JPS61228826A - Electrocardiograph - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Industrial Application Field The present invention detects cardiac potentials from multiple points on the body surface, and uses the detected electrocardiographic signals to create a cardiac potential distribution map on the body surface or heart surface. This invention relates to an electrocardiograph that is created and detects electrocardial diseases from an electrocardiogram.

B. Prior art The electrocardiograph that is commonly used measures temporal potential changes at six points on the chest, and displays the time on the horizontal axis and the potential on the vertical axis. Heart abnormalities were discovered from the observed waveforms. However, depending on this type of electrocardiograph,
It is difficult to clearly examine all cardiac electrical phenomena. In recent years, the most advanced electrocardiograph has been installed on the body surface near the heart, at 80 to 200 electrodes, and the electrocardiogram collects cardiac potential from all of them to comprehensively judge the electrical phenomena of the heart. A meter was developed.

As shown in FIG. 1, this electrocardiograph creates a body surface electrogram near the heart at a certain time. This body surface electrogram shows the height of the body surface potential using equipotential lines to examine the potential distribution on the body surface.The potential of each electrode at a certain time is stored, for example, temporarily in memory, and each Based on the potential of the electrodes, equipotential points are calculated by a computer, and equipotential lines are drawn, for example, on a VcXY plotter with a pitch of several tens of microports or on a monitor television.

This electrocardiograph displays multiple potential distribution maps at regular time intervals, and by looking at changes in the body surface electrogram, it can detect expansion of the positive or negative area on the surface of the heart, the state of contraction, and changes in the potential gradient. etc. are obvious at a glance, and electrocardiographic phenomena are clearly displayed.

By the way, the cardiac potential detected by the electrodes is an extremely low electrical signal of only a few millivolts, and the electrical impedance of the body, the electrodes, and the body itself is extremely high.Therefore, the input impedance of the amplifier connected to the electrodes is also extremely low. M
Due to the extremely high impedance of Ω or more, the
It is susceptible to induced noise in the range of 0 to 60 Hz. Therefore, the electrocardiographic signal induced in each electrode is an alternating current of 50 or 60 Hz.
The induced noise component is removed by a filter.

The above-mentioned inductive noise can also be removed by not using a filter and by narrowing the amplification bandwidth of the electrocardiographic signal amplifier to 50 to 60 Hz or less. IC8
Problems with the conventional methods In either method, the electrocardiographic signal from which inductive noise has been removed is transmitted with a considerable delay depending on the frequency component, that is, as the frequency component of the electrocardiographic signal approaches 50 to 60 Hz. . Conventional electrocardiographs display changes in cardiac potential at each measurement point, with time on the horizontal axis and cardiac potential on the vertical axis. There are no negative effects.By the way, based on the cardiac potential detected by many electrodes,
An electrocardiograph that displays a potential distribution diagram on the body surface has a phase delay in the electrocardiographic signal amplifier around 5 (1" 60 Hz), which causes electrical phenomena that occur rapidly in a narrow region of the body surface, such as
It is not possible to accurately capture cardiac electrical phenomena such as so-called break-through, in which a negative region suddenly appears in a positive region, and its shape changes considerably in about 2 milliseconds.

The present invention was developed with the aim of eliminating this drawback, and an important purpose of the present invention is to accurately detect sudden electrical phenomena unique to the heart, such as breakthroughs, that occur on the body surface or the heart surface. It is to provide an electrocardiograph that can be displayed.

D. Means for solving the conventional problems Each electrocardiographic signal detected by a plurality of electrodes is separately and independently amplified by an amplifier. The amplifier that amplifies each electrocardiogram signal is
The phase delay at 50 or 60 Hz is set to 45 degrees or less with respect to 10 Hz, and a potential distribution map is created based on an electrocardiographic signal with a small phase delay.

E6 Actions and Effects At 50 or 60 Hz, an electrocardiographic signal amplifier with little phase delay amplifies fast rising and falling electrocardiographic signals without time delay. Therefore, one of the many electrodes,
Alternatively, when the cardiac potential changes instantaneously across several electrodes, this is transmitted without time delay, the potential difference with the instantaneous contact electrodes is accurately measured, and a locally changed potential distribution map is displayed.

How the phase delay adversely affects the electrocardiogram is explained based on FIGS. 1 and 2.

Figure 1 is a body surface potential diagram of an electrocardiograph that uses an amplifier to capture all electrocardiogram signals with a phase shift within ±3 degrees at Q, 1H2 to 100Hz. ,C,D,
The phase of the electrocardiogram signal detected by electrodes E and F is
A potential distribution diagram calculated with a delay of 90 degrees in z is shown.

Figures 1 and 2 were measured on the same person under the same conditions. However, since the measurements in FIG. 2 were made with the electrodes reattached, there are some differences in the equipotential lines at locations other than the phase lag portions.

In addition, in the electrocardiographic potential distribution diagram in Fig. 2, in order to clarify the influence of phase delay, only the electrocardiographic signals at points A, B, C, D, E, and F are delayed by a bandpass 7' ilter. Ike's electrocardiogram signal had a phase delay of 3 degrees or less.

As is clear from these figures, near the measurement point where the phase of the amplifier lags, rapid voltage changes cannot be followed, resulting in distortion of the equipotential lines.

Furthermore, Figures 3 and 4 are electrocardiograms with different measurement times; in Figure 3, the phase lag of all measurement points is within 3 degrees at 60H2K, and in Figure 4, the phase lag of all measurement points is within 3 degrees, and in Figure 4, points A, B, - --- It is a cardiac potential distribution diagram when points E and F6 are delayed by 90 degrees at 60H2. At this time, there are no sudden changes in electrical potential in the heart;
There is almost no distortion in the potential distribution diagram due to the phase delay of the amplifier.

Figures 1 and 2 are body surface electrocardiograms when the electrocardiogram changes significantly, as shown by the arrow α in Figure 5. Figures 3 and 4 are body surface electrocardiograms when the electrocardiogram changes significantly, as shown by the arrow α in Figure It is a body surface electrocardiogram when the electrocardiogram changes slowly as indicated by β.

From this, if there is a phase lag in the amplifier, the electrocardiogram will not be able to clearly display the rapid fluctuation portion when the electrocardiogram changes rapidly. This is because the amplifier's transmission characteristics transmit electrocardiographic signals that change slowly without any phase delay, but as shown in Figure 6, rapid changes cause a time delay (1,) and each Even if the phase characteristics of all amplifiers are the same, the electrocardiographic signals detected at the point electrodes will differ in time due to the difference in the rate of change of the electrocardiographic waveform.
Points that change slowly are transmitted as they are in the waveform,
Points that change rapidly are transmitted with a time delay. For this reason,
This is the same situation as if each amplifier had a phase difference, causing distortion in the displayed potential distribution diagram.

F. Preferred Embodiment The electrocardiograph shown in FIG. 7 includes a plurality of amplifiers 1 for amplifying electrocardiographic signals detected by electrodes, and A for converting the output signal of the amplifiers 1 from an analog quantity to a digital quantity. /D converter 2, A/D converter 2 and memory 3 are sterilized,
It is provided with a controller 5 that sends the output of the A/D converter 2 to all the memories 3, and an arithmetic display means 4 that performs arithmetic processing on the values stored in the memory 3 to create a potential distribution diagram.

Amplifier 1 amplifies the detected potential of each electrode separately. Therefore, when there are 80 to 200 electrodes, each detecting a separate cardiac potential, 80 to 200 amplifiers are required.

The amplifier amplifies, for example, 1000 to 2000 times the several millivolt electrocardiographic signal induced in the electrodes. This amplifier 1 transmits the electrocardiographic signal to the A/D converter with a small phase difference.

The phase delay of the amplifier is due to the frequency components included in the electrocardiogram signal,
It is determined by considering the resolution ability of the electrode and measurement error.

The electrocardiogram signal includes frequency components of several tens of Hz.

If you measure the potential distribution diagram at regular intervals and look at the changes, the changes will not change significantly over most of the time if you measure at 2 millisecond intervals. Therefore, if an amplifier can shift the time delay of a 60H2'' signal within 2 milliseconds, the phase lag angle at 60Hz will be within 45 degrees. However, within the heartbeat, there is a time period in which the equivalent potential distribution map changes every 2 milliseconds, although this is an extremely short time period. In order to more accurately display the potential distribution diagram in this time period, it is preferable to set the time delay of 6g+z- to 1 millisecond or less, that is, to set the phase delay to within about 20 degrees.

The ideal amplifier is 1-100Hz as shown in Figure 8.
It is determined that the phase shift in the angle is within ±5 degrees. 5QH2
Alternatively, an amplifier with a small phase difference at 60 Hz cannot remove the induced noise from the 5QH2 or 60 Hz AC 100 V power supply induced in the electrode.

As mentioned earlier, electrocardiographs that measure electrocardiographic waveforms at six points on the body surface near the heart, with time on the horizontal axis and voltage on the vertical axis, produce 50 or 60 H2 induced noise in the observed waveforms. This has a significant negative impact on the observation of electrocardiographic waveforms.

However, since the electrocardiograph of the present invention displays a potential distribution map based on the difference in potential between each observation point, even if induced noise of the same phase and level appears in all electrodes, calculations are made based on the potential difference component. It does not have much of an adverse effect on the processed potential distribution map. That is, waveform distortion due to induced noise is extremely small.

From this, compared to the conventional electrocardiograph that observes 6-point waveforms, the electrocardiograph of the present invention is resistant to induced noise of 50 or 60 Hz, and noise from 100 V AC is induced to the detection potential of the electrodes to some extent. can be measured accurately.

In addition, the induced noise induced in the electrode
By connecting a head amplifier close to the electrodes, the amount can be reduced sufficiently so as not to affect the measurement.

While the heart beats one or several times, the controller 5
The electrocardiographic log signal from the amplifier 1 is A/D converted at intervals of several hundred microseconds or several milliseconds, and is sent to the memory 3 for storage.

There is one A/D converter 2 for each electrode, that is, the same number as the number of electrodes, and each electrode detects the A/D converter 2.
All the electrocardiographic signals amplified by the controller 5 are simultaneously A/D converted and stored in the memory 3 under the control of the controller 5.

The calculation display means 4 calculates the body surface at a specific time based on the voltage value of each electrode at each time stored in the memory 3.
Alternatively, the entire potential distribution map on the surface of the heart, etc. is calculated and displayed on a monitor television, xY plotter, etc.

The potential distribution map on the heart surface is calculated by a computer based on the detected potential on the body surface and the resistance value between the heart and the body surface.

In the electrocardiograph shown in FIG. 9, the arithmetic processing means includes a sample hold circuit 6 and a light emitting diode 7.

The sample and hold circuits 6, which have the same number of electrodes, temporarily store the output signal of the amplification N1 as a signal from the controller, and the storage potential of the sample and hold circuit 6 is amplified by the power amplifier 8, and the light emitting diode 7 is Shine brightly according to the voltage value.

Further, in the electrocardiograph shown in FIG. 10, the arithmetic processing means 4 includes a resistance matrix circuit 9 and a light emitting diode 7.

As shown in FIG. 11, the resistance matrix circuit 9 has the output of the booster 1 connected to the intersection point A of the resistances connected in a grid pattern,
A light emitting diode 7 is connected to the intersections a, b, c, d...y of the resistors connected to B-...I, and connected to this intersection.

In FIGS. 8 and 9, light emitting diodes 7 are arranged corresponding to positions where electrodes are attached to the body surface, and the potential on the body surface is indicated by the luminance of the light emitting diodes.

The electrocardiograph shown in FIG. 3 can observe the electrocardiographic potential distribution map on the body surface at a certain time while standing still. In the electrocardiograph shown in FIG. 4, a light emitting diode 7 displays the potential distribution on the body surface in real time.

[Brief explanation of the drawing]

Figures 1 to 4 are electrocardiograms on the body surface, Figure 5 is an electrocardiogram waveform showing the measurement time of the electrocardiograms on the body surface in Figures 1 to 4, and Figure 6 is a solid line. 7, 9, and 10 are block diagrams showing an example of an electrocardiograph; FIG. is a phase characteristic graph of the amplifier, and FIG. 11 is a resistor matrix circuit diagram. 1. Multiplier, 2. A/D converter, 3. Memory, 4. Arithmetic display means, 5. Controller, 6. Sample and hold circuit, 7. Light emitting diode, 8. Power amplifier. , 9...resistance matrix circuit,

Claims (6)

[Claims] (1) Electrodes that detect cardiac potentials from multiple points on the body surface, multiple amplifiers that amplify each cardiac potential detected by the electrodes, and calculation display means that creates a cardiac potential distribution map from the output signals of the amplifiers. In an electrocardiograph consisting of
An electrocardiograph characterized in that a phase delay at 0 Hz is 45 degrees or less with respect to 10 Hz. (2) The phase characteristics of each amplifier are ±2 at 5 to 100Hz.
The electrocardiograph according to claim (1), which is within 0 degrees. (3) The electrocardiograph according to claim (1), wherein the electrodes detect cardiac potentials at 80 to 200 points. (4) The electrocardiograph according to claim (1), wherein the calculation display means displays an electrocardiogram on the body surface. (5) The electrocardiograph according to claim (1), wherein the calculation display means displays a potential distribution diagram on the surface of the heart. (6) The electrocardiograph according to claim (1), wherein the calculation display means continuously displays the potential distribution on the body surface in brightness.