KR20040107884A - telemetric device for monitoring autonomic nervous activity - Google Patents

Abstract

PURPOSE: A telemetric device is provided to eliminate an electrode line, and obtain an electrocardiogram by integrating an electrocardiogram electrode, a signal amplifier, and a micro processor in an electromagnetic interference shielding epoxy accommodation unit. CONSTITUTION: A telemetric device comprises an electrocardiogram transmitting unit and an electrocardiogram receiving unit. The electrocardiogram transmitting unit includes electrocardiogram electrodes(2,2a) driven by button type lithium cells(1,1a) so as to sense electrocardiogram signals from a body surface; an electrocardiogram amplifier(3), and a micro processor(4) embedded with a program. The electrocardiogram receiving unit includes an antenna(8) for receiving/transmitting electrocardiogram signals, a high input impedance amplifier(3b), a low pass filter(6), and a receiving micro processor(4a).

Description

Wireless device for monitoring autonomic nervous activity

The present invention relates to a device for diagnosing cardiac autonomic nerve activity by wirelessly measuring the evaluation index of the time domain and frequency domain of heart rate variability.

Cardiac activity is autonomously regulated and controlled by the autonomic nerves, sympathetic and parasympathetic, given by the brainstem. ECG fluctuations (heart rate fluctuations) expressed as a result of myocardial electrical excitability include these autonomic nerve activities. Comparing autonomic activity with cars, sympathetic nerves are in Excel and parasympathetic nerves are in brakes. Therefore, since the heart rate variability obtained in the electrocardiogram reflects the change of autonomic nerve activity, that is, the dynamic control activity, it is possible to diagnose the abnormality of the autonomic nerve activity transmitted from the brain stem to the heart by analyzing the heart rate variability.

The excessively excited state of sympathetic nerve activity and the rapid decline of parasympathetic nerve in cardiac autonomic nerve activity are often caused by lethal arrhythmia, and the excessive excitability of such sympathetic nerve activity leads to heart attack or stroke. In most cases, Therefore, it is strongly required to accurately diagnose such changes in autonomic nerve activity because it is possible to prevent sudden death or lethal arrhythmias by administering a therapeutic agent that inhibits sympathetic nerve activity.

There are two conventional methods for diagnosing autonomic nerve activity. First of all, there is a method of diagnosing blood chemicals by changing blood chemicals related to autonomic nerve activity such as dopamine through blood tests. The drawback of these chemicals is that they can only monitor severe autonomic neuronal activity and instantaneous changes. Second is autonomic neurological activity diagnosis through heart rate fluctuation by 24 hour holter device. Such a halter device is rarely used when it is not a severe heart disease, and even if it is used, the device itself is expensive and it takes an average of more than a week to interpret and diagnose the measured ECG signal. In particular, the ECG signal obtained from Holter includes severe noise caused by the movement of the electrode and the body connected between the electrode and the Holter device. Diagnosing autonomic nerve activity using the Holter device is not straightforward.

In order to diagnose cardiac autonomic nerve activity, there are time domain and frequency domain analysis in order to measure electrocardiogram and to analyze heart rate variability in measured ECG.

In heart rate variability, the time domain indicators show the mean RR interval (heart rate = 60 / (RR interval) per minute) in the NN interval (for example, 5 minutes interval), the standard deviation of the RR interval in the NN interval (SDNN), and the coefficient of variation = SDNN / (average NN interval) is used. Standard deviations represent changes in sympathetic nerve activity, and coefficients of variation reflect changes in parasympathetic nerve activity (Kleiger R; Cardiological Clinics 1992; 10; 487-498).

Frequency spectrum analysis of heart rate variability includes power spectrum analysis by autoregression and power spectrum analysis by fast Fourier transform. The power spectrum of heart rate variability has two characteristic frequency ranges. That is, low frequency band (LF: 0.004-0.15 Hz) and high frequency band (HF: 0.20-0.45 Hz). This ratio of low-frequency power to total power (LF / (HF + LF)) reflects cardiac sympathetic nerve activity and high-frequency power reflects parasympathetic nerves (Ori Z: Cardiological Clinics 1992; 10; 499). -533)

In hypertensive patients, sympathetic nerve activity is excessively excited while parasympathetic nerve activity is reduced. In particular, the cardiac disease causing sudden death can be observed that the parasympathetic nerve activity is excessively reduced. In addition, in patients undergoing surgery under anesthesia, the use of anesthetics to monitor the real-time continuous and continuous monitoring of excessive sympathetic nerve activity and parasympathetic nervous tension is the only method through analysis of heart rate variability. . Therefore, monitoring of autonomic nerve activity to reduce the risk of anesthesia is currently strongly demanded.

The simplest real-time method of measuring changes in autonomic nerve activity is to analyze heart rate variability by measuring ECG. The most difficulty in diagnosing autonomic nervous system activity caused by heart rate fluctuation by using electrocardiogram measuring device is severe vibration of electrocardiogram wave due to shaking of wire connected between electrode and signal processing circuit and bio noise that affects when attached to body surface. to be. This external noise changes the baseline of the ECG and appears as a simple mechanical noise in the extracted heart rate variability. In the long-term measurement of cardiac autonomic nerves, stable ECG waveforms are obtained to obtain accurate heart rate fluctuations.

Conventionally, many devices for measuring ECG have been developed, but most of them are clinical, complex, expensive to use, and there are many disadvantages such as the risk of electric shock and inability to carry by using AC. In particular, solving the noise problem from the electrode line is not simple.

Accordingly, the present invention is to solve this problem, and eliminated the exposed electrode line of the conventional electrocardiograph or the Holter electrocardiograph, and integrated the electrocardiogram electrode, the signal amplifier and a single microprocessor in the electromagnetic wave blocking epoxy storage unit to measure the electrocardiogram The system transmits the measured ECG signals wirelessly, receives the coded signals, extracts the components of the heart rate with a microprocessor, displays them on a portable monitor (PDA, etc.) and installs the time domain analysis method and the frequency domain analysis method of the heart rate fluctuations. An object of the present invention is to provide a wireless autonomous neuronal activity diagnostic device.

1 is a block diagram of a wireless autonomic nerve activity diagnostic apparatus according to the present invention,

FIG. 2 is a block diagram specifically illustrating the configuration of an ECG transmitter and a receiver for obtaining an ECG signal, transmitting a signal, and calculating heart rate fluctuation.

3 is a graph showing one example of the continuous electrocardiogram (a), the R-R interval variation (b), and the power spectrum (c) of the heart rate variation measured by the apparatus of the present invention.

<Description of the symbols for the main parts of the drawings>

T: ECG transmitter R: ECG receiver

S: ECG monitor 1,1a: button battery

2: positive electrode 2a: negative electrode

3: ECG amplifier 3b: high input impedance amplifier

4: microprocessor 4a: receiving microprocessor

5: transmitter circuit box 6: low pass filter

7: receiving circuit box 8: antenna

9: serial transmission line

In order to achieve the above object, the present invention provides an electrocardiogram transmitter comprising a single microprocessor for converting, encoding, and transmitting a surface electrode, a signal amplifier, and an amplified electrocardiogram signal for digital electrocardiogram, and the coded electrocardiogram signal. The present invention provides an electrocardiogram receiver for wirelessly receiving and amplifying a heartbeat to extract a heartbeat, and furthermore, it is preferable that the autonomous nerve activity diagnosis program including a time domain analysis method and a frequency domain analysis method is installed.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

An example of the configuration of the present invention is an electrocardiogram (signal) transmitting unit (T) for measuring, storing, or encoding and transmitting an electrocardiogram signal as shown in FIG. 1, amplifying and low-passing the transmitted signal, and performing peak detection of the electrocardiogram. It consists of an ECG signal receiving unit (R) for storing or transmitting to the portable ECG monitor (S).

In FIG. 2, the ECG signal transmitter T and the ECG signal receiver R are illustrated in detail. In order to drive each transmitter and receiver for a long time, 2.5 Volt small button-type lithium batteries 1 and 1a are mounted.

In the electrocardiogram signal transmitting unit (T), a device for detecting a minute electrical signal indicating the progress of electrical excitability of the myocardium, the positive electrode (2) and the negative electrode (2a) made of silver chloride are placed at a distance of 3 cm, and the measured small electrocardiogram is measured. In order to amplify the signal 500 times, an ECG amplifier 3 using a low power driving differential amplifier INA118 is mounted adjacent to an electrode, and the amplified signal is input to a single microprocessor 4 for transmission.

The single microprocessor (18-pin PIC16C71 type) installed has a built-in A / D converter for converting the input ECG signal into a digital signal, and the digital ECG signal uses an RLC circuit and an antenna 8, which are transmission / reception means (not shown). Via the serial binary code type, it is wirelessly transmitted and received to the ECG receiver R.

The electrodes 2, 2a, the signal amplifier 3, the single microprocessor 4, the button-type lithium battery for power supply, and the antenna wire are preferably housed in a circuit box 5 made of a soft polyepoxide. , It is preferable to install so that the electrode button that can be connected to the disposable ECG electrode on the surface is exposed. Since the weight of the circuit box is 7-10 grams, the circuit box is fixed to the chest with a waterproof tape (preferably waterproof tape is integrated into the circuit box, such as a disposable band-aid). The cardiograph can also be measured and transmitted. In addition, since a high input impedance amplifier 3b is used between the transmitter and the receiver, transmission is possible even if the distance is maintained at least 10 meters.

The ECG signal receiving unit R is composed of a high input impedance amplifier 3b, a low pass filter 6, a microprocessor 4a for signal conversion, input / output and transmission, in addition to the transmission and reception means, and the heartbeat in the microprocessor in real time. Built-in extractable program, and stores the program that can handle the time domain and frequency domain of heart rate fluctuation, which is an index of autonomic nerve activity, and transfers ECG information signals processed by these programs to portable ECG monitor (S). Means for transmitting and displaying, wherein the high input impedance amplifier 3b, the low pass filter 6, and the microprocessors 4a are housed in the receiving circuit holder 7 similarly to the electrocardiogram transmitter T. . In addition, when displaying the ECG monitor S on a portable terminal such as a PDA, a mobile phone, or a laptop, which can execute at least a program, some programs such as a program for calculating the time domain index and the frequency domain index of heart rate fluctuation, It is also possible to mount the program on a portable terminal such as a PDA, a mobile phone, a notebook, and to process it. Furthermore, the ECG receiver R may be integrated with a portable terminal such as a PDA, a mobile phone, a notebook, or provided with only necessary means. It may be mounted as a module.

In Fig. 3, examples of calculating the continuous electrocardiogram signal, heart rate fluctuation and power spectrum of the heart rate fluctuation measured by the apparatus of the present invention are shown in graphs (a) to (c).

In the RR interval variation of the illustrated electrocardiogram, the indicators of the time domain are the average RR interval (842 ms) of the NN interval (300 seconds), the standard deviation of the RR interval of the NN interval (SDNN = 30 ms), and the coefficient of variation (CV = SDNN / ( Mean NN interval), 0.00001). Standard deviations represent changes in sympathetic nerve activity, and coefficients of variation (CV) reflect changes in parasympathetic nerve activity.

In the R-R interval variation shown, the power spectrum by the autoregression method has two peak values, a low frequency band (LF: 0.004-0.15 Hz) and a high frequency band (HF: 0.20-0.45 Hz). The ratio of low frequency power to total power (LF / (HF + LF)) reflects cardiac sympathetic nerve activity and high frequency power reflects parasympathetic nerve. In the subjects with such RR interval variability, administration of cardiac sympathetic nerve blocker (Propranol, 0.1mg / 100g) and parasympathetic nerve blocker (Atropine, 0.1mg / 100g) decreases the low frequency and high frequency range as shown by the dotted line. It could be observed. It can be seen that the device of the present invention accurately diagnoses changes in cardiac sympathetic activity and parasympathetic nerve activity, that is, autonomic nerve activity.

As described above, the present invention eliminates the electrode wire that causes external noise between the amplification and integration of the ECG electrode, the single amplifier, the microprocessor and the small DC power supply into the small storage box, and wirelessly to allow the behavior of the subject to be free. It has the effect of transmitting the ECG signal, and the transmitted ECG signal is amplified by the high input impedance amplifier and has the effect of being configured to extract the heart rate fluctuation.

In particular, unlike conventional large-scale electrocardiographs, it uses the effect of using a button-type micro DC power supply, a single amplifier for weight reduction, and a single microprocessor built-in A / D converter. It has the effect of being able to connect freely with a portable monitor.

The present invention also has the effect that it is possible to operate embedded in a portable terminal such as a PDA, a mobile phone to receive and display the ECG signal and time domain analysis program and frequency domain analysis program reflecting autonomic nerve activity.

Claims (4)

An apparatus for diagnosing wireless autonomic nerve activity, comprising: a positive electrode and a negative electrode, a single amplifier and a single microprocessor of a low power direct current power source, and a means for transmitting an electrocardiogram signal. Means for wirelessly receiving electrocardiogram signal information processed and processed by an electrocardiogram electrode, a single amplifier and a single microprocessor, a high input impedance amplifier for amplifying the received signal, and an A / D converter for converting it into a digital signal Wireless autonomic nerve activity diagnostic apparatus comprising a means for including a built-in program for extracting the heartbeat information from the ECG signal information and transmitting the ECG signal to an external display terminal. It consists of a surface electrode, a single amplifier, and a single microprocessor, and the program is installed in the portable terminal so that it can calculate the time domain index and the frequency domain index of heart rate variability by transmitting a serial ECG signal to a portable terminal such as a PDA or a mobile phone. Wireless autonomic nervous system diagnostic apparatus, characterized in that the configuration. The method according to any one of claims 1 to 3, wherein the exposed electrode wire is removed and the disturbance to ECG measurement and signal processing is minimized. Wireless ECG diagnostic apparatus, characterized in that the ECG electrodes, the signal amplifier, a single microprocessor, a supply-type button battery and an antenna line are housed in a circuit box made of a soft polyepoxide.