An electrocardiogram (ECG) is one of the simplest and oldest tests of the heart. It remains an integral part of the assessment of cardiac patients, providing important information to medical personnel on every continent. An ECG is a representation of the electrical activity of the heart muscle over time on paper or electronic media.

The ECG is recorded on special calibrated paper. The horizontal axis of a square (the smallest division) 1 mm long is equal to 0.04 s. Each large block 5 mm wide corresponds to 0.2 s. The top black marks indicate 3 second intervals. A vertical line consisting of two large blocks is equal to 1 millivolt (mV).

The process of impulse propagation through the heart is reflected by teeth, intervals and segments. The teeth are designated by the letters of the Latin alphabet - P, Q, R, S, T, U. When deciphering an ECG recording, all segments and intervals must be calculated with an accuracy of 0.01 s. The Q and S waves are always negative, while the R wave is positive. When interpreting the P and T waves, attention is paid to the shape, amplitude and sign (-+, +, +-). In relation to the isoline, the ST segment is considered: below or above the isoline, on the isoline, by how many millimeters.

Contractions of the left and right atria correspond to P-waves. Normally, the time interval from the beginning of a rounded tooth to its completion ranges from 0.06 to 0.1 s, and the amplitude value ranges from 0.5 to 2.5 mm (0.05 - 0.25 mV).

The ventricular QRS complex begins with a downward deflection of the Q wave, continues with an ascending line of the R wave, and ends with a downward deflection of the S wave. In a healthy person, intraventricular conduction, which is reflected by the complex, lasts from 0.06 to 0.11 s. When interpreting the ECG, pay special attention to the Q wave. It should not last more than 0.04 s and exceed 1/3 of the R wave. Q-wave is a wave of necrosis if it exceeds standard values. All pathological changes are indicated by a capital letter and placed next to an exclamation mark.

The T wave reflects the process of returning to normal state (repolarization) of the ventricular myocardium. Normally, its unequal rounded apex is directed in the same direction as the QRS complex. The normal value is 0.16-0.24 s. The display of negative isosceles coronary (peaked) teeth is characteristic of myocardial ischemia.

The ST segment in healthy people should be on the isoline. It can deviate no more than 1 mm (0.1 mV) up or down. This is the second most important place on the ECG, since a deviation of the segment above normal characterizes damage to the myocardium of the heart.

Sometimes the T wave is followed by a small U wave. It has no diagnostic value, but when deciphering the electrocardiogram it should not be confused with the P wave.

From the ECG you can calculate your heart rate (HR). To do this, calculate the number of blocks with a side of 5 mm in one RR interval. Divide 300 by the resulting number. For example, 4 squares in an interval corresponds to 75 beats per minute. The greater the RR distance, the lower the heart rate. In a healthy person, the heart rate at rest varies from 60 to 90 beats per minute. The increase in contractions is called tachycardia, the opposite process is called bradycardia.

The heart pattern can be regular or irregular. Consider the RR interval again. If its values ​​are the same or have a spread of up to 10%, then the rhythm will be classified as regular.

The location of the heart in the chest cavity is determined by the electrical axis of the heart (EOS). As a rule, it corresponds to the anatomical axis of the heart. Normally, the EOS is located in the range of 0-90°. If the angle is less than 0°, then the EOS is said to deviate to the left. If it takes values ​​more than 90° - to the right.

The information provided will make the ECG printout much easier to read and interpret, but the healthcare professional should still have the final say.

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The analysis of any ECG must begin with checking the correctness of its registration technique. Firstly, it is necessary to pay attention to the presence of various interferences, which may be caused by inductive currents, muscle tremors, poor contact of the electrodes with the skin and other reasons. If the interference is significant, the ECG should be retaken.

Secondly, it is necessary to check the amplitude of the control millivolt, which should correspond to 10 mm.

Thirdly, the speed of paper movement during ECG recording should be assessed.

When recording an ECG at a speed of 50 mm·s -1, 1 mm on paper tape corresponds to a time period of 0.02 s, 5 mm - 0.1 s, 10 mm - 0.2 s; 50 mm - 1.0 s.

In this case, the width of the QRS complex usually does not exceed 4-6 mm (0.08–0.12 s), and the QT interval is 20 mm (0.4 s).

When recording an ECG at a speed of 25 mm s -1, 1 mm corresponds to a time interval of 0.04 s (5 mm - 0.2 s), therefore, the width of the QRS complex, as a rule, does not exceed 2–3 mm (0.08– 0.12 s), and the Q-T interval - 10 mm (0.4 s).

To avoid errors in interpreting ECG changes, when analyzing each of them, you should strictly adhere to a certain decoding scheme, which you need to remember well.

General scheme (plan) of ECG decoding

I. Heart rate and conduction analysis:

1) assessment of the regularity of heart contractions;

2) heart rate calculation;

3) determination of the source of excitation;

4) assessment of the conductivity function.

II. Determination of heart rotations around the anteroposterior, longitudinal and transverse axes:

1) determination of the position of the electrical axis of the heart in the frontal plane;

2) determination of the rotation of the heart around the longitudinal axis;

3) determination of the rotation of the heart around the transverse axis.

III. Analysis of the atrial P wave.

IV. Analysis of the ventricular QRST complex:

1) analysis of the QRS complex;

2) analysis of the RS–T segment;

3) T wave analysis;

4) analysis of the Q-T interval.

V. Electrocardiographic report.

Heart rate and conduction analysis

Heart rhythm analysis includes determination of regularity and heart rate, source of excitation, as well as assessment of conduction function.

Heart rate regularity analysis

The regularity of heartbeats is assessed by comparing the duration of the R–R intervals between successively recorded cardiac cycles. The R-R interval is usually measured between the tips of the R (or S) waves.

A regular or correct heart rhythm (Fig. 1.13) is diagnosed when the duration of the measured R–R intervals is the same and the spread of the obtained values ​​does not exceed ±10% of the average duration of the R–R intervals. In other cases, an abnormal (irregular) heart rhythm is diagnosed. An abnormal heart rhythm (arrhythmia) can occur with extrasystole, atrial fibrillation, sinus arrhythmia, etc.

Heart rate calculation

Heart rate is calculated using various methods, the choice of which depends on the regularity of the heart rhythm.

With the correct rhythm, heart rate is determined by the formula:

where 60 is the number of seconds in a minute, R–R is the duration of the interval, expressed in seconds.

Rice. 1.13. Assessing heart rate regularity

It is much more convenient to determine heart rate using special tables in which each value of the R–R interval corresponds to a heart rate indicator.

If the ECG rhythm is abnormal, the ECG in one of the leads (most often in standard II) is recorded longer than usual, for example, for 3–4 s.

At a paper speed of 50 mm·s -1, this time corresponds to a segment of the ECG curve 15–20 cm long. Then the number of QRS complexes recorded in 3 s (15 cm of paper tape) is counted, and the result is multiplied by 20.

If the rhythm is incorrect, you can also limit yourself to determining the minimum and maximum heart rate. The minimum heart rate is determined by the duration of the longest R–R interval, and the maximum heart rate is determined by the shortest R–R interval.

In a healthy person at rest, the heart rate ranges from 60–90 beats/min. An increase in heart rate (more than 90 beats/min) is called tachycardia, and a decrease (less than 60 beats/min) is called bradycardia.

O.S. Sychev, N.K. Furkalo, T.V. Getman, S.I. Deyak "Fundamentals of electrocardiography"

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What does it represent?

An electrocardiogram measures the electrical activity of the heart muscle, or the potential difference between two points. The mechanism of the heart is described in the following stages:

1. When the heart muscle does not contract, the structural units of the myocardium have a positively charged cell membrane and a negatively charged core. As a result, the ECG machine draws a straight line.
2. The conduction system of the heart muscle generates and distributes excitation or electrical impulse. Cell membranes take over this impulse and move from a state of rest to excitation. Cell depolarization occurs - that is, the polarity of the inner and outer membranes changes. Some ion channels open, and potassium and magnesium ions change places throughout the cells.
3. After a short period of time, the cells return to their previous state, returning to their original polarity. This phenomenon is called repolarization.

In a healthy person, excitement causes the heart to contract, and recovery relaxes it. These processes are reflected on the cardiogram by teeth, segments and intervals.

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How is it carried out?

An electrocardiogram is performed as follows:

• The patient in the doctor's office takes off his outer clothing, frees his legs, and lies on his back.
• The doctor cleans the electrode fixation sites with alcohol.
• Cuffs with electrodes are attached to the ankles and certain areas of the arms.
• The electrodes are attached to the body in a strict sequence: a red electrode is attached to the right hand, a yellow electrode is attached to the left. A green electrode is fixed on the left leg, black color refers to the right leg. Several electrodes are fixed on the chest.
• ECG recording speed is 25 or 50 mm per second. During the measurements, the person lies quietly, and the doctor controls his breathing.

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ECG elements

Several consecutive teeth are combined into intervals. Each tooth has a specific meaning, marking and classification:

• P - designation of a tooth that records how much the atria have contracted;
• Q, R, S - 3 teeth that record the contraction of the ventricles;
• T - shows the degree of relaxation of the ventricles;
• U is not always a fixed tooth.

Q, R, S are the most important indicators. Normally, they go in the order: Q, R, S. The first and third tend downward, as they indicate excitation of the septum. The Q wave is especially important, since if it is widened or deepened, this indicates necrosis of certain areas of the myocardium. The remaining teeth in this group, directed vertically, are designated by the letter R. If their number is more than one, this indicates pathology. R has the greatest amplitude and is best distinguished during normal heart function. In case of illness, this tooth stands out weakly and is not visible in some cycles.

A segment is an interdental straight isoline. The maximum length is fixed between the teeth S-T and P-Q. Impulse delay occurs in the atrioventricular node. A straight P-Q isoline appears. An interval is considered to be a section of a cardiogram containing a segment and waves. The values ​​of the Q-T and P-Q intervals are considered to be the most responsible.

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Decoding the results

Determination of the main indicators of an ECG recording is carried out according to the following scheme:

1. Conductivity and rhythm are analyzed. The doctor has the opportunity to calculate and analyze the regularity of heart contractions using the ECG. Then he calculates heart rate, finds out what caused the excitation and evaluates conductivity.
2. It is determined how the heart is rotated relative to the longitudinal, transverse and anteroposterior axes. The electrical axis is determined in the anterior plane, as well as the rotation of the heart muscle around the longitudinal and transverse lines.
3. The P wave is calculated and analyzed.
4. The doctor analyzes the QRST complex in the following order: QRS complex, size of the RS-T segment, position of the T wave, duration of the Q-T interval.

Normally, the segments between the tops of the R waves of adjacent complexes should correspond to the intervals between the P waves. This indicates a sequential contraction of the heart muscle and the same frequency of the ventricles and atria. If this process is disrupted, arrhythmia is diagnosed.

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How is heart rate calculated?

To calculate the number of heartbeats, the doctor divides the length of the tape per minute by the distance between the R waves in millimeters. The length of the minute recording is 1500 or 3000 mm. The measurements are recorded on graph paper, a cell contains 5 mm, and this length is equal to 300 or 600 cells. The method for quickly calculating heart rate is based on the formula heart rate = 600 (300) mm/distance between teeth. The disadvantage of this method of calculating heart rate: in a healthy person, the heart rate deviation is up to 10%. If the patient has an arrhythmia, this error increases significantly. In such cases, the doctor calculates the average of several measurements.

Another method for calculating heart rate = 60/R-R, where 60 is the number of seconds, R-R is the interval time in seconds. This method requires concentration and time from the specialist, which is not always feasible in a clinic or hospital. Normal heart rate is 60-90 beats. If the pulse is too high, tachycardia is diagnosed. Contractions less than 60 times per minute indicate bradycardia.

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Patients want to know...

Yes, patients want to know what the strange teeth on the tape left by the recorder mean, so before going to the doctor, patients want to decipher the ECG themselves. However, everything is not so simple and in order to understand the “sophisticated” record, you need to know what the human “motor” is.

The heart of mammals, which includes humans, consists of 4 chambers: two atria, endowed with auxiliary functions and having relatively thin walls, and two ventricles, which bear the main load. The left and right parts of the heart are also different. Providing blood to the pulmonary circulation is less difficult for the right ventricle than pushing blood into the systemic circulation with the left. Therefore, the left ventricle is more developed, but also suffers more. However, regardless of the difference, both parts of the heart must work evenly and harmoniously.

The heart is heterogeneous in its structure and electrical activity, since contractile elements (myocardium) and non-contractile elements (nerves, vessels, valves, fatty tissue) differ from each other in varying degrees of electrical response.

Typically, patients, especially older ones, worry about whether there are signs of myocardial infarction on the ECG, which is quite understandable. However, to do this you need to learn more about the heart and the cardiogram. And we will try to provide this opportunity by talking about waves, intervals and leads and, of course, about some common heart diseases.

Heart Abilities

We first learn about the specific functions of the heart from school textbooks, so we imagine that the heart has:

1. Automatically, caused by the spontaneous generation of impulses, which then cause its excitation;
2. Excitability or the ability of the heart to activate under the influence of exciting impulses;
3. Conductivity or the “ability” of the heart to ensure the conduction of impulses from the place of their origin to the contractile structures;
4. Contractility, that is, the ability of the heart muscle to contract and relax under the control of impulses;
5. Tonicity, in which the heart does not lose its shape in diastole and ensures continuous cyclic activity.

In general, the heart muscle in a calm state (static polarization) is electrically neutral, and biocurrents(electrical processes) are formed in it under the influence of exciting impulses.

Biocurrents in the heart can be recorded

Electrical processes in the heart are caused by the movement of sodium ions (Na+), which are initially located outside the myocardial cell, into it and the movement of potassium ions (K+), rushing from inside the cell to the outside. This movement creates the conditions for changes in transmembrane potentials throughout the entire cardiac cycle and repeated depolarizations(excitation, then contraction) and repolarizations(transition to the original state). All myocardial cells have electrical activity, but slow spontaneous depolarization is characteristic only of the cells of the conduction system, which is why they are capable of automatism.

Excitement spreading through conducting system, sequentially covers the parts of the heart. Starting in the sinoatrial (sinus) node (the wall of the right atrium), which has maximum automaticity, the impulse passes through the atrial muscles, the atrioventricular node, the bundle of His with its legs and is directed to the ventricles, stimulating parts of the conduction system even before the manifestation of its own automaticity .

Excitation that occurs on the outer surface of the myocardium leaves this part electronegative in relation to areas not affected by excitation. However, due to the fact that body tissues have electrical conductivity, biocurrents are projected onto the surface of the body and can be recorded and recorded on a moving tape in the form of a curve - an electrocardiogram. The ECG consists of waves that are repeated after each heartbeat, and through them shows the disorders that exist in the human heart.

How is an ECG taken?

Many people can probably answer this question. Making an ECG, if necessary, will also not be difficult - there is an electrocardiograph in every clinic. ECG technique? It only seems at first glance that it is so familiar to everyone, but meanwhile, only medical workers who have undergone special training in taking an electrocardiogram know it. But we hardly need to go into details, since no one will allow us to do such work without preparation anyway.

Patients need to know how to properly prepare: that is, it is advisable not to overeat, not to smoke, not to drink alcoholic beverages and medications, not to get involved in heavy physical labor and not to drink coffee before the procedure, otherwise you can fool the ECG. Tachycardia will definitely be ensured, if not something else.

So, a completely calm patient undresses to the waist, frees his legs and lies down on the couch, and the nurse will lubricate the necessary places (leads) with a special solution, apply electrodes from which wires of different colors go to the device, and take a cardiogram.

The doctor will decipher it later, but if you are interested, you can try to figure out your teeth and intervals yourself.

Teeth, leads, intervals

This section may not be of interest to everyone, in which case you can skip it, but for those who are trying to understand their ECG on their own, it may be useful.

The waves in the ECG are designated using Latin letters: P, Q, R, S, T, U, where each of them reflects the state of different parts of the heart:

• P – atrial depolarization;
• QRS wave complex – ventricular depolarization;
• T – ventricular repolarization;
• A weak U wave may indicate repolarization of the distal portions of the ventricular conduction system.

To record an ECG, 12 leads are usually used:

• 3 standard – I, II, III;
• 3 reinforced unipolar limb leads (according to Goldberger);
• 6 reinforced unipolar chest (according to Wilson).

In some cases (arrhythmias, abnormal location of the heart), there is a need to use additional unipolar chest and bipolar leads according to Neb (D, A, I).

When interpreting the ECG results, the duration of the intervals between its components is measured. This calculation is necessary to assess the rhythm frequency, where the shape and size of the teeth in different leads will be an indicator of the nature of the rhythm, the electrical phenomena occurring in the heart and (to some extent) the electrical activity of individual sections of the myocardium, that is, the electrocardiogram shows how our heart works at that time. or another period.

Video: lesson on ECG waves, segments and intervals

ECG analysis

A more rigorous interpretation of the ECG is made by analyzing and calculating the area of ​​the teeth when using special leads (vector theory), however, in practice, they mainly make do with such an indicator as electrical axis direction, which is the total QRS vector. It is clear that everyone’s chest is structured differently and the heart does not have such a strict arrangement, the weight ratio of the ventricles and the conductivity inside them are also different for everyone, therefore, when deciphering, the horizontal or vertical direction of this vector is indicated.

Doctors carry out ECG analysis in a sequential order, determining the norm and violations:

1. Assess the heart rhythm and measure the heart rate (with a normal ECG - sinus rhythm, heart rate - from 60 to 80 beats per minute);
2. Intervals (QT, normal – 390-450 ms) are calculated, characterizing the duration of the contraction phase (systole) using a special formula (I often use Bazett’s formula). If this interval lengthens, then the doctor has the right to suspect ischemic heart disease, atherosclerosis, myocarditis, rheumatism. Hypercalcemia, on the contrary, leads to a shortening of the QT interval. The conductivity of the pulses reflected through the intervals is calculated using a computer program, which significantly increases the reliability of the results;
3. The position of the EOS begins to be calculated from the isoline along the height of the teeth (normally R is always higher than S) and if S exceeds R and the axis deviates to the right, then they think about disturbances in the activity of the right ventricle, if on the contrary - to the left, and the height of S is greater than R in II and III leads – left ventricular hypertrophy is suspected;
4. The QRS complex is studied, which is formed during the conduction of electrical impulses to the ventricular muscle and determines the activity of the latter (the norm is the absence of a pathological Q wave, the width of the complex is not more than 120 ms). If this interval shifts, then we speak of blockades (full or partial) of the bundle branches or conduction disturbances. Moreover, incomplete blockade of the right bundle branch is an electrocardiographic criterion of right ventricular hypertrophy, and incomplete blockade of the left bundle branch may indicate left ventricular hypertrophy;
5. They describe the ST segments, which reflect the period of restoration of the initial state of the heart muscle after its complete depolarization (normally located on the isoline) and the T wave, which characterizes the process of repolarization of both ventricles, which is directed upward, asymmetrical, its amplitude is lower than the wave in duration and is longer than the QRS complex.

The decoding work is carried out only by a doctor, however, some ambulance paramedics perfectly recognize common pathologies, which is very important in emergency cases. But first, you still need to know the ECG norm.

This is what the cardiogram of a healthy person looks like, whose heart works rhythmically and correctly, but not everyone knows what this record means, which can change under various physiological conditions, such as pregnancy. In pregnant women, the heart takes a different position in the chest, so the electrical axis shifts. In addition, depending on the duration, the load on the heart is added. An ECG during pregnancy will reflect these changes.

ECG indicators in children are also excellent; they will “grow” with the baby, and therefore will change according to age; only after 12 years, the child’s electrocardiogram begins to approach the ECG of an adult.

The most disappointing diagnosis: heart attack

The most serious diagnosis on an ECG, of course, is myocardial infarction, in the recognition of which the cardiogram plays the main role, because it is it (the first!) that finds areas of necrosis, determines the location and depth of the lesion, and can distinguish an acute infarction from aneurysms and scars of the past.

The classic signs of myocardial infarction on the ECG are the registration of a deep Q wave (OS), segment elevationST, which deforms R, smoothing it, and the subsequent appearance of a negative pointed isosceles tooth T. This elevation of the ST segment visually resembles a cat’s back (“cat”). However, a distinction is made between myocardial infarction with and without the Q wave.

Video: signs of a heart attack on an ECG

When there's something wrong with your heart

Often in ECG conclusions you can find the expression: “Left ventricular hypertrophy.” As a rule, such a cardiogram is obtained by people whose hearts have had an additional load for a long time, for example, due to obesity. It is clear that the left ventricle has a hard time in such situations. Then the electrical axis deviates to the left, and S becomes greater than R.

Video: cardiac hypertrophy on ECG

Sinus arrhythmia is an interesting phenomenon and you should not be afraid of it, since it is present in healthy people and does not give any symptoms or consequences, rather it serves to rest the heart, therefore it is considered a cardiogram of a healthy person.

Video: arrhythmias on ECG

Violation of intraventricular impulse conduction manifests itself in atrioventricular blockades and bundle branch blocks. Right bundle branch block - high and wide R wave in the right precordial leads, with left leg block- small R and wide deep S wave in the right chest leads, in the left chest leads - R is widened and jagged. Both legs are characterized by expansion of the ventricular complex and its deformation.

Atrioventricular blocks, causing disruption of intraventricular conduction, are expressed in three degrees, which are determined by how the conduction reaches the ventricles: slowly, sometimes or not at all.

But all these, one might say, are “flowers”, since there are either no symptoms at all, or they do not have such a terrible manifestation, for example, shortness of breath, dizziness and fatigue can occur with atrioventricular block, and even then only to the 3rd degree, and 1 of it a degree is generally very common for young, trained people.

Video: ECG blockades

Video: bundle branch block on ECG

Holter method

HM ECG - what kind of abbreviation is this so incomprehensible? This is the name for long-term and continuous recording of an electrocardiogram using a portable portable tape recorder, which records the ECG on magnetic tape (Holter method). Such electrocardiography is used to detect and register various disorders that occur periodically, so a regular ECG is not always able to recognize them. In addition, deviations may occur at certain times or under certain conditions, so in order to compare these parameters with the ECG recording, the patient conducts very detailed diary. In it, he describes his feelings, records the time of rest, sleep, wakefulness, any active activity, notes the symptoms and manifestations of the disease. The duration of such monitoring depends on the purpose for which the study was prescribed, however, since the most common is recording an ECG during the day, it is called daily allowance, although modern equipment allows monitoring for up to 3 days. And a device implanted under the skin takes even longer.

Daily Holter monitoring is prescribed for rhythm and conduction disorders, painless forms of coronary heart disease, Prinzmetal's angina and other pathological conditions. Also, indications for the use of Holter are the presence of an artificial pacemaker in the patient (control over its functioning) and the use of antiarrhythmic drugs and drugs for the treatment of ischemia.

Get ready Holter monitoring is also easy, but men should shave the electrode attachment points, as hair will distort the recording. Although it is believed that daily monitoring does not require special preparation, the patient, as a rule, is informed what he can and cannot do. Of course, you cannot immerse yourself in a bath; the device does not like water procedures. There are those who don’t even accept showers, all you have to do is endure, unfortunately. The device is sensitive to magnets, microwaves, metal detectors and high voltage lines, so it’s better not to test it for strength, it will still write incorrectly. He doesn't like it synthetics and all kinds of metal jewelry, so for a while you should switch to cotton clothes, and forget about jewelry.

Video: doctor about Holter monitoring

Bicycle and ECG

Everyone has heard something about such a bicycle, but not everyone has ridden it (and not everyone can). The fact is that hidden forms of coronary circulatory insufficiency, excitability and conduction disorders are poorly detected on an ECG taken at rest, therefore it is customary to use the so-called bicycle ergometer test, in which the cardiogram is recorded using dosed increasing (sometimes constant) loads. During an ECG with stress, the patient's overall response to this procedure, blood pressure and pulse are simultaneously monitored.

The maximum heart rate during a bicycle ergometric test depends on age and is 200 beats minus the number of years, that is, 20-year-olds can afford 180 beats/min, but at 60 years old 130 beats/min will be the limit.

A bicycle ergometer test is prescribed if necessary:

• To clarify the diagnosis of coronary artery disease, rhythm and conduction disorders that occur in a latent form;
• To evaluate the effectiveness of treatment of coronary heart disease;
• Select medications for an established diagnosis of IHD;
• Select training and load regimens during the rehabilitation period for patients who have suffered myocardial infarction ( before the expiration of a month from the onset of MI, this is possible only in specialized clinics!);
• To provide a prognostic assessment of the condition of patients suffering from coronary heart disease.

However, performing an ECG with a load also has its contraindications, in particular, suspicion of myocardial infarction, angina pectoris, aortic aneurysms, some extrasystoles, chronic heart failure at a certain stage, cerebrovascular accident and thrombophlebitis are an obstacle to the test. These contraindications are absolute symptoms of hypertension

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Almost every person who has undergone an electrocardiogram is interested in the meaning of different teeth and the terms written by the diagnostician. Although only a cardiologist can give a full interpretation of an ECG, everyone can easily figure out whether their heart cardiogram is good or if there are some abnormalities.

Indications for an ECG

A non-invasive study - an electrocardiogram - is performed in the following cases:

• The patient complains of high blood pressure, chest pain and other symptoms indicating cardiac pathology;
• Deterioration in the well-being of a patient with a previously diagnosed cardiovascular disease;
• Abnormalities in laboratory blood tests - increased cholesterol, prothrombin;
• In preparation for surgery;
• Detection of endocrine pathology, diseases of the nervous system;
• After severe infections with a high risk of heart complications;
• For prophylactic purposes in pregnant women;
• Examinations of the health status of drivers, pilots, etc.

Decoding ECG - numbers and Latin letters

A full-scale interpretation of the cardiac cardiogram includes an assessment of the heart rhythm, the functioning of the conduction system and the condition of the myocardium. For this, the following leads are used (electrodes are installed in a certain order on the chest and limbs):

• Standard: I - left/right wrist on the hands, II - right wrist and ankle area on the left leg, III - left ankle and wrist.
• Strengthened: aVR - right wrist and combined left upper/lower limbs, aVL - left wrist and combined left ankle and right wrist, aVF - left ankle area and combined potential of both wrists.
• Thoracic (potential difference between the electrode with a suction cup located on the chest and the combined potentials of all extremities): V1 - electrode in the IV intercostal space along the right border of the sternum, V2 - in the IV intercostal space to the left of the sternum, V3 - on the IV rib along the left-sided parasternal line, V4 - V intercostal space along the left midclavicular line, V5 - V intercostal space along the anterior axillary line on the left, V6 - V intercostal space along the mid-axillary line on the left.

Additional pectorals - located symmetrically to the left pectoralis with additional V7-9.

One cardiac cycle on the ECG is represented by the PQRST graph, which records electrical impulses in the heart:

• P wave - displays atrial excitation;
• QRS complex: Q wave - the initial phase of depolarization (excitation) of the ventricles, R wave - the actual process of ventricular excitation, S wave - the end of the depolarization process;
• T wave - characterizes the extinction of electrical impulses in the ventricles;
• ST segment - describes the complete restoration of the original state of the myocardium.

When deciphering ECG indicators, the height of the teeth and their location relative to the isoline, as well as the width of the intervals between them, are important.

Sometimes a U pulse is recorded behind the T wave, indicating the parameters of the electrical charge carried away with the blood.

Interpretation of ECG indicators - the norm in adults

On the electrocardiogram, the width (horizontal distance) of the teeth - the duration of the period of excitation of relaxation - is measured in seconds, the height in leads I-III - the amplitude of the electrical impulse - in mm. A normal cardiogram in an adult looks like this:

• Heart rate - normal heart rate is within 60-100/min. The distance from the tops of adjacent R waves is measured.
• EOS - the electrical axis of the heart is considered to be the direction of the total angle of the electrical force vector. The normal value is 40-70º. Deviations indicate rotation of the heart around its own axis.
• The P wave is positive (directed upward), negative only in lead aVR. Width (duration of excitation) - 0.7 - 0.11 s, vertical size - 0.5 - 2.0 mm.
• PQ interval - horizontal distance 0.12 - 0.20 s.
• The Q wave is negative (below the isoline). Duration 0.03 s, negative height value 0.36 - 0.61 mm (equal to ¼ of the vertical size of the R wave).
• The R wave is positive. What matters is its height - 5.5 -11.5 mm.
• S wave - negative height 1.5-1.7 mm.
• QRS complex - horizontal distance 0.6 - 0.12 s, total amplitude 0 - 3 mm.
• The T wave is asymmetrical. Positive height 1.2 - 3.0 mm (equal to 1/8 - 2/3 of the R wave, negative in the aVR lead), duration 0.12 - 0.18 s (longer than the duration of the QRS complex).
• ST segment - passes at the level of the isoline, length 0.5 -1.0 s.
• U wave - height 2.5 mm, duration 0.25 s.

Abbreviated results of ECG interpretation in adults and the norm in the table:

During normal research (recording speed - 50 mm/sec), ECG interpretation in adults is carried out according to the following calculations: 1 mm on paper when calculating the duration of intervals corresponds to 0.02 sec.

A positive P wave (standard leads) followed by a normal QRS complex means normal sinus rhythm.

Normal ECG in children, interpretation

Cardiogram parameters in children are somewhat different from those in adults and vary depending on age. Interpretation of the ECG of the heart in children, normal:

• Heart rate: newborns - 140 - 160, by 1 year - 120 - 125, by 3 years - 105 -110, by 10 years - 80 - 85, after 12 years - 70 - 75 per minute;
• EOS - corresponds to adult indicators;
• sinus rhythm;
• tooth P - does not exceed 0.1 mm in height;
• length of the QRS complex (often not particularly informative in diagnosis) - 0.6 - 0.1 s;
• PQ interval - less than or equal to 0.2 s;
• Q wave - unstable parameters, negative values ​​in lead III are acceptable;
• P wave - always above the isoline (positive), the height in one lead can fluctuate;
• S wave - negative indicators of variable value;
• QT - no more than 0.4 s;
• The duration of the QRS and the T wave are equal, 0.35 - 0.40.

Example of an ECG with rhythm disturbance

Based on deviations in the cardiogram, a qualified cardiologist can not only diagnose the nature of the heart disease, but also record the location of the pathological focus.

Arrhythmias

The following cardiac rhythm disorders are distinguished:

1. Sinus arrhythmia - the length of the RR intervals fluctuates with a difference of up to 10%. It is not considered a pathology in children and young people.
2. Sinus bradycardia is a pathological decrease in the frequency of contractions to 60 per minute or less. The P wave is normal, PQ from 12 s.
3. Tachycardia - heart rate 100 - 180 per minute. In teenagers - up to 200 per minute. The rhythm is correct. With sinus tachycardia, the P wave is slightly higher than normal, with ventricular tachycardia, the QRS length indicator is above 0.12 s.
4. Extrasystoles are extraordinary contractions of the heart. Single ones on a regular ECG (on a 24-hour Holter - no more than 200 per day) are considered functional and do not require treatment.
5. Paroxysmal tachycardia is a paroxysmal (several minutes or days) increase in heart rate up to 150-220 per minute. It is characteristic (only during an attack) that the P wave merges with the QRS. The distance from the R wave to the P height of the next contraction is less than 0.09 s.
6. Atrial fibrillation is an irregular contraction of the atria with a frequency of 350-700 per minute, and of the ventricles - 100-180 per minute. There is no P wave, there are small-to-large undulating oscillations along the entire isoline.
7. Atrial flutter - up to 250-350 atrial contractions per minute and regular slow ventricular contractions. The rhythm may be correct; the ECG shows sawtooth atrial waves, especially pronounced in standard leads II - III and thoracic leads V1.

Deviation of EOS position

A change in the total EOS vector to the right (more than 90º), a higher value of the height of the S wave compared to the R wave indicate pathology of the right ventricle and His bundle block.

When the EOS is shifted to the left (30-90º) and there is a pathological ratio of the heights of the S and R waves, left ventricular hypertrophy and blockade of the bundle branch of His are diagnosed. Deviation of EOS indicates a heart attack, pulmonary edema, COPD, but it can also be normal.

Violation of the conduction system

The following pathologies are most often recorded:

• 1st degree of atrioventricular (AV) block - PQ distance more than 0.20 s. After each P, QRS naturally follows;
• Atrioventricular block, stage 2. - a gradually lengthening PQ throughout the ECG sometimes displaces the QRS complex (Mobitz type deviation 1) or a complete loss of QRS is recorded against the background of a PQ of equal length (Mobitz 2);
• Complete block of the AV node - the atrial heart rate is higher than the ventricular heart rate. PP and RR are the same, PQ are different lengths.

Selected heart diseases

The results of ECG interpretation can provide information not only about the heart disease that has occurred, but also about the pathology of other organs:

1. Cardiomyopathy - atrial hypertrophy (usually the left one), low-amplitude waves, partial blockade of the His, atrial fibrillation or extrasystoles.
2. Mitral stenosis - the left atrium and right ventricle are enlarged, the EOS is deviated to the right, often atrial fibrillation.
3. Mitral valve prolapse - flattened/negative T wave, some QT prolongation, depressed ST segment. Various rhythm disturbances are possible.
4. Chronic pulmonary obstruction - EOS is to the right of normal, low-amplitude waves, AV block.
5. Damage to the central nervous system (including subarachnoid hemorrhage) - pathological Q, wide and high-amplitude (negative or positive) T wave, pronounced U, long duration of QT rhythm disturbance.
6. Hypothyroidism - long PQ, low QRS, flat T wave, bradycardia.

Quite often, an ECG is performed to diagnose myocardial infarction. At the same time, each of its stages corresponds to characteristic changes in the cardiogram:

• ischemic stage - a pointed T with a sharp apex is recorded 30 minutes before the onset of necrosis of the heart muscle;
• stage of damage (changes are recorded in the first hours to 3 days) - ST in the form of a dome above the isoline merges with the T wave, shallow Q and high R;
• acute stage (1-3 weeks) - the worst cardiogram of the heart during a heart attack - preservation of the dome-shaped ST and the transition of the T wave to negative values, decreased height of R, pathological Q;
• subacute stage (up to 3 months) - comparison of ST with the isoline, preservation of pathological Q and T;
• stage of scarring (several years) - pathological Q, negative R, smoothed T wave gradually comes to normal values.

There is no need to sound the alarm if you find pathological changes in the ECG issued to you. It should be remembered that some deviations from the norm occur in healthy people.

If an electrocardiogram reveals any pathological processes in the heart, you will definitely be scheduled for a consultation with a qualified cardiologist.

How to read an ECG? How to decipher an electrocardiogram yourself? What does the ECG show? Decoding a cardiogram in children and adults: general principles, reading the results, an example of deciphering an ECG in different leads Electrocardiography (ECG)– one of the electrophysiological methods for recording the biopotentials of the heart. Electrical impulses from the heart tissue are transmitted to skin electrodes located on the arms, legs and chest. This data is then output either graphically on paper or displayed on a display. In the classic version, depending on the location of the electrode, the so-called standard, reinforced and chest leads are distinguished. Each of them shows bioelectric impulses taken from the heart muscle at a certain angle. Thanks to this approach, the electrocardiogram ultimately shows a complete description of the functioning of each section of the cardiac tissue. Figure 1. ECG tape with graphical data What does the ECG of the heart show? Using this common diagnostic method, you can determine the specific location where the pathological process occurs. In addition to any disturbances in the functioning of the myocardium (heart muscle), the ECG shows the spatial location of the heart in the chest. Main tasks of electrocardiography Timely detection of irregularities in rhythm and heart rate (detection of arrhythmias and extrasystoles). Determination of acute (myocardial infarction) or chronic (ischemia) organic changes in the heart muscle. Detection of disturbances in the intracardiac conduction of nerve impulses (impaired conduction of an electrical impulse through the conduction system of the heart (blockade)). Definition of some acute (PE - pulmonary embolism) and chronic (chronic bronchitis with respiratory failure) pulmonary diseases. Detection of electrolyte (potassium, calcium levels) and other changes in the myocardium (dystrophy, hypertrophy (increase in the thickness of the heart muscle)). Indirect registration of inflammatory heart diseases (myocarditis). Disadvantages of the method The main disadvantage of electrocardiography is the short-term recording of indicators. Those. The recording shows the work of the heart only at the time the ECG is taken at rest. Due to the fact that the above-described disorders can be transient (appear and disappear at any time), specialists often resort to daily monitoring and recording of an ECG with stress (stress tests). Indications for an ECG Electrocardiography is performed routinely or as an emergency. Routine ECG registration is carried out during pregnancy, when a patient is admitted to a hospital, in the process of preparing a person for operations or complex medical procedures, to assess cardiac activity after certain treatment or surgical medical interventions. For preventive purposes, an ECG is prescribed: people with high blood pressure; with vascular atherosclerosis; in case of obesity; with hypercholesterolemia (increased cholesterol levels in the blood); after some infectious diseases (tonsillitis, etc.); for diseases of the endocrine and nervous systems; persons over 40 years of age and people exposed to stress; for rheumatological diseases; people with occupational risks and hazards to assess professional suitability (pilots, sailors, athletes, drivers...). On an emergency basis, i.e. “this minute” an ECG is prescribed: for pain or discomfort behind the sternum or in the chest; in case of sudden shortness of breath; with prolonged severe pain in the abdomen (especially in the upper sections); in case of persistent increase in blood pressure; when unexplained weakness occurs; in case of loss of consciousness; in case of chest injury (in order to exclude heart damage); at the time of or after a heart rhythm disturbance; for pain in the thoracic spine and back (especially on the left); with severe pain in the neck and lower jaw. Contraindications to ECG There are no absolute contraindications to taking an ECG. Relative contraindications to electrocardiography may include various violations of the integrity of the skin at the sites where the electrodes are attached. However, it should be remembered that in case of emergency indications, an ECG should always be taken without exception. Preparation for electrocardiography There is also no special preparation for an ECG, but there are some nuances of the procedure that the doctor should warn the patient about. It is necessary to know whether the patient is taking heart medications (a note must be made on the referral form). During the procedure you cannot talk or move; you must lie down, relax and breathe calmly. Listen and follow simple commands from medical staff, if necessary (inhale and hold for a few seconds). It is important to know that the procedure is painless and safe. Distortion of the electrocardiogram recording is possible when the patient moves or in case of improper grounding of the device. Incorrect recording may also be caused by loose contact of the electrodes to the skin or incorrect connection. Interference in the recording often occurs due to muscle tremors or electrical interference. Carrying out electrocardiography or how to do an ECG Figure 2. Application of electrodes during ECG When recording a cardiogram, the patient lies on his back on a horizontal surface, arms extended along the body, legs straightened and not bent at the knees, chest bare. One electrode is attached to the ankles and wrists according to the generally accepted scheme: to the right hand - a red electrode; to the left hand - yellow; to the left leg - green; to the right leg - black. Then 6 more electrodes are placed on the chest. After the patient is fully connected to the ECG machine, a recording procedure is performed, which on modern electrocardiographs lasts no more than one minute. In some cases, the health care provider asks the patient to inhale and not breathe for 10-15 seconds and makes additional recordings during this time. At the end of the procedure, the ECG tape indicates age, full name. patient and the speed at which the cardiogram was taken. Then a specialist deciphers the recording. ECG interpretation and interpretation The electrocardiogram is deciphered by either a cardiologist, a functional diagnostics doctor, or a paramedic (in an emergency setting). The data is compared with a reference ECG. The cardiogram usually shows five main waves (P, Q, R, S, T) and a subtle U-wave. Figure 3. Basic characteristics of the cardiogram Table 1. ECG interpretation in adults is normal ECG interpretation in adults, norm in the table Various changes in the teeth (their width) and intervals may indicate a slowdown in the conduction of a nerve impulse through the heart. T wave inversion and/or a rise or fall in the ST interval relative to the isometric line indicates possible damage to myocardial cells. When deciphering an ECG, in addition to studying the shapes and intervals of all waves, a comprehensive assessment of the entire electrocardiogram is carried out. In this case, the amplitude and direction of all waves in standard and enhanced leads are studied. These include I, II, III, avR, avL and avF. (see Fig. 1) Having a summary picture of these ECG elements, one can judge the EOS (electrical axis of the heart), which shows the presence of blockages and helps determine the location of the heart in the chest. For example, in obese individuals, the EOS may be deviated to the left and down. Thus, the ECG interpretation contains all the information about the source of the heart rhythm, conductivity, the size of the heart chambers (atria and ventricles), changes in the myocardium and electrolyte disturbances in the heart muscle. The main and most important clinical significance of the ECG is in myocardial infarction and cardiac conduction disorders. By analyzing the electrocardiogram, you can obtain information about the focus of necrosis (localization of myocardial infarction) and its duration. It should be remembered that the ECG assessment should be carried out in conjunction with echocardiography, 24-hour (Holter) ECG monitoring and functional stress tests. In some cases, the ECG may be practically uninformative. This is observed with massive intraventricular blockades. For example, LBBB (complete block of the left bundle branch). In this case, it is necessary to resort to other diagnostic methods. Video on the topic “ECG norm” An ECG device was invented by an English scientist more than a century ago. He recorded the electrical activity of the heart muscle and recorded this data on a special paper tape. Naturally, throughout its existence it has been modernized several times, but the basic principle of operation, which is based on the recording of electrical impulses, has remained unchanged. Now it is available in any hospital, ambulance teams and local therapists are equipped with it. A lightweight and mobile electrocardiograph helps save lives with its ability to quickly take an ECG. Speed ​​and accuracy are important for patients with pulmonary embolism, myocardial infarction, bradycardia, and diseases that require emergency medical care. Deciphering ECG readings is not a problem for an experienced doctor. Many cardiac diagnoses are established on the basis of this monitoring, and most of them unmistakably indicate cardiovascular pathologies. What you need to know about ECG principles An outsider, which is any cardiology patient, is not able to understand the incomprehensible teeth and peaks displayed by the electrocardiograph recorder. It is difficult for people without special education to understand what the doctor sees there, but the general principles of the work of the heart are quite clear to everyone. Man is a mammal and his heart consists of 4 chambers. These are two atria with thin walls that perform auxiliary work, and two ventricles, which withstand the main loads. There are certain differences between the right and left side of the heart. It is easier for the body to supply blood to the pulmonary circulation through the right ventricle than to push blood into the systemic circulation through the left ventricle. Therefore, the left one is more developed, but there are more diseases that affect it. But despite this fundamental difference, human health largely depends on the coherence and uniformity of the work of all parts of the organ. In addition, the parts of the heart differ in their structure and intensity of electrical activity. The myocardium, that is, contractile complexes, and nerves, valves, fatty tissue, vessels, in fact – irreducible elements, differ in the degree and speed of response to electrical impulses. Cardiologists recognize cardiac pathologies due to their in-depth knowledge of the principles of heart function and the ability to interpret an electrocardiogram. The intervals, waves, and leads must be viewed in a single context that defines common heart conditions. There are not so many specific functions of the heart; it has: Automatically, that is, it spontaneously generates impulses that lead to its excitation. Excitability, responsible for the possibility of cardiac activation under the influence of an exciting impulse. Conductivity. The heart can ensure the conduction of an impulse from the place of its origin to the contractile structure involved in the process. Contractility. This is the ability of the heart muscle to contract and relax under the control of the current impulse. Tonicity. When the heart does not lose its shape in diastole and is able to provide constant activity according to the physiological cycle. The calm state of the heart, called static polarization, is electrically neutral, and at the stage of generation and conduction of exciting impulses, implying an electrical process, characteristic biocurrents are formed. How to decipher an ECG: what does the doctor focus on? Carrying out an ECG procedure today is not difficult; any hospital is equipped with these devices. But what is included in the complex of manipulations and what is usually regarded as the norm? The technique of performing an electrocardiogram is familiar only to health workers who undergo an additional training cycle. The patient should know about the rules for preparing for an ECG. Before monitoring you need: Can't convey. Stop smoking, drinking coffee and alcohol. Avoid taking medications. Avoid strenuous physical activity before the procedure. All this will affect the results of the electrocardiogram in the form of tachycardia or more serious disorders. The patient, who is in a calm state, undresses to the waist, takes off his shoes and lies down on the couch. The nurse treats the lead sites with a special solution, attaches the electrodes and takes readings. Then its data is transferred to a cardiologist for decoding. Each wave on the ECG is designated as a capital letter, P, Q, R, S, T, U. P – atrial depolarization. When the QRS waves are complex, they speak of ventricular depolarization. T – ventricular repolarization. A blurred U wave indicates repolarization of the distal portions of the conduction system. If the teeth are directed upwards, then they are positive, those that are directed downwards are negative. The Q and S waves will always be negative, and the R waves will always be positive. To collect data, 12 leads are used: Standard: I, II, III. Reinforced unipolar limb leads – three. Reinforced unipolar chest - six. In case of pronounced arrhythmia or abnormal position of the heart, there is a need to use additional chest leads, bipolar and unipolar (D, A, I). When deciphering the results, the doctor measures the duration of the intervals between each of the ECG indicators. In this way, an assessment is made of the rhythm frequency, when the size and shape of the tooth in different leads determines the nature of the rhythm, the electrical phenomena occurring in the heart and the electrical activity of each section of the myocardium. In essence, an ECG demonstrates the complex functioning of the heart in a single period. Detailed interpretation of the ECG: normal, pathologies and diseases If a strict decoding is necessary, an analysis and calculation of the area of ​​the teeth is carried out using additional leads, according to the vector theory. But in everyday practice, they much more often resort to such an indicator as the direction of the electrical axis. It is the total QRS vector. Naturally, each person has individual physiological characteristics of the structure of the chest, and the heart can be displaced from its usual location. In addition, the weight ratio of the ventricles and the intensity and velocity of conduction within them may also vary. Therefore, decoding requires a description of both the vertical and horizontal directions along this vector. Decoding can only be carried out in a certain sequence, which helps to differentiate normal indicators from detected violations: The heart rate is assessed and the heart rate is measured. A normal ECG is characterized by sinus rhythm with a heart rate of 60-80 beats/minute. Intervals are calculated indicating the duration of systole (contraction phase). This is done using a special Bazett formula. Normal QT is 390/450ms; if it lengthens, a diagnosis of ischemic heart disease, myocarditis, rheumatism, or atherosclerosis can be made. If the interval is shortened, hypercalcemia is suspected. The intervals reflect the conductivity of the impulses; it is calculated using special automatic programs, which only increases the diagnostic value of the results. The position of the EOS is calculated from the isoline and is guided by the height of the teeth. Under normal conditions, the R wave will always be higher than the S wave. And if, on the contrary, with simultaneous deviation of the axis to the right, then functional failures in the right ventricle are assumed. With axis deviation to the left, respectively, to the left, provided that S is greater than R in leads II and III. This indicates left ventricular hypertrophy. The QRS complex formed when impulses are conducted to the muscles of the ventricles is examined. The complex determines the functional load of the ventricles. In a normal state, there is no pathological Q wave, and the width of the entire complex does not exceed 120 ms. When this interval shifts, a diagnosis of complete or partial block of the bundle branches is made or conduction disorders are spoken of. Incomplete blockade of the right leg acts as an electrocardiographic indicator of hypertrophic changes in the right ventricle, and incomplete blockade of the left leg is evidence of hypertrophy of the left ventricle. The ST segments are described, reflecting the period of restoration of the initial state of the heart muscle from the moment of its complete depolarization. Normally they are located along the isoline. And also the T wave, reflecting the process of ventricular repolarization. The process is directed upward, with asymmetry, and its amplitude should normally be below the T wave. It is longer in duration than the QRS complex. A full transcript can only be carried out by a doctor, but if necessary, an ambulance paramedic can also do this. Deviations from the norm: physiological aspects This is an image of a normal cardiogram of a healthy person. His heart works smoothly, with a regular rhythm and correctly. But these indicators can change and vary under different physiological conditions. One such condition is pregnancy. In women carrying a child, the heart shifts somewhat relative to its normal anatomical location in the chest, and therefore the electrical axis also shifts. It all depends on the period, since every month increases the load on the heart. During pregnancy, all these changes will be displayed on the ECG, but will be regarded as a conditional norm. The children's cardiogram is also different, the indicators of which change according to age as the child grows. And only after 12 years, the ECG of children begins to resemble the gastrointestinal tract of adults. Sometimes situations arise when two ECGs for the same patient, taken even just a few hours apart, are strikingly different. Why is this happening? To get accurate results, you need to take into account many influencing factors: A distorted ECG recording may be the result of a device malfunction or other technical problems. For example, if the results were incorrectly glued together by a healthcare worker. Please note that some Roman symbols look identical both inverted and in normal position. There are situations when the chart is cut incorrectly, which leads to the loss of the last or first tooth. It is also important how well the patient prepared. Anything that stimulates the heart rate will certainly affect the ECG results. It is advisable to take a shower before the procedure, but you should not use body cosmetics. And during the process of taking a cardiogram, the patient should be in a relaxed state. The possibility of incorrect placement of the electrodes cannot be ruled out. It is best to trust electrocardiographs to check your heart; they carry out the analysis with maximum accuracy. To confirm the diagnosis found on the ECG, the doctor always prescribes several additional studies. First, the rhythm, heart rate and type of ECG are described. Then, obvious changes are briefly indicated, for example, such as complete blockade of PNPG, suspicion of LV hypertrophy, acute myocardial infarction of anterior localization. If the ECG data is ambiguous, then only morphological changes in the ECG are described, for example, instead of the diagnosis of “coronary heart disease,” they write “impaired myocardial repolarization in the left precordial leads.” There are various ECG description options. Previously, the height (eg, R wave in millivolts or millimeters) and width (eg, P wave and QRS complex in seconds) of individual waves and the duration of the intervals (PQ or QT in seconds) were first measured and the results of the measurement were reported in the conclusion. However, currently this is done by the device itself using the built-in programs. Therefore, we will not dwell on this in detail. 1. Cardiac rhythm: First describe the rhythm, such as sinus rhythm or atrial fibrillation. 2. Heart rate: for example, 60 per minute or 80 per minute. 3. ECG type: left or right type. 4. Interpretation of the ECG form: it is enough to summarize the pathological data and changes, for example, “the P wave in lead II is widened to 0.14 s, the QRS complex in leads V5 and V6 is deformed and widened (0.13 s). The height of the R wave in leads V5 and V6 is increased and amounts to 3 mV, the ST segment is horizontal, below the isoline (0.3 mV), the T wave is negative (-0.5 mV).” 5. At the end, you need to draw up a short conclusion, first indicating the heart rhythm, heart rate and type. Then, if possible, a diagnosis is formulated (if there is no doubt about it), for example: “complete block of the right bundle branch,” “acute myocardial infarction of the anterior wall,” “suspicious hypokalemia,” “WPW syndrome,” “ventricular tachycardia.” In unclear cases, when clinical data are absent, only a morphological description of ECG changes is provided. For example, instead of a diagnosis of coronary artery disease, a violation of repolarization in the precordial leads is indicated. Wrong conclusion unacceptable, since this can, as mentioned earlier, cause irreparable damage to the patient’s health.