates a buzzer sound. The buzzer 13 is used, for example, to generate a warning sound to alert the user of the nerve stimulation apparatus 1 or to generate an operation sound to notify the user that the operation has been performed. The configuration of the buzzer 13 is not particularly limited. For example, a piezoelectric buzzer can be used.
The buzzer 13 is electrically connected to the control unit 49 and is driven by the control unit 49.

The control unit 49 is a device part that controls the entire operation of the nerve stimulation device 1, and includes a display unit 11, an operation unit 12, a buzzer 13, a changeover switch unit 45, a pulse generation circuit unit 44, a power supply circuit 41, and an electrocardiogram signal process. The unit 42 and the electrocardiogram signal analysis unit 43 are communicably connected.
Examples of the control performed by the control unit 49 include the control described below.
For example, the control unit 49 analyzes the operation input from the operation unit 12 and transmits a control signal for performing an operation according to the operation input to each device part, numerical information input from the operation unit 12, etc. Or remember.
In addition, the control unit 49 causes the display unit 11 to display information necessary for operations, warnings, and the like as necessary.
In addition, the control unit 49 causes the buzzer 13 to generate an operation confirmation sound or a warning sound regarding the electrical stimulation operation or the information on the electrocardiographic signal of the patient P as necessary.
Further, when an operation input for starting an electrical stimulation is made from the operation unit 12, the control unit 49 generates a control signal for generating a pulse signal for performing the electrical stimulation, and the pulse generation circuit unit 44. To send. For example, the control unit 49 sends a control signal to the changeover switch unit 45 to perform control to switch the pulse generation circuit unit 44 between the first state and the second state. Further, the control unit 49 sends a control signal to the pulse generation circuit unit 44 to perform polarity inversion control of the pulse signal.
Further, the control unit 49 performs control to sample the A / D conversion of the electrocardiogram signal transmitted from the electrocardiogram signal processing unit 42.

  The device configuration of the control unit 49 includes a computer including a CPU, a memory, an input / output interface, an external storage device, and the like, whereby a control program having the above control functions is executed.

Here, a detailed configuration example of the pulse generation circuit unit 44 and the changeover switch unit 45 in the present embodiment will be described. The pulse generation circuit unit 44 and the changeover switch unit 45 can be configured by combining appropriate hardware in accordance with the signal waveform of the pulse signal.
The configuration example described below is an example in which the pulse signal has a constant current type biphasic waveform with a constant current amplitude.
FIG. 7 is a schematic circuit diagram showing a configuration of a pulse generation circuit unit of the nerve stimulation apparatus according to the first embodiment of the present invention. FIG. 8 is a schematic circuit diagram illustrating a state in which the pulse generation circuit unit of the nerve stimulation apparatus according to the first embodiment of the present invention is blocked and the stimulation electrode is conducted to the reference potential unit.
It is a circuit diagram.

  As shown in FIG. 7, the pulse generation circuit unit 44 includes analog switches 50 and 51 and a constant current circuit 52.

Each of the analog switches 50 and 51 is a two-element type analog switch, and includes input terminals S1, S2, S3, and S4, output terminals OUT1 and OUT2, and control input terminals IN1 and IN2. However, in FIG. 7, the control input terminal IN2 in the analog switch 50 and the control input terminal IN1 in the analog switch 51 are not shown (the same applies to FIG. 8).
In the analog switch 50 (51), one of the input terminals S1 and S2 is output from the output terminal OUT1 and one of the input terminals S3 and S4 is output according to the level of the signal input to the control input terminal IN1 (IN2). It is electrically connected to the terminal OUT2.
In the present embodiment, when the input signal to the control input terminal IN1 (IN2) is high (low), the input terminal S1 and the output terminal OUT1, and the input terminal S3 and the output terminal OUT2 are conducted, and the control input terminal When the input signal to IN1 (IN2) is low (high), the switch input terminal S2 and the output terminal OUT1 are connected to the input terminal S4 and the output terminal OUT2.

The input terminal S1 of the analog switch 50 is connected to, for example, a + 12V output terminal in the power supply circuit 41 in order to form a pulse signal. Similarly, the input terminal S3 is connected to the ground (GND) via a constant current circuit 52 described later in order to close a circuit that generates a pulse signal. Similarly, the input terminals S2 and S4 are connected to the ground.
Here, the ground is a signal ground, which is a reference potential portion of the circuit board on which the pulse generation circuit section 44 is formed, and is common to the reference potential section of the electrocardiogram signal processing section 42 as described above.

The input terminals S1 and S4 of the analog switch 51 are electrically connected to the output terminal OUT1 of the analog switch 50. The input terminals S2 and S3 of the analog switch 51 are electrically connected to the output terminal OUT2 of the analog switch 50.
The output terminals OUT1 and OUT2 of the analog switch 51 are connected to the terminals T1 and T2 by wiring on a substrate (not shown).
The terminals T1 and T2 are electrically connected to the stimulation electrode 34B that is the positive electrode of the electrode holding unit 30 and the stimulation electrode 34A that is the negative electrode, respectively, via a connector and a wiring (not shown).

The analog switches 50 and 51 are communicably connected to the control unit 49. A pulse width control signal 101 and a polarity inversion control signal 102 are input from the control unit 49 to the control input terminals IN1 and IN2 of the analog switches 50 and 51, respectively.
Here, the pulse width control signal 101 is a signal that defines the pulse width of the unit pulse in the pulse signal by switching the analog switch 50 between the on state and the off state.
In the present embodiment, the time corresponding to the pulse width of the unit pulse becomes high and the analog switch 50 is turned on, and in the time zone when the unit pulse is not generated, it becomes low and the analog switch 50 is turned off. .
When the analog switch 50 is turned off, as shown in FIG. 8, the electric circuit of the pulse generation circuit unit 44 is cut off, and the output terminals OUT1 and OUT2 are conducted to the ground. For this reason, regardless of the state of the analog switch 51, the terminals T1 and T2 become reference potentials. As a result, the stimulation electrodes 34B and 34A connected to the terminals T1 and T2, respectively, also become the reference potential. No current flows between the stimulation electrodes 34A and 34B.

The polarity inversion control signal 102 is a signal that defines the time width of the polarity inversion unit in the unit pulse of the pulse signal by switching the analog switch 51.
In this embodiment, it becomes low at the generation timing of the polarity inversion part of the unit pulse, and it is in an inversion state in which the input terminal S2 (S4) of the analog switch 51 and the output terminal OUT1 (OUT2) are conducted. Further, it becomes high at the timing when the polarity inverting unit is not generated, so that the input terminal S1 (S3) and the output terminal OUT1 (OUT2) of the analog switch 51 are brought into a non-inverted state.
In this embodiment, as will be described later, the unit pulse is generated in the order of a positive pulse and a negative pulse (polarity inversion part).

The constant current circuit 52 is a circuit for constant current control of a current flowing between the input terminal S3 and the ground, and includes, for example, an operational amplifier 53, a transistor 54, and a resistor 55.
The non-inverting input terminal (+) of the operational amplifier 53 receives the DAC signal 100 sent from the control unit 49 in order to set the current value flowing from the input terminal S3 to the ground.
The DAC signal 100 is a signal having a voltage level corresponding to the magnitude of the current amplitude set in the pulse signal. From the control unit 49 based on the voltage value calculated by the control unit 49 from the current amplitude of the necessary pulse signal. Is output.
The inverting input terminal (−) of the operational amplifier 53 is connected to the ground via the resistor 55.
The output terminal of the operational amplifier 53 is connected to the base of the transistor 54.
The collector of the transistor 54 is connected to the input terminal S3. The emitter of the transistor 54 is connected to the ground via a resistor 55.

With such a configuration, a voltage equal to the voltage value V _DAC of the DAC signal 100 input to the non-inverting input terminal (+) of the operational amplifier 53 is applied to the resistor 55 connected to the ground. For this reason, a constant current determined by Ohm's law from the voltage value V _DAC and the resistance value of the resistor 55 flows.
In the present embodiment, for example, a voltage value _{V DAC} of the DAC signal 100, by changing the 0.1V～2.0V, the constant current _{I m} is to vary the 1MA～20mA.
In the present embodiment, such a current setting is made possible by using a constant voltage source of +12 V, but this is an example. For example, the voltage value of the constant voltage source can be appropriately changed depending on the load impedance on the living body side and the current value required for treatment.

With such a configuration, in the pulse generation circuit unit 44, when the analog switch 50 is in an ON state and the stimulation electrodes 34A and 30B are brought into contact with the inner wall of the blood vessel, the living tissue is interposed between the stimulation electrodes 34A and 30B. A circuit is formed in which a constant current flows regardless of the impedance.
At this time, when the pulse width control signal 101 is high and the polarity inversion control signal 102 is high, the circuit shown in FIG. 7 is formed. In other words, the connection between the output terminal OUT1 of the analog switch 50 and the output terminal OUT1 of the analog switch 51, and the connection between the output terminal OUT2 of the analog switch 51 and the output terminal OUT2 of the analog switch 50, are connected to the terminal T1. A circuit is formed in which a current flows from the stimulated electrode 34B toward the stimulated electrode 34A connected to the terminal T2.
Further, when the pulse width control signal 101 is high and the polarity inversion control signal 102 is low, although not particularly illustrated, the analog switch 51 is switched and the polarities of the output terminals OUT1 and OUT2 are inverted. A circuit is formed in which a current flows from the connected stimulation electrode 34A toward the stimulation electrode 34B connected to the terminal T1.

In the present embodiment, in this way, when the pulse width control signal 101 is high, a circuit is formed in which a current flows between the stimulation electrodes 34A and 34B. Therefore, the analog switch 50 realizes a first state in which the pulse generation circuit unit 44 is closed and a pulse signal is generated.
On the other hand, when the pulse width control signal 101 is low, the pulse generation circuit unit 44 is cut off, and the second state in which the stimulation electrodes 34A and 34B are conducted to the ground is realized.
For this reason, in this embodiment, the analog switch 50 in the pulse generation circuit unit 44 constitutes a changeover switch unit 45.

Next, the operation of the nerve stimulation apparatus 1 will be described focusing on the generation and blocking operation of the pulse signal.
FIG. 9 is a timing chart illustrating an operation of generating a pulse signal of the nerve stimulation apparatus according to the first embodiment of the present invention. FIG. 10 is a schematic graph showing a pulse signal application pattern in the stimulus application mode of the nerve stimulation apparatus according to the first embodiment of the present invention. In FIG. 10, the horizontal axis represents time, and the vertical axis represents current.

In order to perform electrical stimulation using the nerve stimulating device 1, as shown in FIG. 1, first, a small incision is made in the blood vessel Bv of the patient P to form an opening, and a cylindrical introducer (not shown) is connected to the blood vessel. Insert inside. Then, the electrode unit 20 is inserted into the blood vessel Bv via an introducer or the like, and the electrode holding unit 30 is placed at an appropriate position in the blood vessel Bv. For example, when stimulating the vagus nerve Vn, it is placed in a blood vessel in which the vagus nerve Vn runs, such as the internal jugular vein P3 or the superior vena cava not shown.
At that time, in order to search for an appropriate indwelling position, a search for searching for the indwelling position in the electrode holding unit 30 while measuring the heart rate detected by an electrocardiograph (not shown) or the electrocardiogram signal detection electrodes 17A and 17B. A search operation is performed by applying electrical stimulation (referred to as a search mode).
Since the heart rate decreases when such electrical stimulation for search is transmitted to the vagus nerve Vn, the position where the heart rate of the patient P decreases most is the optimal indwelling position. Therefore, when the electrode holding unit 30 is moved and such an optimum position is specified, the electrode holding unit 30 is placed at that position.
When the electrode holding unit 30 is left in this way, electrical stimulation for treatment is applied in accordance with the treatment schedule of the patient P (referred to as stimulation application mode).

In the search mode and the stimulus application mode, the pulse signals applied to the electrode holding unit 30 may have different waveform types. However, in this embodiment, the waveform types are the same, for example, the intensity, the pulse An example in which only waveform setting conditions such as width, repetition frequency, and application time are different will be described.
The waveform setting conditions are stored in the control unit 49 or can be set via the operation unit 12 according to the respective uses of the search mode and the stimulus application mode, and the pathological condition and treatment purpose of the patient P.
The control unit 49 determines the magnitude of the DAC signal 100 and the generation timing of the pulse width control signal 101 and the polarity inversion control signal 102 based on such waveform setting conditions, and the control program stored in the control unit 49 Are transmitted to the pulse generation circuit unit 44.
The operations relating to generation and stop of the pulse signal described below are the same in the search mode and the stimulus application mode.

Here, the operation when generating the pulse signal 110 shown in FIG. 9 will be described. The pulse signal 110 has a constant current biphasic waveform with a constant current amplitude.
Pulse signal 110, the pulse width T _P, the current amplitude has a signal waveform unit pulse P _S of ± I _m is repeated with a period tau. The period τ is τ = 1 / f, where f is the repetition frequency.
Unit pulse P _S, the pulse width T _+, a square wave of current amplitude + I _m and (positive pulse), a pulse width T which follow _-, square wave polarity is inverted current amplitude -I _m (negative pulse ) a two-phase square wave _{with, T} +, T _- is may be different from each _other, T _{+ +} T - = a _{T P.}
Pulse signal 110, for example, in the search mode, often continuously generate repeat unit pulse P _S in the period tau. Further, the stimulus application mode, during a predetermined stimulation time period of the unit pulse P _S tau, continuously generate, during a predetermined dwell time, by resting, waveform group of a plurality of unit pulses P _S Is often generated intermittently.

To generate such a pulse signal 110, the control unit 49, as shown in FIG. 9, _{V DAC} voltage value, the square wave pulse width _{T P,} the DAC signal 100 that repeats with a period tau, operational amplifier 53 To the non-inverting input terminal (+).
In parallel with this, the control unit 49 sends a pulse width control signal 101 that goes high in synchronization with the DAC signal 100 to the input terminal IN1 of the analog switch 50.
The control unit 49, in parallel with this, from high to low after a time from the rising of the DAC signal 100 has elapsed by T ₊ changes to the low, after a time from the rising of the DAC signal 100 has elapsed by T _P A polarity inversion control signal 102 that goes high is sent to the input terminal IN 2 of the analog switch 51.

Thus, during the time T ₊ when the pulse width control signal 101 is high and the polarity inversion control signal 102 is high, I corresponding to the voltage value V _DAC of the DAC signal 100 from the stimulation electrode 34B toward the stimulation electrode 34A. _m current flows in a positive pulse of the unit pulse P _S is generated.
In this manner, when the pulse signal 110 is applied to the electrode holding unit 30, electrical stimulation is applied to the patient P.
Following this, during the time T ₋ when the pulse width control signal 101 is high and the polarity inversion control signal 102 is low, the voltage value V _DAC of the DAC signal 100 corresponds to the stimulation electrode 34B from the stimulation electrode 34A. current I _m flows, negative pulse of the unit pulse P _S is generated for.
Following this, during the time _{tau-T P,} the voltage value of the DAC signal 100 0V, a pulse width control signal 101 is low, the polarity inversion control signal 102 becomes high, the current value of the pulse signal 110 becomes 0 .

In this manner, the control unit 49 generates the DAC signal 100, the pulse width control signal 101, and the polarity inversion control signal 102 as the waveform control signals.
The DAC signal 100 is an intensity signal that sets the magnitude of the pulse signal 110.
Pulse width control signal 101 is adapted to a timing signal for setting a generation timing and pulse width T _P of the unit pulse P _S.
The polarity inversion control signal 102, the negative pulse generation timing and pulse width T of the unit pulse P _{S -} indicates the timing signal to set.

FIG. 10 shows an example of the pulse signal 110 in the stimulus application mode.
Pulse signal 110, the control unit 49 are controlled in a pattern that repeats the stimulation group generating operation performed during the stimulation time T _on, the stimulation stopping operation performed during the pause time T _off alternately.
Pulse signal 110 constitute a waveform group W repeating a unit pulse _{P S} repetition frequency f in the stimulation time _{T on.}
The pulse signal 110 is stopped within the dwell time T _off and the current amplitude is zero.
The length of the pause time _{T off} is set longer than the interval of the unit pulse _{P S} between the stimulation time _{T on.} Pause time _{T off} is a long time it is preferable than the stimulation time _{T on.}

The setting condition of the pulse signal 110 can be appropriately set by the operator inputting from the operation unit 12. In the present embodiment, for example, the pulse width _{T P} of the unit pulse _{P S} can be set in the range of 100Myusec～1msec. Repetition frequency f of the unit pulse _{P S} can be set between the 10Hz～20Hz. For example, when the repetition frequency f is set to 20 Hz, the repetition period τ is 50 msec.

Next, an operation for acquiring an electrocardiogram signal will be described.
FIG. 11 is a schematic graph showing an example of a patient's electrocardiogram signal. FIG. 12 is a schematic graph showing an example of a pulse signal applied by the nerve stimulation apparatus according to the first embodiment of the present invention. The horizontal axes in FIG. 11 and FIG. 12 are time axes with a common scale. FIG. 13 is a timing chart showing an operation for acquiring an electrocardiogram signal in the period B in FIGS.

The electrocardiogram signal processing unit 42 of the neurostimulator 1 acquires the electrocardiogram signals detected by the electrocardiogram signal detection electrodes 17 </ b> A and 17 </ b> B and sends them to the control unit 49. Specifically, first, the differential amplifier 60 amplifies an electrocardiogram signal composed of a differential voltage of the electrocardiogram signal detection electrode 17B with respect to the electrocardiogram signal detection electrode 17A. Low frequency noise is removed from the amplified electrocardiogram signal by the high-pass filter 61. Further, the electrocardiogram signal is amplified by the amplifier circuit 62. Further, the electrocardiographic signal is sent to the control unit 49 when the high frequency noise is removed by the low pass filter 63.
As the electrocardiogram signal 120 sent from the electrocardiogram signal processing unit 42 to the control unit 49, for example, a waveform as schematically shown in FIG. 11 is obtained. However, depending on the environment, noise that cannot be sufficiently removed by the ECG signal processing unit 42 may be superimposed on the ECG signal 120.

The electrocardiogram signal processing unit 42 is electrically connected to the ground which is a reference potential unit (see FIG. 6). For this reason, the reference potential of the electrocardiogram signal 120 is defined by the ground.
However, the electrocardiogram signal detection electrodes 17A and 17B are extended to the outside of the apparatus main body 10 and arranged and used on the body surface of the patient P. The electrocardiogram signal detection electrodes 17A and 17B are electrically connected to the circuit board on which the electrocardiogram signal processing unit 42 is formed via the wiring 17a. Thus, since the electrocardiogram signal detection electrodes 17A and 17B and the wiring 17a have a long distance from the reference potential portion, it is easy to pick up external noise. For example, it is easy to pick up commercial power supply noise radiated into the air. The signal level detected by the electrocardiogram signal detection electrodes 17A and 17B is generally as weak as about 1 mV to 1.5 mV. For this reason, when the reference electrode is not provided near the arrangement position of the electrocardiogram signal acquisition electrodes 17A and 17B, depending on the environment, the signal to be detected is almost buried in commercial power supply noise of 50 Hz to 60 Hz.

In the present embodiment, as shown in FIG. 6, when the analog switch 50 is in the OFF state, the stimulation electrodes 34A and 34B are always conducted to the ground. Therefore, the stimulation electrodes 34A and 34B are electrodes arranged in close contact with the patient P, like the electrocardiogram signal detection electrodes 17A and 17B, and share the reference potential portion with the electrocardiogram signal detection electrodes 17A and 17B. ing.
Accordingly, the stimulation electrodes 34A and 34B serve as reference electrodes for the electrocardiogram signal detection electrodes 17A and 17B while being conducted to the ground.
As a result, while the stimulation electrodes 34A and 34B are electrically connected to the ground, external noise superimposed on the detection signals of the electrocardiogram signal detection electrodes 17A and 17B is remarkably reduced.

In the present embodiment, the control unit 49 samples the electrocardiogram signal 120 acquired while the stimulation electrodes 34A and 34B are connected to the ground, and acquires the waveform of the electrocardiogram signal 120.
The electrocardiogram signal 120 of the patient P shows a periodic pattern as shown in FIG. 11 according to the heart rate. Heart rate H (bpm), for example, when the R-R interval electrocardiographic signal and _T R (sec), which is H = 60 / _{T R.} Normal value for adult R-R interval T _R is approximately 1 second.
For example, if the repetition frequency f of the unit pulse _{P S} is 10Hz～20Hz, Between stimulation time _{T on} the waveform group W is applied, during the R-R interval, is about 10 to 20 pieces of unit pulses _{P S} Applied.
Therefore, as schematically shown in FIG. 12, between one R wave of the electrocardiographic signal 120, a plurality of unit pulses P _S is applied.
In the following, as an example, the setting conditions of the pulse signal 110 are: T _on = 10 (sec), T _off = 50 (sec), f = 20 (Hz), τ = 50 (msec), T _P = 200 (μsec) ), T ₊ = T ₋ = 100 (μsec) will be described as an example (hereinafter referred to as a setting example).

As shown in FIG. 13, in the time domain overlapping the R-wave of the electrocardiographic signal 120 at time t0, the analog switch 50 is switched on, the application of the unit pulse P _S is started. In this case, the stimulation electrodes 34A and 34B that have been conducted to the ground until the time t0 when the analog switch 50 is in the off state are released from the conduction state to the ground at the time t0. The conductive released state, the pulse width control signal 101 from the control unit 49 continues from the time t0 to be high until the time _{t1 (t1 = t0 + T P} ). When the pulse width control signal 101 is switched to low at time t1, the analog switch 50 is turned off.
At time t10 at which time passes τ from the time t0, again, the pulse width control signal 101 goes high, the application of the next individual pulse P _S is started. Unit pulse _{P S} is applied to the time _{t11 (= t10 + T P)} .
For this reason, the analog switch 50 is turned off between times t1 and t10, and the stimulation electrodes 34A and 34B are conducted to the ground. The stimulation electrodes 34A and 34B function as reference electrodes in the detection of the electrocardiogram signals of the electrocardiogram signal detection electrodes 17A and 17B between times t1 and t10. For this reason, the superimposition of noise on the electrocardiogram signal 120 is suppressed.
On the other hand, since the stimulation electrodes 34A and 34B do not function as reference electrodes during the times t0 to t1 and t10 to t11, external noise is superimposed on the electrocardiogram signal 120 between the times t0 to t1 and t10 to t11. There is a possibility. For example, noise N may be superimposed as shown by a two-dot chain line in FIG.
Since the noise N is amplified together with the signal component by the amplifier circuit 62, the low-pass filter 63 may not be able to remove the noise N sufficiently.

When the electrocardiogram signal 120 is sent from the electrocardiogram signal processing unit 42 to the control unit 49, the control unit 49 performs A / D conversion on the electrocardiogram signal 120 and acquires the waveform of the electrocardiogram signal 120. Therefore, the control unit 49 generates the sampling signal 140 that defines the sampling frequency, and samples the electrocardiogram signal 120 using the sampling signal 140 as a trigger. As the sampling frequency, an appropriate frequency can be set according to the information of the cardiac function to be analyzed. For example, when the heart rate is analyzed as the heart function information, the sampling frequency is preferably 100 Hz or more.
The control unit 49 of this embodiment performs sampling only at the timing when the analog switch 50 is turned off. Therefore, the control unit 49 determines a sampling period in which sampling is permitted based on the pulse width control signal 101 in a period in which the pulse width control signal 101 is low. The controller 49 samples the electrocardiogram signal 120 using only the sampling signal 140 generated within the sampling period as a trigger.
In the above setting example, T _P = 0.2 (msec) and τ−T _P = 49.8 (msec). Therefore, stimulation electrodes 34A, 34B may be a period for applying the unit pulse _{P S} as waveform group W, 99.6% of the stimulation time _{T on} serves as the reference electrode.

Sampling period in the present embodiment, as shown by broken line 150, the period, excluding the timing of the pulse width control signal 101 is high, the timing of time T _D after the pulse width control signal 101 is changed from high to low, the It is.
Time T _D, the noise due to the application of the pulse signal 110, for example, signals including noise such as transients immediately after application of the pulse signal 110 is set to a length which is not sampled. Time T _D, for example, such as in accordance with the intensity of the pulse signal 110, can be changed. The time _{T D,} for example, about 0.1msec~2msec are preferred. However, when the noise immediately after application of the pulse signal 110 is small, T _D = 0 may be set.

The control unit 49 does not perform sampling during a period other than the sampling period (indicated by “off” in FIG. 13). For example, the control unit 49 samples the electrocardiogram signal 120 at the timings of the signals s1 to s4 and s6 in the sampling signal 140 shown in FIG. 13, but the timing of the signal s5 generated between times t10 and t12. Then, sampling is not performed.
For this reason, the control part 49 acquires discrete data, such as data d1-d4, d6, as the waveform data 130 corresponding to the waveform of the electrocardiogram signal 120, for example.
The control unit 49 sends the acquired waveform data 130 to the electrocardiogram signal analysis unit 43.

  In this embodiment, the electrocardiogram signal analysis unit 43 analyzes the waveform of the waveform data 130 and calculates the heart rate. For example, the electrocardiogram signal analysis unit 43 extracts an R wave from the waveform data 130 and calculates a heart rate from the interval between the peaks of the R wave. The peak of the R wave can be estimated by interpolating the waveform data 130, for example. However, when the sampling frequency has a sufficient magnitude as compared with the required measurement accuracy, the waveform data 130 that simply gives the maximum value of the waveform data 130 may be used as the peak of the R wave.

Since the heart rate calculated in this way is based on the waveform data 130 acquired when the stimulation electrodes 34A and 34B function as reference electrodes, noise is suppressed. For this reason, the measurement accuracy of the heart rate is good.
The electrocardiogram signal analysis unit 43 sends the calculated heart rate to the control unit 49.
In the control unit 49, for example, the heart rate is displayed on the display unit 11. For this reason, the user or operator of the nerve stimulation apparatus 1 can monitor the state of the patient P or check the therapeutic effect of electrical stimulation by looking at the heart rate displayed on the display unit 11.

  The control unit 49 can also monitor the state of the patient P based on the heart rate transmitted from the electrocardiogram signal analysis unit 43. For example, the control unit 49 is configured to detect, for example, a tachycardia state or a bradycardia state based on an allowable range of heart rate stored in advance or time-lapse data of the measured heart rate. In this case, when it is determined that the heart rate is in an abnormal state, the control unit 49 stops the application of the pulse signal 110 or activates the buzzer 13 to generate a warning sound that notifies the abnormal state. Safety measures such as can be taken.

The control unit 49 may monitor the therapeutic effect of the patient P based on the heart rate, and change the setting condition of the pulse signal 110 according to the therapeutic effect. For example, the control unit 49, if the heart rate rises, therapeutic because less effective, or increasing the intensity or pulse width of the pulse signal 110, or increasing the stimulation time T _on. When the heart rate decreases, the therapeutic effect has increased, and the control unit 49 performs the opposite control. Thereby, the control part 49 can perform the feedback control of the parameter of the pulse signal 110, aiming at the appropriate range of the heart rate.

As described above, the control method of the nerve stimulation apparatus 1 includes the following first to fifth steps.
In the first step, stimulation electrodes 34A and 34B and electrocardiogram signal detection electrodes 17A and 17B are arranged on the patient P.
In the second step, the stimulation electrodes 34A and 34B arranged on the patient P are connected to the pulse generation circuit unit 44, and electrical stimulation is applied from the stimulation electrodes 34A and 34B.
In the third step, the stimulation electrodes 34 </ b> A and 34 </ b> B are conducted to the reference potential portion of the pulse generation circuit unit 44 and the generation of electrical stimulation is stopped.
In the fourth step, when the stimulation electrodes 34A and 34B are conducted to the reference potential portion, the electrocardiogram signal processing unit 42 having a common reference potential portion is used from the ECG signal detection electrodes 17A and 17B arranged on the patient P. To obtain an electrocardiogram signal.
In the fifth step, the waveform of the electrocardiogram signal is acquired based on the electrocardiogram signal acquired when the stimulation electrodes 34A and 34B are conducted to the reference potential portion.
In particular, in this embodiment, when the stimulation electrodes 34A and 34B are conducted to the reference potential portion, the waveform of the electrocardiographic signal is always acquired.

According to the nerve stimulation apparatus 1 of the present embodiment, the stimulation electrodes 34 </ b> A and 34 </ b> B are electrically connected to the reference potential unit of the pulse generation circuit unit 44 when an electrocardiogram signal is acquired. At this time, since the stimulation electrodes 34A and 34B that are in contact with the patient P serve as reference electrodes when the electrocardiogram signal is acquired, the electrocardiogram signal can be acquired with high accuracy. Therefore, the nerve stimulation apparatus 1 does not have to be provided with a dedicated reference electrode for measuring an electrocardiogram signal, and thus has a simple configuration as compared with a case where a dedicated reference electrode is provided.
Further, since the stimulation electrodes 34A and 34B perform electrical stimulation and are always attached to the patient P, it is possible to save the trouble of attaching a dedicated reference electrode to the patient P. Also for the patient P, since the number of electrodes to be mounted is reduced, the movement becomes easier and the stress is reduced.

[Second Embodiment]
Next, a nerve stimulation apparatus according to a second embodiment of the present invention will be described.
FIG. 14 is a schematic circuit diagram illustrating configurations of a pulse generation circuit unit and a changeover switch unit of the nerve stimulation apparatus according to the second embodiment of the present invention. FIG. 15 is a functional block diagram showing a functional configuration of an electrocardiogram signal processing unit of the nerve stimulation apparatus according to the second embodiment of the present invention.

As shown in FIG. 1, the nerve stimulation device 70 of the present embodiment includes an electrode unit 20 that is inserted into the blood vessel of the patient P, as in the first embodiment, and the vagus nerve Vn of the patient P or the like. It can be electrically stimulated and used, for example, for the treatment of tachycardia and chronic heart failure.
As shown in FIG. 5, the nerve stimulation apparatus 70 is replaced with a pulse generation circuit unit 84 (first electric circuit) in place of the pulse generation circuit unit 44, the changeover switch unit 45, and the control unit 49 in the first embodiment. A changeover switch unit 85 and a control unit 89.
Hereinafter, a description will be given centering on differences from the first embodiment.

As shown in FIG. 14, the pulse generation circuit unit 84 includes analog switches 50 and 51 and a constant current circuit 52 as in the first embodiment. However, this embodiment is different from the first embodiment in that the input terminals S2 and S4 of the analog switch 50 are connected to the ground via the changeover switch 86.
The changeover switch 86 is opened and closed in response to a switch control signal 103 from the control unit 89. As the changeover switch 86, for example, an appropriate switch such as an analog switch, a relay, or a semiconductor switch can be employed.
In this embodiment, the changeover switch 86 is opened when the switch control signal 103 is high and closed when the switch control signal 103 is low.
The ground (GND) through which the changeover switch 86 is conducted is a reference potential unit common to the pulse generation circuit unit 84 and the electrocardiogram signal processing unit 42, as in the first embodiment.

The changeover switch unit 85 includes an analog switch 50 and a changeover switch 86.
The changeover switch unit 85 makes the stimulation electrodes 34A and 34B conductive to the ground only when the analog switch 50 is in an off state and the changeover switch 86 is closed.

The control unit 89 is communicably connected to the changeover switch 86 and is different from the control unit 49 of the first embodiment in that a switch control signal 103 is sent to the changeover switch 86.
Control unit 89, waveform group W stimulation electrodes 34A of the pulse signal 110, the stimulation time _{T on} to be applied to 34B, the switch control signal 103 to high, the downtime _{T off} to pause the waveform group W of the pulse signal 110 The switch control signal 103 is set to low.
The control unit 89 sets the sampling period of the electrocardiogram signal at a timing when the switch control signal 103 is low.

The operation of the nerve stimulation device 70 will be described focusing on differences from the first embodiment.
FIG. 16 is a timing chart showing the operation of the nerve stimulation apparatus according to the second embodiment of the present invention.

In the nerve stimulation device 70, in the stimulation application mode, intermittent electrical stimulation similar to that in the first embodiment is applied. That is, as indicated by a broken line 160 in FIG. 16, the stimulation time _Ton and the rest time _Toff are alternately repeated. In stimulation time _{T on,} the pulse signal 110 which constitutes a waveform group W stimulation electrodes 34A, is applied to 34B.
In the first embodiment, also in the stimulation time T _on, the pulse width control signal 101 during the low to sample for acquiring electrocardiographic signals. However, in the present embodiment, the control unit 89 goes high in synchronism with the stimulation time T _on, sends a switch control signal 103 goes low in synchronism with the rest time T _off the changeover switch 86.
Therefore, in the present embodiment, the stimulation electrodes 34A, 34B is only the timing of the pause time _{T off,} is conducted to the ground.

As indicated by a broken line 170 in FIG. 16, the control unit 89 sets the sampling period of the electrocardiogram signal at the timing when the switch control signal 103 is high and the time T _d after the switch control signal 103 changes from high to low. Set to a period excluding timing.
The time _Td is set to a length at which noise accompanying application of the waveform group W is not sampled. The time _Td can be changed according to the intensity of the pulse signal 110, for example. The time _{T d,} for example, about 0.1msec~2msec are preferred. However, when the noise of the waveform group W is small, T _d = 0 may be set.

According to the nerve stimulation device 70 of the present embodiment, the stimulation electrodes 34A and 34B are electrically connected to the reference potential unit of the pulse generation circuit unit 84 when an electrocardiogram signal is acquired. At this time, since the stimulation electrodes 34A and 34B that are in contact with the patient P serve as reference electrodes when the electrocardiogram signal is acquired, the electrocardiogram signal can be acquired with high accuracy. Therefore, the nerve stimulation device 70 does not need to be provided with a dedicated reference electrode for measuring an electrocardiogram signal, and thus has a simple configuration as compared with a case where a dedicated reference electrode is provided.
Further, since the stimulation electrodes 34A and 34B perform electrical stimulation and are always attached to the patient P, it is possible to save the trouble of attaching a dedicated reference electrode to the patient P. Also for the patient P, since the number of electrodes to be mounted is reduced, the movement becomes easier and the stress is reduced.

  In the above description of each embodiment, an example in which the vagus nerve Vn is electrically stimulated through the blood vessel Bv has been described. However, this is only an example, and the nerve stimulation device stimulates nerves other than the vagus nerve. May be. Further, in this case, the stimulation electrode can be disposed in a suitable blood vessel that can transmit the stimulation to the nerve that performs stimulation, or in a site other than the blood vessel in the body.

  In the description of each of the above embodiments, the analog switches 50 and 51 are used as switching means for generating a pulse signal. However, the switching means for generating the pulse signal is not limited to the analog switch. For example, a relay or a semiconductor switch may be used.

In the description of each of the above embodiments, when the control unit acquires the waveform of the electrocardiogram signal, the control unit acquires the electrocardiogram signal from the electrocardiogram signal processing unit 42, and the acquired electrocardiogram signal in the sampling period. The example of sampling in the range has been described.
However, the control unit may acquire the waveform data by removing the data within the sampling period after sampling the entire ECG signal from the ECG signal processing unit 42 at a constant sampling frequency. .

In the description of each of the above embodiments, when the control unit acquires the waveform of the electrocardiogram signal, the control unit acquires the electrocardiogram signal from the electrocardiogram signal processing unit 42, and the acquired electrocardiogram signal in the sampling period. The example of sampling in the range has been described.
However, the control unit samples the entire electrocardiogram signal from the electrocardiogram signal processing unit 42 at a constant sampling frequency, and together with the waveform of the electrocardiogram signal in the second state, the electrocardiogram signal in the first state. May be sent to the electrocardiogram signal analysis unit 43. However, in this case, the electrocardiogram signal analysis unit 43 performs analysis using only the waveform of the electrocardiogram signal corresponding to the second state when analyzing the waveform of the electrocardiogram signal. Thereby, in the analysis performed by the electrocardiogram signal analysis unit 43, the accuracy of the analysis result is good.

  Further, all the components described above can be implemented by being appropriately combined or deleted within the scope of the technical idea of the present invention.

DESCRIPTION OF SYMBOLS 1,70 Neural stimulation apparatus 17A, 17B Electrocardiogram signal detection electrode 20 Electrode unit 21 Lead part 30 Electrode holding part 34A, 34B Stimulation electrode 42 Electrocardiogram signal processing part (electrocardiogram signal acquisition part)
43 ECG signal analysis units 44, 84 Pulse generation circuit unit (stimulus generation unit)
45, 85 selector switch 46 pulse width monitor 49, 89 controller 50, 51 analog switch 52 constant current circuit 86 selector switch 101 pulse width control signal 102 polarity inversion control signal 103 switch control signal 107 pulse width control signal 110 pulse signal 120 ECG signal 130 Waveform data 140 Sampling signal Bv Blood vessel P Patient (living body)
P3 Internal jugular vein Vn vagus nerve (nerve)

Claims (11)

A stimulation electrode for applying electrical stimulation to nerves of a living body;
A stimulus generator connected to the stimulus electrode and including a first electrical circuit for generating the electrical stimulus;
An electrocardiogram signal detection electrode disposed on the living body and detecting an electrocardiogram signal of the living body;
An electrocardiogram signal acquisition unit including a second electric circuit having a common reference potential unit with the first electric circuit, wherein the electrocardiogram signal detected by the electrocardiogram signal detection electrode is acquired by the second electric circuit. When,
A first state in which the first electrical circuit is closed to generate the electrical stimulation; a second state in which the first electrical circuit is interrupted and the stimulation electrode is conducted to the reference potential portion; A changeover switch section for selectively switching between,
Switching the changeover switch section between the first state and the second state;
When switching to the first state, the electrical stimulation is generated by the stimulation generator,
A control unit that acquires a waveform of the electrocardiogram signal based on the electrocardiogram signal acquired by the electrocardiogram signal acquisition unit when switched to the second state;
A nerve stimulation apparatus comprising: The controller is
The nerve stimulation apparatus according to claim 1, wherein the waveform of the electrocardiogram signal is always acquired when the changeover switch unit is switched to the second state. The controller is
Stops the electrical stimulation for a longer time than the stimulation group generation operation for periodically generating the electrical stimulation to the stimulation generation unit a plurality of times and the interval between the electrical stimulations during the stimulation group generation operation. The stimulus stop operation to perform the control to alternately repeat,
The nerve stimulation apparatus according to claim 1, wherein the waveform of the electrocardiogram signal is acquired only when the changeover switch unit is switched to the second state during the stimulus stop operation. The electrocardiogram signal analysis part which analyzes the waveform of the electrocardiogram signal acquired by the control part and acquires the information on the heart function of the living body is provided. The nerve stimulating device according to item. The electrocardiogram signal analysis unit
Of the waveform of the electrocardiogram signal, information on the heart function of the living body is obtained by analyzing the waveform after a predetermined time has elapsed since the changeover switch unit was switched to the second state. The nerve stimulation apparatus according to claim 4, wherein The controller is
4. The waveform of the electrocardiogram signal is acquired after a predetermined time has elapsed since the changeover switch unit was switched to the second state. 5. Neural stimulator. A method for controlling a nerve stimulation apparatus, comprising: a stimulation electrode for applying electrical stimulation to a nerve of a living body; and an electrocardiographic signal detection electrode for detecting an electrocardiographic signal of the living body,
Disposing the stimulation electrode and the electrocardiogram signal detection electrode on the living body;
Connecting a stimulation electrode disposed on the living body to a first electric circuit that generates the electrical stimulation, and applying the electrical stimulation from the stimulation electrode;
Conducting the stimulation electrode to a reference potential portion of the first electrical circuit and stopping the generation of the electrical stimulation;
When the stimulation electrode is conducted to the reference potential portion, the electrocardiogram signal is acquired from the electrocardiogram signal detection electrode arranged in the living body using a second electric circuit having a common reference potential portion. To do
Acquiring the waveform of the electrocardiogram signal based on the electrocardiogram signal acquired when the stimulation electrode is conducted to the reference potential portion;
A method for controlling a nerve stimulation apparatus. When the stimulation electrode conducts to the reference potential portion,
The method for controlling a nerve stimulation apparatus according to claim 7, wherein the waveform of the electrocardiogram signal is always acquired. When applying the electrical stimulation from the stimulation electrode,
A stimulation group generation operation for periodically generating the electrical stimulation a plurality of times; and a stimulation stop operation for stopping the electrical stimulation for a time longer than the generation interval of the electrical stimulation during the stimulation group generation operation. , Repeat alternately,
The method of controlling a nerve stimulation device according to claim 7, wherein the waveform of the electrocardiogram signal is acquired only when the stimulation electrode is conducted to the reference potential portion in the stimulation stop operation. After acquiring the waveform of the electrocardiogram signal,
The method for controlling a nerve stimulation apparatus according to any one of claims 7 to 9, wherein the information on the cardiac function of the living body is acquired by analyzing a waveform of the electrocardiographic signal. When analyzing the waveform of the electrocardiogram signal,
The method according to claim 10, wherein analysis is performed using a waveform after a predetermined time has elapsed since the stimulation electrode is conducted to the reference potential portion.

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