JPH0550938B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrocardiogram signal transmitting device suitable for transmitting electrocardiogram waveforms including pacemaker pulses.

[Summary of the invention]

The present invention relates to an electrocardiographic signal transmitting device suitable for transmitting electrocardiogram waveforms including pacemaker pulses, and in an electrocardiographic signal transmitting device adapted to transmit pacemaker pulses superimposed on an electrocardiographic signal. The pacemaker pulse detection and separation means includes a pacemaker pulse detection and separation means that detects and separates the pacemaker pulse superimposed in the pacemaker pulse, and an addition pulse generation means that synchronizes with the pacemaker pulse and generates a pulse having a width wider than the pacemaker pulse width. Position information of pacemaker pulses can be obtained in a narrow band by superimposing a summation pulse with a wider pacemaker pulse width, which is an output of the summation pulse generation means, on the electrocardiographic signal from which the pacemaker pulse, which is the output of the summation pulse generation means, has been removed. This makes it possible to transmit data without deteriorating the detection accuracy.

[Conventional technology]

Pacemakers are used to normalize heartbeat by applying electrical stimulation to the myocardium of patients whose generation and transmission of spontaneous electrical pulses are inhibited.
In general, there are two types: one that supplies electricity from outside the body and one that is implanted inside the body.Usually, electrodes are implanted in the heart muscle, and the circuit consists of an oscillator circuit that generates pulses with a width of 0.2 to 2 ms, and the power source is a mercury battery, etc. It is used.

There is also a need to monitor electrocardiograms of patients using such pacemakers.

Figures 3 and 4 show typical electrocardiogram waveforms and their time waveforms.
The wave corresponds to the contraction of the atrium, the QRS wave corresponds to the contraction of the ventricle, and the T wave corresponds to the expansion of the ventricle. Furthermore, the time values of these waves have physiological significance as shown in FIG.

Now, when considering a monitoring device that monitors the electrocardiogram waveform of a patient using a pacemaker, the pacemaker pulse is superimposed on the electrocardiogram and observed, but the monitoring device monitors the R wave in the electrocardiogram waveform or the pacemaker pulse. Detects and separates pulses,
If the heart rate is automatically counted and an abnormal value is found, it is necessary to issue an alarm and notify the doctor or nurse. Therefore, the separation performance between pacemaker pulses and electrocardiogram R waves is of great significance; if the separation performance is insufficient, the monitoring device will continue to count pacemaker pulses even though the heart has stopped, mistaking them as R waves. It is possible that the alarm will not be issued.

As mentioned above, the pacemaker pulse has a pulse width of 0.2 to 2 ms, and the voltage of the electrocardiographic signal changes depending on the electrode position during electrocardiogram measurement, but it is about several mV to 1 V, and the detection range conditions are very wide. . Furthermore, in order to send electrocardiogram waveforms to the monitoring device without distortion, the frequency band required for the monitoring device is 30 to 50Hz, and the frequency band required for diagnostic equipment such as electrocardiographs is 30 to 50Hz.
Although the frequency is 100Hz, a bandwidth of 1 to 2kHz is required to transmit pacemaker pulses without distortion. or,
Among electrocardiographic signals, R waves have a particularly important meaning. Since this R wave has the highest frequency component and the amplitude is large as shown in FIG. 3, the separation performance between this R wave and the pacemaker pulse becomes a problem as described above. Furthermore, the presence or absence of pacemaker pulses and their position on the electrocardiogram are important information.

A transmitting/receiving device for transmitting, detecting and separating such pacemaker pulses will be explained with reference to FIGS. 5 and 6.

FIG. 5 shows a transmitting device, and an electrocardiographic signal and a pacemaker pulse (hereinafter referred to as a biological signal) are supplied to an input terminal 1 through an electrocardiogram electrode placed on a patient using a pacemaker. This biological signal is amplified by an amplifier 2, and its amplified output is supplied to a pulse detection circuit 3 and a switching circuit 4. The pulse detection circuit 3 detects pacemaker pulses included in the electrocardiographic signal and supplies the detection signal to the low-pass filter 8 and the removal control pulse generation circuit 5. The removal control pulse generation circuit 5 differentiates the rising pulse of the pulse detection circuit 3, triggers a monostable multivibrator, etc., generates a removal control pulse of a predetermined width, and controls the switching circuit 4 for the period of this generated removal control pulse. Open state. That is, the pulse detection circuit 3, the removal control pulse generation circuit 5, and the switching circuit 4 constitute a pacemaker pulse removal circuit 6. When the switching circuit 4 is in the closed state, the electrocardiographic signal included in the biological signal is supplied to the low-pass filter 7.
The electrocardiographic signals and pacemaker pulses from which pacemaker pulses have been removed and which have been supplied to low-pass filters 7 and 8 are supplied to modulators 9 and 10, respectively, and after addition are supplied to main modulator 11. Modulators 9 and 10 are FM modulators. The main modulator 11 is an FM or AM modulator, and in the multiplex modulation method using subcarriers, the FM-FM or FM-AM method is used.
In the case of time-series multiplex transmission such as PWM, two transmission channels are used, one channel transmits pacemaker pulses, and the other channel transmits electrocardiographic signals. Note that 12 is a transmitting antenna.

FIG. 6 shows a receiving device, in which the transmitted radio waves from the transmitting antenna 12 received by the receiving antenna 13 are transmitted to the tuner demodulator circuit 14 to FM-FM, FM-
The AM or PWM signal is demodulated, this demodulated signal is supplied to the demodulators 15 and 16, the pacemaker pulse and the electrocardiographic signal are demodulated, and the electrocardiographic signal from which the pacemaker pulse has been removed is used for measurement in the measuring section 32. Furthermore, the pacemaker pulse and electrocardiogram signal output from the demodulators 15 and 16 are added and displayed on the display device 3.
3 or is displayed or recorded on the recorder 17 or the like.

In the conventional transmitting and receiving device described above, an example was explained in which the electrocardiographic signal and the pacemaker pulse were transmitted through separate systems, but as shown in FIGS. 7 and 8, the transmitting device side transmits the pacemaker pulse and the electrocardiographic signal. A method without separation has also been proposed. Figures 7 and 8
The figure shows a system diagram of the transmitter and receiver, and parts corresponding to those in FIGS. 5 and 6 are designated by the same reference numerals.

A biological signal that is a mixture of an electrocardiographic signal and a pacemaker pulse is supplied to the input terminal 1, amplified by the amplifier 2, and then supplied to the low-pass filter 7a. The upper limit cutoff frequency of this low-pass filter 7a is selected to be approximately 300 Hz so as to broaden the frequency characteristics of the modulator 9 and the main modulator 11. Modulator 9 and main modulator 1
1, the FM-FM modulation method is generally used. FM− transmitted from the transmitting antenna 12
The FM-modulated biosignal is received by the receiving antenna 13 of the receiving device shown in FIG. 8, and after being tuned by the tuner 14, it is FM demodulated, for example, and further FM demodulated by the next-stage demodulator 15. It is supplied to the pacemaker pulse separation circuit 18 in the next stage. This pacemaker pulse separation circuit 18 has a frequency of 120Hz to 300Hz.
Bandpass filter 19 that passes the Hz band
, a detection comparator 20 connected to the output of the bandpass filter 19 for detecting pacemaker pulses, a removal control pulse generation circuit 5 for removing pacemaker pulses based on the output of the detection comparator 20, and a switching circuit 4, The switching circuit 4 is controlled to be "on" or "off" by the output of the removal control pulse generating circuit 5. Pacemaker pulses are output to the output terminal 23 while the switching circuit 4 is off, and electrocardiographic signals from which the pacemaker pulses have been removed are output to the output terminal 22 through the low-pass filter 21 during the "on" period. Note that the upper limit cutoff frequency of the low-pass filter 21 is 100Hz.

[Problem to be solved by the invention]

The transmitting device shown in FIG. 5 above amplifies the electrocardiographic signal and then detects and separates the pacemaker pulse.
The electrocardiographic signal from which the pacemaker pulse has been removed and the pacemaker pulse are transmitted through separate systems, and the receiving device uses the electrocardiographic signal from which the pacemaker pulse has been removed for measurement as shown in Figure 6, and adds the pacemaker pulses transmitted through the separate system. This is used as a display signal. This method has high detection accuracy because pacemaker pulses are detected and separated after the electrocardiogram amplifier 2, but in order to transmit pacemaker pulses using PWM etc., a dedicated transmission line with relatively good frequency characteristics is required. It is necessary to use it. As a result, a problem arises in that the occupied bandwidth of radio waves becomes wider.

Furthermore, a system using a plurality of subcarriers similarly has the problem of widening the occupied radio wave bandwidth, and requires a dedicated subcarrier modulator and demodulator for transmitting pacemaker pulses.

Furthermore, in the case of the transmitter and receiver shown in Figures 7 and 8, the transmitter side does not separate the pacemaker pulses, but spreads the frequency characteristics of the modulator and transmits them as is, and the receiver side detects the pacemaker pulses. At the same time, a circuit for separating is provided. In this case, as mentioned above, an occupied band of 1 to 2 kHz is required to transmit pacemaker pulses without distortion, but if you try to secure a band of 1 to 2 kHz by expanding the frequency characteristics of the modulator, the occupied band The upper limit cut-off frequency of the low-pass filter 21 is selected to be about 300 Hz because it is impossible to take many radio wave channels for the transmitter/receiver (telemeter). Since it is difficult to secure a sufficient transmission band in this way, it is not possible to sufficiently raise the narrow pacemaker pulse. For this reason, the detection performance of pacemaker pulses is lower than that of the method of detecting on the transmitter side shown in Figure 5, and there is a problem that pacemaker pulses with a width of 1 ms or less cannot be detected, and if the electric field becomes weaker, There was also the problem that pulse noise, which was mistaken for pacemaker pulses, was mixed into the electric signal, causing the detection and separation circuits to malfunction.

The present invention was made in view of the above-mentioned problems, and its purpose is to stably detect and separate electrocardiographic signals including pacemaker pulses even if the S/N of the transmission path deteriorates, and to The purpose of this invention is to obtain an electrocardiographic signal transmitting device capable of transmitting pacemaker pulses.

[Means to solve the problem]

An example of the electrocardiographic signal transmitting device of the present invention is an electrocardiographic signal transmitting device configured to transmit a pacemaker pulse 25 superimposed on an electrocardiographic signal as shown in FIGS. 1 and 2. A pacemaker pulse detection and separation means 6 detects and separates the pacemaker pulse 25 superimposed on the electrocardiogram signal, and an addition pulse synchronizes with the pacemaker pulse 25 and generates a pulse having a width wider than the width of the pacemaker pulse 25. generating means 24, which superimposes an addition pulse 27, which is the output of the addition pulse generation means 24, with a wider pacemaker pulse width, on the electrocardiographic signal from which the pacemaker pulse 25, which is the output of the pacemaker pulse detection and separation means 6, has been removed. It is designed so that it is sent out.

[Effect]

According to the electrocardiographic signal transmitting device of the present invention, the electrocardiographic signal superimposed on the electrocardiographic signal is separated by the pacemaker pulse detection and separation means 6, and the added pulse is added to the biological signal from which the pacemaker pulse is removed from the electrocardiographic signal. Since the addition pulse generated by the generating means 24, that is, the pulse with an expanded pacemaker pulse width, is added and transmitted, even if a pulse with a short pacemaker pulse width is sent to a transmission path with a deteriorated S/N ratio, it will not be received. On the device side, an electrocardiographic signal transmitting device that can stably perform detection and separation can be obtained.

〔Example〕

Hereinafter, one embodiment of the electrocardiogram signal transmitting device of the present invention will be described with reference to FIGS. 1 and 2.

Corresponding parts in FIGS. 1 and 2 to those in FIGS. 3 to 8 are designated by the same reference numerals.

In FIG. 1, an input terminal 1 is supplied with an electrocardiographic signal of a patient using a pacemaker, so that the pacemaker pulse and the electrocardiographic signal are superimposed and input. The biological signal supplied to input terminal 1 is 1 to 2k.
The biological signals including pacemaker pulses are faithfully amplified by passing through the Hz electrocardiogram amplifier 2. An example of the biological signal amplified by this amplifier 2 is shown in FIG. 2A. As is clear from this waveform, there is a large difference in frequency components between the pacemaker pulse 25 and the P, R, T waves, etc. of the electrocardiogram signal, and even the R wave, which has a high frequency component in the electrocardiogram signal, has a high frequency component. The highest frequency of
It is up to 100Hz, but pacemaker pulses can go up to 2kHz. The output amplified by the electrocardiogram amplifier 2 is sent to the switching circuit 4 in the pacemaker pulse removal circuit 6.
and is supplied to the bandpass filter 19. The bandwidth of the bandpass filter 19 is selected to be 120Hz to 1.2kHz, the pacemaker pulses 25 within this band are separated by the bandpass filter 19, and the pacemaker pulses 25 separated by the detection comparator 20.
5 is detected and supplied to a removal control pulse generating circuit 5 composed of a mono-multivibrator or the like, to generate a removal pulse 26 of a predetermined width for removing the pacemaker pulse as shown in FIG. 2B. The rising edge of the pacemaker pulse 25 of the detection comparator 20 is simultaneously supplied to the addition pulse generation circuit 24, and the pulse width τ ₂ shown in FIG. 2C, which is wider than the pacemaker pulse width τ 1, is generated _.
The addition pulse 27 is generated. This addition pulse generation circuit 24 may also be constructed from a mono-multivibrator or the like.

The switching circuit 4 is turned off by the removal pulse 26 generated by the removal control pulse generation circuit 5, and the pacemaker pulse 25 is removed from the electrocardiographic signal.

A delay circuit 28 composed of a resistor R and a capacitor C is provided at the subsequent stage of the switching circuit 4, and through this delay circuit 28, the biological signal from which the pacemaker pulse 25 has been removed and the addition pulse 27 which has expanded the pulse width of the pacemaker pulse 25 are combined. Addition circuit 29 adds addition pulse 27 shown in FIG. 2C to the electrocardiogram signal whose timing has been adjusted and pacemaker pulse 25 has been removed
Then, an electrocardiographic signal for transmission (hereinafter referred to as a transmission signal) 30 processed into a wide pacemaker pulse as shown in FIG. 2D is obtained. Such a transmission signal 30
is band-limited by a low-pass filter 7 , a subcarrier is FM-modulated by a transmission signal 30 by a modulator 9 , further FM-modulated by a main modulator 11 , and transmitted from a transmitting antenna 12 .

In reality, the subcarrier is controlled by the low battery signal and the electrode abnormality signal by the modulator 31 shown by the broken line.
It is FM modulated and supplied to the main modulator 11,
Since it is not directly related to the configuration of the present invention, its specific configuration and operation will be omitted.

With the above configuration, the upper limit cutoff frequency of the low-pass filter 7 is set to 300Hz, and the pulse width of the addition pulse is τ ₂
Select the time constant of the addition pulse generation circuit 24 and
If you set it to 5ms, in the 300Hz frequency band
The pulse width that can rise up to 90% is
Since the pulse width is 1.2 ms, the pacemaker pulse processed to have a pulse width τ ₂ of 5 ms, that is, the transmission signal 30 having the addition pulse 27 can be transmitted by sufficiently raising the pulse.

In this case, the pacemaker pulse included in the electrocardiogram signal, that is, the pacemaker pulse 25 in the biological signal
Even if it has a pulse width τ ₁ of 0.1 to 0.5 ms with high frequency components as shown in Figure 2 A, the detection accuracy is degraded because the electrocardiogram amplifier 2 is selected to have no detection distortion. Never.

The receiving device is the same as the conventional configuration shown in FIG. 8, so the configuration is omitted, but the transmitting device is
By making improvements as shown in the figure, the performance of the receiving apparatus can be improved without changing the conventional configuration. In the conventional receiving apparatus shown in FIG. 8, it was necessary to lower the level of the detection comparator 20 because it was necessary to detect pulses of small amplitude.
In this case, when the received electric field strength decreased, it was easy to malfunction due to noise, but in the present invention, the level of the detection comparator 20 of the receiving device can be set high regardless of the amplitude of the pacemaker pulse 25, so that the weak electric field It is possible to reduce malfunctions.

In the above-described embodiment, the addition pulse generation circuit 24 uses impulses as the addition pulses, but burst-like addition pulses may also be generated.

The electrocardiographic signal transmitting device of the present invention has the following effects.

(b) Pacemaker pulse position information can be transmitted in a narrow band.

(b) Since pacemaker pulses are detected close to the signal source where the rising edges of the pulses are less likely to deteriorate, pulse detection accuracy is high.

(c) Detection accuracy will not deteriorate even if the pulse is narrow and has a small amplitude, which is difficult to transmit in the frequency band of the transmission path.

(d) In the case of wireless transmission, pacemaker pulse detection accuracy does not deteriorate even if the electric field strength becomes weak and the signal-to-noise ratio deteriorates.

Note that the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the gist of the present invention.

〔Effect of the invention〕

According to the electrocardiographic signal transmitting device of the present invention, position information of pacemaker pulses can be transmitted in a narrow band without deteriorating detection accuracy.

[Brief explanation of drawings]

Fig. 1 is a system diagram showing an embodiment of the electrocardiographic signal transmitting device of the present invention, Fig. 2 is a waveform explanatory diagram of Fig. 1, Fig. 3 is an electrocardiogram waveform diagram, and Fig. 4 is a time value of a normal electrocardiogram. 5 and 7 are system diagrams of conventional electrocardiographic signal transmitting devices, and FIGS. 6 and 8 are system diagrams of conventional electrocardiographic signal transmitting devices. 2 is an amplifier, 4 is a switching circuit, 5 is a removal control pulse generation circuit, 6 is a pacemaker pulse removal circuit, 7 is a low-pass filter, 9 is a modulator, 11 is a main modulator, 19 is a band-pass filter, 20 is a comparator, 24 is an addition pulse generation circuit.

Claims (1)

[Scope of Claims] 1. An electrocardiographic signal transmitting device used in a patient monitoring device using wireless transmission, comprising a separating means for detecting a pacemaker pulse superimposed on an electrocardiographic signal and separating the pacemaker pulse, and the pacemaker. Pacemaker pulse detection and separation means comprising a detection means for detecting the edge of a pulse, a removal pulse generation means for generating a removal pulse for removing the pacemaker pulse by the output of the detection means, and a switching means controlled by the removal pulse. and an addition pulse generating means for generating an addition pulse having a width wider than the pacemaker pulse width in synchronization with the pacemaker pulse, and adding the addition pulse to the electrocardiographic signal from which the pacemaker pulse has been removed. An electrocardiographic signal transmitting device characterized by transmitting an electrocardiographic signal.