JPH04319333A - Electrocardiographic wave form recorder - Google Patents

Abstract

PURPOSE:To realize the reduction of a circuit scale and provide a small and lightweight recorder by accurately retaining a reference level potential difference, forming a reference pulse capable of indicating correctly the potential regardless of a position where the reference pulse is superimposed, and conducting recording by inserting the reference pulse into a free position in an electrocardiographic wave form. CONSTITUTION:The switch circuit 22 of a reference pulse insertion circuit 7 is controlled by means of a switch control signal SSW2, and a reference pulse PST retaining correctly a 1mV reference level on the basis of taken out bias voltage VBI1, VBI2 is formed, and the reference pulse PST is inserted into a free position in an electrocardiographic wave form WEH by controlling a switch circuit 21 of a reference pulse insertion circuit 7 by means of a switch control signal SSW1.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention relates to an electrocardiographic waveform recording device,
In particular, the present invention relates to an electrocardiographic waveform recording device suitable for so-called Holter electrocardiography, which records electrocardiographic waveforms over a long period of time.

0002

2. Description of the Related Art Holter electrocardiography is a method for collecting and analyzing electrocardiogram waveforms. Holter electrocardiography is a method of recording electrocardiographic waveforms in daily life using a portable recorder (tape recorder) over a long period of 24 hours or more, and analyzing the obtained electrocardiographic waveforms.

[0003] Since recording is carried out over a long period of time,
Electrocardiographic waveform recording devices are also required to be small and lightweight so that they can be carried for long periods of time. As a conventional electrocardiogram recording device, an analog tape recorder is generally used, and the electrocardiogram waveform is recorded at low speed on a compact cassette, a microcassette, or the like.

When recording an electrocardiogram waveform, in order to accurately know the peak level of the displayed electrocardiogram waveform and to calibrate the gain, a reference pulse representing a reference level, for example 1 mV, is applied for several seconds after the start of recording. It is attached to the recording of the electrocardiogram waveform for ~ several minutes.

An example of an electrocardiographic waveform recording device that can add the above-mentioned reference pulse to electrocardiographic waveform recording is shown in FIG.

In the configuration shown in FIG. 7, an analog signal extracted from an electrode 60 attached to a human body (not shown) is supplied to a non-inverting terminal of a differential amplifier 63 via an amplifier 61 and a resistor 62. has been done. Further, the analog signal taken out from the electrode 60 described above is supplied to the inverting terminal of the differential amplifier 63 via an amplifier 64 and a resistor 65. The analog signal mentioned above is an electrical signal output from the myocardium when the heart beats.

On the other hand, the above-mentioned reference pulse PST is
8. This reference pulse PST is supplied to the non-inverting terminal of the differential amplifier 63 via a capacitor 69, a buffer 70, and a resistor 71.

Furthermore, a bias voltage V is applied to maintain the baseline level LSL of the electrocardiogram waveform shown in FIG. 8 at a constant level.
BI via the resistor 73, buffer 70, and resistor 71,
It is supplied to the non-inverting terminal of the differential amplifier 63.

The output of the differential amplifier 63 is supplied to an A/D converter 75 via a low-pass filter 66, and is also fed back to the inverting terminal of the differential amplifier 63 via a resistor 67.

[0010] The A/D converter 75 samples the above-mentioned analog signal at the timing of a sampling signal of a predetermined frequency supplied via a terminal 76, and converts it into digital data. This digital data is supplied to a signal processing circuit 77.

[0011] In the signal processing circuit 77, the digital data supplied from the A/D converter 75 is subjected to processing such as addition of an error correction code, filtering, interleaving, channel coding, etc., to form a digital recording signal. Ru.

This digital recording signal is sent to the recording amplifier 78.
is supplied to the magnetic head 79 via the
is recorded on the magnetic tape 80 by.

[0013]

As shown in the above-mentioned prior art, there is a problem in that simply adding the reference pulse PST to the electrocardiographic waveform may not accurately display the reference level.

[0014] The electrocardiographic waveform recording device used in Holter electrocardiography is generally required to be small and lightweight, so the reference pulse PST is usually maintained for several seconds to several minutes after the start of electrocardiographic waveform recording. It is automatically added to the electrocardiogram waveform recording.

For this reason, if the reference pulse PST is added to the electrocardiographic waveform in an unfavorable state, it may be recorded in the unfavorable state, and an improvement has been desired. An example will be explained below.

FIG. 8 shows one-beat electrocardiographic waveforms WEH1 and WEH2 consisting of P wave P, QRS wave QRS, and T wave T.
It is shown. In addition, QRS wave QRS is Q wave Q, R
It consists of wave R and S wave S.

As mentioned above, simply adding the reference pulse PST to the electrocardiogram waveform does not allow the reference pulse PST to be added to the electrocardiogram waveform, for example, P wave P, T wave, as shown by the dashed line in FIG. It may be superimposed on T, etc.

In such a case, even if the electrocardiogram waveform is displayed on recording paper or other display means, the level of the reference pulse PST will vary, making it difficult to display the reference pulse PST correctly. As a result, it is not possible to correctly display 1 mV as a reference level.

Accordingly, an object of the present invention is to provide an electrocardiographic waveform recording device that can accurately record a reference level in any case. Another object of the present invention is to provide an electrocardiographic waveform recording device that can easily form and record a reference pulse for representing a reference level.

[0020]

[Means for Solving the Problem] The invention as claimed in claim 1 provides an electrocardiographic waveform recording device that inserts and records a reference signal into an electrocardiographic waveform, in which a first switch means controlled by a first pulse is provided. a second switch means controlled by the second pulse; and a bias means connected to the second switch means whose connection is switched by the second pulse, the bias means being connected to the input side of the first switch means. The electrocardiographic waveform signal and the output from the bias means are supplied via the second switch means, and the electrocardiographic waveform signal and the output from the bias means are supplied to the first switch by controlling the first pulse. It is configured to be selectively taken out from the means.

[0021] The invention of claim 2 is an electrocardiographic waveform recording device that inserts and records a reference signal into an electrocardiographic waveform, in which a predetermined signal is supplied to one terminal, and the signal is delayed for a predetermined period. The present invention is configured to include an AND gate and an OR gate whose other terminals are supplied with a delayed signal, and to form a first pulse and a second pulse based on the signal and the delayed signal.

[0022]

[Operation] In the electrocardiographic waveform recording device according to claim 1, the first
Before the pulse is supplied, the electrocardiographic waveform is selected by the first switch means.

[0023] At a predetermined timing, the first pulse
When the signal is supplied to the first switch means, the connection state is controlled in the first switch means so as to select the output from the second switch means. While the first pulse is being supplied to the first switch means, the output from the second switch means is selected in place of the electrocardiographic waveform.

[0024] Before the second pulse is supplied, the second
Since the switch means is connected to the first bias voltage at a relatively low level, the first bias voltage is output from the second switch means via the first switch means.

[0025] At a predetermined timing, the second pulse
When the voltage is supplied to the second switch means, the connection state is switched to a relatively high level second bias voltage in the second switch means. Only while the second pulse is being supplied to the second switch means, the second bias voltage is output from the second switch means via the first switch means.

[0026] Therefore, a reference pulse formed by the first and second bias voltages is inserted into the electrocardiographic waveform. Since this reference pulse displays a reference level of 1 mV due to the potential difference between the first and second bias voltages, the reference level can be correctly displayed regardless of the position where the reference pulse is applied.

[0027] In the electrocardiographic waveform recording device according to claim 2,
When forming the above-mentioned first pulse and second pulse,
A signal defining the timing of the reference pulse is provided to one terminal of the AND gate and the OR gate.

Further, a delayed signal obtained by delaying the signal defining the timing of the reference pulse by a predetermined period is supplied to the other terminals of the AND gate and the OR gate.

A second pulse is formed from the AND gate, which is at a high level only during a period when both the signal and the delayed signal are at a common high level. Further, the OR gate generates a first pulse that is at a high level only during a period when either the signal or the delayed signal is at a high level.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 6. In the configuration of FIG. 1, an analog signal taken out from one terminal of an electrode 1 attached to a human body (not shown) is supplied to a non-inverting terminal of a differential amplifier 2, and from the other terminal of the electrode 1. The extracted analog signal is supplied to the inverting terminal of the differential amplifier 2. This analog signal is an electrical signal output from the myocardium when the heart beats.

An analog signal SHR representing an electrocardiographic waveform is supplied from the differential amplifier 2 to a reference pulse insertion circuit 7 via a high-pass filter 5 consisting of a capacitor 3 and a resistor 4 and an amplifier 6. Figure 3C is connected between resistor 4 and ground.
A bias voltage VBI0 is provided in order to keep constant the baseline level LSL of the electrocardiographic waveform shown in FIG.

In the first pulse generation circuit 8, a switch control signal SSW1 is generated, and the switch control signal SSW1 is supplied to the reference pulse insertion circuit 7. In the second pulse generation circuit 9, a switch control signal SSW2 is generated, and the switch control signal SSW2 is supplied to the reference pulse insertion circuit 7. The switch control signals SSW1 and SSW2 may be formed by software using a microprocessor instead of the first pulse generation circuit 8 and the second pulse generation circuit 9.

The configuration of the reference pulse insertion circuit 7 is shown in FIG. In the configuration of FIG. 2, 21 and 22 are respectively
It represents a switch circuit, and VBI1 and VBI2 are respectively
Represents bias voltage. In addition, the bias voltage VBI1
, VBI2 is set to [VBI1<VBI2]. The potential difference between the bias voltages VBI1 and VBI2 [=VBI2-VBI1] is, for example, 1 mV.
It is said that

The terminal 21a of the switch circuit 21 is the terminal 23
The terminal 21b is connected to the terminal 22c of the switch circuit 22, and the terminal 21c is connected to the output terminal 24. This switch circuit 21 is controlled by a switch control signal SSW1 supplied via a terminal 25.

The terminal 22a of the switch circuit 22 is connected to the bias voltage VBI1, the terminal 22b is connected to the bias voltage VBI2, and the terminal 22c is connected to the terminal 21b of the switch circuit 21 described above. This switch circuit 22 is controlled by a switch control signal SSW2 supplied via a terminal 26.

In a normal state in which the switch control signal SSW1 shown in FIG. 3A is supplied to the terminal 25 at a low level, for example, the switch circuit 21 supplies the terminals 21a and 25 with the switch control signal SSW1 shown in FIG.
1c is connected. Therefore, the analog signal SHR representing the electrocardiographic waveform supplied via the terminal 23 is selected and output from the terminal 24.

The switch control signal SSW is connected to the terminal 25 mentioned above.
1 is supplied at a high level, for example, the terminals 21b and 21c of the switch circuit 21 are connected, and the output of the switch circuit 22 is selected.

In the switch circuit 22, in a normal state where the switch control signal SSW2 shown in FIG. 3B is supplied at a low level, for example, terminals 22a and 22c are connected. Therefore, at this time, bias voltage VBI1 is taken out from terminal 24 via switch circuits 22 and 21.

In the above state, the terminals 22b and 22c of the switch circuit 22 are connected only during the period when the switch control signal SSW2 is supplied to the terminal 26, for example, at a high level.

At this time, bias voltage VBI2 is taken out from terminal 24 via switch circuits 22 and 21.

FIG. 3C shows a state in which the reference pulse PST formed by the bias voltages VBI1 and VBI2 described above is superimposed on the electrocardiographic waveform.

In FIG. 3C, the electrocardiographic waveform WE at the first beat
A reference pulse PST is inserted between H1 and the second beat electrocardiographic waveform WEH2. In this reference pulse PST, the bias voltage V is applied between time points t0 to t1 and t2 to t3.
BI1 is applied, and a bias voltage VBI2 is applied between time points t1 and t2.

As shown in FIG. 3C, from time t1 to t2
The bias voltage VBI2 added to the time t0~
Bias voltage VBI added to t1, t2 to t3
1 has a potential difference of 1 mV as a reference level [=VBI
2-VBI1], no matter where the reference pulse PST is recorded in the electrocardiogram waveform WEH, it is guaranteed that the
The reference level of mV can be displayed correctly, and when displayed on recording paper or other display means, the reference level can be displayed correctly.

In the electrocardiographic waveform, it is desirable that the reference pulse PST is displayed at a period and position similar to the electrocardiographic waveforms WEH1 and WEH2, so if the bias voltage VBI0 and the bias voltage VBI1 are made equal, the electrocardiographic waveform can be further improved. Easy to see and high level switch control signal SSW1
By adjusting the timing of supplying the reference pulse PST, the reference pulse PST can be inserted at any position in the electrocardiographic waveform WEH.

In this way, the electrocardiographic waveform WEH is formed by superimposing the reference pulse PST. Analog signal SHR0 representing this electrocardiographic waveform WEH is supplied to A/D converter 11 via low-pass filter 10.

The A/D converter 11 generates an analog signal S representing the above-mentioned electrocardiographic waveform WEH at the timing of a sampling signal of a predetermined frequency supplied via the terminal 16.
HR0 is sampled and converted to digital data. This digital data is supplied to the signal processing circuit 12.

[0047] In the signal processing circuit 12, the digital data supplied from the A/D converter 11 is subjected to processing such as addition of an error correction code, filtering, interleaving, channel coding, etc., to form a digital recording signal. Ru.

[0048] This digital recording signal is sent to the recording amplifier 13.
is supplied to the magnetic head 14 via the
is recorded on the magnetic tape 15 by.

According to this embodiment, the switch circuit 22 of the reference pulse insertion circuit 7 is controlled by the switch control signal SSW2, and the extracted bias voltages VBI1, VB
Based on I2, a reference pulse PST that correctly maintains a reference level of, for example, 1 mV can be formed, and the switch circuit 21 of the reference pulse insertion circuit 7 generates the switch control signal SS.
Controlled by W1, reference pulse PST is converted into electrocardiographic waveform WE
It can be inserted at any position in H.

In this way, the reference pulse PST can be inserted at any position in the electrocardiographic waveform WEH, and the reference level can always be correctly set no matter where the reference pulse PST is recorded in the electrocardiographic waveform WEH. It can be displayed on recording paper or other display means.

FIGS. 4 to 6 show modifications of this embodiment. In the configuration of the embodiment shown in FIGS. 1 to 3 described above, the switch control signals SSW1 and SSW2 are generated using the first pulse generation circuit 8 and the first pulse generation circuit 9.

As mentioned above, in Holter electrocardiography,
Since electrocardiographic waveforms are recorded over a long period of time, electrocardiographic waveform recording devices are required to be small and lightweight so that they can be carried for long periods of time.

In the configuration of the above-described embodiment, two pulse generating circuits, wiring, etc. are required, which may increase the circuit scale. Therefore, by forming these two switch control signals SSW1 and SSW2 in one circuit, it becomes possible to further reduce the circuit scale, and a compact and lightweight recording device suitable for Holter electrocardiography becomes possible. .

Therefore, in this modification, the two switch control signals SSW1 and SSW2 are collectively generated by the pulse generating circuit 31. Below, Figure 4
A modification will be described with reference to FIGS. 6 to 6. Note that parts common to those in the above-mentioned embodiment are given the same reference numerals, and redundant explanations will be omitted.

The configuration of the pulse generating circuit 31 in FIG. 4 is shown in FIG. A pulse PT that defines the generation timing of the reference pulse PST shown in FIG. 6A is transmitted via the terminal 35.
1 is supplied to one terminal of each of an AND gate 36 and an OR gate 37, as well as an integrating circuit 40 consisting of a resistor 38 and a capacitor 39. The reference pulse PST may be used as the above-mentioned pulse PT1.

In the integrating circuit 40, the pulse PT1 is delayed to form the pulse PT2 shown in FIG. 6B. This pulse PT2 is supplied to the other terminals of the AND gate 36 and the OR gate 37, respectively. The pulse width of this pulse PT2 can be set appropriately by appropriately determining the values of the resistor 38 and capacitor 39.

In the OR gate 37, the pulses PT1, PT
The switch control signal SSW1 that becomes high level is formed at time points t0 to t3 when one of the two signals becomes high level. This switch control signal SSW1 is taken out from the terminal 42,
It is supplied to the reference pulse insertion circuit 7.

In the AND gate 36, the pulses PT1, P
At the time t1 to t2 when both T2 become high level,
A switch control signal SSW2 having a high level is generated. This switch control signal SSW2 is taken out from the terminal 41 and supplied to the reference pulse insertion circuit 7.

According to this modification, the AND gate 36,
By using a pulse generating circuit 31 consisting of an OR gate 37 and an integrating circuit 40, a switch control signal S is generated from a pulse PT1 that defines the generation timing of a reference pulse PST.
SW1 and SSW2 can be formed, thereby making it possible to further reduce the circuit scale and making possible a compact and lightweight recording device suitable for Holter electrocardiography.

[0060]Although this embodiment is explained using an electrocardiogram waveform as an example, the present invention is not limited to this.
It is also possible to apply to other narrowband, low-frequency biological signals, such as myoelectric waveforms and brain waves.

[0061]

According to the electrocardiographic waveform recording apparatus according to the invention of claim 1, only while the first pulse is being supplied to the first switch means, the first switch means The connection state is controlled to select the output from the second switch means, and in this state, the second switch means selects the output from the first switch means.
A first bias voltage at a relatively low level is applied to the switching means until the second pulse is applied, and a first bias voltage at a relatively high level is applied only while the second pulse is applied. Since two bias voltages are supplied, the first and second bias voltages can form a reference pulse that accurately maintains the potential difference at the reference level.
This has the advantage that the reference pulse can be inserted at any position in the electrocardiographic waveform.

[0062] Further, there is an effect that the potential difference between the second bias voltage and the first bias voltage as a reference level can be correctly displayed regardless of the position where the reference pulse is superimposed.

According to the electrocardiographic waveform recording device according to the second aspect of the invention, the signal for determining the timing of the reference pulse is
By supplying the signal to one terminal of the AND gate and the OR gate, and supplying a signal obtained by delaying the signal to the other terminal of the AND gate and the OR gate, the first and second pulses can be formed. .

[0064] This makes it possible to further reduce the circuit scale, and has the effect of making possible a compact and lightweight recording device suitable for Holter electrocardiography.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of an electrocardiographic waveform recording device according to the present invention.

FIG. 2 is a circuit diagram showing a reference pulse insertion circuit.

FIG. 3 is an explanatory diagram showing a state in which a reference pulse is inserted into an electrocardiographic waveform.

FIG. 4 is a block diagram showing a modification of the electrocardiographic waveform recording device according to the present invention.

FIG. 5 is a block diagram showing a pulse generation circuit.

FIG. 6 is a timing chart showing the operation of the pulse generation circuit.

FIG. 7 is a block diagram showing a conventional electrocardiographic waveform recording device.

FIG. 8 is an explanatory diagram showing a state in which a reference pulse is superimposed on an electrocardiographic waveform.

[Explanation of symbols]

7 Reference pulse insertion circuit 8 First pulse generation circuit 9 Second pulse generation circuit 21, 22 Switch circuit 35 Terminal 36 AND gate 37 OR gate 40 Integrating circuit SSW1, SSW2 Switch control signals VBI, VB
I0, VBI1, VBI2 Bias voltage SHR
Analog signal PT1, PT2 pulse

Claims (2)

[Claims] 1. An electrocardiographic waveform recording device that inserts and records a reference signal into an electrocardiographic waveform, comprising: a first switching means controlled by a first pulse; and a second switching means controlled by a second pulse. bias means connected to the second switch means and whose connection is switched by the second pulse, and an electrocardiographic waveform signal on the input side of the first switch means; The output from the bias means is supplied via the second switch means, and the electrocardiographic waveform signal and the output from the bias means are selectively transmitted from the first switch means by the control of the first pulse. An electrocardiographic waveform recording device characterized in that the electrocardiogram is taken out. 2. In an electrocardiographic waveform recording device that inserts and records a reference signal into an electrocardiographic waveform, a predetermined signal is supplied to one terminal, and a delayed signal obtained by delaying the signal for a predetermined period is generated. and an AND gate and an OR gate supplied to the other terminal, and based on the above signal and the delayed signal, the first
An electrocardiographic waveform recording device, characterized in that it forms a pulse and a second pulse.