JP2691817B2 - Portable electrocardiograph - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is to carry a patient on a daily basis to measure electrocardiographic data, record electrocardiographic data for a certain period of time before or after subjective symptoms, or continuously, and, if necessary, electrocardiographic waveforms. The present invention relates to a portable electrocardiograph configured to be reproduced and displayed as.

[0002]

2. Description of the Related Art When an electrocardiogram waveform is reproduced and displayed to determine the presence or absence of heart disease, S is used as a reference material for qualitative diagnosis.
Often we observe changes in T levels.

The electrocardiographic data to be displayed on a display device such as a liquid crystal as an electrocardiographic waveform is often so-called event-recorded electrocardiographic data. This event recording is performed by pressing the event switch when the patient feels subjective symptoms such as palpitation or chest pain during measurement, and, for example, the electrocardiogram for a total of 2 minutes from 1 minute before the subjective symptoms to 1 minute after the subjective symptoms. It stores data.

In the conventional method of reproducing and displaying the electrocardiogram waveform in the portable electrocardiograph, the level corresponding to the potential 0 mV of the A / D converted value of the electrocardiogram signal is set as the zero level line, and the zero level line is displayed above and below the display screen. It was set to match the center position in the direction.

When a diagnostician such as a doctor makes a qualitative diagnosis by observing how the ST level changes, he or she operates the left and right scroll keys to change the electrocardiogram waveform in the time axis direction (horizontal direction). Scroll one heartbeat at a time. In this case, the display magnification of the electrocardiogram waveform is set large so that the change in ST level can be well understood.

[0006]

However, in the case of an electrocardiographic waveform in which a zero level sway occurs at the time of measurement, scrolling by one heartbeat at a large display magnification causes the electrocardiographic waveform to be displayed on the screen as the zero level sway occurs. Since it is displayed in a state of being largely shaken in the vertical direction, it becomes difficult for the diagnostician to correctly read the change in ST level. If the vertical shake becomes excessively large, the ST level itself cannot be read.

When it becomes difficult or impossible to read the change in the ST level while scrolling by one heartbeat, the diagnostician interrupts the scrolling temporarily and operates the up / down scroll keys to make a large shake in the upward or downward direction. The electrocardiogram waveform is moved to an appropriate position, and the left and right scroll keys are operated again to scroll the electrocardiogram waveform one beat at a time.

When the measured electrocardiogram waveform has a fluctuation of zero level, the troublesome correction work as described above has to be repeated many times. This required a very time-consuming work, which was a great obstacle to the diagnosis based on the reading of ST level changes.

The present invention was devised in view of such circumstances, and when a change in the ST level is read while scrolling the ECG waveform with a large display magnification set, the ECG waveform is measured at the time of measurement. An object of the present invention is to enable the ECG waveform to be scrolled while always being displayed at an appropriate position, even if it involves zero level sway.

[0010]

A portable electrocardiograph according to the present invention displays means for storing electrocardiogram data obtained from a patient and electrocardiogram waveforms under the display magnification selected in the reproduction display mode. And a selected display magnification is equal to or higher than a predetermined magnification, a predetermined time before the R wave apex is determined as a display reference point for each heartbeat, and the A / D conversion value at the display reference point is displayed in advance. And a means for displaying an electrocardiogram waveform in a state of being coincident with a central base line fixedly set at a substantially central position in the vertical direction of the screen.

[0011]

The baseline when the display magnification is equal to or higher than the predetermined magnification is a central baseline fixedly set in advance at a substantially central position in the vertical direction of the display screen. Then, for each heartbeat, the A / D converted value before the R wave apex is obtained as the display reference point, and the electrocardiogram waveform is displayed so that the A / D converted value at the display reference point is located at the central baseline. To do.
Therefore, regardless of whether or not the electrocardiographic waveform is associated with zero level fluctuation during measurement, and regardless of the scrolling of the electrocardiographic waveform in the time axis direction, the electrocardiographic waveform of each heartbeat is always displayed at the proper position. Can, ST
The level change can be read accurately and easily.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a portable electrocardiograph according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing an electrical configuration of a main part of the portable electrocardiograph.

In the figure, 2 is a body surface electrode to be worn on a patient, 4 is an electrocardiographic amplifier for amplifying an electrocardiographic signal picked up by the body surface electrode 2, and 6 is an amplified analog electrocardiographic signal for digital electrocardiographic data. Convert A
A / D converter, 8 is a central processing unit of a microcomputer and is in charge of overall control, 10 is a ROM storing programs, 12 is a RAM as a working memory, and 14 is a liquid crystal driver which is driven and controlled by the CPU 8. , 16 are liquid crystal display devices configured by arranging fine liquid crystal display elements in a matrix vertically and horizontally so that various data can be displayed in any of numerical values, graphs, and waveforms.
Reference numeral 8 is a touch key for inputting various operations, and 20 is an event switch that is pressed when the patient feels subjective symptoms such as palpitation or chest pain. The touch keys 18 are formed on a transparent plate according to the key display of the liquid crystal display device 16.

The RAM 12 stores electrocardiogram data sampled by the A / D converter 6 together with time information.
8 has a storage area for temporarily storing in a memory loop method. The CPU 8 has a function of calculating the heart rate based on the electrocardiogram data temporarily stored in the RAM 12. The RAM 12 has an area for storing heart rate / trend data obtained by calculation together with time information. The CPU 8 has a function of causing the RAM 12 to store, as event waveform data, a total of 2 minutes of electrocardiographic data, one minute before and one minute before and after the operation of pressing the event switch 20. RAM1
2 is the electrocardiogram data of at least 2 heartbeats and 48
It has enough capacity to store the heart rate / trend data for time.

2 to 4 show memory maps of the RAM 12.

As shown in FIG. 2, the RAM 12 comprises a main body side RAM 12a and a battery backed up IC card side RAM 12b. The main body side RAM 12a is a waveform measurement buffer area having an area for temporarily storing sampled electrocardiogram data for at least two heartbeats.

The IC card side RAM 12b stores a header portion 12b ₁ (see FIG. 3 for details) for storing the time when the electrocardiogram data measurement is started and the time when the event is recorded. Area 12b ₂ for storing data and waveform data, area 12b ₃ for storing QRS data and waveform data at the first event recording as event A, and QRS data and waveform data at the second event recording for event B Area 12b ₄ and an area 12b ₅ for storing the heart rate / trend data when displaying 24 hours on one screen as heart rate / trend data to be calculated within 48 hours, respectively. area 12b ₆ for storing 48 times the heart rate trend data when displaying 60-minutes on one screen, 1 Area 1 to store 288 times the heart rate trend data in the case of displaying the minutes minutes on one screen
2b ₇ and so on. Areas 12b _{2 to} 12b ₄ are event buffer areas.

The data structure of the area 12b ₂ ~12b ₄ is as shown in FIG. 4, because QRS time, each heartbeat QRS from the first one heartbeat data events recorded
A time point 160 msec before the R wave apex of the group is shown. And channel 0 at that QRS time
The A / D conversion value in channel 1 is stored for each heartbeat. Channels 0 and 1 are due to the difference in electrode arrangement. In this way, for each heartbeat, R
The point of the present invention is to store the A / D conversion value 160 msec before the wave peak.

FIG. 5 shows the dot configuration of the display screen of the liquid crystal display device 16 in which fine liquid crystal display elements are arranged in a matrix in the vertical and horizontal directions and various data can be displayed by any of numerical values, graphs and waveforms.

The display screen has 80 dots in the vertical direction (Y axis direction: potential axis direction) and 128 dots in the horizontal direction (X axis direction: time axis direction), and the upper left corner of the screen has X coordinate = 0, Y coordinate. It is the origin of = 0.

A display example on the liquid crystal display device 16 is shown in FIGS.

On this display screen, displays corresponding to various keys of the touch key 18 are also displayed.

FIG. 6 is a display example of the electrocardiogram waveform 100 when the display magnification is a general magnification other than the maximum magnification. d ₁ is A /
A zero level line corresponding to 0 mV of the D conversion value, d ₂ is a zero level line d ₁ and an up scroll key for scrolling the electrocardiogram waveform upward, and d ₃ is a zero level line d ₁ and the electrocardiogram waveform downward. Down scroll key for scrolling, d ₄ is zero level line d ₁
Is a centering key for moving to the center of the screen.

FIG. 7 shows a display example of the electrocardiogram waveform 200 when the display magnification is the maximum magnification. d ₅ is R wave vertices in one heartbeat, from R-wave vertex d ₅ in d ₆ is one heartbeat 160m
A display reference point set before sec, d ₇ is a display magnification switching key, and d ₈ is a waveform scroll key for scrolling the displayed waveform. Of these, d _8-1 and d _8-2 are 1
A right scroll key and a left scroll key for moving in heartbeat units, and d _8-3 and d _8-4 are a right skip key and a left skip key for scrolling by one screen unit.

In this embodiment, when the display magnification is the maximum magnification, the display reference point d ₆ is obtained for each heartbeat, and the A / D conversion value of each display reference point d ₆ is always displayed in advance on the display screen. The point is that the electrocardiogram waveform is displayed in a state in which it coincides with the central baseline d _center fixedly set at just the central position in the vertical direction.

Next, the operation of the portable electrocardiograph of this embodiment will be described with reference to the flow charts shown in FIGS.

When the power is turned on, the control operation by the CPU 8 is started. The electrocardiogram signal picked up by the body surface electrode 2 and amplified by the electrocardiographic amplifier 4 is A / D
Input to converter 6. The CPU 8 performs the following control operation according to the program read from the ROM 10.

When the power is turned on, the liquid crystal display device 16 is
The notation of the measurement key and the reproduction key is displayed as the touch key 18.

First, in step S1, it is determined whether or not the measurement key of the touch key 18 has been operated. If it is determined that the operation key has been operated, the routines of steps S2 to S8 are executed. Otherwise, in step S9, it is determined whether or not the reproduction key of the touch keys 18 is operated. If it is determined that the reproduction key is operated, the process proceeds to step S10, and if not, the process returns to step S1.

In step S10, the operation waits until either the event reproduction key or the trend reproduction key is pressed, and when it is judged that the trend reproduction key is operated, the routines of steps S11 and S12 are executed, and the event reproduction key is executed. Is determined to have been operated, step S
The routine of 13 to S23 is executed (details will be described later).

After the power is turned on, generally, the measurement key is first input. Therefore, the process proceeds to step S2 to control the A / D converter 6, and the A / D converter 6
The sampled ECG signal after amplification is sampled at predetermined time intervals, converted into digital ECG data by A / D conversion, and taken into the CPU 8. And CPU8
In step S3, the continuously sampled electrocardiogram data is transferred to the main body side RAM 12a in the RAM 12 together with the time information and is temporarily stored by the memory loop method.

FIG. 10 shows a detailed flow of the data storing operation in this memory loop method. In step S3-1, the CPU 8 transfers the electrocardiogram data, which has been digitally converted by the A / D converter 6, to the waveform measurement buffer area of the RAM 12a on the main body side in the RAM 12 and temporarily stores it. In step S3-2, it is determined whether or not the event storage based on the operation of the event switch 20 has been completed.
-3, but when it is completed, step S in FIG.
Skip to 4 (search for R-wave vertex).

In step S3-3, the CPU 8 causes the RA
The event buffer area of the IC card side RAM 12b in M12 is updated and stored so that the electrocardiogram data for the latest one minute before that is always stored as a starting point.

The stored contents are constantly changing until the event switch 20 is operated.

In step S3-4, it is determined whether or not the event switch 20 has been operated. If it is not operated, the process skips to step S4. If it is operated, the process proceeds to step S3-5 and the IC card side of the RAM 12 is operated. The update storage of the latest one minute of electrocardiographic data in the RAM 12b is stopped, and the latest one minute of electrocardiographic data stored at that time is stored together with time information on the IC card side RA.
It is fixedly stored in the event buffer area of M12b. Then, the electrocardiogram data for one minute thereafter is added together with the time information and fixedly stored.

As described above, when a patient feels subjective symptoms such as palpitation or chest pain and operates the event switch 20, the electrocardiographic data for a total of 2 minutes, one minute before and after the operation, is used as event waveform data (electrocardiographic data during an attack). IC card side RAM1 in RAM12 with time information
It is stored in 2b. Then, step S3-
After setting the event storage completion flag in step 6, step S
Proceed to 4.

Here, the description of the flow is returned to FIG.

The CPU 8 is RAM 12 in step S4.
An electrocardiogram waveform is analyzed based on the electrocardiogram data read out from the PC to search for data corresponding to the R-wave peak serving as a delimiter of one heartbeat. The R-wave vertex is a portion having the sharpest rise in the QRS complex, which is a feature point of the electrocardiogram waveform. As a method of searching for the R wave apex, for example, the value of the electrocardiogram data at a certain point in time exceeds 70% of the maximum value of the electrocardiogram data group within one heartbeat before that, and is a local maximum point. This can be realized by determining the conditions.

When it is recognized as the R-wave apex, step S5
Otherwise, returns to step S2 through steps S7 and S8, and then steps S2 to S4 and S
7. Repeat S8.

When the R wave apex is found, the process proceeds to step S5, and the heart rate is calculated. That is, the reciprocal of the time from the R-wave peak of the previous heartbeat to the R-wave peak of the current heartbeat is determined, and this is defined as the heart rate. The time is obtained by [sampling number × sampling cycle] between both R wave vertices.

Next, the CPU 8 transfers and stores the heart rate / trend data together with the time information in the IC card side RAM 12b in the RAM 12 in step S6.

As described above, the heart rate / trend data for one heartbeat is calculated and stored in the IC card side RAM 12b. The calculation / storing of the heart rate / trend data is repeated until the stop key of the touch key 18 is operated or 48 hours have elapsed from the start of measurement. That is, when it is determined in step S7 that the stop key of the touch keys 18 is operated, the process returns to step S1, and when it is determined in step S8 that the measurement time exceeds 48 hours, the power is automatically turned off. Then, the measurement of the electrocardiogram data is completed.

Unless the stop key is operated midway, the heart rate / trend data for each heartbeat for a maximum of 48 hours are stored in the IC card side RAM 12b of the RAM 12 together with the time information.

After the stop key is operated, or 48
When the power is turned on again after a lapse of time, the determination in step S1 is usually negative and the process proceeds to step S9. That is, the operation of the play key on the touch key 18 is waited for, and the process proceeds to step S10. Step S1
At 0, it waits for operation of either the trend reproduction key or the event reproduction key.

When it is determined in step S10 that the trend reproduction key has been operated, the process proceeds to step S11 and the heart rate /
Replay the trend graph. The detailed routine of this step S11 is shown in FIG. That is, step S
11-1, the CPU 8 sends the heart rate / trend data from the IC card side RAM 12b in the RAM 12 to the CPU.
8, and the heart rate / trend data is converted into the display data of the heart rate / trend graph in step S11-2. This heart rate / trend graph is
The horizontal axis represents time and the vertical axis represents the heart rate, which is a graph showing the temporal variation of the heart rate.

Then, the CPU 8 carries out step S11-3.
The display data of the heart rate / trend graph is transferred to the liquid crystal driver 14 with, and the liquid crystal driver 14 is transmitted with step S11-4
To display a heart rate / trend graph on the liquid crystal display device 16. Such a display is performed in step S12 of FIG.
The process is continued until it is determined that the stop key of the touch keys 18 has been operated.

If it is determined in step S10 that the event reproduction key has been operated, step S13
Proceed to. In step S13, the coordinate values on the screen for determining the zero level line d ₁ corresponding to the A / D converted value of the electrocardiogram signal of 0 mV are initialized. Step S14
Then, the electrocardiogram waveform 100 at the general magnification (other than the maximum magnification) is displayed on the liquid crystal display device 16 based on the initial coordinate value of the zero level line d ₁ . FIG. 12 shows the detailed routine of step S14.

In step S14-1, the electrocardiogram data (event electrocardiogram data) of the event waveform to be reproduced and displayed, which is determined by the waveform number, is read from the event buffer area of the RAM 12b in the RAM 12 of the IC card.

In step S14-2, the event waveform data to be reproduced and displayed is converted into display data with reference to the previously set zero level line d ₁ . Then, in step S14-3, the display data of the event waveform is transferred to the liquid crystal driver 14, the liquid crystal driver 14 is controlled in step S14-4 to display the electrocardiogram waveform 100 at the general magnification, and in step S15 of FIG. move on.

Here, the waveform numbers will be described. The waveform number means each event record (0, A,
It is assumed that the waveform number 0 of the oldest heartbeat obtained in B) is 0, and the numbers are sequentially assigned to new heartbeats in the following. This waveform number is used during waveform reproduction, and the heartbeat waveform of the waveform number to be displayed is displayed starting from the left end of the screen and directed toward the right side.

In the next step S15, the CPU 8 determines whether or not the display magnification is set to the maximum value, and when it is the general magnification, it executes the routine of steps S16 to S20 → S14, S15, and when it is the maximum magnification. Step S21-
The routine of S23 → S14 and S15 is executed.

Here, first, the case where the display magnification is set to the general magnification will be described. In this case, the process proceeds to step S16, and it is determined whether the display position of the waveform has been changed. That is, the up scroll key d shown in FIG.
₂ , down scroll key d ₃ or centering key d ₄
It is determined whether any one of them has been operated. When this determination is affirmative, the process proceeds to step S17, and the A / D
The zero level line d ₁ corresponding to the converted value of 0 mV is reset. FIG. 13 shows a detailed routine for resetting the display position of the zero level line.

[0054] At step S17-1, by operating the upward scroll key d ₂ or down scroll key d _3, seek should move the current zero-level line d ₁ what dots on or down. Step S17-2
Then, it is determined how many dots from the origin position the new zero level line d _{1 corresponds} to on the display screen. When the centering key d ₄ is operated, it is not necessary to perform any calculation, and the dot value corresponding to the central position stored in the ROM 10 in advance is set. Further, it is determined from which position on the display screen the sampling data should be displayed under the current general magnification. Then, step S1
Proceeding to 7-3, the obtained position is stored in the variable indicating the display position used at the time of waveform reproduction display.

When the process of step S17-3 is completed, the process proceeds to step S18. When the determination in step S16 is negative, steps S16 and S17 are skipped and the process proceeds to step S18. In step S18, the left and right scroll keys of the displayed waveform (d _8-1 , d _8-2 , d _8-3 or d _8-3
8-4 ) determines whether or not it has been operated. When the operation is not performed, the process skips to step S20, but when it is determined that the operation is performed, the process proceeds to step S19 to reset the waveform number of the heartbeat to be displayed next.

In the next step S20, it is determined whether or not the stop key of the touch keys 18 is operated. When the stop key is operated, the process returns to step S1.
Otherwise, the process returns to step S14, and the electrocardiogram waveform 100 (general magnification) of the new waveform number selected by the waveform scroll is displayed on the liquid crystal display device 16 with the newly set zero level line d ₁ as the reference. To do.

Next, an explanation will be given of the operation characteristic of the present invention.

When it is determined in step S15 that the display magnification by operating the display magnification switching key d ₇ is set to the maximum value, steps S21 to S23 → S1.
4, the display reference point d ₆ which is 160 msec before the R-wave apex d ₅ is obtained for each heartbeat, and each display reference point d ₆ is executed, as illustrated in FIG.
Of the electrocardiogram waveform 200 at the maximum magnification while always adjusting the A / D converted value at 4 to match the central baseline d _center (fixed in advance at the central position in the vertical direction of the display screen). Display.

That is, in step S21, the baseline display position for the display waveform is newly set. The detailed routine of this step S21 is shown in FIG.

In step S21-1, the display reference point d ₆ in the waveform of the heartbeat to be displayed is calculated (time calculation), and the A / D conversion value at the display reference point d ₆ is stored in RA.
Find the address on M12. Here, the display reference point d ₆
Is the R-wave apex d at that heartbeat in this embodiment.
_It is 160 msec before ₅ .

The address where the A / D converted value of the display reference point d ₆ is stored can be easily obtained as follows. Area of the IC card side RAM12b 12b ₂ ~1
A large number of A / D converted values of electrocardiogram signals sampled at regular intervals are stored in 2b ₄ in association with time information, while the data structures of the areas 12b _{2 to} 12b ₄ are individual waveform numbers. QR, which is a time 160 msec before the R wave apex for a predetermined time for each heartbeat corresponding to
Since the A / D converted value at the S time is stored, it is possible to easily know the address where the A / D converted value of the display reference point d ₆ is stored.

In step S21-2, the A / D conversion value of the display reference point d ₆ is converted into a dot value based on the just center position in the vertical direction, which is a prescribed baseline, and the center baseline is converted. Based on the d _center , the position on the display screen from which the sampling data is to be displayed starting from the above address is calculated under the maximum magnification. Then, in step S21-3, the above-obtained position is stored in a variable indicating the display position used during waveform reproduction display.

When the process of step S21-3 is completed, the process proceeds to step S22, and it is determined whether the left and right scroll keys (d _8-1 , d _8-2 , d _8-3 or d _8-4 ) of the displayed waveform have been operated. to decide. When no operation is performed, the process directly returns to step S14, but when it is determined that the operation is performed, the process proceeds to step S23, the waveform number of the heartbeat to be displayed next is reset, and then the process returns to step S14. Then, the R wave vertex d ₅ of the corresponding waveform number
The central baseline d _{ce NTER} to reconfigure to match (which as a new baseline display position A / D conversion value of the display reference point d ₆ before a predetermined time 160msec is updated every heartbeat than ), And the electrocardiogram waveform 200 of the new waveform number selected by the waveform scroll.
The (maximum magnification) is displayed on the liquid crystal display device 16.

[0064] As described above, when the maximum magnification is selected, for each heart beat, R-wave vertex d ₅ predetermined time than (16
0 msec) A / D converted value at the previous display reference point d ₆ is set as a new baseline display position and the center baseline d
_Since it coincides with the _center , that is, since the predetermined display reference point d ₆ is displayed on the central baseline d _{center at} any heartbeat, it is determined whether or not the baseline is shaken at the time of measurement. Regardless of the ST level change, it can be displayed in an appropriate state at all times, and based on the accurate observation of the ST level change, it is qualitatively determined whether or not the subjective symptom is derived from heart disease. Diagnosis can be made quickly and accurately. When it is derived from heart disease, it will be extremely advantageous in swiftly and accurately performing the necessary treatments such as elucidation of the mechanism of occurrence, determination of severity, confirmation of drug effect, etc. .

Instead of the above embodiment, the following operation may be performed. Assuming that the maximum magnification is selected as a condition for setting the A / D conversion value at the display reference point a predetermined time before the R-wave apex to the baseline display position that is always fixed at a fixed position. However, it is assumed that a predetermined display magnification higher than a predetermined one is selected, and the display reference point is not set 160 msec before the R wave apex but is set a predetermined time before. Alternatively, the baseline display position is not set to the exact center position in the vertical direction of the display screen, but to a predetermined position that is arbitrarily determined near the center position.

Further, the electrocardiographic waveform to be displayed need not be limited to the electrocardiographic waveform over a certain time period before and after the subjective symptom when the event switch 20 is pushed according to the subjective symptom, and the capacity of the IC card side RAM 12b is large. By doing so, the waveform of the electrocardiogram data stored continuously may be used.

[0067]

As described above, according to the portable electrocardiograph according to the present invention, when a change in ST level is read while scrolling the electrocardiogram waveform with a large display magnification, the electrocardiogram waveform is measured. Even if it is accompanied by a zero level sway, the ECG waveform can be scrolled while always being displayed at an appropriate position, so that the ST level change can be read and the heart disease can be diagnosed accurately and easily.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an electrical configuration of a main part of a portable electrocardiograph according to one embodiment of the present invention.

FIG. 2 is a memory map of a RAM in the embodiment.

FIG. 3 is a memory map of a RAM in the embodiment.

FIG. 4 is a memory map of a RAM in the embodiment.

FIG. 5 is a dot configuration diagram of a display screen in the example.

FIG. 6 is a display example of an electrocardiogram waveform in the case of a general magnification according to the embodiment.

FIG. 7 is a display example of an electrocardiogram waveform in the case of the maximum magnification in the embodiment.

FIG. 8 is a flowchart for explaining the operation of the embodiment.

FIG. 9 is a flowchart for explaining the operation of the embodiment.

FIG. 10 is a flowchart for explaining the operation of the embodiment.

FIG. 11 is a flowchart for explaining the operation of the embodiment.

FIG. 12 is a flowchart illustrating the operation of the embodiment.

FIG. 13 is a flowchart for explaining the operation of the embodiment.

FIG. 14 is a flowchart for explaining the operation of the embodiment.

[Explanation of symbols]

2 body surface electrode 4 electrocardiographic amplifier 6 A / D converter 8 CPU 10 ROM 12 RAM 12a main body side RAM 12b IC card side RAM 14 liquid crystal driver 16 liquid crystal display device 18 touch key 20 event switch 100 electrocardiogram waveform at general magnification 200 ECG waveform at maximum magnification d ₁ Zero level line d ₂ Up scroll key d ₃ Down scroll key d ₄ Centering key d ₅ R wave vertex d ₆ Display reference point d ₇ Display magnification switching key d ₈ Left and right scroll keys

Claims (1)

(57) [Claims] 1. A means for storing electrocardiogram data obtained from a patient, a means for displaying an electrocardiogram waveform under the display magnification selected in the reproduction display mode, and a display magnification selected being equal to or greater than a predetermined magnification. For each heartbeat, a predetermined time before the R-wave apex was obtained as a display reference point, and the A / D conversion value at the display reference point was fixed in advance at a substantially central position in the vertical direction of the display screen. A portable electrocardiograph, comprising: a means for displaying an electrocardiogram waveform in a state of being coincident with a central baseline.