DE2014630A1 - Electrocardiometer - Google Patents

Description

PATENT LAWYERS

DR. E. WIEGAND DIPL-ING. W. NIEMANN ^ ui 4 630

DR. M, KOHLER DIPL-ING. G. GERNHARDT

MUNICH HAMBURG

TELEPHONE = 395314 2000 H AM B U RG 50, 2 * h 3.70

TELEGRAMS: KARPATENT KONl GSTRASSE 28

W. 23931/69 4 / Pa

Frigitronics, Inc.,
Bridgeport, Connecticut (V.St.A.)

Electrocardiometer.

The invention relates to an electrocardiometer.

The routine electrocardiogram is a careful one and indispensable device for a thorough examination of a person to find out whether they have an abnormal ^ · men has heart condition. However, it has various disadvantages in that

1. it requires specially trained personnel,

2. twelve pairs of wires connected to the person Need to become,

3. It takes about 15 minutes to do this to finish, and it requires an additional time for a specialist to review the results of the various Interpret readings on the electrocardiogram.

Accordingly, it cannot be used as a safety measure by, for example, relatively little trained personnel

or for a quick examination in the practice of one Doctor, in the practice of a dentist, for examinations for insurance companies and for companies that do their work? presented a physical examination to be used.

Attempts have been made to simplify the electrocardiogram by using only four or five pairs of leads and attempts are still being made

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been to use an appropriate form of computer, around those in the different pairs of lines. to analyze the tensions received, to the time of the specialist in interpreting the results of such an electrocardiogram to save. However, to date there has been no form of electrocardiographic Devices which are used as a safety measure have been put into practice can and which allows a quick examination of a number of people simply walking through a corridor can use two electrodes with their hands for about 15 seconds and get a preliminary examination of the condition of such a person's electrocardiogram leaves.

Through lengthy experiments in the interpretation of electrocardiograms, it has been found that one of the key properties of abnormal electrocardiograms is the condition of a small or shallow T-wave in the line pair between the right and left arms, which line is designated I such that the T-wave amplitude spaces are less than about 16 % of the QRS wave amplitude peak. It has been found that abnormal cardiac conditions manifest themselves in different ways in the vast majority of cases, but that in about 80 % of cases they are indicated at least by this condition of the line IT wave amplitude which is less than a certain ratio of the QRS- Wave amplitude tip is.

The typical electrocardiographic pattern consists of three major electrical deflections, the P-wave, which represents the atrial depolarization, the QRS-WeHe, which represents the depolarization of the ventricles, and the T wave, which represents the repolarization of the ventricles.

Accordingly, it is an object of the invention to to provide an apparatus for simple electrooardiographic interpretation.

Another object of the invention is to provide a

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ORIGINAL INSPECTED

To create electrocardiometers which show the maximum 'amplitudes of various waves of electrical activity of the Heart compares. -

Another object of the invention is to provide a Electrocardiometer to create whichever one is given Percentage of the QRS wave with the maximum amplitude of the T-wave compares.

Another object of the invention is to provide a To have an electrocardiometer which indicates an abnormality when either the T-wave appears too late or Is too small in amplitude relative to the QRS wave. gj

Finally, the invention wants to create a simple electrocardiometer, which by relatively little trained personnel can be operated by simply one Measuring instrument read or lamps observed which indicate an abnormal or normal condition "

The invention can be embodied in an electrocardiometer to obtain electrical deflections of the QRS wave, which represents the depolarization of the ventricles, and the T-wave, which indicates the repolarization of the ventricles, and it includes a pair of leads and parts around effectively arranging this pair of conductors parallel to the heart, a first device for measuring the amplitude of the QRS wave parallel to the pair of conductors, and a second device for measuring the amplitude of the QRS wave direction for measuring the amplitude of the T-wave parallel to the line pair, as well as means for comparing these amplitudes, as well as display means which indicate when the T-wave amplitude is greater or less than about 12 to 18 % of the QRS wave amplitude.

In the following description, embodiments of the invention are described in conjunction with the drawings explained.

The Flg. 1 and 2 together show a circuit diagram of a preferred embodiment of an electrocardlometer.

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Pig. Figure 5 shows a modified embodiment of a Amplifier.

Fig. 4 is a series of voltage plots, which reproduce the operation of the electrocardiometer of FIGS. 1 and 2 and

Fig. 5 is a modified embodiment of the reading circuit of Fig. 2.

Figures 1 and 2 show a preferred embodiment of an electrocardiometer 11, however, it should be understood that many different forms of electrical circuit may be used and that the following description of the preferred embodiment is only one of the many possibilities that may be used. The electrocardlometer 11 includes various major components, namely an amplifier 12, a trigger circuit 15, a multivibrator circuit 14, a peak reading memory circuit 15, a zero-sequence hold circuit 16 and a reading circuit 17.

The typical electrocardlogram shows the electrical activity of the heart. The processes which occur and which produce the activity are the depolarization and the repolarization of the myocardium. The typical electrooardlographic pattern is shown in Figure 4 above. It consists of three major electrical deflections, the P-wave, which represents atrial depolarization, the QRS-wave, which represents the depolarization of the ventricles, and the T-wave, which represents the repolarization of the ventricles. The repolarization of the atria is usually obscured. A fourth deflection, the U-wave, is insignificant on line I.

The upper part of FIG. 1 shows an amplifier 12, which consists, for example, of three different working amplifiers 2o, 21 and 22, which have integrated circuit amplifiers with a combined gain of about 1,000 when the feedback loops are considered. Head

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Contact resistors 23 * coupling capacitors 24, feedback resistors 25 and feedback capacitors 26 are selected to have a resistance-to-capacitance ratio in order to obtain a bandwidth of 0.5 Hz to 30 Hz. This bandwidth allows the heartbeat electrical signals to pass through, but removes most of the trace noise and interference, and removes noise from a power source having a frequency of 60 Hz. Terminals 27 and 28 are the input terminals from the right arm and left Arm and are identical to lead I or the first pair of leads of the usual M electrocardiogram. These can be removed between the arms or between the shoulders, however, for the sake of simplicity, they are preferably removed between the hands of the person being examined, and conveniently they can dip their hands comfortably in small metal bowls containing a saline solution as a good conductive electrolyte. the connections 27 and 28 with dia & en. S @ halen are connected. It has been found that contact with the arms or with the hands is not critical «

The input at terminals 27 and 28 is about 0.65 millivolts peak, choosing the R wave. In the combined gain of about loooo in the amplifier 12 the output at point A is the typical ECG signal by m to the first pair of lines with a R-Wellenamplifcudeaspitze of about 6.5 volts and a typical elektroeardiographische shaft in Fig. 4 shown above. Energy from + and -Io to 15 volts is fed to the working amplifier, but this is not indicated in the drawing. The amplifier could be completely built in with the resistors, capacitors and transistors instead of working amplifiers 2o, 21 and 22 as desired.

At the top right of Fig. 1 is the trigger circuit 13 shown. This contains a reversible transistor amplifier 31 with a gain of 2 to 3 «The one

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output is the signal at terminal A ₁ and the output circuit contains a diode 32, a resistor 33 and a capacitor 34. The time constant of the RC circuit 33, 34 is about 1 second, which is on the order of a perlode of a human heartbeat. Capacitor 34 becomes negatively charged as the R-wave amplitude increases and then discharges toward +15 volts as shown. The negative part of this Aiiag & ftges is referred to as the R-Trlgger or RT signal and is used to trigger the first of the four successive monostable multi-vibrators in the circuit 14.

The lower part of Fig. 1 shows the four monostable multivibrators 35, 36, 37 and 38, welohe with the exception of different time constants are equal to one another, as indicated in FIG. 4. In each of these monostable vibrators the second pair of transistors is usually conductive, and is turned off at the time during which the first pair of transistors is turned on by an input signal. The length of time during which the first transistor of the pair being on, which is the unstable state, depends on the R-C time constants of the circuit in catfish known per se «.

The first monostable multivibrator 35 is in his unstable state triggered by the RT trigger signal during the period during which the EKG-R wave is approaching its top. There are three voltage attacks across the common emitter resistor 39. Accordingly, output B switches from -12 volts to +15 volts during a period of 100 milliseconds, as shown in FIG. 4.

This loo millisecond period contains the time during which the R-wave is at its greatest amplitude When the voltage at terminal B returns to -12 volts by turning on the second pair of transistors, the next multivibrator 36 is triggered, and

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its output C goes from -12 volts to +15 volts over a period of 3.00 milliseconds. This period contains the entire T-wave of normal electrocardiography on the first pair of leads. The third multivibrator 37 is activated when the voltage at terminal C returns to -12 volts. This third multivibrator 37 has a period of 25 milliseconds, as shown in FIG. 4, and then the fourth multivibrator 38 is triggered. The 25 millisecond period of + 1 ^ VoIt at terminal D is usually present after the T-wave has ended and before the P-wave has started. The fourth monostable Multivi- __ M Brator 38 produces an output of +15 volts during a period of 25 milliseconds at the terminal E, and it begins when the voltage returns to D to -12 volts. The complete subject matter continues from Fig. 1 to Fig. 2 , and the left hand side of Fig. 2 shows three identical tip outlet storage current circuits 15, each of which is made up of three H-channel field effect junction transistors 42, 43 and 44 with interchangeable sources and Sink exists · The first two-field transistors 42 and 43 are usually open switches in each of the circuits. The first set of FET connectors 42 is closed by the * lfj volt signals at terminals B, C and D * and these connect the EKG signal A to the diode capacitor j (| Hetzwerk, which has a diode 45 and iron capacitor 46. The signal A is thus passed through the appropriate diode to charge the capacitor 46, which reads the peak values of the R-wave, the T- wave and the Naoh T reference level and When sensed by the voltage follower FET 44, these voltages are available at points F, Q and H at low impedance like the outputs of the voltage followers in whose circuits the transistors 44 are connected a usually open switch, which closes sfeh, especially to discharge the capacitor to which it is assigned, namely

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to -8 volts at the point in time at which the +15 volt voltage is present at the terminal £, whereby the peak read-out memory electric circuits 15 for the next cardiographic Cycle to be prepared. The voltage waveforms in these circuits at terminals F, G and H are shown in FIG.

The three zero-sequence holding circuits 16 shown in the right half of FIG. 2 exist each of a usually open switch, as shown in the FET switch 49, a charge-storing capacitor 5o and a voltage lag part, which as Field effect transistor 51 is shown. Every transistor 49 and 51 has an interchangeable source and sink, and is a junction transistor with field effect and N-channels. The voltage at terminal D in Fig. 1 is used to turn on the FET switches because by the time M +15 volts are present on terminal D, the peak read memory circuits 15 have the maximum R-wave, maximum T-wave and post-T reference voltages on the terminals F, 0 and H contain the inputs to the zero follower hold circuits 16.

Terminals J, K and L are set to voltages corresponding to the peak of the preceding R wave (at terminal A) of the maximum amplitude of the previous T-wave and the current near-run T reference level for the duration of a cardiographic Cycle held. This is also shown in FIG. At the end of the time period determined by the cardiographic Once the cycle is determined, the corresponding voltages of the subsequent cycle are applied to the gates of the zero-sequence holding circuit 16. Accordingly, these three voltages can produce an abrupt change at the end of each of these cycles. The reading circuit 17 supplies, as in the lower one Part of the Flg. 2, the answer to the question. (1) Is the maximum amplitude of the T-wave at the K port less, equal to or greater than X percent of the maximum amplitude

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tude of the R-wave at connection J, where both are related to the post-T reference level at connection L? (2) Is the maximum T-wave amplitude equal to any percent of the maximum R-wave amplitude? To answer the first stamp, a predetermined Vein is set on the potentiometer 5 ^, which is connected in parallel to the terminals J and L, so that the micro-ammeter 55 set to zero center between X percent of the maximum R-voltage and the total T. - Shaft voltage is connected. In this way, the measuring instrument is deflected to the right for a "greater than" answer, to the left for a "less than ^rt answer and stops for an" equal to "answer Movement of the potentiometer calibrated from zero to 100% per percent when the pointer is moved from the L terminal to the J. The setting at which the meter is zero is the percentage of the maximum R wave amplitude at which the T-wave maximum amplitude is the same, both of which are related to the reference level present at the L terminal.

The measuring switch 57 is in the correct position for Reading of the above information is set. this is a two-pole switch with four positions, and when the switch is moved to the next position 59, connects he the meter 55 between earth and voltage at connection A through a filter 6o. A near zero reading indicates that junctions that have been introduced by the application of the electrode have settled or have disappeared and that the device is ready for reading. The other two switch positions 6l and 62 are connected to the reading instrument to determine the state of the + and -15 volts energy supply, e.g. batteries, can be read off.

Figure 4 shows the voltage waveforms present at the various locations in the circuits indicated by the letters A through L. The EKO

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-lo on the first pair of leads is represented by two cardiographic cycles on waveform A with a large difference in R-to-T ratio to indicate how. marked changes in the EKO affect the P through L waveforms. Waveform B indicates the voltage at terminal B and indicates that it will go from -12 to +15 volts over a period of 100 milliseconds after it is triggered by the RT trigger signal from trigger circuit 13 . Waveform C, shown in Figure 4, begins at the point at which the wave ends at port B and lasts for} oo milliseconds, which is sufficient for the usual T-wave of a normal electrocardiogram. Waveform B lasts for 25 milliseconds and is initiated when waveform C ends. This waveform D gives a post-T voltage level to provide a reference level from which the R and T waves are measured. The waveform E as shown in Figure 4 occurs upon termination of the D wave at terminal D, and this wave at terminal E is used to trigger the peak read storage circuits 16 to operate the FET switches 43 to make conductive and the capacitors 46 to discharge.

In Figure 4, the voltage waveform at terminal F W is shown following the top of the rising QRS wave until the peak voltage is reached, at which point diode 45 prevents reverse current and hence the voltage of capacitor 46 on The peak value remains, and the follow-up voltage 44 holds this peak voltage at the terminal F. This is maintained for a total of loo + Joo + 25 or 425 milliseconds until the signal at port E appears. The voltage waveform Ο in Fig. 4 shows that the voltage is initially -8 volts, then rises to the level of the signal at A as the T-wave rises, after which it remains at that peak amplitude until the end of that wave, which in turn

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425 milliseconds after the trigger signal at the terminal RT. The waveform at the terminal H is in FIG and shows it increases from -8 volts to a reference level established at the post-T time is, namely a time after the T-wave has passed. During the time during which for the voltages at terminals F, G and H are not recorded, these points are located on '-8 volts. The signals at connections J, K and L can

where they are not present are not shown, since at this point in time the values depend on the R-wave and the T-WeI-M Ie which precede those shown. At the time """""" of the second pulse at terminal D the measuring instrument 55 would pivot out of a right deflection with a sufficiently good EKG and pivot out to the left with an abnormal EKG if the potentiometer 54 has been set to 25 % «.

In a recent examination of at least 200 normal and abnormal electrocardiograms, it has been found that there is a relatively sharp section or a relatively sharp cutoff between normal and abnormal when the height of the T-wave is 14-16 % of the R-wave. If the T wave is greater than 16 % _s , this usually indicates a normal slectrocardiogram, and if the T * wave is less than 16 #, it is usually associated with abnormal electrocardiograms. Depending on the age of the examinee and other factors, a percentage between 12 and 18 % can be considered the dividing line between normal and abnormal. When these criteria are used, in 99 out of approximately 10,000 randomly selected normal electrocardiograms showed a normal relationship between the R wave and the TT wave, and 1 out of 10,000 abnormal cardio grams showed an abnormal relationship,

This electrooardiographic test, which is only on the potential difference between the right arm and

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left arm is much simpler than the usual twelve pairs of wires in electrocardiograms, which one requiring trained professional 15 minutes to complete this process and then a specialist to interpret require. It has been found that using a single pair of leads with a direct reading from normal to abnormal takes only about 15 to 150 seconds.

Based on the data available, this test, if applied to a select group of people, would theoretically select 80% of those with abnormal electrocardiograms, while false positives only occur in 1 % of normal ones. The practical application of such a test can be recognized if it is assumed that when examining a population of 1,000 people, Io % of them have abnormal electrocardiograms. ■ The results from these theoretical investigations are shown in the following table.

No. Percent of the total population

X. population lo.ooo loo 2. normal 9.OOO2 90.0 a. checked normally
b. false positive 8.91ο
9o 89.I
0.9 2. abnormal l.ooo lo.o a. checked abnormally
b. false negative 8oo
2oo 8.0
2.0 4th Overall error (2b + j5b) 29o 2.9 5. checked correctly overall
(2a + 3a) 9.7I0 97.1

The time saved with such an examination compared to the usual electrocardiography is recognized, when it is taken into account that the study time of this population is about 83.3 hours or about 2 weeks would take. A common electrocardiograph

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on this population it would take 2500 hours or 62 working weeks. This investigation would be 97 * 1 % accurate and correct.

From the foregoing it can be seen that the electrocardiometer 11 provides a means for comparing the amplitude of the T wave with the amplitude of the QRS wave, and in particular that it compares the peak amplitude of these two waves. Further, the electrocardiometer circuit indicates the abnormality of a T wave which is late, that is, the QT interval is a long time. As k is apparent from the waveform at terminal G in Fig., Appear if the tip of the T-wave at the end of 4oo Mulisekunden-time delay period has not occurred, which is created by the first and the second monostable multivibrator 35 and 36, this as an abnormally low amplitude of the T wave, and as a result, the meter 55 indicates it as an abnormality. Furthermore, if the T-wave has not terminated at the end of the 400 millisecond time delay, the waveform at port H (FIG. 4) is incremented. The effect of a more positive post-T reference is the same as that of a less positive T-wave, and as a result, the meter 55 indicates it as abnormal. The time period in the preferred embodiment is 400 milliseconds, which is approximately one-half the period of the oardiographic cycle between successive QRS waves.

Fig..3 shows a modified circuit for the amplifier 12, which is shown in the upper part of FIG is. 3 shows this modified amplifier circuit 65, which contains four working amplifiers instead of them, as shown in the preferred embodiment. Separate inputs at connections 27 and 28 lead to separate working amplifiers before the two signals in the last two working amplifiers, which are in cascade are switched, can be combined with one another. The working amplifier circuit of Fig.

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in the same way as that shown in FIG.

Fig. 5 shows a reading circuit 69, which is a modified version of that at 17 in the lower part of the Fig. 2 could be used. The visual display, whereby one of two lamps 7o and 71 lights up, answers this question with yes or no: If the maximum amplitude of the T-wave is greater than X percent of the maximum R wave amplitude, both at the Naoh T reference level are related? X is determined by the setting of potentiometer 54. An operating amplifier 72 has an input connected that comes from the potentiometer 54, the parallel is connected to terminals J and L, and the other input is connected to terminal K as a post-T reference.

The working amplifier 72 is connected in a two-tap circuit so that its output is at 75 +12 volts is when Tmax is greater than X percent of Rmax, and is -12 volts when Tmax is less than percent of Rmax. This output, when it is +12 volts, makes an NPN transistor 74 conductive, and the -12 volt output makes a PNP transistor 75 conductive. The N-channel transistors 76 and 77 with field effect, which are connected in series with the transistors 74 and 75, respectively, are for example made conductive for loo milliseconds, and are made through the R-wave signal is initiated at terminal 5. While of the loo milliseconds of each cardiographic cycle, one of the capacitors 78 or 79 discharges through one of the transistors 76 or 77 with field effect and accordingly the transistor 74 or 75 * which is determined by the input of the circuit with two taps, and the lamp 7o or 71 * which is assigned to transistor 74 or 75, is made to light up.

The R-C networks can have a time constant of about 0.8 seconds and allow a full 15 volt charge to charge capacitors 78 and 79 between the discharges. The discharge time is based on a working

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cycle limited by about Io % . Therefore, when using Io volts and 20 milliamps lamps, the average current requirement is only + or -2 milliamps depending on which lamp is lit. .

The present invention is set out in the appended claims and also explained in the above description. The invention has been described in preferred embodiments with a certain degree of detail. However, the invention is not limited to these embodiments, and many changes in the details of the circuit can be made within the scope of the disclosed spirit and made in the combination of the circuit elements will.

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Claims (16)

20U63Q Claims IJ electrocardiometer for generating electrical deflections of the QRS worlds, which represents the ventricle depolarization, and the T-wave, which represents the ventricle repolarization, characterized by a pair of lines which can be connected parallel to the heart, a first device for measuring the amplitude of the QRS wave on the line pair, and a second device for measuring the amplitude of the T-wave parallel to the lines, as well as a device for comparing these amplitudes, and a display device that indicates when the T-wave amplitude is smaller than about 12 to Ib is ¹ % of the QRS wave amplitude. 2. electrocardiometer according to claim 1, characterized in that the first device has a part for measuring the peak amplitude of the QRS wave. 3. electrocardiometer according to claim 2, characterized in that that the second means includes parts for measuring the peak amplitude of the T-wave. 4. electrocardiometer according to claim 1, characterized in that that the second means have parts for measuring the peak amplitude of the T-wave during a time interval contains, as well as means, which this time interval at a point in time after the occurrence of the QRS wave and at a End time before the next QRS wave occurs. 5. electrocardiometer according to claim 4, characterized by a device which the time interval approximately at half a period between successive QRS waves completed. 6. electrocardiometer according to claim 4, characterized by means which the time interval in accordance initiates with the occurrence of a QRS wave, as well as a device which this time interval after a given tent delay. 109808/1202 7. electrocardiometer according to claim 6, characterized in that that the first means includes parts for measuring the peak amplitude of the QRS wave. 8. An electrocardiometer according to claim 1, characterized in that the display device operates or displays when the value of the T-wave peak amplitude is less than about 16 % of the QRS-wave peak amplitude. 9. electrocardiometer according to claim 1, characterized in that that the display device is a measuring instrument, and circuit parts are provided which supply this measuring instrument with power so that it is on an essentially consistent reading during any given cycle between successive QRS waves remain. 10. Electrocardiometer according to claim 9 *, characterized in that that the measuring instrument has a certain proportion of the QRS wave peak amplitude with the T-wave peak amplitude compares. 11. Electrocardiometer according to claim 1, characterized in that the display device 'is a lamp,. ^ Which can light up in accordance with the ratio of the amplitude of the QRS wave and the T wave. 12. electrocardiometer according to claim 1, characterized in that the display device has a first and a second lamp that comes on at each period of heartbeat can light up selectively. 135. Electrocardiometer according to claim 1, characterized by parts for initiating the start of a cycle, which means for sensing the rising peak of the QRS wave contain. 14. Electrocardiometer according to claim 13, characterized in that that the device initiating the cycle includes an RC time delay device which has a period on the order of the period of a human heartbeat. 109808/120 2 -Ib- 20U630 15. electrocardiometer according to claim 13, characterized in that the device initiating the cycle is a Contains a plurality of monostable multivibrators that are triggered sequentially, and triggering the first of the multivibrators starts the cycle. 16. Electrocardiometer according to claim 1, characterized by a memory circuit for reading the tip Read the peak amplitude of each QRS wave and the T wave. 17 «electrocardiometer according to claim 16, characterized in that the storage circuit reading the tip contains a capacitor which is charged by the positive rising voltage, and a diode which prevents the capacitor from discharging, so that the voltage across the Capacitor charges and stays at the peak of the applied voltage. Ib. Electrocardiometer according to claim 17 « -Hold through a zero sequence ^ circuit, the voltage sequence contains parts to create stresses that depend on Aon the capacitor voltage remain at a constant level during a complete cycle 109808/1202