Decipher the heart cardiogram online. What ECG indicators are normal in adults? Teeth and Spacing Analysis

• assessment of heart rate regularity,
• heart rate (HR) counting,
• determination of the source of excitation,
• conductivity assessment.

Determination of the electrical axis of the heart.

Analysis of the atrial P wave and P-Q interval.

Analysis of the ventricular QRST complex:

• QRS complex analysis,
• analysis of the RS - T segment,
• T wave analysis,
• Q-T interval analysis.

Electrocardiographic report.

Normal electrocardiogram.

1) Checking the correct ECG registration

At the beginning of each ECG tape there must be calibration signal- so-called reference millivolt. To do this, at the beginning of the recording, a standard voltage of 1 millivolt is applied, which should display a deviation of 10 mm. Without a calibration signal, the ECG recording is considered incorrect. Normally, in at least one of the standard or enhanced limb leads, the amplitude should exceed 5 mm, and in the chest leads - 8 mm. If the amplitude is lower, it is called reduced ECG voltage, which occurs in some pathological conditions.

Reference millivolt on the ECG (at the beginning of the recording).

2) Analysis heart rate and conductivity:

1. assessment of heart rate regularity

Rhythm regularity is assessed by R-R intervals. If the teeth are at an equal distance from each other, the rhythm is called regular, or correct. The variation in the duration of individual R-R intervals is allowed no more than ± 10% from their average duration. If the rhythm is sinus, it is usually regular.

1. heart rate counting(heart rate)

The ECG film has large squares printed on it, each of which contains 25 small squares (5 vertical x 5 horizontal). To quickly calculate your heart rate when the right rhythm count the number of large squares between two adjacent teeth R - R.

At belt speed 50 mm/s: HR = 600 / (number of large squares).
At belt speed 25 mm/s: HR = 300 / (number of large squares).

On the overlying ECG interval R-R is equal approximately 4.8 large cells, which at a speed of 25 mm/s gives 300 / 4.8 = 62.5 beats/min.

At a speed of 25 mm/s each small cell equal to 0.04 s, and at a speed of 50 mm/s - 0.02 s. This is used to determine the duration of the teeth and intervals.

If the rhythm is incorrect, it is usually considered maximum and minimum heart rate according to the duration of the smallest and largest R-R interval, respectively.

1. determination of the excitation source

In other words, they are looking for where pacemaker, which causes contractions of the atria and ventricles. Sometimes this is one of the most difficult stages, because various disorders of excitability and conduction can be very confusingly combined, which can lead to incorrect diagnosis and improper treatment. To correctly determine the source of excitation on an ECG, you need to know well conduction system of the heart.

Sinus rhythm(This normal rhythm, and all other rhythms are pathological).
The source of excitation is in sinoatrial node. Signs on the ECG:

• in II standard lead P waves are always positive and are located before each QRS complex,
• P waves in the same lead have the same shape at all times.

P wave in sinus rhythm.

ATRIAL rhythm. If the source of excitation is located in the lower parts of the atria, then the excitation wave propagates to the atria from bottom to top (retrograde), therefore:

• in leads II and III the P waves are negative,
• There are P waves before each QRS complex.

P wave during atrial rhythm.

Rhythms from the AV connection. If the pacemaker is in the atrioventricular ( atrioventricular node) node, then the ventricles are excited as usual (from top to bottom), and the atria - retrograde (i.e. from bottom to top). At the same time, on the ECG:

• P waves may be absent because they are superimposed on normal QRS complexes,
• P waves can be negative, located after the QRS complex.

Rhythm from the AV junction, superimposition of the P wave on the QRS complex.

Rhythm from the AV junction, the P wave is located after the QRS complex.

Heart rate with a rhythm from the AV junction is less than sinus rhythm and is approximately 40-60 beats per minute.

Ventricular, or IDIOVENTRICULAR, rhythm(from Latin ventriculus [ventrikulyus] - ventricle). In this case, the source of rhythm is the ventricular conduction system. Excitation spreads through the ventricles in the wrong way and is therefore slower. Features of idioventricular rhythm:

• QRS complexes are widened and deformed (they look “scary”). Normally, the duration of the QRS complex is 0.06-0.10 s, therefore, with this rhythm, the QRS exceeds 0.12 s.
• There is no pattern between QRS complexes and P waves because the AV junction does not release impulses from the ventricles, and the atria can be excited from the sinus node, as normal.
• Heart rate less than 40 beats per minute.

Idioventricular rhythm. The P wave is not associated with the QRS complex.

1. conductivity assessment.
   To properly account for conductivity, the recording speed is taken into account.

To assess conductivity, measure:

• duration P wave(reflects the speed of impulse transmission through the atria), normally up to 0.1 s.
• duration interval P - Q(reflects the speed of impulse conduction from the atria to the ventricular myocardium); interval P - Q = (wave P) + (segment P - Q). Fine 0.12-0.2 s.
• duration QRS complex(reflects the spread of excitation through the ventricles). Fine 0.06-0.1 s.
• internal deviation interval in leads V1 and V6. This is the time between the beginning of the QRS complex and the R wave. Normal in V1 up to 0.03 s and in V6 up to 0.05 s. Used mainly to recognize bundle branch blocks and to determine the source of excitation in the ventricles in the case of ventricular extrasystole(extraordinary contraction of the heart).

Measuring the internal deviation interval.

3) Determination of the electrical axis of the heart.
In the first part of the series about ECG it was explained what it is electrical axis of the heart and how it is determined in the frontal plane.

4) Atrial P wave analysis.
Normally, in leads I, II, aVF, V2 - V6, the P wave always positive. In leads III, aVL, V1, the P wave can be positive or biphasic (part of the wave is positive, part is negative). IN lead aVR The P wave is always negative.

Normally, the duration of the P wave does not exceed 0.1 s, and its amplitude is 1.5 - 2.5 mm.

Pathological deviations P wave:

• Pointed high P waves of normal duration in leads II, III, aVF are characteristic of right atrial hypertrophy, for example, with “pulmonary heart”.
• Split with 2 apexes, widened P wave in leads I, aVL, V5, V6 is characteristic of left atrial hypertrophy, for example, with mitral valve defects.

Formation of the P wave (P-pulmonale) with hypertrophy of the right atrium.

Formation of the P wave (P-mitrale) with hypertrophy of the left atrium.

P-Q interval: fine 0.12-0.20 s.
An increase in this interval occurs when the conduction of impulses through the atrioventricular node is impaired ( atrioventricular block, AV block).

AV block There are 3 degrees:

• I degree - P-Q interval enlarged, but each P wave has its own QRS complex ( no loss of complexes).
• II degree - QRS complexes partially fall out, i.e. Not all P waves have their own QRS complex.
• III degree - complete blockade carrying out in the AV node. The atria and ventricles contract at their own rhythm, independently of each other. Those. idioventricular rhythm occurs.

5) Ventricular QRST analysis:

1. QRS complex analysis.

The maximum duration of the ventricular complex is 0.07-0.09 s(up to 0.10 s). The duration increases with any bundle branch block.

Normally, the Q wave can be recorded in all standard and enhanced limb leads, as well as in V4-V6. The amplitude of the Q wave normally does not exceed 1/4 R wave height, and the duration is 0.03 s. In lead aVR, there is normally a deep and wide Q wave and even a QS complex.

The R wave, like the Q wave, can be recorded in all standard and enhanced limb leads. From V1 to V4, the amplitude increases (in this case, the r wave of V1 may be absent), and then decreases in V5 and V6.

The S wave can have very different amplitudes, but usually no more than 20 mm. The S wave decreases from V1 to V4, and may even be absent in V5-V6. In lead V3 (or between V2 - V4) “ transition zone ” (equality of R and S waves).

1. RS - T segment analysis

The S-T segment (RS-T) is a segment from the end of the QRS complex to the beginning of the T wave. The S-T segment is especially carefully analyzed in case of coronary artery disease, since it reflects the lack of oxygen (ischemia) in the myocardium.

Fine S-T segment located in the limb leads on the isoline ( ± 0.5 mm). In leads V1-V3, the S-T segment may shift upward (no more than 2 mm), and in leads V4-V6 - downward (no more than 0.5 mm).

The point at which the QRS complex transitions to the S-T segment is called the point j(from the word junction - connection). The degree of deviation of point j from the isoline is used, for example, to diagnose myocardial ischemia.

1. T wave analysis.

The T wave reflects the process of repolarization of the ventricular myocardium. In most leads where a high R is recorded, the T wave is also positive. Normally, the T wave is always positive in I, II, aVF, V2-V6, with T I > T III, and T V6 > T V1. In aVR the T wave is always negative.

1. Q-T interval analysis.

The Q-T interval is called electrical ventricular systole, because at this time all parts of the ventricles of the heart are excited. Sometimes after the T wave there is a small U wave, which is formed due to short-term increased excitability of the ventricular myocardium after their repolarization.

6) Electrocardiographic report.
Should include:

1. Source of rhythm (sinus or not).
2. Regularity of rhythm (correct or not). Usually sinus rhythm is normal, although respiratory arrhythmia is possible.
3. Position of the electrical axis of the heart.
4. Presence of 4 syndromes:

• rhythm disturbance
• conduction disturbance
• hypertrophy and/or overload of the ventricles and atria
• myocardial damage (ischemia, dystrophy, necrosis, scars)

Examples of conclusions(not quite complete, but real):

Sinus rhythm with heart rate 65. Normal position electric axle hearts. No pathology was identified.

Sinus tachycardia with heart rate 100. Single supragastric extrasystole.

Sinus rhythm with heart rate 70 beats/min. Incomplete blockade of the right bundle branch. Moderate metabolic changes in the myocardium.

Examples of ECGs for specific diseases of cardio-vascular system- next time.

Electrocardiography or ECG of the heart is a test in which a device senses the electrical activity of the heart. ECG results are a graph, usually written on graph paper as a curve, showing changes in voltage between two points over time.

Electrocardiography is a quick, cheap and easy test for people that tells important information about the function of the heart. Therefore, it belongs to the basic medical examinations.

Many people know which doctor does an ECG. An electrocardiogram is performed by a cardiologist, who also interprets it. Today, cardiologist services are available online, where it is also possible to evaluate the results of the examination - that is, calmly go to the page - and decipher your cardiac activity!

Operating principle

An incentive to reduce any muscle cells is a change in voltage between the internal and external environment of the cell. The same applies to the heart muscle, whose cells must work very stably.

The initial electrical impulse is produced in specialized cells in the atrium cluster (sinus node), from where shortcuts distributed throughout the heart so that the heart muscle contracts in a coordinated manner and effectively pushes blood out of the cavities of the heart.

When the heart muscle weakens, the tension returns to its original state. These electrical changes during cardiac work spread to the surface of the body (we are talking about millivolts), where they are scanned through electrodes - this is brief ECG description.

When and why is it carried out?

An ECG is a necessary examination if heart disease is suspected. Electrocardiography is used in diagnosis ischemic changes heart muscle, i.e. changes from lack of oxygen, the most serious manifestation which is the death of heart cells due to lack of oxygen - myocardial infarction.

In addition, ECG analysis may show arrhythmia, an abnormal heart rhythm.

Conclusion The ECG also reveals the expansion of the heart in case of its failure or embolism pulmonary artery. A cardiogram is usually performed as part of the preoperative evaluation before a planned procedure under general anesthesia, or during a general examination.

There is no need to follow any special regime before the examination. All that matters is calmness.

Carrying out an examination

The ECG is the same for adults and children. The patient undergoing examination must undress to the waist, if necessary, remove socks or stockings - must be accessible rib cage patient's ankle and wrist.

The examination is carried out in a lying position. The nurse or doctor performing the examination applies a small amount of conductive gel to the skin of the patient, adult or child, to improve the transmission of electrical signals to the electrodes. Then the electrodes themselves are attached using rubber suction cups. There are also electrodes in the form of stickers (disposable), already impregnated with gel.

There are a total of 10 electrodes: 6 on the chest and 1 on each limb. When all electrodes are placed, the electrocardiograph is turned on, and within a few seconds the paper with the electrocardiographic curve comes out of the device - the electrocardiography is completed.

ECG modification

There are several ways to measure basic heart indicators:

• daily allowance ECG monitoring according to Holter;
• intermittent daily monitoring;
• load monitoring;
• esophageal monitoring.

24-hour Holter ECG monitoring

This examination is carried out mainly in adults; the person being examined wears the attached device for 24-48 hours. The electrodes are placed on the chest and the device is attached around the waist, the patient can operate it normally and perform any other normal activities.

This test is very important in diagnosing heart rhythm disturbances that occur periodically, to confirm or rule out certain problems associated with heart disease. The patient keeps a diary during the examination, and if symptoms of the disease appear, he independently records the time. The doctor can subsequently interpret the ECG in this time period.

This test is also used primarily in adults for symptoms that occur less frequently. The person wears the device for longer than a day or two, activating it when difficulties arise.

Load monitoring

Usually called bicycle ergometry; examines the work of the heart under increased load. The examination can be carried out in both adults and children. The patient receives exercise on a treadmill, while the device reflects his cardiac activity.

Esophageal monitoring

This is a less common examination, performed on an empty stomach. The patient has an electrode inserted into the esophagus through the mouth or nose. The electrode is thus very close to the left atrium, which provides a better waveform than a conventional recording, making the ECG easier to read. Used in cases where, with classical ECG interpretation was uncertain, or as therapeutic method, when electrical stimulation provides a physiological healthy rhythm.

Decoding the curve

Decoding the cardiogram consists of 10 points:

• heartbeat;
• sinus rhythm;
• heart rate;
• P wave;
• PQ interval;
• QRS complex;
• ST segment;
• T wave;
• QT interval;
• axis of the heart.

The following table provides the norm indicators:

The norm in the table is indicated for adults. In children, the ECG norm is different and varies depending on age-related changes.

The most important parameter in the question of how to decipher a cardiogram is the QRS complex, its shape and ECG waves. The basis of vibrations and deviations are changes electric field hearts. Sinus arrhythmia on the ECG is characterized by irregular R-R intervals, i.e., repeating the QRS.

The duration of the QRS complex is measured from the beginning of the Q wave to the end of the S wave, and indicates the duration of contraction of the cardiac chamber. Normal ECG in this regard it is 0.08-0.12 seconds. The QRS shape in a healthy patient should be regular and constant.

In principle, the ideal cardiogram is constantly repeating QRS complexes at regular intervals, and the QRS has the same shape.

To decipher the cardiogram of the heart, in addition to manual reading, today a specialized software. It not only decrypts the data, but also analyzes the signal. Modern methods are able to detect even the smallest details much more accurately pathological changes heart rate.

P wave

A physiological P wave precedes each QRS complex, from which it is separated by a PQ interval. The frequency of occurrence thus coincides with the frequency of systole.

The positivity and negativity, amplitude and duration of the P wave are assessed:

• Positivity and negativity. Physiologically, the P wave in leads I and II is positive, in lead III it is positive or negative. Negative P in lead I or II is pathological.
• Amplitude. In normal mode, the amplitude of the P wave does not exceed 0.25 mV. Higher values ​​indicate hypertrophy.
• The duration of the P wave does not exceed 0.11 seconds. Lengthening indicates dilatation of the atrium, the wave is called P mitral, and is typical of mitral valve stenosis.

PQ interval

The PQ interval corresponds to atrial systole and air retention in the AV node. Measured from the beginning of the P wave to the beginning of the ventricular complex. Normal values– from 0.12 to 0.20 seconds.

Pathology:

• prolonged PQ interval occurs in AV node blocks;
• a shortened PQ interval indicates preexcitation syndrome (air bypassing the AV node through parallel connections).

If the P wave does not contain a cardiac cardiogram, the PQ interval is not deciphered (the same applies to the case if the P wave does not depend on the QRS complex).

QRS complex

The QRS complex represents the contraction of the ventricular cardiac muscle:

• Q – first negative oscillation, may be absent;
• R – each positive oscillation. Usually only one is present. If there is more than 1 vibration of R in a complex, it is indicated by an asterisk (for example, R*);
• S – every negative oscillation after at least one R. A larger number of oscillations is designated similarly to R.

The QRS complex evaluates 3 factors:

• duration;
• presence and duration of Q;
• Sokolov indices.

If, after a general ECG assessment, LBBB is detected, Sokolov indices are not measured.

QRS indicators:

• QRS duration. The physiological duration of the QRS complex is up to 0.11 s. Pathological extension up to 0.12 s. may indicate incomplete blockade, myocardial infarction and ventricular hypertrophy. Extension over 0.13 s. indicates LBBB.
• Q fluctuations. Q oscillations are detected in all terminals. They are usually present. However, their duration does not exceed 0.03 s. The only exception is the aVR oscillation, in which Q is not abnormal.

Q longer than 0.04 s. clearly shows the scar after myocardial infarction. Based on the data of their individual vibrations, it is possible to determine the location of the infarction (anterior wall, septal, diaphragmatic).

Sokolov indices (Sokolov-Lyon criteria for ventricular hypertrophy)

From the size of the amplitude of QRS oscillations, the thickness of the chamber wall can be approximately determined. For this purpose, Sokolov indices are used, 1 for the right and 2 for the left ventricle.

Indicators for the right ventricle:

• the sum of the P wave amplitudes in leads V1, S and lead V6 usually does not exceed 1.05 mV;
• normal readings: R (V1) S + (V6)<1,05 мВ;
• right ventricular hypertrophy on ECG: ≥ 1.05 mV.

To determine left ventricular hypertrophy, there are 2 Sokolov indices (LK1, LK2). In this case, the amplitudes are also summed, but in the S vibration in tap V1 and in the R vibration in taps V5 or V6.

• LK1: S (V1) + R (V5)<3,5 мВ (норма);
• LK2: S (V1) + R (V6)<4 мВ (норма).

If the measured values ​​exceed the norm, they are marked as pathological. The following indicators indicate left ventricular hypertrophy:

• LK1: S (V1) + R (V5) > 3.5 mV;
• LK2: S (V1) + R (V6) > 4 mV.

T wave

The T wave on the ECG represents repolarization of the ventricular myocardium and is physiologically concordant. Otherwise it is described as discordant, which is pathological. The T wave is described in leads I, II and III, in aVR and in the thoracic leads V3-V6.

• I and II – positive concordant;
• III – concordant (polarity does not matter);
• aVR – negative T wave on ECG;
• V3-V6 – positive.

Any deviation from the norm is pathological. Sometimes the T wave is bipolar, in which case it is described as preterminally negative (-/+) or terminally negative (+/-).

Deviations of the T wave occur during myocardial hypoxia.

A tall T wave (i.e., gothic) is typical of an acute heart attack.

QT interval

The distance from the beginning of the ventricular QRS complex to the end of the T wave is measured. Normal values ​​are 0.25-0.50 s. Other values ​​indicate an error in the examination itself or in the ECG assessment.

Research results

The result of the study is available immediately, then its assessment (decoding the ECG) depends on the doctor. It can determine whether the heart is suffering from a lack of oxygen, whether it is working in the correct rhythm, whether the number of beats per minute is correct, etc.

Some heart diseases, however, may not be detected by an ECG. These include, for example, arrhythmia, which manifests itself periodically, or disturbances in cardiac activity during any physical activity. If such a cardiac disorder is suspected, the doctor should perform some additional tests.

ECG interpretation of an electrocardiogram is considered a complex process that only a diagnostician or cardiologist can do. They carry out decoding, identifying various defects and disruptions in the functioning of the human heart muscle. This diagnostic method is widely used today in all medical institutions. The procedure can be done either in a clinic or in an ambulance.

Electrocardiography is a science that studies the rules of the procedure, ways to interpret the results obtained, and explains unclear points and situations. With the development of the Internet, you can even decipher an ECG yourself, using special knowledge.

The electrocardiogram is deciphered by a special diagnostician who uses an established procedure that determines normal indicators and their deviations.

Heart rate and heart rate are assessed. In a normal state, the rhythm should be sinus, and the frequency should be from 60 to 80 beats per minute.

Intervals are calculated that characterize the duration of the moment of contraction. Special formulas are used here.

The normal QT interval is 390 - 450 ms. If the interval is violated, if it lengthens, the diagnostician may suspect atherosclerosis, rheumatism or myocarditis, as well as coronary heart disease in the patient. Also, the interval may shorten, and this indicates the presence of hypercalcemia. These parameters are calculated using a specialized automatic program that provides reliable results.

The location of the EOS is calculated from the isoline along the height of the teeth. If the indicators are significantly higher than each other, an axis deviation is noticed, defects in the functioning of the right or left ventricle are suspected.

An indicator showing the activity of the ventricles, the QRS complex, is formed during the passage of electrical impulses to the heart. It is considered normal when there is no defective Q wave and the distance does not exceed 120 ms. When this interval shifts, it is customary to talk about a conduction defect, or it is also called bundle branch block. In case of incomplete blockade, RV or LV hypertrophy can be suspected depending on the location of the line on the ECG. The transcript describes ST particles, which reflect the time of restoration of the initial position of the muscle relative to its complete depolarization. Under normal conditions, the segments should fall on the isoline, and the T wave, which characterizes the work of both ventricles, should be asymmetrical and directed upward. It should be longer than the QRS complex.

Only doctors specially involved in this can correctly decipher ECG indicators, but often an ambulance paramedic with extensive experience can easily recognize common heart defects. And this is extremely important in emergency situations.

When describing and deciphering the diagnostic procedure, various characteristics of the work of the heart muscle are described, which are indicated by numbers and Latin letters:

• PQ is an indicator of atrioventricular conduction time. In a healthy person it is 0.12 - 0.2 s.
• P - description of the work of the atria. It may well indicate atrial hypertrophy. In a healthy person, the norm is 0.1 s.
• QRS - ventricular complex. In normal condition, the indicators are 0.06 - 0.1 s.
• QT is an indicator that can indicate cardiac ischemia, oxygen starvation, heart attack and rhythm disorders. The normal value should be no more than 0.45 s.
• RR - the gap between the upper points of the ventricles. Shows the constancy of heart contractions and allows you to count their frequency.

Cardiogram of the heart: interpretation and main diagnosed diseases

Decoding a cardiogram is a long process that depends on many indicators. Before deciphering the cardiogram, it is necessary to understand all the deviations in the functioning of the heart muscle.

Atrial fibrillation is characterized by irregular contractions of the muscle, which can be completely different. This violation is dictated by the fact that the clock is set not by the sinus node, as it should happen in a healthy person, but by other cells. The heart rate in this case ranges from 350 to 700. In this condition, the ventricles are not fully filled with incoming blood, which causes oxygen starvation, which affects all organs in the human body.

An analogue of this condition is atrial fibrillation. The pulse in this state will be either below normal (less than 60 beats per minute), or close to normal (60 to 90 beats per minute), or above the specified norm.

On the electrocardiogram, you can see frequent and constant contractions of the atria and, less often, the ventricles (usually 200 per minute). This is atrial flutter, which often occurs already in the acute phase. But at the same time, the patient tolerates it more easily than flickering. Blood circulation defects in this case are less pronounced. Trembling can develop as a result of surgery, various diseases such as heart failure or cardiomyopathy. When a person is examined, fluttering can be detected due to rapid rhythmic heartbeats and pulse, swollen veins in the neck, increased sweating, general impotence and shortness of breath.

Conduction disorder - this type of heart disorder is called blockade. The occurrence is often associated with functional disorders, but it can also be the result of various types of intoxication (due to alcohol or taking medications), as well as various diseases.

There are several types of disorders that a heart cardiogram shows. Deciphering these violations is possible based on the results of the procedure.

Sinoatrial - with this type of blockade, there is difficulty in the exit of the impulse from the sinus node. As a result, there is a syndrome of weakness of the sinus node, a decrease in the number of contractions, defects in the circulatory system, and as a result, shortness of breath and general weakness of the body.

Atrioventricular (AV block) - characterized by a delay in excitation in the atrioventricular node longer than the set time (0.09 seconds). There are several degrees of this type of blocking.

The number of contractions depends on the degree, which means the blood flow defect is more difficult:

• I degree - any compression of the atria is accompanied by an adequate amount of compression of the ventricles;
• II degree - a certain amount of compression of the atria remains without compression of the ventricles;
• III degree (absolute transverse block) - the atria and ventricles are compressed independently of each other, which is clearly shown by deciphering the cardiogram.

Conduction defect through the ventricles. The electromagnetic impulse from the ventricles to the muscles of the heart spreads through the trunks of the His bundle, its legs and branches of the legs. A blockage can occur at every level, and this will immediately affect the electrocardiogram of the heart. In this situation, it is observed that the excitation of one of the ventricles is delayed, because the electrical impulse goes around the blockage. Doctors divide blockages into complete and incomplete, as well as permanent or non-permanent blockages.

Myocardial hypertrophy is clearly shown by a cardiac cardiogram. Interpretation on the electrocardiogram - this condition shows the thickening of individual areas of the heart muscle and stretching of the chambers of the heart. This happens with regular chronic overload of the body.

• Syndrome of early ventricular repolarization. Often, this is the norm for professional athletes and people with congenitally large body weight. It does not provide a clinical picture and often goes away without any changes, so the interpretation of the ECG becomes more complicated.
• Various diffuse disorders in the myocardium. They indicate a myocardial nutritional disorder, as a result of dystrophy, inflammation or cardiosclerosis. The disorders are quite treatable and are often associated with a disorder of the body’s water and electrolyte balance, taking medications, and heavy physical activity.
• Non-individual changes in ST. A clear symptom of a disorder in myocardial supply, without severe oxygen starvation. Occurs during hormone imbalance and electrolyte imbalance.
• Distortion along the T wave, ST depression, low T. The cat's back on the ECG shows the state of ischemia (oxygen starvation of the myocardium).

In addition to the disorder itself, their position in the heart muscle is also described. The main feature of such disorders is their reversibility. Indicators, as a rule, are given for comparison with old studies in order to understand the patient’s condition, since it is almost impossible to read the ECG yourself in this case. If a heart attack is suspected, additional studies are performed.

There are three criteria by which a heart attack is characterized:

• Stage: acute, acute, subacute and cicatricial. Duration from 3 days to lifelong condition.
• Volume: large-focal and small-focal.
• Location.

Whatever the heart attack, this is always a reason to place a person under strict medical supervision, without any delay.

ECG results and heart rate description options

ECG results provide an opportunity to look at the state of a person’s heart. There are different ways to decipher rhythm.

Sinus- This is the most common signature on the electrocardiogram. If no other indicators are indicated besides heart rate, this is the most successful forecast, which means the heart is working well. This type of rhythm suggests a healthy state of the sinus node, as well as the conduction system. The presence of other records proves existing defects and deviations from the norm. There is also atrial, ventricular or atrioventricular rhythm, which show which cells of specific parts of the heart set the rhythm.

Sinus arrhythmia- often normal in young adults and children. This rhythm is characterized by exit from the sinus node. However, the intervals between heart compressions are different. This is often associated with physiological disorders. Sinus arrhythmia should be carefully monitored by a cardiologist to avoid the development of serious diseases. This is especially true for people with a predisposition to heart disease, as well as if arrhythmia is caused by infectious diseases and heart defects.

Sinus bradycardia- characterized by rhythmic compression of the heart muscle with a frequency of about 50 beats. In a healthy person, this condition can often be observed in a state of sleep. This rhythm can manifest itself in people who are professionally involved in sports. Their ECG waves are different from those of an ordinary person.

Persistent bradycardia can characterize weakness of the sinus node, manifested in such cases by more rare contractions at any time of the day and under any condition. If a person experiences pauses during contractions, then surgery is prescribed to install a stimulator.

Extarsystole. This is a rhythm defect, which is characterized by extraordinary compressions outside the sinus node, after which the ECG results show a pause of increased length, called compensatory. The patient feels the heartbeat as uneven, chaotic, too fast or too slow. Sometimes patients are bothered by pauses in heart rhythm. Often there is a feeling of tingling or unpleasant tremors behind the breastbone, as well as a feeling of fear and emptiness in the stomach. Often such conditions do not lead to complications and do not pose a threat to humans.

Sinus tachycardia- with this disorder, the frequency exceeds the normal 90 beats. There is a division into physiological and pathological. Physiological is understood as the onset of such a state in a healthy person under certain physical or emotional stress.

May occur after drinking alcoholic beverages, coffee, or energy drinks. In this case, the condition is temporary and goes away quite quickly. The pathological appearance of this condition is characterized by periodic heartbeats that bother a person at rest.

The causes of the pathological appearance may be elevated body temperature, various infectious diseases, blood loss, long periods without water, anemia, etc. Doctors treat the underlying disease, and tachycardia is stopped only when the patient has a heart attack or acute coronary syndrome.

Paroxysmal tachycardia- in this condition, a person experiences a rapid heartbeat, expressed in an attack that lasts from several minutes to several days. The pulse may increase to 250 beats per minute. There are ventricular and supraventricular forms of such tachycardia. The main reason for this condition is a defect in the passage of electrical impulses in the conductive system. This pathology is quite treatable.

You can stop an attack at home with the help of:

• Holding your breath.
• Forced cough.
• Immersion of face in cold water.

WPW syndrome is a subtype of supraventricular tachycardia. The main provocateur of an attack is an additional nerve bundle, which is located between the atria and ventricles. To eliminate this defect, surgery or drug treatment is required.

CLC- extremely similar to the previous type of pathology. The presence of an additional nerve bundle here contributes to early excitation of the ventricles. The syndrome, as a rule, is congenital and manifests itself in a person with attacks of rapid rhythm, which is very clearly shown by ECG waves.

Atrial fibrillation- may be characterized by attacks or be permanent. The person feels pronounced atrial flutter.

ECG of a healthy person and signs of changes

The ECG of a healthy person includes many indicators by which a person’s health is judged. The ECG of the heart plays a very important role in the process of identifying abnormalities in the functioning of the heart, the most terrible of which is considered to be myocardial infarction. Necrotic zones of infarction can be diagnosed exclusively using electrocardiogram data. Electrocardiography also determines the depth of damage to the heart muscle.

ECG norms for a healthy person: men and women

ECG standards for children

An ECG of the heart is of great importance in diagnosing pathologies. The most dangerous heart disease is myocardial infarction. Only an electrocardiogram will be able to recognize the necrotic areas of the infarction.

Signs of myocardial infarction on an ECG include:

• the necrosis zone is accompanied by changes in the Q-R-S complex, resulting in the appearance of a deep Q wave;
• the damage zone is characterized by a displacement (elevation) of the S-T segment, smoothing the R wave;
• the ischemic zone changes the amplitude and makes the T wave negative.

Electrocardiography also determines the depth of damage to the heart muscle.

How to decipher a heart cardiogram yourself

Not everyone knows how to decipher a heart cardiogram on their own. However, with a good understanding of the indicators, you can independently decipher the ECG and detect changes in the normal functioning of the heart.

First of all, it is worth determining the heart rate indicators. Normally, the heart rhythm should be sinus; the rest indicate the possible development of arrhythmia. Changes in sinus rhythm, or heart rate, suggest the development of tachycardia (faster rhythm) or bradycardia (slower rhythm).

Abnormal data of waves and intervals are also important, since you can read the cardiogram of the heart yourself using their indicators:

1. Prolongation of the QT interval indicates the development of coronary heart disease, rheumatic disease, and sclerotic disorders. A shortening of the interval indicates hypercalcemia.
2. An altered Q wave is a signal of myocardial dysfunction.
3. Sharpening and increased height of the R wave indicate hypertrophy of the right ventricle.
4. A split and widened P wave indicates left atrial hypertrophy.
5. An increase in the PQ interval and disruption of impulse conduction occurs with atrioventricular block.
6. The degree of deviation from the isoline in the R-ST segment diagnoses myocardial ischemia.
7. Elevation of the ST segment above the isoline is a threat of acute infarction; a decrease in the segment registers ischemia.

The cardiac ruler consists of divisions (scales) defining:

• heart rate (HR);
• QT interval;
• millivolts;
• isoelectric lines;
• duration of intervals and segments.

This simple and easy-to-use device is useful for everyone to have for independently deciphering the ECG.

ECG is the most common method for diagnosing the heart organ. Using this technique, you can obtain sufficient information about various pathologies in the heart, as well as carry out monitoring during therapy.

What is electrocardiography?

Electrocardiography is a method for studying the physiological state of the heart muscle, as well as its performance.

For the study, a device is used that registers all changes in physiological processes in the organ and, after processing the information, displays it in a graphic image.

The graph shows:

• Conduction of electrical impulses by the myocardium;
• Heart muscle contraction frequency (HR - );
• Hypertrophic pathologies of the cardiac organ;
• Scars on the myocardium;
• Changes in myocardial functionality.

All these changes in the physiology of the organ, and in its functionality, can be recognized on the ECG. Cardiograph electrodes record bioelectric potentials that appear during contraction of the heart muscle.

Electrical impulses are recorded in different parts of the heart organ, so there is a potential difference between the excited areas and the non-excited areas.

It is this data that is captured by the device’s electrodes, which are attached to different parts of the body.

Who is prescribed an ECG test?

This technique is used for the diagnostic study of certain cardiac disorders and abnormalities.

Indications for use of ECG:

Why is the inspection carried out?

Using this method of checking the heart, it is possible to determine abnormalities in cardiac activity at an early stage of the development of pathology.

An electrocardiogram can detect the most minor changes occurring in an organ that exhibits electrical activity:

• Thickening and expansion of chamber walls;
• Deviations from standard heart sizes:
• The focus of necrosis during myocardial infarction;
• The size of ischemic myocardial damage and many other abnormalities.

It is recommended to conduct a diagnostic study of the heart after the age of 45, since during this period the human body undergoes changes at the hormonal level, which affects the functioning of many organs, including the functioning of the heart.

It is enough to undergo an ECG for preventive purposes once a year.

Types of diagnostics

There are several methods for diagnostic testing of Ekg:

• Research technique at rest. This is a standard technique that is used in any clinic. If the ECG readings at rest do not give a reliable result, then it is necessary to use other methods of ECG examination;
• Verification method with load. This method includes a load on the body (an exercise bike, a treadmill test). In this method, a sensor for measuring cardiac stimulation during exercise is inserted through the esophagus. This type of ECG is capable of identifying pathologies in the heart organ that cannot be recognized in a person at rest. Also, a cardiogram is done at rest after exercise;
• Monitoring for 24 hours (Holter study). According to this method, a sensor is installed in the patient’s chest area, which records the functioning of the heart organ for 24 hours. With this method of research, a person is not freed from his daily household responsibilities, and this is a positive fact in this monitoring;
• ECG through the esophagus. This testing is performed when it is not possible to obtain the necessary information through the chest.

If the symptoms of these diseases are pronounced, you should visit a therapist or cardiologist and undergo an ECG.

• Chest pain near the heart;
• High blood pressure - hypertension;
• Heart pain due to temperature changes in the body;
• Age over 40 calendar years;
• Inflammation of the pericardium - pericarditis;
• Rapid heartbeat - tachycardia;
• Irregular contraction of the heart muscle - arrhythmia;
• Inflammation of the endocardium - endocarditis;
• Pneumonia - pneumonia;
• Bronchitis;
• Bronchial asthma;
• Angina pectoris - coronary heart disease;
• Atherosclerosis, cardiosclerosis.

And also with the development of such symptoms in the body:

• Dyspnea;
• Dizziness;
• Headache;
• Fainting;
• Heartbeat.

Contraindications for using ECG

There are no contraindications for performing an ECG.

There are contraindications for stress testing (stress ECG method):

• Cardiac ischemia;
• Exacerbation of existing cardiac pathologies;
• Acute myocardial infarction;
• Arrhythmia in severe stage;
• Severe form of hypertension;
• Infectious diseases in acute form;
• Severe heart failure.

If an ECG is needed through the esophagus, then a disease of the digestive system is a contraindication.

An electrocardiogram is safe, and this test can be performed on pregnant women. ECG does not affect the intrauterine formation of the fetus.

Preparing for the study

This test does not require any necessary preparation before studying.

But there are some rules for this:

• You can eat before the procedure;
• You can take water without limiting your quantity;
• Do not take drinks containing caffeine before the cardiogram;
• Before the procedure, avoid drinking alcoholic beverages;
• Do not smoke before the ECG.

Execution technique

An electrocardiogram is performed in each clinic. If there is an emergency hospitalization, then an ECG can be done within the walls of the emergency room, and an ECG can also be brought by an emergency doctor upon arrival to the call.

Technique for performing a standard ECG at a doctor’s appointment:

• The patient needs to lie in a horizontal position;
• The girl needs to take off her bra;
• Areas of the skin on the chest, hands and ankles are wiped with a damp cloth (for better conduction of electrical impulses);
• Electrodes are attached to clothespins on the ankles of the legs and on the hands, and 6 electrodes with suction cups are placed on the chest;
• After this, the cardiograph is turned on and the recording of the functioning of the cardiac organ on thermal film begins. The cardiogram graph is written in the form of a curve;
• The procedure takes no more than 10 minutes. The patient does not feel discomfort; there are no unpleasant feelings during the ECG;
• The cardiogram is deciphered by the doctor who performed the procedure and the decoding is transferred to the patient’s attending doctor, which allows the doctor to find out about pathologies in the organ.

Correct application of electrodes by color is necessary:

• On the right wrist - a red electrode;
• On the left wrist there is a yellow electrode;
• Right ankle - black electrode;
• The left ankle is a green electrode.

Correct placement of electrodes

Reading results

After the result of studying the cardiac organ is obtained, it is deciphered.

The result of an electrocardiographic study includes several components:

• Segments - ST, as well as QRST and TP- this is the distance that is marked between the teeth located nearby;
• Teeth - R, QS, T, P- these are angles that have an acute shape and also have a downward direction;
• PQ interval is a gap that includes teeth and segments. The intervals include the time period of passage of the impulse from the ventricles to the atrium chamber.

The waves on the electrocardiogram recording are designated by the letters: P, Q, R, S, T, U.

Each letter of the teeth is a position in the parts of the heart organ:

• R— depolarity of the atria of the myocardium;
• QRS- ventricular depolarity;
• T- ventricular repolarization;
• U wave, which is mild, indicates the process of repolarization of areas of the ventricular conduction system.

The paths along which the discharges move are indicated on the 12-lead cardiogram. When deciphering, you need to know which leads are responsible for what.

Standard leads:

• 1 - first lead;
• 2 - second:
• 3 - third;
• AVL is analogous to lead No. 1;
• AVF is analogous to lead No. 3;
• AVR - display in mirror format of all three leads.

Thoracic leads (these are points that are located on the left side of the sternum in the area of ​​the heart organ):

• V No. 1;
• V No. 2;
• V No. 3;
• V No. 4;
• V No. 5;
• V No. 6.

The value of each lead records the course of an electrical impulse through a specific location in the cardiac organ.

Thanks to each lead, the following information can be recorded:

• The cardiac axis is designated - this is when the electrical axis of the organ is combined with the anatomical cardiac axis (clear boundaries of the location of the heart in the sternum are indicated);
• The structure of the walls of the atrium and ventricular chambers, as well as their thickness;
• The nature and strength of blood flow in the myocardium;
• The sinus rhythm is determined and whether there are any interruptions in the sinus node;
• Are there any deviations in the parameters of the passage of impulses along the wire pathways of the organ?

Based on the results of the analysis, the cardiologist can see the strength of excitation of the myocardium and determine the time period during which systole passes.

Photo gallery: Indicators of segments and scars

Heart organ norms

All basic values ​​are included in this table and mean normal indicators for a healthy person. If minor deviations from the norm occur, then this does not indicate pathology. The reasons for small changes in the heart do not always depend on the functionality of the organ.

indicator of cardiac teeth and segments	normative level in adults	normal children
Heart rate (heart muscle contraction frequency)	from 60 beats per minute to 80 beats	110.0 beats/minute (up to 3 calendar years);
		100.0 beats/minute (up to 5th birthday);
		90.0 -100.0 beats/minute (up to 8 calendar years);
		70.0 - 85.0 beats/minute (up to 12 years of age).
T	0.120 - 0.280 s	-
QRS	0.060 - 0.10 s	0.060 - 0.10 s
Q	0.030 s	-
PQ	0.120 s - 0.2 s	0.20 s
R	0.070 s - 0.110 s	no more than 0.10 s
QT	-	no more than 0.40 s

How to decipher a cardiogram yourself

Everyone wants to decipher a cardiogram before even reaching the attending doctor’s office.

The main task of the organ is performed by the ventricles. The chambers of the heart have partitions between them that are relatively thin.

The left side of the organ and its right side also differ from each other and have their own functional responsibilities.

The load on the right side of the heart and on its left side is also different.

The right ventricle performs the function of providing biological fluid - pulmonary blood flow, and this is a less energy-consuming load than the function of the left ventricle to push blood flow into the large blood flow system.

The left-sided ventricle is more developed than its right neighbor, but it also suffers much more often. But regardless of the degree of load, the left side of the organ and the right side must work harmoniously and rhythmically.

The structure of the heart does not have a uniform structure. It contains elements that are capable of contracting - this is the myocardium, and elements that are irreducible.

The irreducible elements of the heart include:

• Nerve fibers;
• Arteries;
• valves;
• Fatty fiber.

All these elements differ in the electrical conductivity of the impulse and the response to it.

Functionality of the heart organ

The cardiac organ has the following functional responsibilities:

• Automatism is an independent mechanism for releasing impulses that subsequently cause cardiac excitation;
• Myocardial excitability is the process of activation of the heart muscle under the influence of sinus impulses;
• Conduction of impulses through the myocardium - the ability to conduct impulses from the sinus node to the contractile function of the heart;
• The crushing of the myocardium under the influence of impulses - this function allows the chambers of the organ to relax;
• Myocardial tonicity is a condition during diastole when the heart muscle does not lose its shape and ensures a continuous cardiac cycle;
• in statistical polarization (diastole state) - electrically neutral. Under the influence of impulses, biocurrents are formed in it.

ECG analysis

A more accurate interpretation of electrocardiography is made by calculating the waves by area, using special leads - this is called vector theory. Quite often in practice, only the direction indicator of the electrical axis is used.

This indicator includes the QRS vector. When deciphering this analysis, the direction of the vector, both horizontal and vertical, is indicated.

The results are analyzed in a strict sequence, which helps to determine the norm, as well as deviations in the functioning of the cardiac organ:

• The first is an assessment of heart rhythm and heart rate;
• Intervals are being calculated (QT at a rate of 390.0 - 450.0 ms);
• The duration of systole qrst is calculated (using the Bazett formula);

If the interval becomes longer, then the doctor may make a diagnosis:

• Pathology atherosclerosis;
• Ischemia of the cardiac organ;
• Inflammation of the myocardium - myocarditis;
• Cardiac rheumatism.

If the result shows a shortened time interval, then pathology can be suspected - hypercalcemia.

If the conductivity of the pulses is calculated by a special computer program, then the result is more reliable.

• EOS position. The calculation is carried out from the isoline based on the height of the teeth of the cardiogram, where the R wave is higher than the S wave. If it is the other way around, and the axis is deviated to the right, then there is a violation in the performance of the right-sided ventricle. If the axis is deviated to the left side, and the height of the S wave is higher than the R wave in the second and third leads, then there is an increase in the electrical activity of the left ventricle, and a diagnosis of left ventricular hypertrophy is made;
• Next, the QRS complex of cardiac impulses is studied, which develop during the passage of electrical waves to the ventricular myocardium, and determines their functionality - according to the norm, the width of this complex is no more than 120 ms and the complete absence of a pathological Q wave. If this interval shifts, then there is a suspicion of blocking the bundle branches, as well as for disturbances in conductivity. Cardiological data on the right-sided bundle branch block are data on hypertrophy of the right-sided ventricle, and blockade of the left branch is on the hypertrophy of the left-sided ventricle;
• After studying the legs of His, a description of the study of ST segments occurs. This segment displays the recovery time of the myocardium after its depolarization, which is normally present on the isoline. The T wave is an indicator of the process of repolarization of the left and right ventricles. The T wave is asymmetrical and has an upward direction. Change of T wave longer than the QRS complex.

This is what the heart of a healthy person looks like in all respects. In pregnant women, the heart is located in a slightly different place in the chest, and therefore its electrical axis is also shifted.

Depending on the intrauterine development of the fetus, additional stress occurs on the heart muscle, and an electrocardiogram during the period of intrauterine development of the child reveals these signs.

Cardiogram indicators in childhood change in accordance with the child’s maturation. ECGs in children also detect abnormalities in the cardiac organ and are interpreted in accordance with the standard scheme. After the age of 12, a child's heart corresponds to an adult's organ.

Is it possible to fool an ECG?

Many people try to fool electrocardiography. The most common place is the military registration and enlistment office.

In order for the cardiogram readings to be abnormal, many take medications that increase or decrease blood pressure, drink a lot of coffee, or take heart medications.

Accordingly, the diagram shows the state of increased heart rate in a person.

Many people do not understand that by trying to deceive the ECG machine, one can develop complications in the heart organ and in the vascular system. The rhythm of the heart muscle may be disrupted and ventricular repolarization syndrome may develop, and this is fraught with acquired heart disease and heart failure.

The following pathologies in the body are most often simulated:

• Tachycardia- increased contraction of the heart muscle. Occurs from high loads to ECG analysis, drinking large amounts of drinks containing caffeine, taking medications to increase blood pressure;
• Early ventricular repolarization (ERV)- this pathology is provoked by taking heart medications, as well as drinking drinks that contain caffeine (energy drinks);
• Arrhythmia- incorrect heart rhythm. This pathology can be caused by taking beta blockers. Limitless consumption of coffee drinks and large amounts of nicotine also disrupt the correct rhythm of the myocardium;
• Hypertension- also provoked by drinking too much coffee and overloading the body.

The danger in wanting to deceive an ECG is that in such an easy way you can actually develop cardiac pathology, because taking cardiac medications by a healthy body causes additional stress on the cardiac organ and can lead to its failure.

Then it will be necessary to conduct a comprehensive instrumental examination to identify pathology in the cardiac organ and in the bloodstream system, and to determine how complicated the pathology has become.

ECG diagnosis: heart attack

One of the most serious cardiac diagnoses, which is detected by the ECG technique, is a bad cardiogram - a heart attack. In case of myocardial infarction, the decoding indicates the area of ​​myocardial damage by necrosis.

This is the main task of the ECG method for myocardium, because the cardiogram is the first instrumental study of pathology during a heart attack.

The ECG determines not only the location of myocardial necrosis, but also the depth to which the necrotic destruction has penetrated.

The ability of electrocardiography is that the device can distinguish the acute form of a heart attack from the pathology of an aneurysm, as well as from old infarction scars.

In the cardiogram, during myocardial infarction, an elevated ST segment is written, as well as the R wave reflects deformation, and provokes the appearance of a sharp T wave. The characteristics of this segment are similar to a cat’s back during a heart attack.

The ECG shows myocardial infarction with the Q wave type, or without this wave.

How to calculate your heart rate at home

There are several methods for counting the number of heart impulses in one minute:

• A standard ECG records at a rate of 50.0 mm per second. In this situation, the contraction frequency of the heart muscle is calculated using the formula - heart rate is equal to 60 divided by R-R (in millimeters) and multiplied by 0.02. There is a formula, with a cardiograph speed of 25 millimeters per second - heart rate is equal to 60 divided by R-R (in millimeters) and multiplied by 0.04;
• You can also calculate the frequency of heart impulses using a cardiogram using the following formulas: at a device speed of 50 millimeters per second, the heart rate is 600, divided by the average coefficient of the totality of cells (large) between the types of R waves on the graph. At a device speed of 25 millimeters per second, the heart rate is equal to the index 300, divided by the average index of the number of cells (large) between the type of R wave on the graph.

ECG of a healthy heart organ and with cardiac pathology

electrocardiography parameters	standard indicator	deciphering deviations and their characteristics
tooth distance R–R	the segments between all R teeth are the same in distance	different distance indicates:
		· about cardiac arrhythmia;
		· pathology of extrasystole;
		· weak sinus node;
		· blockade of cardiac conduction.
Heart rate	up to 90.0 beats per minute	· tachycardia - heart rate higher than 60 pulses per minute;
		· bradycardia - heart rate less than 60.0 beats per minute.
P wave (atrial contractility)	ascends in an arcing pattern, approximately 2 mm high, anterior to each R wave, and may also be absent from leads 3, V1, and AVL	· with thickening of the walls of the atria myocardium - a tooth up to 3 mm high and up to 5 mm wide. Consists of 2 halves (double-humped);
		· if the rhythm of the sinus node is disturbed (the node does not send an impulse) - complete absence in leads 1, 2, as well as FVF, from V2 to V6;
		· in atrial fibrillation - small waves that are present in the spaces of the R-type waves.
interval between teeth of types P–Q	line between teeth type P - Q horizontal 0.10 seconds - 0.20 seconds	· atrioventricular block of the heart muscle - in case of an increase in the interval by 10 millimeters at an electrocardiograph recording speed of 50 millimeters per second;
		· WPW syndrome - when the interval between these teeth is shortened by 3 millimeters.
QRS complex	the duration of the complex on the graph is 0.10 seconds (5.0 mm), after the complex there is a T wave, and there is also a straight line that is located horizontally	· blocking of the bundle branches - an enlarged ventricular complex means hypertrophy of the myocardial tissue of these ventricles;
		· paroxysmal type of tachycardia - if the complexes go up and have no gaps. This may also indicate the disease ventricular fibrillation;
		· infarction of the cardiac organ - a complex in the form of a flag.
type Q	the wave is directed downward with a depth of at least one-fourth of the R wave; also, this wave may not be present on the cardiogram	a Q wave, deep down and wide along the line, in standard types of leads or chest leads - these are signs of a heart attack in the acute stage of the pathology.
R wave	a tall tooth, which is directed upward, 10.0 - 15.0 millimeters high with sharp ends. Present in all types of leads.	· hypertrophy of the left ventricle - different in height in different leads and more than 15.0 - 20.0 millimeters in leads No. 1, AVL, as well as V5 and V6;
		· blocking of the bundle branches - notching and bifurcation at the top of the R wave.
S tooth type	present in all types of leads, the tooth is directed downward, has a sharp end, its depth is from 2.0 to 5.0 millimeters in leads of the standard type.	· according to the standard in the chest leads, this wave looks with a depth equal to the height of the R wave, but it should be higher than 20.0 millimeters, and in leads of types V2 and V4, the depth of the S wave is equal to the height of the R wave type. Low depth or jaggedness S in leads 3, AVF, V1, and V2 is left ventricular hypertrophy.
cardiac segment S–T	in accordance with a straight line that lies horizontally between the types of teeth S - T	· ischemia of the cardiac organ, heart attack and angina pectoris are marked by a segment line up or down by more than 2.0 millimeters.
T-prong	directed upward along an arc type with a height less than 50% of the height from the R wave, and in lead V1 it has an equal height to it, but not more than it.	· cardiac ischemia or overload of the cardiac organ - a high double-humped tooth with a sharp end in the chest leads, as well as standard ones;
		· myocardial infarction in the acute stage of the disease - this T wave is combined with an S–T type interval, as well as with an R wave, and a flag appears on the graph.

Description and characteristics of electrocardiography, which are normal or pathological, are given in a simplified version of the decrypted information.

A complete decoding, as well as a conclusion about the functionality of the cardiac organ, can only be given by a specialized doctor - a cardiologist who has a complete and expanded professional circuit for reading an electrocardiogram.

In case of disorders in children, a professional opinion and evaluation of the cardiogram is issued only by a pediatric cardiologist.

Video: Daily monitoring.

Conclusion

ECG readings are the basis for making an initial diagnosis during emergency hospitalization, as well as for establishing a final cardiac diagnosis, together with other instrumental diagnostic methods.

The importance of ECG diagnostics was appreciated back in the 20th century, and to this day electrocardiography remains the most common research technique in cardiology. Using the ECG method, diagnostics is made not only of the heart organ, but also of the vascular system of the human body.

The advantage of electrocardiography is its simplicity of execution, low cost for diagnosis and accuracy of indications.

To use the results of an ECG to make an accurate diagnosis, it is necessary only by comparing its results with the results of other diagnostic studies.

Allows you to monitor the condition of your heart and monitor the ECG. Monitor the signs of a normal ECG. You do a study and after 30 seconds you receive an automatic conclusion about the condition of your heart. If necessary, you can send the study for medical supervision.

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ECG is the main method for diagnosing heart rhythm disorders. This publication briefly presents signs of a normal ECG. The ECG recording is carried out in a position comfortable for the patient, breathing should be calm. To record an ECG, 12 main leads are most often used: 6 from the limbs and 6 from the chest. The project offers an analysis of microalternations in six leads (only electrodes placed on the limbs are used), which allow one to independently identify possible abnormalities in the functioning of the heart. Using the project, analysis of 12 leads is also possible. But at home, it is difficult for an untrained person to correctly position the chest electrodes, which can lead to incorrect recording of the electrocardiogram. Therefore, the CARDIOVISOR device, which records 12 leads, is purchased by cardiologists.

To obtain 6 standard leads, electrodes are applied as follows:
. Lead I: left hand (+) and right hand (-)
. Lead II: left leg (+) and right arm (-)
. Lead III: left leg (+) and left arm (-)
. aVR - enhanced abduction from the right hand (short for augmented voltage right - enhanced potential on the right).
. aVL - enhanced abduction from the left arm
. aVF - increased abduction from the left leg

The figure shows an electrocardiogram obtained by a client in a website project

Each lead characterizes the work of a specific area of ​​the myocardium. Leads I and aVL reflect the potentials of the anterior and lateral walls of the left ventricle. Leads III and aVF reflect the potentials of the inferior phrenic (posterior) wall of the left ventricle. Lead II is intermediate and confirms changes in the anterolateral or posterior wall of the left ventricle.

The heart consists of two atria and two ventricles. The mass of the atria is much smaller than the mass of the ventricles, so the electrical changes associated with atrial contraction are small. They are associated with the P wave. In turn, when the ventricles are depolarized, high-amplitude fluctuations are recorded on the ECG - this is the QRS complex. The T wave is associated with the return of the ventricles to a state of rest.

When analyzing an ECG, a strict sequence is followed:
. Heart rhythm
. Intervals reflecting conductivity
. Electrical axis of the heart
. Description of QRS complexes
. Description of ST segments and T waves

Heart rhythm and heart rate

Heart rhythm is an important indicator of heart function. Normally, the rhythm is sinus (the name is associated with the sinus node - the pacemaker, thanks to whose work the impulse is transmitted and the heart contracts). If depolarization does not begin in the sinus node, then in this case they speak of arrhythmia and the rhythm is named after the department from which depolarization begins. Heart rate (HR) is determined on the ECG by the distance between the R waves. The heart rhythm is considered normal if the duration of the R-R intervals is the same or has a slight variation (up to 10%). Normal heart rate is 60-80 beats per minute. The ECG machine advances the paper at a speed of 25mm/s, so a large square (5mm) corresponds to 0.2 seconds (s) or 200 milliseconds (ms). Heart rate is measured using the formula
Heart rate = 60/R-R,
where R-R is the distance between the highest teeth associated with ventricular contraction.

An acceleration of the rhythm is called tachycardia, and a slowdown is called bradycardia.
An ECG analysis should be performed by a cardiologist. Using CARDIOVISOR, the client of the project can take an ECG independently, since all calculations are carried out by a computer program, and the patient sees the final result analyzed by the system.

Intervals reflecting conductivity

By the intervals between the P-QRS-T waves, one can judge the conductivity of the electrical impulse between the parts of the heart. Normally, the PQ interval is 120-200 ms (3-5 small squares). The PQ interval can be used to judge the conduction of an impulse from the atria through the atrioventricular (atrioventricular) node to the ventricles. The QRS complex characterizes the excitation of the ventricles. The width of the QRS complex is measured from the beginning of the Q wave to the end of the S wave. Normally, this width is 60-100 ms. They also look at the nature of the teeth of this complex. Normally, the Q wave should be no more than 0.04 s in duration and not exceed 3 mm in depth. An abnormal Q wave may indicate myocardial infarction.

QT interval characterizes the total duration of ventricular systole (contraction). The QT includes the interval from the beginning of the QRS complex to the end of the T wave. Bazett's formula is often used to calculate the QT interval. This formula takes into account the dependence of the QT interval on the rhythm frequency (QTc). Normally, the QTc interval is 390-450 ms. Prolongation of the QT interval indicates the development of coronary heart disease, atherosclerosis, rheumatism or myocarditis. A shortened QT interval may indicate hypercalcemia.
All intervals reflecting the conductivity of the electrical impulse are calculated by a special program, which allows you to obtain fairly accurate examination results, which are visible in the system diagnostic cabinet mode.

Electrical axis of the heart (EOS)

Determining the position of the electrical axis of the heart makes it possible to identify areas of disturbance in the conduction of the electrical impulse. The position of the EOS is assessed by cardiologists. When using, data on the position of the electrical axis of the heart is calculated automatically and the patient can view the result in his diagnostic room. To determine the EOS, look at the height of the teeth. Normally, the R wave should be larger than the S wave (counted from the isoline) in leads I, II and III. Deviation of the axis to the right (the S wave is larger than the R wave in lead I) indicates problems in the functioning of the right ventricle, and deviations to the left (the S wave is larger than the R wave in leads II and III) may indicate left ventricular hypertrophy.

Description of the QRS complex

The QRS complex arises due to the conduction of an impulse through the septum and myocardium of the ventricles and characterizes their work. Normally, there is no pathological Q wave (no wider than 20-40 ms and no deeper than 1/3 of the R wave). In lead aVR, the P wave is negative, and the QRS complex is oriented downward from the isoelectric line. The width of the QRS complex normally does not exceed 120 ms. An increase in this interval may indicate bundle branch block (conduction disorder).

Drawing. Negative P wave in lead aVR (isoelectric line indicated in red).

P wave morphology

The P wave reflects the propagation of the electrical impulse through both atria. The initial part of the P wave characterizes the activity of the right atrium, and the final part - the left atrium. Normally, the P wave should be positive in leads I and II, aVR - negative, usually positive in aVF and inconsistent in leads III and aVL (can be positive, inverted or biphasic). The normal width of the P wave is at least 0.12 s (120 ms). With an increase in the width of the P wave, as well as its doubling, we can talk about a violation of the impulse conduction - atrioventricular block occurs (figure).

Drawing. Doubling and increasing the width of the P wave

Description of ST segments and T waves

ST segment corresponds to the period when both ventricles are completely covered by excitation, measured from the end of the S wave to the beginning of the T wave. The duration of ST depends on the pulse rate. Normally, the ST segment is located on an isoline, ST depression is allowed up to 0.5 mm, its elevation in standard leads should not exceed 1 mm. ST segment elevation is observed in acute infarction and pericarditis, and depression indicates myocardial ischemia or the influence of cardiac glycosides.

T wave characterizes the process of repolarization (return of the ventricles to their original state). During normal heart function, the T-wave is directed upward in leads I and II, but in lead aVR it will always be negative. A tall and pointed T wave is observed with hyperkalemia, while a flat and elongated wave indicates the opposite process - hypokalemia. A negative T wave in leads I and II may indicate ischemia, infarction, hypertrophy of the right and left ventricles, or pulmonary embolism.

The main parameters that are used to analyze the ECG using the standard method are described above. The project offers ECG analysis, which is based on the dispersion mapping method. It is based on the formation of an information-topological model of small ECG oscillations - microalterations of the ECG signal. Analysis of these deviations makes it possible to identify pathology in the heart at earlier stages, in contrast to the standard ECG analysis method.

Rostislav Zhadeiko, especially for the project.