Cardiogram of the heart qrs. Why do they do an ECG of the heart? Explanation of analysis, norms, indications and contraindications. What is an ECG, how is the procedure performed?

ECG interpretation is performed by a qualified specialist. This functional diagnostic method checks:

Heart rhythm: what is the state of the electrical impulse generators and the cardiac systems that conduct these impulses.
Heart muscle: its condition and performance, damage, inflammation and other pathological processes that could affect the condition of the heart.

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Patients receive an electrocardiogram along with its results. It is impossible to decipher it yourself. To read the diagram, you will need special medical education. There is no need to be nervous before meeting with a functional diagnostician. At the appointment, he will explain all the risks of the diagnosis and prescribe effective treatment. But if the patient is diagnosed with a serious illness, then a consultation with a cardiologist will be required.

When the ECG interpretation does not give clear results, the doctor may prescribe additional studies:

ECG monitoring;
Holter (monitoring of heart function throughout the day);
Ultrasound of the heart muscle;
Treadmill (test for heart performance during exercise).

The results of measurements using these studies are an accurate indicator of heart function. If there are no malfunctions in the myocardium, the tests will have good results.

On the ECG of a healthy person, the inscription “Sinus rhythm” is found. If a frequency of beats per minute up to 90 is added to this inscription, the results are good, the heart works without interruption. Sinus rhythm is an indicator of the rhythm of the sinus node, which is the main rhythm producer for regulating and generating electrical impulses with the help of which the heart muscle contracts. An electrocardiogram description that includes sinus rhythm is the norm, indicating the health of the sinus node and the heart muscle itself.

If the heart cardiogram does not have any other marks in its description, it indicates complete heart health. Sinus rhythm can be replaced by atrial, atrioventricular or ventricular. These types of rhythms indicate that contractions are carried out precisely by these parts of the heart, which is considered a pathology.

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What is sinus arrhythmia?

Sinus arrhythmia is a common diagnosis in childhood and adolescence. It is characterized by different time intervals between sinus contractions of the heart muscle. Experts say that this pathology can be caused by changes at the physiological level. Up to 40% of sinus arrhythmias should be controlled by a cardiologist. Patients should be examined and re-tested every 3-4 months. Such precautions will protect you as much as possible from the development of more serious heart diseases.

Sinus bradycardia is a rhythm of heart contractions up to 50 times per minute. This phenomenon is also possible in healthy people during sleep or in professional athletes. Bradycardia of a pathological nature may be a sign of sick sinus syndrome. This case implies severe bradycardia, reaching up to 35 heartbeats per minute. This pathology can be observed all the time, and not just at night.

If bradycardia consists of pauses between contractions of up to 3 seconds during the day and up to 5 seconds at night, there may be a disruption in the supply of oxygen to the tissues, which usually leads to fainting. Only an electrical pacemaker, which is placed directly on the heart during surgery, will help get rid of this problem. The installation takes place at the site of the sinus node, which further allows the heart to work without failures.

The causes of a poor cardiogram may be associated with sinus tachycardia, which is a contraction of the heart rate more than 90 times per minute. It is divided into tachycardia of a physiological and pathological nature. Healthy people can experience sinus tachycardia during physical and emotional stress, drinking coffee or strong tea, alcoholic drinks and energy drinks. Sinus tachycardia after active pastime is a brief manifestation. After the manifestation of an increased number of beats, the rhythm returns to its normal state in a fairly short time after reducing the intensity of physical activity.

With tachycardia of a pathological nature, a rapid heartbeat bothers the patient all the time. The cause of increased heart rate can be: increased body temperature, infection, blood loss, dehydration, anemia and more. The root cause causing tachycardia needs to be treated. Relief of sinus tachycardia occurs only in the case of myocardial infarction or acute coronary syndrome.

How does extrasystole manifest?

A specialist can identify this pathology immediately, since this is a change in rhythm, the nature of which is foci behind the sinus rhythm. They give extra contractions of the heart muscle. After this process, a pause doubled in time appears, the name of which is compensatory. Patients believe that such a change in heartbeat occurs due to nervous stress. Rhythm can be either rapid or slow, sometimes chaotic. The patient himself can notice the dips that occur in the rhythm of the heartbeat.

An example of deciphering an ECG with extrasystole is an example of pathology that is visible even to non-specialists. Some patients complain not only of changes in rhythm, but also of unpleasant and painful sensations in the chest area. They experience tremors, tingling, and a sinking feeling of fear rising in their stomach.

Such manifestations are not always pathological and life-threatening.

Many types of extrasystoles do not inhibit blood circulation and do not reduce the performance of the heart.

Extrasystoles are divided into 2 types:

functional (manifest against a background of panic and nerves);
organic (if a person has heart defects, myocarditis and congenital problems with the cardiovascular system).

In 20% of cases, the cause of the disease is intoxication or heart surgery. A single manifestation of extrasystole occurs rarely (up to 5 times in 1 hour). Such gaps are functional in nature and are not an obstacle to normal blood supply. There are moments when paired extrasystoles occur. They appear after a series of normal contractions. It is this rhythm that is an obstacle to the normal functioning of the heart muscle. For an accurate diagnosis of this manifestation, an additional ECG and Holter analysis is prescribed for a day.

Main classes of pathology

Extrasystoles also have the form of allorhythmia. When an extrasystole appears on every second contraction, experts diagnose bigeminy, on every third - trigeminy, on every fourth - quadrigeminy. According to Laum’s classification, extrasystoles of ventricular nature are divided into 5 classes depending on the daily examination indicators:

1. Single cases of disease manifestations up to 60 times every hour, united by one focus (monotopic).
2. Constant monotopic changes, occurring more than 5-6 times every minute.
3. Constant polymorphic (have different shapes) and polytopic (have different centers of occurrence) changes.
4. Paired or group, accompanied by episodic attacks of paroxysmal tachycardia.
5. Early manifestation of extrasystoles.

No medications are prescribed for treatment. When the disease manifests itself less than 200 times a day (Holter monitoring will help establish the exact number), extrasystoles are considered safe, so there is no need to worry about their manifestations. Regular examinations by a cardiologist are required every 3 months.

If the patient’s electrocardiogram reveals pathological contractions more than 200 times every day, then additional examinations are prescribed. Specialists prescribe ultrasound of the heart and magnetic resonance imaging (MRI) of the heart muscle. Treatment of the manifestation is specific and requires a special approach, since it is not the extrasystoles that are treated, but the root causes of their occurrence.

Paroxysmal tachycardia

Paroxysm is a manifestation of an attack. This process of increased heart rate can last for several hours or several days. The electrocardiogram displays equal intervals between muscle contractions. But the rhythm changes and can reach more than 100 beats in 1 minute (the average is 120-250 times).

Doctors distinguish supraventricular and ventricular types of tachycardia. The basis of this pathology is the abnormal circulation of electrical impulses in the cardiovascular system. You can get rid of this manifestation at home, but for a while: you need to hold your breath, start coughing hysterically, or dip your face in cold water. But such methods are ineffective. Therefore, there is a medical method for the treatment of paroxysmal tachycardia.

One of the types of supraventricular tachycardia is Wolff-Parkinson-White syndrome. The title includes the names of all the doctors who described it. The reason for this type of tachycardia is the appearance of an extra bundle of nerves between the atria and ventricles, which conducts the rhythm faster than the main driver. As a result, the heart contracts one extra time. This pathology can be treated conservatively or surgically. The operation is prescribed only in case of low effectiveness or the patient is allergic to the active components of treatment, in case of atrial fibrillation or heart defects of various types.

Clerk-Levy-Christesco syndrome is a manifestation similar to the previous pathology, but it is characterized by earlier than normal stimulation of the ventricles with the help of an additional bundle through which the nerve impulse passes. The syndrome is a congenital pathology. If you decipher the cardiogram of the heart, its manifestation can be seen immediately by attacks of rapid heartbeat.

Atrial fibrillation

During fibrillation, irregular contractions of the heart muscle are observed with intervals between contractions of varying lengths. This is explained by the fact that the rhythm is set not by the sinus node, but by other cells of the atria. The frequency of contractions can reach even 700 beats in 1 minute. Full contraction of the atria is simply absent; it occurs due to muscle fibers, which do not allow the ventricles to be completely filled with blood. The consequence of this process is a deterioration in the heart’s output of blood, which leads to oxygen starvation of organs and tissues of all body systems.

Atrial fibrillation also has another name: atrial fibrillation. In fact, not all atrial contractions travel directly to the ventricles. This results in a decrease in the normal heart rate (bradysystole, which has a beat rate of less than 60 times per minute). But the heart contraction can be normal (normosystole, 60-90 times per minute) or increased (tachysystole, more than 90 times per minute).

Determining atrial fibrillation on an electrocardiogram is easy, since attacks are difficult to miss. The onset of an attack in 90% of cases is a strong shock to the heart muscle. Next, a series of arrhythmic oscillations of the heart develops with an increased or normal frequency. The patient's condition also worsens: he becomes weak, sweaty, and dizzy. The patient awakens to a pronounced fear of death. Shortness of breath and an agitated state may occur. Sometimes loss of consciousness occurs. Reading a cardiogram at the final stage of an attack is also easy: the rhythm returns to normal. But the patient feels a strong desire to urinate, during which a fairly large amount of fluid comes out.

The disease is relieved using reflex methods, drugs in the form of tablets or injections. Less commonly, specialists perform cardioversion - stimulation of the heart muscle using an electric defibrillator. If attacks of ventricular fibrillation are not eliminated within 2 days, complications may occur. Pulmonary embolism and stroke may occur.

A constant form of flicker, in which neither medications nor electrical stimulation of the heart helps, becomes commonplace in the patient’s life and is felt only during tachysystole (increased heart rate). If the electrocardiogram reveals tachysystole and atrial fibrillation, then it is necessary to reduce the number of heart contractions to normal without trying to make them rhythmic. Atrial fibrillation can appear against the background of coronary heart disease, thyrotoxicosis, heart defects of various types, diabetes mellitus, sick sinus syndrome, intoxication after alcohol poisoning.

Atrial flutter

Atrial flutter is constant and frequent contractions of the atria (more than 200 times per minute) and ventricles (less than 200 times). Flutter in 90% of cases has an acute form, but is tolerated much better and easier than fibrillation, since changes in blood circulation are less pronounced. The development of flutter is possible against the background of heart disease (cardiomyopathy, heart failure), after surgery on the heart muscle. With obstructive pulmonary disease, it practically does not manifest itself. It is easy to read an ECG for this disease, as it is manifested by frequent rhythmic heartbeat, swollen veins in the neck, shortness of breath, increased sweating and weakness.

In the normal state, electrical excitation is generated in the sinus node, which passes through the conduction system. It experiences a physiological delay of literally a split second in the area of the atrioventricular node. The atria and ventricles, whose function is to pump blood, are stimulated by this impulse. When an impulse is delayed in some part of the system, it reaches other areas of the heart later, which leads to disruptions in the normal operation of the pumping system. Changes in conductivity are called blockade.

The occurrence of blockades is a functional disorder. But the reason for their occurrence in 75% of cases is alcohol or drug intoxication and organic diseases of the heart muscle. There are several types of blockades:

1. Sinoatrial block: the passage of an impulse directly from the sinus node is difficult. Then this blockade develops into sick sinus syndrome, leading to a decrease in the number of contractions until a new blockade occurs, disruption of the peripheral blood supply, shortness of breath, weakness, dizziness and loss of consciousness.
2. Samoilov-Wenckebach block - the second degree of sinoatrial block.
3. Atrioventricular block is a delayed excitation of the atrioventricular node for more than 0.09 seconds. There are 3 degrees of blockade of this type. With the highest degree of disease, the ventricles contract more often. Therefore, at the highest stages, blood circulation disorders become more severe.

Conduction disturbances in the ventricles

The electrical signal travels inside the ventricles to special cells made of muscle tissue. The propagation of this signal is carried out through systems such as the bundle of His, its legs and their branches. The cause of a bad cardiogram is the occurrence of disturbances in the conductivity of the electrical signal. Specialists can easily diagnose this deviation from the norm on an ECG. At the same time, the diagram clearly shows that one of the ventricles is stimulated later than the second, because the signaling is produced with a delay, passing along bypass paths due to the blockade of the desired area.

The blockade is classified not only by place of origin, but also by type. There are complete and incomplete blockades, permanent and non-permanent. The root causes of blockades inside the ventricles are the same as in other diseases with poor conduction: ischemic disease, cardiomyopathy, defects of various types, fibrosis, cancer of the heart. The consumption of antiarrhythmic drugs, increased potassium levels in the blood, oxygen starvation, and more can affect the occurrence of the disease.

The most common blockage of the superior branch is on the left bundle branch. The second place is taken by the blockade of the entire area of the right leg. It does not occur due to other heart diseases. Left leg block occurs when the myocardium is damaged by a number of diseases. The lower branch of the left leg suffers from pathological changes in the structure of the human chest. It can also occur when the right ventricle is overloaded.

Registration of an electrocardiogram is a way to study electrical signals generated during the activity of the heart muscles. To record electrocardiogram data, 10 electrodes are used: 1 zero on the right leg, 3 standard from the limbs and 6 in the heart area.

The result of taking electrical indicators, the work of various parts of the organ, is the creation of an electrocardiogram.

Its parameters are recorded on special roll paper. The paper moving speed is available in 3 options:

25 mm.sec;
50 mm.sec;
100 mm.sec;

There are electronic sensors that can record ECG parameters on the hard drive of the system unit and, if necessary, display this data on a monitor or print it on the required paper formats.

Decoding of the recorded electrocardiogram.

The result of the analysis of electrocardiogram parameters is given by a cardiologist. The recording is deciphered by the doctor by establishing the duration of the intervals between the various elements of the recorded indicators. An explanation of the features of the electrocardiogram contains many points:

Normal ECG readings.

Consideration of a standard cardiogram of the heart is represented by the following indicators:

Electrocardiogram in case of myocardial infarction.

Myocardial infarction occurs due to exacerbation of coronary artery disease, when the internal cavity of the coronary artery of the heart muscle narrows significantly. If this disorder is not corrected within 15–20 minutes, the death of the heart muscle cells that receive oxygen and nutrients from this artery occurs. This circumstance creates significant disturbances in the functioning of the heart and turns out to be a severe and serious threat to life. If a heart attack occurs, an electrocardiogram will help identify the location of necrosis. The indicated cardiogram contains noticeably manifested deviations in the electrical signals of the heart muscle:

Heart rhythm disorder.

A disorder of the rhythm of contraction of the heart muscles is detected when changes appear on the electrocardiogram:

Hypertrophy of the heart.

An increase in the volume of the heart muscles is an adaptation of the organ to new operating conditions. Changes appearing on the electrocardiogram are determined by high bioelectric strength, a characteristic muscle area, a delay in the movement of bioelectric impulses in its thickness, and the appearance of signs of oxygen starvation.

Conclusion.

Electrocardiographic indicators of heart pathology are varied. Reading them is a complex activity that requires special training and improvement of practical skills. A specialist characterizing an ECG needs to know the basic principles of cardiac physiology and various versions of cardiograms. He needs to have skills in identifying abnormalities in cardiac activity. Calculate the impact of medications and other factors on the occurrence of differences in the structure of ECG waves and intervals. Therefore, the interpretation of the electrocardiogram should be entrusted to a specialist who has encountered in his practice various types of deficiencies in the functioning of the heart.

ECG - what is it?

Electrocardiography (cardiogram) is a determination of the electrical activity of the heart.

Using this procedure you can find out:

heart rate and conductivity;
presence of blockades;
sizes of the ventricles and atria;
level of blood supply to the heart muscle.

A cardiogram is the main study that can identify a number of dangerous diseases - myocardial infarction, heart defects, heart failure, arrhythmia.

A cardiogram helps identify abnormalities in the functioning of the heart.

Thanks to an ECG, it is possible to detect not only cardiac disorders, but also pathologies in the lungs, endocrine system (diabetes mellitus), blood vessels (high cholesterol, high blood pressure).

No special preparation is required to undergo a heart examination. In public hospitals, an ECG requires a referral from the attending physician; the procedure is free.

Private clinics do not require a referral, but here the study is paid:

the price for registering a cardiogram without decoding is 520–580 rubles;
the cost of decryption itself is from 430 rubles;
ECG at home - from 1270 to 1900 rubles.

The cost of the procedure depends on the procedure and the level of qualification of the hospital.

ECG methods

For a comprehensive diagnosis of cardiac activity, there are several methods for conducting an electrocardiogram - a classic heart cardiogram, Holter ECG and stress ECG.

Classic cardiogram

The most common and simple way to study the strength and direction of electrical currents that appear during each impulse of the heart muscle. The duration of the procedure does not exceed 5 minutes.

During this time, specialists manage to:

study the electrical conductivity of the heart;
detect heart attack pericarditis;
examine the chambers of the heart, identify thickening of their walls;
determine the effectiveness of the prescribed therapy (how the heart works after taking certain medications).

A classic cardiogram is a simple and accessible method of studying the heart.

The disadvantage of this method is that it is carried out at rest. Therefore, pathologies that manifest themselves under stress (emotional, physical) or during sleep cannot be detected by this diagnostic method. In these cases, the doctor relies on the patient’s complaints, main signs and may prescribe other types of research.

The technique allows you to identify pathologies that do not appear in a calm state. The device records cardiac activity throughout the day and makes it possible to determine the moment of failure in the patient’s usual conditions (during physical activity, during stress, during sleep, while walking or running).

Thanks to the Holter study, it is possible to:

determine at what moments an irregular heart rhythm appears and what provokes it;
identify the source of the feeling of squeezing or burning in the chest, fainting or dizziness.

The method also helps to identify ischemia (insufficient blood flow to the heart muscle) in its early stages.

Heart rhythms using the Holter method are measured for at least 24 hours

Stress ECG is monitoring of heart function during exercise (exercises on a treadmill, exercise on an exercise bike). It is performed when the patient experiences periodic disturbances in cardiac activity that electrocardiography cannot detect at rest.

ECG with stress makes it possible to:

identify factors that provoke deterioration of the condition during physical activity;
find the cause of sudden surges in blood pressure or irregular heartbeat;
monitor exercise after a heart attack or surgery.

The study allows you to select the most appropriate therapy and monitor the effect of medications.

Stress ECG is performed to study the work of the heart under stress.

Indications for electrocardiography

Typically, a cardiac cardiogram is prescribed based on the patient’s complaints and the presence of unpleasant symptoms:

pressure surges, often upward;
difficulty breathing, turning into shortness of breath even in a calm state;
pain in the heart area;
heart murmurs;
diabetes mellitus;
destruction of joints and muscles with damage to blood vessels and the heart (rheumatism);
causeless pulse disturbance.

A cardiogram is always prescribed after a stroke, frequent fainting, and also before any surgical intervention.

If you have frequent pain in the heart, you need to do a cardiogram

Preparing for the study

Electrocardiography does not require special preparation. For more reliable indicators, experts recommend following simple rules on the eve of the study.

Rest. You need to get a good night's sleep, avoid emotional outbursts and stressful situations, and do not overstrain your body with physical activity.
Food. Do not overeat before the procedure. Doctors sometimes recommend fasting heart monitoring.
Drink. A few hours before the cardiogram, it is recommended to drink less fluid to reduce the load on the heart.
Meditation. Before the procedure itself, you need to calm down, take a deep breath, then exhale. Normalizing breathing has a positive effect on the functioning of the cardiovascular system.

Simple recommendations allow you to obtain the most accurate and objective cardiology results using any research method.

Before performing an ECG, you need to get a good night's sleep.

How is an ECG performed?

Many have encountered a cardiac cardiogram and know that the procedure takes 5-7 minutes and consists of several stages.

The patient needs to expose the chest, forearms, wrists and lower legs. Lie down on the couch.
The specialist treats the areas where the electrodes will be adjacent with alcohol and a special gel, which promotes a better fit of the wires.
After securing the cuffs and suction cups, the cardiograph is turned on. Its operating principle is that it uses electrodes to read the rhythm of heart contractions and record any disturbances in the functioning of a vital organ in the form of graphic data.

The resulting cardiogram requires decoding, which is carried out by a cardiologist.

To measure heart rhythms, special suction cups are placed in the area of the heart.

Contraindications for electrocardiography

A regular ECG does not harm the body. The equipment reads only cardiac currents and does not affect other organs. Therefore, it can be done during pregnancy, children and adults.

But electrocardiography with a load has serious contraindications:

third stage hypertension;
severe circulatory disorders;
thrombophlebitis in exacerbation;
myocardial infarction in the acute period;
enlargement of the walls of the heart;
severe infectious diseases.

You can’t do a cardiogram if you have thrombophlebitis

Decoding the results

Cardiograph data reflects the functioning of a vital organ and is the basis for making a diagnosis.

ECG analysis algorithm

The sequence of studying cardiac activity consists of several stages:

Assessment of the work of the heart muscle - rhythm and contraction of the organ. Study of intervals and identification of blockades.
Assessment of ST segments and identification of pathological Q waves.
Study of R waves.
Examination of the left and right ventricles to identify their hypertrophy.
Studying the location of the heart and determining its electrical axis.
Study of the T wave and other changes.

Electrocardiography analysis consists of 3 main indicators, which are schematically depicted on the cardiograph tape:

serrations (prominences or depressions with sharp ends above a straight line);
segments (segments connecting teeth);
interval (a distance consisting of a tooth and a segment).

When decoding the cardiogram, the following parameters are taken into account:

systolic indicator - the amount of blood that is ejected by the ventricle in 1 contraction;
minute indicator - the volume of blood passed through the ventricle in 1 minute;
Heart rate (HR) – the number of heart beats in 60 seconds.

After analyzing all the characteristics, you can see the general clinical picture of cardiac activity.

Normal ECG in adults

An inexperienced person will not be able to decipher the resulting diagram on his own, but it is still possible to have a general idea of the state. To do this, it is necessary to understand the main characteristics of such monitoring within normal limits.

Table “Indicators of a good ECG”

Indicator	Normal in adults	Symbols and description
QRS complex	0.06–0.1 s	Shows ventricular excitation. QRS in a normal ECG is the width from the R wave to the S wave, which does not exceed 100 ms. The duration of electrical cardiac activity is no more than 2.6 mV. The amplitude of the teeth in the chest leads is always greater (up to 0.8 cm), and in the standard leads it is smaller (up to 0.5 cm)
P wave	0.07–0.12 s	The atrial rhythm, which normally should be sinus, reflects the excitation of the atria.
Q wave	0.04 s	Shows excitation of the left half of the septum between the ventricles
T wave	0.12–0.28 s	Displays recovery processes in the myocardium. The normal T wave interval varies between 100–250 ms
PQ wave	0.12–0.2 s	Indicates the time it takes for excitation to travel through the atria to the ventricular myocardium
Heart rate	65–90 beats per minute	Displays heart rhythm

What the main indicators of heart activity look like in a cardiogram is shown in the photo.

Normal cardiogram in children

Some ECG parameters in a child differ from adult parameters and depend on age:

Heart rate - from 135 (in a newborn baby) to 75–80 (in a teenager).
EOS (electrical axis of the heart) - normally, the total angle of the electrical force vector should not exceed 45–70 degrees. In a newborn, the heart is deviated to the right; in children under 14 years of age, the axis is vertical.
The heart rhythm is sinus.

The location and duration of the waves correspond to the normal cardiogram of an adult.

Normal heart parameters in a child

Any deviations from the norm in the interpretation of the cardiogram are a reason for a more detailed examination of the person.

There are several end results of an ECG:

low-amplitude ECG - decreased wave height (QRS complex) in all leads - a common sign of myocardial dystrophy;
borderline or atypical ECG - some parameters do not correspond to the norm, but do not belong to severe pathologies.
pathological ECG - serious abnormalities in cardiac activity that require immediate medical intervention.

Cardiogram with deviations

Not all changes in the cardiogram should be taken as an indicator of serious heart problems. Rhythm disturbances or a reduction in the width of segments between the teeth in a healthy person can be a consequence of emotional overstrain, stress, or physical activity. In this case, it is better to go through the monitoring again and double-check the results.

Table “Pathological disorders of cardiac activity”

Type of deviations	Name of the disease	Decoding
Heart rhythm disturbance	Sinus arrhythmia (refers to borderline ECG)	The R-R width varies within 10% of the norm (not a pathology in children and adolescents).
	Sinus bradycardia	Heart rate is less than 63 beats per minute, PQ waves are more than 0.12 s, P waves are normal
	Tachycardia	Pulse 120-185 beats. The P wave moves upward – sinus tachycardia; QRS complex longer than 0.12 s – ventricular tachycardia
Change in the position of the EOS (cardiomyopathy)	His bundle block, pathological changes in the right ventricle	Very high tooth S compared to R, axis shifted to the right by more than 90 degrees
Change in the position of the EOS (cardiomyopathy)	Left gastric hypertrophy (occurs with heart attack, pulmonary edema)	Left axis shift 40-90 degrees, very tall S and R teeth
Changes in the conduction system	Atrioventricular block (AV) 1st degree	The PQ duration exceeds 0.20 s, the T wave changes with the QRS complex
	Atrioventricular block 2nd degree	Gradual increase in PQ, which leads to complete replacement of QRS
	Complete AV node block	Change in contraction frequency in the atria (higher than in the ventricles). The PP and RR teeth are the same, the PG segments are different
Other heart diseases	Mitral stenosis	Increased size of the right ventricle and left atrium, axis deviation to the right
	Mitral valve prolapse	The T wave is directed downward, the ST segment is depressed, the QT is lengthened
	Hypothyroidism	Slow heart rate, straight line T wave equation (flat wave), long PQ segment, low QRS complex
Disorders in myocardial infarction	Ischemic stage	The angle of the T wave becomes higher and sharper half an hour before the process of death of the heart muscle begins.
	Damage stage	Dome-shaped formation from the ST segment and T wave, increased R height, shallow Q (indicators reflect the condition of the heart immediately after a heart attack and up to 3 days after it)
	Acute form (very poor cardiogram)	Oval ST segment, deepening of T, decrease in R and pathological change in the Q wave
	Subacute degree	The T and Q waves remain pathologically altered, the absence of the ST segment (smoothed out to a straight line)
	Scar formation	The T wave is normalized, the Q wave remains pathological, the R wave is deepened (negative)

This interpretation of the ECG allows an inexperienced person to roughly navigate the general ECG scheme. It is important to remember that only a specialist can read electrocardiography and make appropriate conclusions. Therefore, there is no need to try to diagnose yourself.

Is it dangerous to perform an ECG?

A classic heart cardiogram simply reads heart impulses and transmits them to paper. The device does not affect the heart or other organs. Therefore, ECG does not pose a danger to children and adults. It can be safely done even for a newborn baby and women during pregnancy.

Monitoring cardiac activity using an ECG allows you to quickly and reliably obtain an analysis of the state of the heart. Thanks to this method, it is possible to quickly detect serious diseases of the cardiovascular system, check the effectiveness of drug treatment and identify diseases of other organs. Cardiography is completely safe for human health (only ECG with stress has contraindications).

The formation of a conclusion on an electrocardiogram (ECG) is carried out by a functional diagnostics doctor or cardiologist. This is a difficult diagnostic process that requires special training and practice. The doctor describing the ECG must know the basics of electrophysiology of the heart, variants of a normal cardiogram, and be able to identify functional and morphological changes in the heart. He must be able to analyze dysfunctions of automaticity, conductivity, excitability of the heart, assess the influence of medications and other external factors on the formation of ECG waves and intervals.

The description of the electrocardiogram includes several successive stages. First, the gender and age of the patient are assessed, since different age groups may have their own ECG characteristics, and the cardiogram also differs in men and women. Then the duration and amplitude of the waves and intervals of the cardiogram are determined. After this, the rhythm and features of the position of the heart in the chest are assessed, conduction disturbances, signs of focal changes in the myocardium and hypertrophy of the heart are analyzed. Then a final conclusion is formed. If possible, the ECG is compared with previously recorded films of the same patient (dynamic analysis).

Analysis of the P wave involves measuring its amplitude, duration, determining its polarity and shape. Determine the duration of the P-Q interval.

Analysis of the ventricular QRS complex is an assessment of the ratio of waves in all leads, measuring the amplitude and duration of these waves.

To analyze the ST segment, it is necessary to determine its displacement up or down relative to the isoelectric line and evaluate the shape of this displacement.

When assessing the T wave, you need to pay attention to its polarity, shape, and amplitude.
Then the Q-T interval is measured and compared with the proper value determined using a special table.

Normal ECG

Normally, the heart rhythm is regular, correct, its source is the sinus node. Sinus rhythm at rest has a rate of 60 to 100 per minute. Heart rate is determined by measuring the distance between adjacent R waves on the ECG (R-R interval).

The direction of the so-called electrical axis of the heart is determined, showing the position of the resulting electromotive force vector (alpha angle). It is indicated in degrees. The normal axis corresponds to an alpha angle value between 40 and 70 degrees.

The presence of rotations of the heart around its axis is determined.

Heart rhythm disturbance

A heart rhythm disorder, or arrhythmia, is diagnosed if the following abnormalities are detected on the ECG:

an increase in heart rate of more than 100 per minute or a decrease of less than 60 per minute;
wrong rhythm;
non-sinus rhythm;
disruption of the electrical signal through the conduction system of the heart.

Arrhythmias are divided into the following main groups.

Based on a violation of impulse formation:

violations of the automatism of the sinus node (sinus tachycardia, bradycardia, arrhythmia);
ectopic (non-sinus) rhythms caused by the predominance of automatism of non-sinus centers (slipping, accelerated ectopic rhythms, migration of the pacemaker);
ectopic rhythms caused by the re-entry mechanism (paroxysmal tachycardia, fibrillation and flutter of the atria and ventricles).

Based on conductivity disorders:

blockades (sinoatrial, intraatrial, atrioventricular, intraventricular blockade, in particular);
ventricular asystole;
ventricular preexcitation syndromes, in particular.

Electrocardiographic signs of these disorders are varied and complex.

Hypertrophy of the heart

Myocardial hypertrophy is an adaptive reaction of the body in response to an increase in load, manifested in an increase in the mass of the heart and the thickness of its walls.

Changes during hypertrophy of any part of the heart are caused by increased electrical activity of the corresponding chamber, slower propagation of the electrical signal in its wall, as well as ischemic and dystrophic changes in the heart muscle.

Using an ECG, you can determine signs of hypertrophy and, as well as their combinations.

Myocardial blood supply disorders

In some cases, an ECG can be used to assess the blood supply to the heart muscle. This method has become especially important in the diagnosis of myocardial infarction: an acute disturbance of blood flow in the coronary vessels, accompanied by necrosis (necrosis) of a section of the heart muscle, followed by the formation of scar changes in this area.

The ECG during the course of myocardial infarction has a natural dynamics, which makes it possible to monitor the development of the process, determine its prevalence and identify complications. Using an ECG, the localization of myocardial infarction is also determined.

Other ECG changes

By analyzing changes in the ventricular complex, ST segment and T wave, many other pathological conditions can be diagnosed, for example, pericarditis, myocarditis, electrolyte disturbances and other processes.

Video course “Everyone can do an ECG”, lesson 1 - “The conduction system of the heart, electrodes”

Video course “Everyone can do an ECG”, lesson 2 - “Tines, segments, intervals”

Video course “Everyone Can Do an ECG,” Lesson 3 - “ECG Analysis Algorithm”

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 the physiological processes in the organ and, after processing the information, displays it in a graphical 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 cardiac organ, so there is a potential difference between the excited and 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):

Coronary heart disease;
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 conductivity 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 (frequency of contraction of the heart muscle)	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 homogeneous 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 on the contrary, 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-sided ventricular hypertrophy is made;
Next, the complex of cardiac impulses QRS 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 formation 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 commission.

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;
Heart rate	up to 90.0 beats 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;
interval between teeth of types P–Q		· 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 a 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;
R wave		· 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;
T-prong		· 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.