Wide qrs complexes on ecg. Electrocardiography or ECG – what is it? Indications for use of ECG

Electrocardiography is one of the most common and most informative methods for diagnosing a huge number of diseases. An ECG involves a graphical display of the electrical potentials that are formed in the beating heart. Indicators are taken and displayed using special devices - electrocardiographs, which are constantly being improved.

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As a rule, during the study, 5 waves are recorded: P, Q, R, S, T. In some moments, it is possible to record a subtle U wave.

Electrocardiography allows you to identify the following indicators, as well as variants of deviations from reference values:

Heart rate (pulse) and regularity of myocardial contractions (arrhythmias and extrasystoles can be detected);
Disturbances in the heart muscle of an acute or chronic nature (in particular, with ischemia or heart attack);
metabolic disorders of the main compounds with electrolytic activity (K, Ca, Mg);
intracardiac conduction disorders;
hypertrophy of the heart (atria and ventricles).

Note:When used in parallel with a cardiophone, the electrocardiograph makes it possible to remotely determine some acute heart diseases (the presence of areas of ischemia or heart attacks).

ECG is the most important screening technique for detecting coronary artery disease. Valuable information is provided by electrocardiography with the so-called. "stress tests".

Isolated or in combination with other diagnostic techniques, ECG is often used in the study of cognitive (thought) processes.

Important:An electrocardiogram must be taken during medical examination, regardless of the age and general condition of the patient.

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ECG: indications for performance

There are a number of pathologies of the cardiovascular system and other organs and systems for which electrocardiographic examination is prescribed. These include:

angina pectoris;
myocardial infarction;
reactive arthritis;
peri- and myocarditis;
periarteritis nodosa;
arrhythmias;
acute renal failure;
diabetic nephropathy;
scleroderma.

With right ventricular hypertrophy, the amplitude of the S wave in leads V1-V3 increases, which may be an indicator of symmetric pathology on the part of the left ventricle.

With left ventricular hypertrophy, the R wave is pronounced in the left precordial leads and its depth is increased in leads V1-V2. The electrical axis is either horizontal or deviated to the left, but can often correspond to the norm. The QRS complex in lead V6 is characterized by a qR or R shape.

Note:This pathology is often accompanied by secondary changes in the heart muscle (dystrophy).

Left atrial hypertrophy is characterized by a fairly significant increase in the P wave (up to 0.11-0.14 s). It acquires a “two-humped” shape in the left chest leads and leads I and II. In rare clinical cases, some flattening of the wave is noted, and the duration of the internal deviation of P exceeds 0.06 s in leads I, II, V6. Among the most prognostically reliable evidence of this pathology is an increase in the negative phase of the P wave in lead V1.

Hypertrophy of the right atrium is characterized by an increase in the amplitude of the P wave (over 1.8-2.5 mm) in leads II, III, aVF. This tooth acquires a characteristic pointed shape, and the electrical axis P is installed vertically or has a slight shift to the right.

Combined atrial hypertrophy is characterized by parallel expansion of the P wave and an increase in its amplitude. In some clinical cases, changes such as sharpening of P in leads II, III, aVF and splitting of the apex in I, V5, V6 are noted. In lead V1, an increase in both phases of the P wave is occasionally recorded.

For heart defects formed during intrauterine development, a significant increase in the amplitude of the P wave in leads V1-V3 is more common.

In patients with a severe form of chronic pulmonary heart disease with emphysematous lung damage, as a rule, an S-type ECG is determined.

Important:combined hypertrophy of two ventricles at once is rarely detected by electrocardiography, especially if the hypertrophy is uniform. In this case, the pathological signs tend to compensate each other.

With “premature ventricular excitation syndrome” on the ECG, the width of the QRS complex increases and the PR interval becomes shorter. The delta wave, which affects the increase in the QRS complex, is formed as a result of an early increase in the activity of areas of the cardiac muscle of the ventricles.

Blockades are caused by the cessation of the electrical impulse in one of the areas.

Impairments in impulse conduction are manifested on the ECG by a change in the shape and increase in the size of the P wave, and with intraventricular block - an increase in QRS. Atrioventricular block can be characterized by loss of individual complexes, an increase in the P-Q interval, and in the most severe cases, a complete absence of connection between QRS and P.

Important:sinoatrial block appears on the ECG as a rather bright picture; it is characterized by the complete absence of the PQRST complex.

In case of heart rhythm disturbances, electrocardiography data is assessed based on the analysis and comparison of intervals (inter- and intra-cycle) for 10-20 seconds or even longer.

The direction and shape of the P wave, as well as the QRS complex, are of great diagnostic importance when diagnosing arrhythmias.

Myocardial dystrophy

This pathology is visible only in some leads. It is manifested by changes in the T wave. As a rule, its pronounced inversion is observed. In a number of cases, a significant deviation from the normal RST line is recorded. Pronounced dystrophy of the heart muscle is often manifested by a pronounced decrease in the amplitude of the QRS and P waves.

If a patient develops an attack of angina, then the electrocardiogram shows a noticeable decrease (depression) in RST, and in some cases, inversion of T. These changes in the ECG reflect ischemic processes in the intramural and subendocardial layers of the cardiac muscle of the left ventricle. These areas are the most demanding for blood supply.

Note:a short-term rise in the RST segment is a characteristic sign of a pathology known as Prinzmetal's angina.

In approximately 50% of patients, between attacks of angina, changes on the ECG may not be recorded at all.

In this life-threatening condition, an electrocardiogram provides information about the extent of the lesion, its exact location and depth. In addition, an ECG allows you to monitor the pathological process over time.

Morphologically it is customary to distinguish three zones:

central (zone of necrotic changes in myocardial tissue);
the zone of pronounced dystrophy of the heart muscle surrounding the lesion;
peripheral zone of pronounced ischemic changes.

All changes that are reflected on the ECG change dynamically according to the stage of development of myocardial infarction.

Dishormonal myocardial dystrophy

Myocardial dystrophy, caused by a sharp change in the patient’s hormonal background, is usually manifested by a change in the direction (inversions) of the T wave. Depressive changes in the RST complex are much less common.

Important: The severity of changes may vary over time. Pathological changes recorded on the ECG are only in rare cases associated with clinical symptoms such as pain in the chest area.

To distinguish the manifestations of coronary artery disease from myocardial dystrophy against the background of hormonal imbalance, cardiologists practice tests using pharmacological agents such as beta-adrenergic receptor blockers and potassium-containing drugs.

Changes in electrocardiogram parameters while the patient is taking certain medications

Changes in the ECG pattern can be caused by taking the following drugs:

drugs from the group of diuretics;
drugs related to cardiac glycosides;
Amiodarone;
Quinidine.

In particular, if the patient takes digitalis preparations (glycosides) in recommended doses, then relief of tachycardia (rapid heartbeat) and a decrease in the Q-T interval are determined. “Smoothing” of the RST segment and shortening of T are also possible. An overdose of glycosides is manifested by such serious changes as arrhythmia (ventricular extrasystoles), AV block and even a life-threatening condition - ventricular fibrillation (requires immediate resuscitation measures).

The pathology causes an excessive increase in the load on the right ventricle, and leads to its oxygen starvation and rapidly increasing dystrophic changes. In such situations, the patient is diagnosed with “acute cor pulmonale.” In the presence of pulmonary embolism, blockade of the branches of the His bundle is not uncommon.

The ECG shows a rise in the RST segment in parallel in leads III (sometimes in aVF and V1,2). There is T inversion in leads III, aVF, V1-V3.

Negative dynamics increase rapidly (a matter of minutes pass), and progression is noted within 24 hours. With positive dynamics, the characteristic symptoms gradually disappear within 1-2 weeks.

Early repolarization of the cardiac ventricles

This deviation is characterized by an upward shift of the RST complex from the so-called isolines. Another characteristic sign is the presence of a specific transition wave on the R or S waves. These changes in the electrocardiogram have not yet been associated with any myocardial pathology, and are therefore considered a physiological norm.

Pericarditis

Acute inflammation of the pericardium is manifested by a significant unidirectional elevation of the RST segment in any leads. In some clinical cases, the displacement may be discordant.

Myocarditis

Inflammation of the heart muscle is noticeable on the ECG by deviations from the T wave. They can vary from a decrease in voltage to an inversion. If, in parallel, the cardiologist conducts tests with potassium-containing drugs or β-blockers, then the T wave remains negative.

Based on the shape and location of the T wave, one can conclude about the process of restoration of the ventricles of the heart after contraction. This is the most variable ECG parameter; it can be affected by myocardial diseases, endocrine pathologies, medication and intoxication. The size, amplitude and direction of the T wave are disrupted; depending on these indicators, a preliminary diagnosis can be established or confirmed.

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The T wave on the ECG is normal in children and adults

The beginning of the T wave coincides with the phase, that is, with the reverse transition of sodium and potassium ions through the membrane of heart cells, after which the muscle fiber becomes ready for the next contraction. Normally, T has the following characteristics:

begins on the isoline after the S wave;
has the same direction as the QRS (positive where R is dominant, negative when S is dominant);
smooth in shape, the first part is flatter;
amplitude T up to 8 cells, increases from 1 to 3 chest leads;
may be negative in V1 and aVL, always negative in aVR.

In newborns, T waves are low in height or even flat, their direction is opposite to the adult ECG. This is due to the fact that the heart turns in direction and takes a physiological position by 2 - 4 weeks. At the same time, the configuration of the teeth on the cardiogram gradually changes. Typical features of a pediatric ECG:

negative T in V4 persists up to 10 years, V2 and 3 – up to 15 years;
adolescents and young adults may have negative T waves in the 1st and 2nd chest leads; this type of ECG is called juvenile;
height T increases from 1 to 5 mm; in schoolchildren it is 3–7 mm (as in adults).

ECG changes and their meanings

Most often, changes are suspected of coronary heart disease, but such a disorder may be a sign of other diseases:

Therefore, to make a diagnosis, all clinical signs and changes in the cardiogram are taken into account as a whole.

Two-phase

On the cardiogram, T first decreases below the isoline, and then crosses it and becomes positive. This symptom is called the “roller coaster” syndrome. May occur in the following pathologies:

Hiss bundle branch block;
increased calcium levels in the blood;
intoxication with cardiac glycosides.

Biphasic T wave with left ventricular hypertrophy

Smoothed

Flattening of the T wave can be caused by:

taking alcohol, Cordarone or antidepressants;
diabetes mellitus or eating a lot of sweets;
fear, excitement;
cardiopsychoneurosis;
myocardial infarction in the scarring stage.

Decrease in indicator

A reduced T is indicated by its amplitude, which is less than 10% of the QRS complex. This symptom on the ECG causes:

coronary insufficiency,
cardiosclerosis,
obesity,
elderly age,
hypothyroidism,
myocardial dystrophy,
taking corticosteroids,
anemia,
tonsillitis.

The T wave on the ECG is smoothed

The T wave can be smoothed in the same conditions as an absent wave, since both definitions characterize low-amplitude oscillations. It should be taken into account that violation of the rules for ECG registration can also cause smoothing of T. It also occurs in metabolic diseases - low function of the thyroid gland (myxedema, hypothyroidism). It can be found in completely healthy people throughout the day in several cardiac cycles (according to Holter monitoring).

Inversion

Inversion (turning over) of the T wave means a change in its position relative to the isoline, that is, in leads with a positive T, it changes its polarity to negative and vice versa. Such deviations can also be normal - in the right chest leads with a juvenile ECG configuration or a sign of early repolarization in athletes.

T wave inversion in leads II, III, aVF, V1-V6 in a 27-year-old athlete

Diseases that are accompanied by T inversion:

myocardial or cerebral ischemia,
influence of stress hormones,
bleeding in the brain,
attack of tachycardia,
violation of impulse conduction along the branches of the Hiss bundle.

Negative T wave

For coronary heart disease, a characteristic sign is the appearance of negative T waves on the ECG, and if they are accompanied by changes in the QRS complex, then the diagnosis of a heart attack is considered confirmed. In this case, changes in the cardiogram depend on the stage of myocardial necrosis:

acute – abnormal Q or QS, ST segment above the line, T positive;
subacute – ST on the isoline, negative T;
in the scar stage, weakly negative or positive T.

A negative T wave in leads V5-V6 (in red) indicates ischemia

A variant of the norm may be the appearance of negative T during frequent breathing, anxiety, after a large meal containing a lot of carbohydrates, as well as due to individual characteristics in some healthy people. Therefore, the detection of negative values cannot be considered a serious illness.

Pathological conditions that are accompanied by negative T waves:

heart disease - angina pectoris, heart attack, cardiomyopathy, inflammation of the myocardium, pericardium, endocarditis, ;
violation of hormonal and nervous regulation of cardiac activity (thyrotoxicosis, diabetes mellitus, diseases of the adrenal glands, pituitary gland);
after or frequent extrasystoles;

Subarachnoid hemorrhage is accompanied by negative T waves

Absence of T wave on ECG

The absence of T on the ECG means that its amplitude is so low that it merges with the isoelectric line of the heart. This happens when:

drinking alcohol;
against the backdrop of excitement, anxiety;
cardiomyopathy in patients with diabetes mellitus;
neurocirculatory dystonia (with a sudden change in body position or after rapid breathing);
insufficient intake of potassium or its loss through sweat, urine, intestinal contents (diarrhea);
scarring of myocardial infarction;
use of antidepressants.

High rate

Normally, in those leads where the highest R is recorded, the maximum amplitude is noted; in V3 - V5 it reaches 15 - 17 mm. Very high T can occur when the influence on the heart of the parasympathetic nervous system, hyperkalemia, subendocardial ischemia (first minutes), alcoholic or menopausal cardiomyopathy, left ventricular hypertrophy, and anemia predominate.

Changes in the T wave on the ECG during ischemia: a - normal, b - negative symmetrical “coronary” T wave,
c - high positive symmetrical “coronary” T wave,
d, e - two-phase T wave,
e - reduced T wave,
g - smoothed T wave,
h - weakly negative T wave.

Flat

A slightly inverted or flattened T may be either a normal variant or a manifestation of ischemic and dystrophic processes in the heart muscle. It occurs with complete blockade of the conduction pathways in the ventricles, myocardial hypertrophy, acute or chronic pancreatitis, taking antiarrhythmic medications, and hormonal and electrolyte imbalance.

Coronary

When the heart muscle is hypoxic, the fibers located under the inner membrane, the endocardium, are most affected. The T wave reflects the ability of the endocardium to maintain a negative electrical potential, therefore, in case of coronary insufficiency, it changes its direction and becomes this shape:

isosceles;
negative (negative);
pointed.

These signs characterize the ischemic wave, or it is also called coronary. Manifestations on the ECG are maximum in those leads where the greatest damage is localized, and in mirror (reciprocal) leads it is sharp and isosceles, but positive. The more pronounced the T wave, the deeper the degree of myocardial necrosis.

Rise of the T wave on the ECG

Moderate physical stress, infectious processes in the body, and anemia lead to an increase in the amplitude of T waves. Elevated T without changes in well-being can occur in healthy people, and can also be a symptom of vegetative-vascular disorders with a predominance of vagal tone.

Depression

A reduced T wave can be a manifestation of cardiomyodystrophy; it occurs with pneumonia, rheumatism, scarlet fever, acute inflammatory process in the kidneys, cor pulmonale and hypertrophic increase in the muscular layer of the myocardium.

The T wave is positive

Normally, T waves in leads should be positive: first, second standard, aVL, aVF, V3-V6. If it appears where in healthy people it is negative or close to the isoelectric line, then this indicates a lack of blood flow through the arteries of the heart (myocardial ischemia), blockade of the branches of the His bundle. Temporary changes are caused by stress, an attack of rapid heartbeat, and intense exercise in athletes.

Nonspecific T wave changes

Nonspecific changes in the T wave include all its deviations from the norm that cannot be associated with any disease. There are such ECG descriptions:

variant of the norm;
with strong compression of the limbs with electrode cuffs;
after taking cardiac glycosides, diuretics, and some drugs to lower blood pressure;
with frequent and intense breathing;
due to abdominal pain;
associated with an imbalance of the main blood electrolytes (sodium, potassium, calcium, magnesium) with vomiting, diarrhea, dehydration, and drinking alcohol on the eve of diagnosis.

In the absence of symptoms (heart pain, shortness of breath, rapid resting pulse, rhythm disturbances, swelling, enlarged liver), such changes are considered minor and do not require treatment. If there are signs of cardiac disease, then daily Holter ECG monitoring is necessary to clarify the diagnosis. It will show whether the restoration of the polarity of the heart muscle will worsen during normal physical activity.

In some cases, nonspecific disturbances in the shape and size of the T wave occur when:

insufficient nutrition of the myocardium (ischemic disease);
increased blood pressure, especially with concomitant hypertrophy (thickening of the heart muscle) of the left ventricle;
violation of intraventricular conduction (branch block).

A synonym for nonspecific changes in the T wave is a doctor’s conclusion: a violation of ventricular repolarization.

Double-humped T waves are their shape, in which instead of one dome-shaped tip, 2 waves appear on the ECG. Such changes most often occur with a lack of potassium. This is manifested by the appearance of a distinct U wave, which is normally indistinguishable. With a pronounced lack of a microelement, this rise is so pronounced that the wave reaches the T level and can even overtake it in amplitude.

Possible causes of double-humped T include:

the use of diuretics that remove potassium;
laxative abuse;
diarrhea, vomiting due to infection;
long-term use of antibiotics, hormones;
profuse sweating;
diseases of the kidneys, adrenal glands, intestines;
overdose of vitamin B12 and folic acid.

Discordant T wave

A T wave is called discordant if its direction is opposite to the ventricular QRS complex. It happens with bundle branch block, as well as during the period of restoration of blood circulation in the heart muscle after a heart attack.

Discordant T-waves may also appear in cases of severe hypertrophy of the left ventricular myocardium, as well as Wellens syndrome - blockage of the left anterior coronary artery. The latter condition is characterized by attacks of angina-type pain, a high risk of heart attack and the absence of other significant ECG changes, except for the direction of T, and normal blood tests.

Tall T waves in precordial leads

Tall T waves in the chest leads are accompanied by angina pectoris. It can be both stable and progressive, that is, threatening the development of myocardial infarction. In this case, it is important to take into account the clinical picture and other ECG changes. A typical sign of ischemic waves is their symmetry.

High T can also manifest itself as:

hyperkalemia (excessive intake of potassium, taking drugs that inhibit its excretion);
anemia;
circulatory disorders in the brain;
left ventricular hypertrophy.

T wave alternation

T wave alternans is understood as any change during exercise: on a treadmill, exercise bike, or administration of medications compared to the ECG at rest. One of the options is to analyze the daily recording (monitoring) of the cardiogram.

The doctor may discover that the shape, direction, duration of T, and its amplitude (height) have changed. But there are also micro-changes that are found when analyzed with special equipment - signal-averaged ECG.

By identifying T wave alternans, the electrical instability of the heart muscle is determined. This means that under the influence of stress or stress, a life-threatening arrhythmia with cardiac arrest can occur. Studying the characteristics of T is necessary if you have:

changes in the duration of the QT interval;
cardiomyopathy due to arrhythmia;
ventricular tachycardia;
ventricular fibrillation.

For information on changes in the T wave on an ECG, watch this video:

Normal QT interval

Normally, the QT interval does not have a constant value. The distance from the beginning of Q to the end of T depends on:

gender and age of the subject;
time of day;
states of the nervous system;
use of medications, especially analogues of stress hormones (Adrenaline, Dopamine, Hydrocortisone);
calcium, magnesium and potassium levels in the blood.

The most significant dependence can be traced to heart rate. Therefore, the calculation formulas that take this indicator into account have been continued. The faster the heart rate, the shorter the QT. When mathematically analyzing ECG data from healthy people, an approximate pattern was derived and is reflected in the table.

QT characteristic	Men, ms.	Women, ms.
Normal
Bit longer
Lengthened
Significantly lengthened
Shortened
Significantly shorter than normal

Shortening the QT interval on the ECG is dangerous, as it provokes complex types of rhythm disturbances. This syndrome can be a congenital feature, and also appears when:

treatment with cardiac glycosides in the usual dose, progresses with its increase;
increased concentrations of potassium and calcium in the blood;
fever;
a shift in the blood reaction to the acidic side (acidosis).

Short QT syndrome can be constant and repeated from cycle to cycle or paroxysmal due to changes in heart rate. Patients with such disorders are prone to dizziness, lightheadedness, and sudden loss of consciousness. In severe cases, there is a risk of sudden cardiac arrest.

Nonspecific ST-T changes

Nonspecific ST-T changes include all minor violations of ST height, smoothing or the opposite direction of T. They “do not reach” obvious pathologies, but the doctor pays attention to them when deciphering them. This can be important, since if there are complaints of heart pain, further examination is necessary. It is also carried out with risk factors:

high pressure,
smoking,
elderly age,
high cholesterol,
sedentary lifestyle.

The main causes of nonspecific symptoms include:

imbalance of electrolytes (potassium, magnesium, calcium);
use of medications;
angina pectoris;
infectious diseases, pulmonary pathology;
pain attack;
consumption of large amounts of food, alcoholic beverages;
left ventricular hypertrophy;
cerebrovascular accident.

Since all these factors are diverse, when making a diagnosis, the doctor takes into account the symptoms and, if necessary, prescribes blood tests, an ECG using the Holter method (24-hour monitoring), and stress tests with exercise.

ST segment elevation

ST segment elevation occurs in the following diseases:

Increasing the segment is a variant of the norm. In this case:

the ST dome is directed downward, turns into a unipolar (concordant) T;
T extended;
changes can be traced in all leads and cycles.

Rising (elevation) can be caused by an increased concentration of potassium in the blood, inflammation (myocarditis) and a tumor process in the heart.

ST Down Shift

A pronounced downward ST shift is a sign of insufficient myocardial nutrition - coronary heart disease. It is clinically manifested by angina pectoris, heart attack, and post-infarction cardiosclerosis. Similar changes, but without clear localization, are characteristic of:

overdose of cardiac glycosides;
use of diuretics;
tachycardia;
increased and frequent breathing;
hypertrophy of the ventricles of the heart;
intraventricular conduction disorders.

The T wave reflects the process of ventricular repolarization after their contraction. This is the most labile wave on the ECG; its changes may be the first sign of impaired blood supply to the myocardium in coronary heart disease. To make a diagnosis, you need to compare the clinical symptoms and other signs on the cardiogram.

Useful video

Watch the video about teeth and intervals:

How to decipher a heart cardiogram: general principles

The main elements of the electrocardiographic curve are:

ECG analysis

Having received an electrocardiogram in his hands, the doctor begins to evaluate it in the following sequence:

Determines whether the heart contracts rhythmically, that is, whether the rhythm is correct. To do this, measures the intervals between the R waves; they must be the same everywhere; if not, this is already an incorrect rhythm.
Calculates the rate at which the heart contracts (HR). This can be easily done by knowing the ECG recording speed and counting the number of millimeter cells between adjacent R waves. Normally, the heart rate should not go beyond 60-90 beats. in a minute.
Based on specific signs (mainly the P wave), it determines the source of excitation in the heart. Normally, this is the sinus node, that is, in a healthy person, sinus rhythm is considered normal. Atrial, atrioventricular and ventricular rhythms indicate pathology.
Evaluates cardiac conductivity by the duration of waves and segments. Each of them has its own norm indicators.
Determines the electrical axis of the heart (EOS). Very thin people are characterized by a more vertical position of the EOS, while overweight people tend to have a more horizontal position. With pathology, the axis shifts sharply to the right or left.
Analyzes teeth, segments and intervals in detail. The doctor writes down their duration on the cardiogram by hand in seconds (this is an incomprehensible set of Latin letters and numbers on the ECG). Modern electrocardiographs automatically analyze these indicators and immediately provide measurement results, which simplifies the doctor’s work.
Gives a conclusion. It necessarily indicates the correctness of the rhythm, the source of excitation, heart rate, characterizes the EOS, and also identifies specific pathological syndromes (rhythm disturbances, conduction disturbances, the presence of overload of certain parts of the heart and myocardial damage), if any.

Examples of electrocardiographic reports

In a healthy person, the ECG conclusion may look like this: sinus rhythm with a heart rate of 70 beats. per minute The EOS is in a normal position, no pathological changes were detected.

Also, for some people, sinus tachycardia (heart rate acceleration) or bradycardia (heart rate slowdown) may be considered a normal variant. In elderly people, quite often the conclusion may indicate the presence of moderate diffuse or metabolic changes in the myocardium. These conditions are not critical and, after receiving appropriate treatment and correcting the patient’s diet, mostly always disappear.

In addition, the conclusion may indicate a nonspecific change in the ST-T interval. This means that the changes are not indicative and their cause cannot be determined by ECG alone. Another fairly common condition that can be diagnosed using a cardiogram is a violation of repolarization processes, that is, a violation of the recovery of the ventricular myocardium after excitation. This change can be caused by both severe heart disease and chronic infections, hormonal imbalance and other reasons that the doctor will subsequently look for.

Conclusions that contain data on the presence of myocardial ischemia, hypertrophy of the heart, rhythm and conduction disturbances are considered prognostically unfavorable.

Interpretation of ECG in children

The whole principle of deciphering cardiograms is the same as in adults, but due to the physiological and anatomical characteristics of the children's heart, there are differences in the interpretation of normal indicators. This primarily concerns heart rate, since in children under 5 years of age it can exceed 100 beats. in a minute.

Also, children may experience sinus or respiratory arrhythmia (increased heart rate during inhalation and decreased during exhalation) without any pathology. In addition, the characteristics of some waves and intervals differ from those of adults. For example, a child may have an incomplete blockade of part of the conduction system of the heart - the right bundle branch. Pediatric cardiologists take all these features into account when making a conclusion based on the ECG.

Features of ECG during pregnancy

The body of a pregnant woman goes through various processes of adaptation to the new position. Certain changes also occur in the cardiovascular system, so the ECG of expectant mothers may differ slightly from the results of a study of the heart of a healthy adult. First of all, in the later stages there is a slight horizontal deviation of the EOS, caused by a change in the relative placement of the internal organs and the growing uterus.

In addition, expectant mothers may experience slight sinus tachycardia and signs of overload in certain parts of the heart. These changes are associated with an increase in blood volume in the body and, as a rule, disappear after childbirth. However, their detection cannot be left without a detailed examination and a more in-depth examination of the woman.

ECG interpretation, normal indicators

Decoding an ECG is the job of a knowledgeable doctor. This method of functional diagnostics evaluates:

heart rate - the state of the generators of electrical impulses and the state of the heart system conducting these impulses
the condition of the heart muscle itself (myocardium). the presence or absence of inflammation, damage, thickening, oxygen starvation, electrolyte imbalance

However, modern patients often have access to their medical documents, in particular, to electrocardiography films on which medical reports are written. With their diversity, these recordings can drive even the most balanced but ignorant person to panic disorder. After all, the patient often does not know for certain how dangerous to life and health is what is written on the back of the ECG film by the hand of a functional diagnostician, and there are still several days before an appointment with a therapist or cardiologist.

To reduce the intensity of passions, we immediately warn readers that with not a single serious diagnosis (myocardial infarction, acute rhythm disturbances), a functional diagnostician will not let a patient leave the office, but, at a minimum, will send him for a consultation with a fellow specialist right there. About the rest of the “open secrets” in this article. In all unclear cases of pathological changes in the ECG, ECG monitoring, 24-hour monitoring (Holter), ECHO cardioscopy (ultrasound of the heart) and stress tests (treadmill, bicycle ergometry) are prescribed.

Numbers and Latin letters in ECG interpretation

PQ- (0.12-0.2 s) – atrioventricular conduction time. Most often it lengthens against the background of AV blockade. Shortened in CLC and WPW syndromes.

P – (0.1s) height 0.25-2.5 mm describes atrial contractions. May indicate their hypertrophy.

QRS – (0.06-0.1s) -ventricular complex

QT – (no more than 0.45 s) lengthens with oxygen starvation (myocardial ischemia, infarction) and the threat of rhythm disturbances.

RR - the distance between the apices of the ventricular complexes reflects the regularity of heart contractions and makes it possible to calculate heart rate.

The interpretation of the ECG in children is presented in Fig. 3

Heart Rate Description Options

Sinus rhythm

This is the most common inscription found on an ECG. And, if nothing else is added and the frequency (HR) is indicated from 60 to 90 beats per minute (for example, HR 68`) - this is the best option, indicating that the heart works like a clock. This is the rhythm set by the sinus node (the main pacemaker that generates electrical impulses that cause the heart to contract). At the same time, sinus rhythm implies well-being, both in the state of this node and the health of the conduction system of the heart. The absence of other records denies pathological changes in the heart muscle and means that the ECG is normal. In addition to sinus rhythm, there may be atrial, atrioventricular or ventricular, indicating that the rhythm is set by cells in these parts of the heart and is considered pathological.

This is a normal variant in young people and children. This is a rhythm in which impulses leave the sinus node, but the intervals between heart contractions are different. This may be due to physiological changes (respiratory arrhythmia, when heart contractions slow down during exhalation). Approximately 30% of sinus arrhythmias require observation by a cardiologist, as they are at risk of developing more serious rhythm disturbances. These are arrhythmias after rheumatic fever. Against the background of myocarditis or after it, against the background of infectious diseases, heart defects and in persons with a family history of arrhythmias.

These are rhythmic contractions of the heart with a frequency of less than 50 per minute. In healthy people, bradycardia occurs, for example, during sleep. Bradycardia also often occurs in professional athletes. Pathological bradycardia may indicate sick sinus syndrome. In this case, bradycardia is more pronounced (heart rate from 45 to 35 beats per minute on average) and is observed at any time of the day. When bradycardia causes pauses in heart contractions of up to 3 seconds during the day and about 5 seconds at night, leads to disturbances in the supply of oxygen to tissues and is manifested, for example, by fainting, an operation is indicated to install a cardiac pacemaker, which replaces the sinus node, imposing a normal rhythm of contractions on the heart.

Sinus tachycardia

Heart rate more than 90 per minute is divided into physiological and pathological. In healthy people, sinus tachycardia is accompanied by physical and emotional stress, drinking coffee, sometimes strong tea or alcohol (especially energy drinks). It is short-lived and after an episode of tachycardia, the heart rate returns to normal within a short period of time after stopping the load. With pathological tachycardia, heartbeats bother the patient at rest. Its causes are fever, infections, blood loss, dehydration, thyrotoxicosis, anemia, cardiomyopathy. The underlying disease is treated. Sinus tachycardia is stopped only in case of a heart attack or acute coronary syndrome.

Extarsystole

These are rhythm disturbances in which foci outside the sinus rhythm give extraordinary cardiac contractions, after which there is a pause of twice the length, called compensatory. In general, the patient perceives heartbeats as uneven, rapid or slow, and sometimes chaotic. The most worrying thing is the dips in heart rate. There may be unpleasant sensations in the chest in the form of tremors, tingling, feelings of fear and emptiness in the stomach.

Not all extrasystoles are dangerous to health. Most of them do not lead to significant circulatory disorders and do not threaten either life or health. They can be functional (against the background of panic attacks, cardioneurosis, hormonal imbalances), organic (with ischemic heart disease, heart defects, myocardial dystrophy or cardiopathy, myocarditis). Intoxication and heart surgery can also lead to them. Depending on the place of occurrence, extrasystoles are divided into atrial, ventricular and anthrioventricular (arising in the node at the border between the atria and ventricles).

Single extrasystoles are most often rare (less than 5 per hour). They are usually functional and do not interfere with normal blood supply.
Paired extrasystoles, two at a time, accompany a certain number of normal contractions. Such rhythm disturbances often indicate pathology and require further examination (Holter monitoring).
Allorhythmias are more complex types of extrasystoles. If every second contraction is an extrasystole, this is bigymenia, if every third contraction is trigymenia, every fourth is quadrigymenia.

It is customary to divide ventricular extrasystoles into five classes (according to Lown). They are assessed during daily ECG monitoring, since the readings of a regular ECG in a few minutes may not show anything.

Class 1 - single rare extrasystoles with a frequency of up to 60 per hour, emanating from one focus (monotopic)
2 – frequent monotopic more than 5 per minute
3 – frequent polymorphic (of different shapes) polytopic (from different foci)
4a – paired, 4b – group (trigymenia), episodes of paroxysmal tachycardia
5 – early extrasystoles

The higher the class, the more serious the violations, although today even classes 3 and 4 do not always require drug treatment. In general, if there are less than 200 ventricular extrasystoles per day, they should be classified as functional and not worry about them. For more frequent cases, ECHO CS is indicated, and sometimes cardiac MRI is indicated. It is not the extrasystole that is treated, but the disease that leads to it.

Paroxysmal tachycardia

In general, a paroxysm is an attack. An attack-like increase in rhythm can last from several minutes to several days. In this case, the intervals between heart contractions will be the same, and the rhythm will increase over 100 per minute (on average from 120 to 250). There are supraventricular and ventricular forms of tachycardia. This pathology is based on abnormal circulation of electrical impulses in the conduction system of the heart. This pathology can be treated. Home remedies to relieve an attack:

holding your breath
increased forced cough
immersing face in cold water

WPW syndrome

Wolff-Parkinson-White syndrome is a type of paroxysmal supraventricular tachycardia. Named after the authors who described it. The appearance of tachycardia is based on the presence of an additional nerve bundle between the atria and ventricles, through which a faster impulse passes than from the main pacemaker.

As a result, an extraordinary contraction of the heart muscle occurs. The syndrome requires conservative or surgical treatment (in case of ineffectiveness or intolerance of antiarrhythmic tablets, during episodes of atrial fibrillation, and with concomitant heart defects).

CLC – syndrome (Clerk-Levi-Christesco)

is similar in mechanism to WPW and is characterized by earlier excitation of the ventricles than normal due to an additional bundle along which the nerve impulse travels. The congenital syndrome is manifested by attacks of rapid heartbeat.

Atrial fibrillation

It can be in the form of an attack or a permanent form. It manifests itself in the form of atrial flutter or fibrillation.

Atrial fibrillation

When flickering, the heart contracts completely irregularly (the intervals between contractions of very different durations). This is explained by the fact that the rhythm is not set by the sinus node, but by other cells of the atria.

The resulting frequency is from 350 to 700 beats per minute. There is simply no full contraction of the atria; contracting muscle fibers do not effectively fill the ventricles with blood.

As a result, the heart’s output of blood deteriorates and organs and tissues suffer from oxygen starvation. Another name for atrial fibrillation is atrial fibrillation. Not all atrial contractions reach the ventricles of the heart, so the heart rate (and pulse) will be either below normal (bradysystole with a frequency of less than 60), or normal (normosystole from 60 to 90), or above normal (tachysystole more than 90 beats per minute ).

An attack of atrial fibrillation is difficult to miss.

It usually starts with a strong beat of the heart.
It develops as a series of absolutely irregular heartbeats with a high or normal frequency.
The condition is accompanied by weakness, sweating, dizziness.
The fear of death is very pronounced.
There may be shortness of breath, general agitation.
Sometimes there is loss of consciousness.
The attack ends with normalization of the rhythm and the urge to urinate, during which a large amount of urine is released.

To stop an attack, they use reflex methods, drugs in the form of tablets or injections, or resort to cardioversion (stimulating the heart with an electric defibrillator). If an attack of atrial fibrillation is not eliminated within two days, the risks of thrombotic complications (pulmonary embolism, stroke) increase.

With a constant form of heartbeat flicker (when the rhythm is not restored either against the background of drugs or against the background of electrical stimulation of the heart), they become a more familiar companion to patients and are felt only during tachysystole (rapid, irregular heartbeats). The main task when detecting signs of tachysystole of a permanent form of atrial fibrillation on the ECG is to slow down the rhythm to normosystole without trying to make it rhythmic.

Examples of recordings on ECG films:

atrial fibrillation, tachysystolic variant, heart rate 160 b'.
Atrial fibrillation, normosystolic variant, heart rate 64 b'.

Atrial fibrillation can develop in the course of coronary heart disease, against the background of thyrotoxicosis, organic heart defects, diabetes mellitus, sick sinus syndrome, and intoxication (most often with alcohol).

Atrial flutter

These are frequent (more than 200 per minute) regular contractions of the atria and equally regular, but less frequent contractions of the ventricles. In general, flutter is more common in the acute form and is better tolerated than flicker, since circulatory disorders are less pronounced. Fluttering develops when:

organic heart diseases (cardiomyopathies, heart failure)
after heart surgery
against the background of obstructive pulmonary diseases
in healthy people it almost never occurs

Clinically, flutter is manifested by rapid rhythmic heartbeat and pulse, swelling of the neck veins, shortness of breath, sweating and weakness.

Conduction disorders

Normally, having formed in the sinus node, electrical excitation travels through the conduction system, experiencing a physiological delay of a split second in the atrioventricular node. On its way, the impulse stimulates the atria and ventricles, which pump blood, to contract. If in any part of the conduction system the impulse is delayed longer than the prescribed time, then excitation to the underlying sections will come later, and, therefore, the normal pumping work of the heart muscle will be disrupted. Conduction disturbances are called blockades. They can occur as functional disorders, but more often they are the result of drug or alcohol intoxication and organic heart disease. Depending on the level at which they arise, several types are distinguished.

Sinoatrial blockade

When the exit of an impulse from the sinus node is difficult. In essence, this leads to sick sinus syndrome, slowing of contractions to severe bradycardia, impaired blood supply to the periphery, shortness of breath, weakness, dizziness and loss of consciousness. The second degree of this blockade is called Samoilov-Wenckebach syndrome.

Atrioventricular block (AV block)

This is a delay of excitation in the atrioventricular node longer than the prescribed 0.09 seconds. There are three degrees of this type of blockade. The higher the degree, the less often the ventricles contract, the more severe the circulatory disorders.

In the first, the delay allows each atrial contraction to maintain an adequate number of ventricular contractions.
The second degree leaves some of the atrial contractions without ventricular contractions. It is described, depending on the prolongation of the PQ interval and the loss of ventricular complexes, as Mobitz 1, 2 or 3.
The third degree is also called complete transverse blockade. The atria and ventricles begin to contract without interconnection.

In this case, the ventricles do not stop because they obey the pacemakers from the underlying parts of the heart. If the first degree of blockade may not manifest itself in any way and can be detected only with an ECG, then the second is already characterized by sensations of periodic cardiac arrest, weakness, and fatigue. With complete blockades, brain symptoms are added to the manifestations (dizziness, spots in the eyes). Morgagni-Adams-Stokes attacks may develop (when the ventricles escape from all pacemakers) with loss of consciousness and even convulsions.

Impaired conduction within the ventricles

In the ventricles, the electrical signal propagates to the muscle cells through such elements of the conduction system as the trunk of the His bundle, its legs (left and right) and branches of the legs. Blockades can occur at any of these levels, which is also reflected in the ECG. In this case, instead of being simultaneously covered by excitation, one of the ventricles is delayed, since the signal to it bypasses the blocked area.

In addition to the place of origin, a distinction is made between complete or incomplete blockade, as well as permanent and non-permanent blockade. The causes of intraventricular blocks are similar to other conduction disorders (ischemic heart disease, myocarditis and endocarditis, cardiomyopathies, heart defects, arterial hypertension, fibrosis, heart tumors). Also affected are the use of antiarthmic drugs, an increase in potassium in the blood plasma, acidosis, and oxygen starvation.

The most common is blockade of the anterosuperior branch of the left bundle branch (ALBBB).
In second place is right leg block (RBBB). This blockade is usually not accompanied by heart disease.
Left bundle branch block is more typical for myocardial lesions. In this case, complete blockade (PBBB) is worse than incomplete blockade (LBBB). It sometimes has to be distinguished from WPW syndrome.
Blockade of the posteroinferior branch of the left bundle branch can occur in individuals with a narrow and elongated or deformed chest. Among pathological conditions, it is more typical for overload of the right ventricle (with pulmonary embolism or heart defects).

The clinical picture of blockades at the levels of the His bundle is not expressed. The picture of the underlying cardiac pathology comes first.

Bailey's syndrome is a two-bundle block (of the right bundle branch and the posterior branch of the left bundle branch).

Myocardial hypertrophy

With chronic overload (pressure, volume), the heart muscle in certain areas begins to thicken, and the chambers of the heart begin to stretch. On the ECG, such changes are usually described as hypertrophy.

Left ventricular hypertrophy (LVH) is typical for arterial hypertension, cardiomyopathy, and a number of heart defects. But even normally, athletes, obese patients and people engaged in heavy physical labor may experience signs of LVH.
Right ventricular hypertrophy is an undoubted sign of increased pressure in the pulmonary blood flow system. Chronic cor pulmonale, obstructive pulmonary diseases, cardiac defects (pulmonary stenosis, tetralogy of Fallot, ventricular septal defect) lead to RVH.
Left atrial hypertrophy (LAH) – with mitral and aortic stenosis or insufficiency, hypertension, cardiomyopathy, after myocarditis.
Right atrial hypertrophy (RAH) – with cor pulmonale, tricuspid valve defects, chest deformities, pulmonary pathologies and PE.
Indirect signs of ventricular hypertrophy are deviation of the electrical axis of the heart (EOC) to the right or left. The left type of EOS is its deviation to the left, that is, LVH, the right type is RVH.
Systolic overload is also evidence of hypertrophy of the heart. Less commonly, this is evidence of ischemia (in the presence of angina pain).

Changes in myocardial contractility and nutrition

Early ventricular repolarization syndrome

Most often, this is a variant of the norm, especially for athletes and people with congenital high body weight. Sometimes associated with myocardial hypertrophy. Refers to the peculiarities of the passage of electrolytes (potassium) through the membranes of cardiocytes and the characteristics of the proteins from which the membranes are built. It is considered a risk factor for sudden cardiac arrest, but does not provide clinical results and most often remains without consequences.

Moderate or severe diffuse changes in the myocardium

This is evidence of a malnutrition of the myocardium as a result of dystrophy, inflammation (myocarditis) or cardiosclerosis. Also, reversible diffuse changes accompany disturbances in water and electrolyte balance (with vomiting or diarrhea), taking medications (diuretics), and heavy physical activity.

This is a sign of deterioration in myocardial nutrition without severe oxygen starvation, for example, in case of disturbances in the balance of electrolytes or against the background of dyshormonal conditions.

Acute ischemia, ischemic changes, T wave changes, ST depression, low T

This describes reversible changes associated with oxygen starvation of the myocardium (ischemia). This can be either stable angina or unstable, acute coronary syndrome. In addition to the presence of the changes themselves, their location is also described (for example, subendocardial ischemia). A distinctive feature of such changes is their reversibility. In any case, such changes require comparison of this ECG with old films, and if a heart attack is suspected, troponin rapid tests for myocardial damage or coronary angiography. Depending on the type of coronary heart disease, anti-ischemic treatment is selected.

Advanced heart attack

It is usually described:

by stages. acute (up to 3 days), acute (up to 3 weeks), subacute (up to 3 months), cicatricial (all life after a heart attack)
by volume. transmural (large focal), subendocardial (small focal)
according to the location of heart attacks. There are anterior and anterior septal, basal, lateral, inferior (posterior diaphragmatic), circular apical, posterobasal and right ventricular.

The whole variety of syndromes and specific changes on the ECG, the difference in indicators for adults and children, the abundance of reasons leading to the same type of ECG changes do not allow a non-specialist to interpret even the finished conclusion of a functional diagnostician. It is much wiser, having the ECG result in hand, to visit a cardiologist in a timely manner and receive competent recommendations for further diagnosis or treatment of your problem, significantly reducing the risks of emergency cardiac conditions.

How to decipher ECG indicators of the heart?

An electrocardiographic study is the simplest, but very informative method of studying the functioning of a patient’s heart. The result of this procedure is an ECG. Incomprehensible lines on a piece of paper contain a lot of information about the state and functioning of the main organ in the human body. Decoding ECG indicators is quite simple. The main thing is to know some of the secrets and features of this procedure, as well as the norms of all indicators.

Exactly 12 curves are recorded on the ECG. Each of them talks about the work of each specific part of the heart. So, the first curve is the anterior surface of the heart muscle, and the third line is its posterior surface. To record a cardiogram of all 12 leads, electrodes are attached to the patient’s body. The specialist does this sequentially, installing them in specific places.

Principles of decoding

Each curve on the cardiogram graph has its own elements:

Teeth, which are convexities directed downwards or upwards. All of them are designated in Latin capital letters. "P" shows the work of the heart's atria. “T” is the restorative capabilities of the myocardium.
Segments represent the distance between several ascending or descending teeth located in the vicinity. Doctors are especially interested in the indicators of such segments as ST, as well as PQ.
An interval is a gap that includes both a segment and a tooth.

Each specific element of the ECG shows a specific process that occurs directly in the heart. According to their width, height and other parameters, the doctor is able to correctly decipher the received data.

How are the results analyzed?

As soon as the specialist gets his hands on the electrocardiogram, its interpretation begins. This is done in a certain strict sequence:

The correct rhythm is determined by the intervals between the “R” waves. They must be equal. Otherwise, we can conclude that the heart rhythm is incorrect.
Using an ECG you can determine your heart rate. To do this, you need to know the speed at which the indicators were recorded. Additionally, you will also need to count the number of cells between the two “R” waves. The norm is from 60 to 90 beats per minute.
The source of excitation in the heart muscle is determined by a number of specific signs. This will be revealed, among other things, by assessing the parameters of the “P” wave. The norm implies that the source is the sinus node. Therefore, a healthy person always has sinus rhythm. If a ventricular, atrial or any other rhythm is observed, this indicates the presence of pathology.
The specialist evaluates the conductivity of the heart. This happens based on the duration of each segment and tooth.
The electrical axis of the heart, if it shifts to the left or right quite sharply, may also indicate the presence of problems with the cardiovascular system.
Each tooth, interval and segment is analyzed individually and in detail. Modern ECG machines immediately automatically provide indicators of all measurements. This greatly simplifies the doctor’s work.
Finally, the specialist makes a conclusion. It indicates the decoding of the cardiogram. If any pathological syndromes were detected, they must be indicated there.

Normal values for adults

The norm of all indicators of the cardiogram is determined by analyzing the position of the teeth. But the heart rhythm is always measured by the distance between the highest teeth “R” - “R”. Normally they should be equal. The maximum difference can be no more than 10%. Otherwise, this will no longer be the norm, which should be within 60-80 pulsations per minute. If the sinus rhythm is more frequent, then the patient has tachycardia. On the contrary, a slow sinus rhythm indicates a disease called bradycardia.

P-QRS-T intervals will tell you about the passage of an impulse directly through all parts of the heart. The norm is an indicator from 120 to 200 ms. On the graph it looks like 3-5 squares.

By measuring the width from the Q wave to the S wave, you can get an idea of the excitation of the ventricles of the heart. If this is the norm, then the width will be 60-100 ms.

The duration of ventricular contraction can be determined by measuring the QT interval. The norm is 390-450 ms. If it is slightly longer, a diagnosis can be made: rheumatism, ischemia, atherosclerosis. If the interval is shortened, we can talk about hypercalcemia.

What do the teeth mean?

When interpreting an ECG, it is imperative to monitor the height of all teeth. It may indicate the presence of serious heart pathologies:

The Q wave is an indicator of excitation of the left cardiac septum. The norm is a quarter of the length of the R wave. If it is exceeded, there is a possibility of necrotic myocardial pathology;
The S wave is an indicator of excitation of those partitions that are located in the basal layers of the ventricles. The norm in this case is 20 mm in height. If there are deviations, this indicates ischemic disease.
The R wave in the ECG indicates the activity of the walls of all ventricles of the heart. It is recorded in all ECG curves. If there is no activity somewhere, then it makes sense to suspect ventricular hypertrophy.
The T wave appears in lines I and II, as directed upward. But in the VR curve it is always negative. When the T wave on the ECG is too high and sharp, the doctor suspects hyperkalemia. If it is long and flat, then there is a risk of developing hypokalemia.

Normal pediatric electrocardiogram readings

In childhood, the norm of ECG indicators may differ slightly from the characteristics of an adult:

The heart rate of children under 3 years old is about 110 pulsations per minute, and at the age of 3-5 years – 100 beats. This figure is already lower in adolescents - 60-90 pulsations.
The normal QRS reading is 0.6-0.1 s.
The P wave should normally not be longer than 0.1 s.
The electrical axis of the heart in children should remain without any changes.
The rhythm is sinus only.
On an ECG, the Q-T interval e may exceed 0.4 s, and the P-Q interval should be 0.2 s.

Sinus heart rate in the cardiogram decoding is expressed as a function of heart rate and respiration. This means that the heart muscle contracts normally. In this case, the pulsation is 60-80 beats per minute.

Why are the indicators different?

Often patients are faced with a situation where their ECG readings are different. What is this connected with? To get the most accurate results, there are many factors to consider:

Distortions when recording a cardiogram may be due to technical problems. For example, if the results are not correctly merged. And many Roman numerals look the same whether upside down or right upside down. It happens that the graph is cut incorrectly or the first or last tooth is lost.
Preliminary preparation for the procedure is important. On the day of the ECG, you should not have a heavy breakfast, it is advisable to even give it up completely. You will have to stop drinking liquids, including coffee and tea. After all, they stimulate the heart rate. Accordingly, the final indicators are distorted. It's best to shower first, but you don't need to apply any body products. Finally, you need to relax as much as possible during the procedure.
Incorrect placement of the electrodes cannot be ruled out.

The best way to check your heart is with an electrocardiograph. He will help you carry out the procedure as correctly and accurately as possible. And to confirm the diagnosis indicated by the ECG results, the doctor will always prescribe additional tests.

An electrocardiogram is the most accessible, common way to make a diagnosis, even in conditions of emergency intervention by an ambulance team.

Now every cardiologist in the visiting team has a portable and lightweight electrocardiograph, capable of reading information by recording on a recorder the electrical impulses of the heart muscle - the myocardium at the moment of contraction.

Anyone, even a child, can decipher an ECG, given the fact that the patient understands the basic canons of the heart. Those very teeth on the tape are the peak (response) of the heart to contraction. The more frequent they are, the faster the myocardial contraction occurs; the fewer there are, the slower the heartbeat occurs, and in fact the transmission of a nerve impulse. However, this is just a general idea.

To make a correct diagnosis, it is necessary to take into account the time intervals between contractions, the height of the peak value, the age of the patient, the presence or absence of aggravating factors, etc.

An ECG of the heart for diabetics who, in addition to diabetes mellitus, also have late cardiovascular complications, allows one to assess the severity of the disease and intervene in a timely manner in order to delay further progression of the disease, which can lead to serious consequences in the form of myocardial infarction, pulmonary embolism and etc.

If the pregnant woman had a bad electrocardiogram, then repeated studies are prescribed with possible daily monitoring.

However, it is worth considering the fact that the values on the tape for a pregnant woman will be slightly different, since during the growth of the fetus there is a natural displacement of the internal organs, which are forced out by the expanding uterus. Their heart occupies a different position in the chest area, therefore, the electrical axis shifts.

In addition, the longer the period, the greater the load the heart experiences, which is forced to work harder in order to satisfy the needs of two full-fledged organisms.

However, you should not worry so much if the doctor reported the same tachycardia based on the results, since it is most often that it can be false, provoked either intentionally or out of ignorance by the patient himself. Therefore, it is extremely important to properly prepare for this study.

In order to pass the test correctly, you need to understand that any excitement, excitement and worry will inevitably affect the results. Therefore, it is important to prepare yourself in advance.

Not acceptable

Drinking alcohol or any other strong drinks (including energy drinks, etc.)

Overeating (best to take on an empty stomach or have a light snack before going out)

Smoking

Using drugs that stimulate or suppress heart activity or drinks (such as coffee)

Physical activity

Stress

There are often cases when a patient, being late for the treatment room at the appointed time, began to worry greatly or frantically rushed to the treasured room, forgetting about everything in the world. As a result, its leaf was riddled with frequent sharp teeth, and the doctor, of course, recommended that his patient undergo the test again. However, in order not to create unnecessary problems, try to calm yourself as much as possible before entering the cardiology room. Moreover, nothing bad will happen to you there.

When the patient is invited, it is necessary to undress to the waist behind a screen (for women, remove their bra) and lie down on the couch. In some treatment rooms, depending on the suspected diagnosis, it is also necessary to free the body from the torso down to the underwear.

After that, the nurse applies a special gel to the lead sites, to which electrodes are attached, from which multi-colored wires are stretched to the reading machine.

Thanks to special electrodes, which the nurse places at certain points, the slightest cardiac impulse is detected, which is recorded using a recorder.

After each contraction, called depolarization, a tooth is displayed on the tape, and at the moment of transition to a calm state - repolarization, the recorder leaves a straight line.

Within a few minutes, the nurse will take a cardiogram.

The tape itself, as a rule, is not given to patients, but is handed directly to the cardiologist who decrypts it. With notes and transcripts, the tape is sent to the attending physician or transferred to the reception desk so that the patient can pick up the results himself.

But even if you pick up a cardiogram tape, you will hardly be able to understand what is depicted there. Therefore, we will try to lift the veil of secrecy a little so that you can at least assess the potential of your heart.

ECG interpretation

Even on a blank sheet of this type of functional diagnostics there are some notes that help the doctor with decoding. The recorder reflects the transmission of an impulse that, over a certain period of time, passes through all parts of the heart.

To understand these scribbles, you need to know in what order and how exactly the impulse is transmitted.

The impulse, passing through different parts of the heart, is displayed on the tape in the form of a graph, which conventionally displays marks in the form of Latin letters: P, Q, R, S, T

Let's figure out what they mean.

P value

The electrical potential, going beyond the sinus node, transmits excitation primarily to the right atrium, in which the sinus node is located.

At this very moment, the reading device will record a change in the form of a peak of excitation of the right atrium. Then it passes through the conduction system - the interatrial bundle of Bachmann - into the left atrium. Its activity occurs at the moment when the right atrium is already fully engulfed in excitement.

On the tape, both of these processes appear as the total value of excitation of both atria of the right and left and are recorded as peak P.

In other words, the P peak is sinus excitation that travels along the pathways from the right to the left atrium.

Interval P - Q

Simultaneously with the excitation of the atria, the impulse that goes beyond the sinus node passes along the lower branch of the Bachmann bundle and enters the atrioventricular junction, which is otherwise called the atrioventricular junction.

There is a natural impulse delay here. Therefore, a straight line appears on the tape, which is called isoelectric.

In assessing the interval, the time it takes for the impulse to travel through this connection and subsequent sections plays a role.

Counting is done in seconds.

Complex Q, R, S

Afterwards, the impulse, passing along the conduction pathways in the form of the His bundle and Purkinje fibers, reaches the ventricles. This whole process is presented on the tape in the form of a QRS complex.

The ventricles of the heart are always excited in a certain sequence and the impulse travels this path in a certain amount of time, which also plays an important role.

Initially, the excitation covers the septum between the ventricles. This takes about 0.03 seconds. A Q wave appears on the diagram, extending just below the main line.

After the impulse for 0.05. sec. reaches the apex of the heart and adjacent areas. A tall R wave forms on the tape.

Then it moves to the base of the heart, which is reflected in the form of a falling S wave. This takes 0.02 seconds.

Thus, QRS is an entire ventricular complex with a total duration of 0.10 seconds.

S-T interval

Since myocardial cells cannot remain excited for a long time, a moment of decline occurs when the impulse fades away. By this time, the process of restoring the original state that reigned before the excitement begins.

This process is also recorded on the ECG.

By the way, in this matter the initial role is played by the redistribution of sodium and potassium ions, the movement of which gives this very impulse. All this is usually called in one word - the process of repolarization.

We will not go into details, but will only note that this transition from excitation to extinction is visible in the interval from S to T waves.

ECG normal

These are the basic designations, looking at which you can judge the speed and intensity of the heart muscle beat. But in order to get a more complete picture, it is necessary to reduce all the data to some single ECG standard. Therefore, all devices are configured in such a way that the recorder first draws control signals on the tape, and only then begins to pick up electrical vibrations from the electrodes connected to the person.

Typically, such a signal is 10 mm in height and 1 millivolt (mV). This is the same calibration, control point.

All measurements of the teeth are made in the second lead. On the tape it is indicated by the Roman numeral II. The R wave should correspond to the control point, and based on it, the norm of the remaining teeth is calculated:

height T 1/2 (0.5 mV)
depth S - 1/3 (0.3 mV)
height P - 1/3 (0.3 mV)
depth Q - 1/4 (0.2 mV)

The distance between the teeth and intervals is calculated in seconds. Ideally, they look at the width of the P wave, which is equal to 0.10 seconds, and the subsequent length of the waves and intervals is equal to 0.02 seconds each time.

Thus, the width of the P wave is 0.10±0.02 sec. During this time, the impulse will cover both atria with excitement; P - Q: 0.10±0.02 sec; QRS: 0.10±0.02 sec; to complete a full circle (excitation passing from the sinus node through the atrioventricular connection to the atria, ventricles) in 0.30±0.02 sec.

Let's look at several normal ECGs for different ages (in a child, in adult men and women)

It is very important to take into account the patient’s age, his general complaints and condition, as well as current health problems, since even the slightest cold can affect the results.

Moreover, if a person plays sports, then his heart “gets used” to working in a different mode, which is reflected in the final results. An experienced doctor always takes into account all relevant factors.

Normal ECG for a teenager (11 years old). For an adult this will not be the norm.

Normal ECG of a young person (age 20 - 30 years).

ECG analysis is evaluated according to the direction of the electrical axis, in which the Q-R-S interval is of greatest importance. Any cardiologist also looks at the distance between the teeth and their height.

The inventory of the resulting diagram is made according to a specific template:

An assessment of the heart rhythm is carried out with the measurement of heart rate (heart rate) at a normal rate: sinus rhythm, heart rate - 60 - 90 beats per minute.
Calculation of intervals: Q-T at a rate of 390 - 440 ms.

This is necessary to estimate the duration of the contraction phase (they are called systoles). In this case, they resort to the Bazett formula. An extended interval indicates coronary heart disease, atherosclerosis, myocarditis, etc. A short interval may be associated with hypercalcemia.

Cardiac electrical axis (ECA) assessment

This parameter is calculated from the isoline taking into account the height of the teeth. With a normal heart rhythm, the R wave should always be higher than S. If the axis deviates to the right, and S is higher than R, then this indicates disorders in the right ventricle, with a deviation to the left in leads II and III - left ventricular hypertrophy.

Evaluation of the Q - R - S complex

Normally, the interval should not exceed 120 ms. If the interval is distorted, then this may indicate various blockades in the conduction pathways (branch branches in the His bundles) or conduction disturbances in other areas. These indicators can detect hypertrophy of the left or right ventricles.

an inventory of the S - T segment is maintained

It can be used to judge the readiness of the heart muscle to contract after its complete depolarization. This segment should be longer than the Q-R-S complex.

What do Roman numerals mean on an ECG?

Each point to which the electrodes are connected has its own meaning. It records electrical vibrations and the recorder reflects them on the tape. To correctly read the data, it is important to correctly install the electrodes on a certain area.

For example:

the potential difference between two points of the right and left hand is recorded in the first lead and is designated I
the second lead is responsible for the potential difference between the right arm and left leg - II
third between left arm and left leg - III

If we mentally connect all these points, we get a triangle named after the founder of electrocardiography, Einthoven.

In order not to confuse them with each other, all electrodes have wires of different colors: red is attached to the left hand, yellow to the right, green to the left leg, black to the right leg, it acts as a grounding connection.

This arrangement refers to a bipolar lead. It is the most common, but there are also single-pole circuits.

Such a single-pole electrode is designated by the letter V. The recording electrode installed on the right hand is designated by the sign VR, on the left, respectively, by VL. On the leg - VF (food - leg). The signal from these points is weaker, so it is usually amplified; the tape is marked “a”.

The chest leads are also slightly different. The electrodes are attached directly to the chest. Receiving impulses from these points are the strongest and clearest. They do not require amplification. Here the electrodes are located strictly according to the agreed standard:

designation	electrode attachment location
V1	in the 4th intercostal space at the right edge of the sternum
V2	in the 4th intercostal space at the left edge of the sternum
V3	halfway between V2 and V4
V4
V5	in the 5th intercostal space at the midclavicular line
V6	at the intersection of the horizontal level of the 5th intercostal space and the midaxillary line
V7	at the intersection of the horizontal level of the 5th intercostal space and the posterior axillary line
V8	at the intersection of the horizontal level of the 5th intercostal space and the midscapular line
V9	at the intersection of the horizontal level of the 5th intercostal space and the paravertebral line

A standard study uses 12 leads.

How to determine pathologies in the heart

When answering this question, the doctor pays attention to the person’s diagram and, based on the basic symbols, can guess which particular department has begun to malfunction.

We will display all the information in table form.

designation	myocardium department
I	anterior wall of the heart
II	summary display I and III
III	posterior wall of the heart
aVR	right lateral wall of the heart
aVL	left anterolateral wall of the heart
aVF	posterior inferior wall of the heart
V1 and V2	right ventricle
V3	interventricular septum
V4	apex of the heart
V5	anterolateral wall of the left ventricle
V6	lateral wall of the left ventricle

Taking into account all of the above, you can learn how to decipher a tape using at least the simplest parameters. Although many serious abnormalities in the functioning of the heart will be visible to the naked eye even with this set of knowledge.

For clarity, we will describe several of the most disappointing diagnoses so that you can simply visually compare the norm and deviations from it.

Myocardial infarction

Judging by this ECG, the diagnosis will be disappointing. The only positive thing here is the duration of the Q-R-S interval, which is normal.

In leads V2 - V6 we see ST elevation.

This is the result acute transmural ischemia(AMI) of the anterior wall of the left ventricle. Q waves are visible in the anterior leads.

On this tape we see a conduction disturbance. However, even with this fact it is noted acute anteroseptal myocardial infarction against the background of right bundle branch block.

The right chest leads dismantle the S-T elevation and positive T waves.

Rhythm - sinus. There are high, regular R waves, and pathology of the Q waves in the posterolateral regions.

Deviation visible ST in I, aVL, V6. All this indicates posterolateral myocardial infarction with coronary heart disease (CHD).

Thus, the signs of myorcardial infarction on the ECG are:

tall T wave
elevation or depression of the S-T segment
pathological Q wave or its absence

Signs of myocardial hypertrophy

Zheludochkov

For the most part, hypertrophy is characteristic of those people whose heart has for a long time experienced additional stress as a result of, say, obesity, pregnancy, or some other disease that negatively affects the non-vascular activity of the entire body as a whole or individual organs (in particular the lungs, kidneys).

Hypertrophied myocardium is characterized by several signs, one of which is an increase in the time of internal deviation.

What does it mean?

Excitement will have to spend more time passing through the cardiac sections.

The same applies to the vector, which is also larger and longer.

If you look for these signs on the tape, the R wave will be higher in amplitude than normal.

A characteristic symptom is ischemia, which is a consequence of insufficient blood supply.

Blood flows through the coronary arteries to the heart, which, as the thickness of the myocardium increases, encounters an obstacle on the way and slows down. Impaired blood supply causes ischemia of the subendocardial layers of the heart.

Based on this, the natural, normal function of the pathways is disrupted. Inadequate conduction leads to disruptions in the process of ventricular excitation.

After which a chain reaction is started, because the work of other departments depends on the work of one department. If there is hypertrophy of one of the ventricles, then its mass increases due to the growth of cardiomyocytes - these are cells that participate in the process of transmitting nerve impulses. Therefore, its vector will be greater than the vector of a healthy ventricle. On the electrocardiogram tape it will be noticeable that the vector will be deviated towards the localization of hypertrophy with a displacement of the electrical axis of the heart.

The main signs also include changes in the third chest lead (V3), which is something like a transshipment, transition zone.

What kind of zone is this?

It includes the height of the R wave and the depth of S, which are equal in absolute value. But when the electrical axis changes as a result of hypertrophy, their ratio will change.

Let's look at specific examples

In sinus rhythm, left ventricular hypertrophy is clearly visible with characteristic tall T waves in the precordial leads.

There is nonspecific ST depression in the inferolateral region.

The EOS (electrical axis of the heart) is deviated to the left with anterior hemiblock and prolongation of the QT interval.

High T waves indicate that in addition to hypertrophy, a person also has hyperkalemia most likely developed against the background of renal failure and, which are characteristic of many patients who have been ill for many years.

In addition, a longer QT interval with ST depression indicates hypocalcemia, which progresses in the later stages (with chronic renal failure).

This ECG corresponds to an elderly person who has serious kidney problems. He is on the verge.

Atrial

As you already know, the total value of atrial excitation on the cardiogram is shown by the P wave. In case of failures in this system, the width and/or height of the peak increases.

With right atrial hypertrophy (RAH), P will be higher than normal, but not wider, since the peak excitation of the RA ends before the excitation of the left. In some cases, the peak takes on a pointed shape.

With HLP, an increase in the width (more than 0.12 seconds) and height of the peak is observed (double hump appears).

These signs indicate a disturbance in impulse conduction, which is called intraatrial block.

Blockades

Blockades refer to any disruptions in the conduction system of the heart.

A little earlier, we looked at the path of the impulse from the sinus node through the pathways to the atria; at the same time, the sinus impulse rushes along the lower branch of Bachmann’s bundle and reaches the atrioventricular connection, passing through it it undergoes a natural delay. After which it enters the ventricular conduction system, presented in the form of bundles of His.

Depending on the level at which the failure occurred, the violation is distinguished:

intraatrial conduction (blockade of sinus impulse in the atria)
atrioventricular
intraventricular

Intraventricular conduction

This system is presented in the form of a trunk of His, divided into two branches - the left and right legs.

The right leg “supplies” the right ventricle, within which it branches into many small networks. Appears in the form of one wide bundle with branches inside the ventricular muscles.

The left leg is divided into anterior and posterior branches, which “adjoin” the anterior and posterior walls of the left ventricle. Both of these branches form a network of smaller branches within the LV musculature. They are called Purkinje fibers.

Right bundle branch block

The course of the impulse first covers the path through the excitation of the interventricular septum, and then the unblocked LV is first involved in the process, through its normal course, and only then the right one is excited, to which the impulse reaches along a distorted path through the Purkinje fibers.

Of course, all this will affect the structure and shape of the QRS complex in the right chest leads V1 and V2. At the same time, on the ECG we will see bifurcated vertices of the complex, similar to the letter “M”, in which R is the excitation of the interventricular septum, and the second R1 is the actual excitation of the RV. S will continue to be responsible for LV excitation.

On this tape we see incomplete blockade of PNPG and AB blockade of the first degree, there are also r traumatic changes in the posterior diaphragmatic region.

Thus, the signs of right bundle branch block are as follows:

prolongation of the QRS complex in standard lead II by more than 0.12 sec.
increase in the time of internal deviation of the RV (in the graph above this parameter is presented as J, which is more than 0.02 seconds in the right chest leads V1, V2)
deformation and splitting of the complex into two “humps”
negative T wave

Left bundle branch block

The course of excitation is similar, the impulse reaches the LV through a roundabout pathway (it does not pass through the left bundle branch, but through the network of Purkinje fibers from the RV).

Characteristic features of this phenomenon on the ECG:

widening of the ventricular QRS complex (more than 0.12 sec)
increase in internal deviation time in a blocked LV (J greater than 0.05 sec)
deformation and bifurcation of the complex in leads V5, V6
negative T wave (-TV5, -TV6)

Block (incomplete) of the left bundle branch

It is also worth paying attention to the fact that the S wave will be “atrophied”, i.e. it will not be able to reach the isoline.

Atrioventricular block

There are several degrees:

I - conduction slowing is characteristic (heart rate is normally in the range of 60 - 90; all P waves are associated with the QRS complex; the P-Q interval is more than normal 0.12 sec.)
II - incomplete, divided into three options: Mobitz 1 (heart rate slows down; not all P waves are associated with the QRS complex; the P - Q interval changes; periodicity 4:3, 5:4, etc. appears), Mobitz 2 (also the same, but the P - Q interval is constant; periodicity 2:1, 3:1), high-grade (heart rate significantly reduced; periodicity: 4:1, 5:1; 6:1)
III - complete, divided into two options: proximal and distal

We’ll go into detail, but we’ll just point out the most important things:

The transit time along the atrioventricular junction is normally 0.10±0.02. Total, no more than 0.12 seconds.
reflected on the interval P - Q
This is where physiological impulse delay occurs, which is important for normal hemodynamics

AV block II degree Mobitz II

Such disturbances lead to failures of intraventricular conduction. Typically, people with this type of tape experience shortness of breath, dizziness, or become overtired easily. In general, this is not so scary and occurs very often even among relatively healthy people who do not particularly complain about their health.

Rhythm disturbance

Signs of arrhythmia are usually visible to the naked eye.

When excitability is disrupted, the time of the myocardial response to an impulse changes, which creates characteristic graphs on the tape. Moreover, it is worth understanding that not in all parts of the heart the rhythm can be constant, taking into account the fact that there is, say, some kind of blockade that inhibits the transmission of impulses and distorts the signals.

So, for example, the following cardiogram indicates atrial tachycardia, and the one below it indicates ventricular tachycardia with a frequency of 170 beats per minute (LV).

Correct is sinus rhythm with a characteristic sequence and frequency. Its characteristics are as follows:

frequency of P waves in the range of 60-90 per minute
R-R interval is the same

the P wave is positive in standard lead II
the P wave is negative in lead aVR

Any arrhythmia indicates that the heart works in a different mode, which cannot be called regular, familiar and optimal. The most important thing in determining the correctness of the rhythm is the uniformity of the P-P wave interval. Sinus rhythm is correct when this condition is met.

If there is a slight difference in the intervals (even 0.04 seconds, not exceeding 0.12 seconds), then the doctor will already indicate a deviation.

The rhythm is sinus, incorrect, since the P-P intervals differ by no more than 0.12 seconds.

If the intervals are more than 0.12 seconds, this indicates an arrhythmia. These include:

extrasystole (most common)
paroxysmal tachycardia
flicker
fluttering, etc.

Arrhythmia has its own focus of localization when a rhythm disturbance occurs on the cardiogram in certain parts of the heart (in the atria, ventricles).

The most striking sign of atrial flutter is high-frequency impulses (250 - 370 beats per minute). They are so strong that they overlap the frequency of sinus impulses. There will be no P waves on the ECG. In their place, sharp, sawtooth, low-amplitude “teeth” (no more than 0.2 mV) will be visible on lead aVF.

Holter ECG

This method is otherwise abbreviated as HM ECG.

What it is?

Its advantage is that it is possible to carry out daily monitoring of the work of the heart muscle. The reading device (recorder) itself is compact. It is used as a portable device capable of recording signals transmitted through electrodes onto magnetic tape for a long period of time.

On a conventional stationary device, it turns out to be quite difficult to notice some periodically occurring surges and disruptions in the functioning of the myocardium (given the asymptomatic nature), and to ensure the correctness of the diagnosis, the Holter method is used.

The patient is asked to independently, after medical instructions, keep a detailed diary, since some pathologies can manifest themselves at a certain time (the heart “prickles” only in the evenings and not always; in the mornings something “presses” on the heart).

While observing, a person writes down everything that happens to him, for example: when he was at rest (sleeping), overtired, running, speeding up, working physically or mentally, nervous, worried. At the same time, it is also important to listen to yourself and try to describe as clearly as possible all your feelings and symptoms that accompany certain actions and events.

Data collection time usually lasts no longer than a day. During such daily monitoring, the ECG allows you to get a clearer picture and determine the diagnosis. But sometimes the data collection time can be extended to several days. It all depends on the person’s well-being and the quality and completeness of previous laboratory tests.

Typically, the basis for prescribing this type of analysis is painless symptoms of coronary heart disease, latent hypertension, when doctors have suspicions or doubts about any diagnostic data. In addition, it may be prescribed when prescribing new medications for the patient that affect the functioning of the myocardium, which are used in the treatment of ischemia, or if there is an artificial pacemaker, etc. This is also done for the purpose of assessing the patient’s condition in order to assess the degree of effectiveness of the prescribed therapy, etc.

How to prepare for HM ECG

Usually there is nothing difficult in this process. However, it is worth understanding that the device can be influenced by other devices, especially those emitting electromagnetic waves.

Interaction with any metal is also not advisable (rings, earrings, metal buckles, etc. should be removed). The device must be protected from moisture (full body hygiene in the shower or taking a bath is unacceptable).

Synthetic fabrics also negatively affect the results, as they can create static voltage (they become electrified). Any such “splash” from clothing, bedspreads, etc. distorts the data. Replace them with natural ones: cotton, linen.

The device is extremely vulnerable and sensitive to magnets, do not stand near a microwave oven or induction hob, and avoid being near high-voltage wires (even if you drive in a car through a small section of the road over which high-voltage lines lie).

How is data collected?

Usually the patient is given a referral, and at the appointed time he comes to the hospital, where the doctor, after some theoretical introductory course, installs electrodes on certain areas of the body, which are connected by wires to a compact recorder.

The recorder itself is a small device that records any electromagnetic vibrations and remembers them. It is attached to the belt and hidden under clothes.

Men sometimes have to shave in advance some areas of the body where electrodes are attached (for example, “free” the chest of hair).

After all the preparations and installation of equipment, the patient can go about his usual activities. He should integrate into his daily life as if nothing had happened, however, without forgetting to take notes (it is extremely important to indicate the time of manifestation of certain symptoms and events).

After the period specified by the doctor, the “subject” returns to the hospital. The electrodes are removed from it and the reading device is taken away.

Using a special program, the cardiologist will process data from the recorder, which, as a rule, is easily synchronized with a PC and will be able to make a specific inventory of all the results obtained.

A method of functional diagnostics such as an ECG is much more effective, since thanks to it you can notice even the slightest pathological changes in the work of the heart, and it is widely used in medical practice to identify life-threatening diseases such as a heart attack.

For diabetics with late cardiovascular complications that have developed against the background of diabetes mellitus, it is especially important to periodically undergo it at least once a year.

If you find an error, please select a piece of text and press Ctrl+Enter.

An electrocardiograph uses a sensor to register and record parameters of heart activity, which are printed on special paper. They look like vertical lines (teeth), the height and location of which relative to the axis of the heart are taken into account when deciphering the pattern. If the ECG is normal, the impulses are clear, even lines that follow at a certain interval in a strict sequence.

An ECG study consists of the following indicators:

Wave R. Responsible for contractions of the left and right atria.
P-Q (R) interval is the distance between the R wave and the QRS complex (the beginning of the Q or R wave). Shows the duration of impulse travel through the ventricles, His bundle and atrioventricular node back to the ventricles.
The QRST complex is equal to the systole (moment of muscle contraction) of the ventricles. The excitation wave propagates at different intervals in different directions, forming Q, R, S waves.
Wave Q. Shows the beginning of the propagation of the impulse along the interventricular septum.
Wave S. Reflects the end of the distribution of excitation through the interventricular septum.
Wave R. Corresponds to the distribution of impulses along the right and left ventricular myocardium.
Segment (R) ST. This is the path of the impulse from the end point of the S wave (in its absence, the R wave) to the beginning of the T.
Wave T. Shows the process of repolarization of the ventricular myocardium (raising the gastric complex in the ST segment).

The video discusses the main elements that make up an electrocardiogram. Taken from the MEDFORS channel.

How to decipher a cardiogram

Age and gender.
Cells on paper consist of horizontal and vertical lines with large and small cells. Horizontal ones are responsible for frequency (time), vertical ones are voltage. A large square is equal to 25 small ones, each side of which is 1 mm and 0.04 seconds. The large square corresponds to 5 mm and 0.2 seconds, and 1 cm of the vertical line is 1 mV of voltage.
The anatomical axis of the heart can be determined using the direction vector of the Q, R, S waves. Normally, the impulse should be conducted through the ventricles to the left and down at an angle of 30-70º.
The reading of the teeth depends on the vector of the excitation wave distribution on the axis. The amplitude differs in different leads, and part of the pattern may be missing. The upward direction from the isoline is considered positive, downward - negative.
The electrical axes of leads Ι, ΙΙ, ΙΙΙ have different locations relative to the axis of the heart, correspondingly appearing with different amplitudes. Leads AVR, AVF and AVL show the difference in potential between the limbs (with a positive electrode) and the average potential of the other two (with a negative one). The AVR axis is directed from bottom to top and to the right, so most of the teeth have a negative amplitude. The AVL lead runs perpendicular to the electrical axis of the heart (EOS), so the total QRS complex is close to zero.

Interference and sawtooth vibrations (frequency up to 50 Hz) displayed in the picture may indicate the following:

muscle tremors (small vibrations with different amplitudes);
chills;
poor contact between skin and electrode;
malfunction of one or more wires;
interference from household electrical appliances.

Registration of cardiac impulses occurs using electrodes that connect the electrocardiograph to the human limbs and chest.

The paths followed by the discharges (leads) have the following designations:

AVL (analogue of the first);
AVF (analogue of the third);
AVR (mirror display of leads).

Designations of chest leads:

Teeth, segments and intervals

You can independently interpret the meaning of the indicators using ECG standards for each of them:

Wave P. Should have a positive value in leads Ι-ΙΙ and be biphasic in V1.
PQ interval. Equal to the sum of the time of contraction of the cardiac atria and their conduction through the AV node.
The Q wave must come before R and have a negative value. In compartments Ι, AVL, V5 and V6 it can be present with a length of no more than 2 mm. Its presence in lead ΙΙΙ should be temporary and disappear after a deep breath.
QRS complex. It is calculated by cells: normal width is 2-2.5 cells, interval is 5, amplitude in the thoracic region is 10 small squares.
Segment S-T. To determine the value, you need to count the number of cells from the J point. Normally, there are 1.5 (60 ms).
The T wave must coincide with the direction of the QRS. It has a negative value in leads: ΙΙΙ, AVL, V1 and standard positive - Ι, ΙΙ, V3-V6.
U wave. If this indicator is displayed on paper, it can occur in close proximity to the T wave and merge with it. Its height is 10% of T in sections V2-V3 and indicates the presence of bradycardia.

How to count your heart rate

The heart rate calculation scheme looks like this:

Identify tall R waves on an ECG image.
Find the large squares between the vertices R is the heart rate.
Calculate using the formula: heart rate = 300/number of squares.

For example, there are 5 squares between the vertices. Heart rate=300/5=60 beats/min.

Photo gallery

Notation for deciphering the study The picture shows normal sinus rhythm of the heart. Atrial fibrillation Heart rate determination method The photo shows the diagnosis of coronary heart disease Myocardial infarction on the electrocardiogram

What is an abnormal ECG

An abnormal electrocardiogram is a deviation of the test results from the norm. The doctor’s job in this case is to determine the level of danger of anomalies in the transcript of the study.

Abnormal ECG results may indicate the following problems:

the shape and size of the heart or one of its walls are noticeably changed;
imbalance of electrolytes (calcium, potassium, magnesium);
ischemia;
heart attack;
change in normal rhythm;
side effect from medications taken.

What does an ECG look like normally and with pathology?

Electrocardiogram parameters in adult men and women are presented in the table and look like this:

ECG parameters	Norm	Deviation	Probable cause of deviation
Distance R-R-R	Even spacing between teeth	Uneven distance	atrial fibrillation; heart block; extrasystole; weakness of the sinus node.
Heart rate	60-90 beats/min at rest	Below 60 or above 90 beats/min at rest	tachycardia; bradycardia.
Atrial contraction - R wave	Directed upward, outwardly resembles an arc. The height is about 2 mm. May not be present in ΙΙΙ, AVL, V1.	height exceeds 3 mm; width more than 5 mm; two-humped species; the tooth is absent in leads Ι-ΙΙ, AVF, V2-V6; small teeth (resembles a saw in appearance).	thickening of the atrial myocardium; the heart rhythm does not originate in the sinus node; atrial fibrillation.
P-Q interval	A straight line between the P-Q teeth with an interval of 0.1-0.2 seconds.	length greater than 1 cm at intervals of 50 mm per second; less than 3 mm.	atrioventricular heart block; WPW syndrome.
QRS complex	Length 0.1 second - 5 mm, then T wave and straight line.	expansion of the QRS complex; there is no horizontal line; type of flag.	ventricular myocardial hypertrophy; bundle branch block; paroxysmal tachycardia; ventricular fibrillation; myocardial infarction.
Q wave	Absent or directed downward with a depth equal to 1/4 of the R wave	Depth and/or width exceeding normal	acute or previous myocardial infarction.
R wave	Height 10-15 mm, pointing upward. Present in all leads.	height more than 15 mm in leads Ι, AVL, V5, V6; the letter M on the point R.	left ventricular hypertrophy; bundle branch block.
S wave	Depth 2-5 mm, sharp end pointing down.	depth more than 20 mm; the same depth as the R wave in leads V2-V4; uneven with a depth of more than 20 mm in leads ΙΙΙ, AVF, V1-V2.	Left ventricular hypertrophy.
S-T segment	Coincides with the distance between the teeth S-T.	Any deviation of the horizontal line greater than 2 mm.	angina pectoris; myocardial infarction; ischemic disease.
T wave	The height of the arc is up to 1/2 of the R wave or coincides (in the V1 segment). Direction - up.	height of more than 1/2 R wave; sharp end; 2 humps; merge with S-T and R in the form of a flag.	heart overload; ischemic disease; acute period of myocardial infarction.

What kind of cardiogram should a healthy person have?

Indications of a good cardiogram for an adult:

The video compares the cardiogram of a healthy and sick person and provides the correct interpretation of the data obtained. Taken from the channel “Life of a Hypertensive”.

Indicators in adults

An example of a normal ECG in adults:

Indicators in children

Electrocardiogram parameters in children:

Rhythm disturbances during ECG interpretation

Heart rhythm disturbances can be observed in healthy people and are a normal variant. The most common types of arrhythmia and conduction system deviation. In the process of interpreting the data obtained, it is important to take into account all indicators of the electrocardiogram, and not each individually.

Arrhythmias

Heart rhythm disturbances can be:

Sinus arrhythmia. Fluctuations in RR amplitude vary within 10%.
Sinus bradycardia. PQ=12 seconds, heart rate less than 60 beats/min.
Tachycardia. The heart rate in adolescents is more than 200 beats/min, in adults it is more than 100-180. During ventricular tachycardia, the QRS indicator is above 0.12 seconds, while sinus tachycardia is slightly higher than normal.
Extrasystoles. Extraordinary contraction of the heart is permissible in isolated cases.
Paroxysmal tachycardia. Increase in heart rate to 220 per minute. During an attack there is a fusion of QRS and P. The range between R and P from the next beat
Atrial fibrillation. Atrial contraction is 350-700 per minute, ventricular contraction is 100-180 per minute, P is absent, fluctuations along the isoline.
Atrial flutter. Atrial contraction is 250-350 per minute, gastric contractions become less frequent. Sawtooth waves in sections ΙΙ-ΙΙΙ and V1.

Deviation of EOS position

Health problems may be indicated by a shift in the EOS vector:

Deviation to the right is more than 90º. In combination with the excess of the height of S over R, it signals pathologies of the right ventricle and His bundle block.
Deviation to the left by 30-90º. With a pathological ratio of the heights of S and R - left ventricular hypertrophy, bundle branch block.

Deviations in the position of the EOS can signal the following diseases:

heart attack;
pulmonary edema;
COPD (chronic obstructive pulmonary disease).

Violation of the conduction system

The ECG conclusion may include the following conduction function pathologies:

AV block of the 1st degree - the distance between the P and Q waves exceeds the interval of 0.2 seconds, the sequence of the path looks like this - P-Q-R-S;
AV block of the 2nd degree - PQ displaces the QRS (Mobitz type 1) or the QRS falls along the length of the PQ (Mobitz type 2);
complete AV block - the frequency of contractions of the atria is greater than that of the ventricles, PP=RR, the length of PQ is different.

Selected heart diseases

A detailed interpretation of the electrocardiogram may show the following pathological conditions:

Disease	Manifestations on the ECG
Cardiomyopathy	teeth with small intervals; His bundle block (partial); atrial fibrillation; left atrial hypertrophy; extrasystoles.
Mitral stenosis	enlargement of the right atrium and left ventricle; atrial fibrillation; deviation of the EOS to the right side.
Mitral valve prolapse	T negative; QT is prolonged; ST depressive.
Chronic pulmonary obstruction	EOS - deviation to the right; low-amplitude waves; AV block.
CNS damage	T - wide and high-amplitude; pathological Q; long QT; expressed by U.
Hypothyroidism	PQ extended; QRS - low; T - flat; bradycardia.

Video

The video course “Everyone Can Do an ECG” discusses heart rhythm disturbances. Taken from the MEDFORS channel.

ECG: indications for performance

Myocardial dystrophy

Dishormonal myocardial dystrophy

Changes in electrocardiogram parameters while the patient is taking certain medications

Early repolarization of the cardiac ventricles

Pericarditis

Myocarditis

The T wave on the ECG is normal in children and adults

ECG changes and their meanings

Two-phase

Smoothed

Decrease in indicator

The T wave on the ECG is smoothed

Inversion

Negative T wave

Absence of T wave on ECG

High rate

Flat

Coronary

Rise of the T wave on the ECG

Depression

The T wave is positive

Nonspecific T wave changes

Discordant T wave

Tall T waves in precordial leads

T wave alternation

Normal QT interval

Nonspecific ST-T changes

ST segment elevation

ST Down Shift

Useful video

How to decipher a heart cardiogram: general principles

ECG analysis

Examples of electrocardiographic reports

Interpretation of ECG in children

Features of ECG during pregnancy

ECG interpretation, normal indicators

Numbers and Latin letters in ECG interpretation

Heart Rate Description Options

Sinus rhythm

Sinus tachycardia

Extarsystole

Paroxysmal tachycardia

WPW syndrome

CLC – syndrome (Clerk-Levi-Christesco)

Atrial fibrillation

Atrial fibrillation

Atrial flutter

Conduction disorders

Sinoatrial blockade

Atrioventricular block (AV block)

Impaired conduction within the ventricles

Myocardial hypertrophy

Changes in myocardial contractility and nutrition

Early ventricular repolarization syndrome

Moderate or severe diffuse changes in the myocardium

Acute ischemia, ischemic changes, T wave changes, ST depression, low T

Advanced heart attack

How to decipher ECG indicators of the heart?

Principles of decoding

How are the results analyzed?

Normal values ​​for adults

What do the teeth mean?

Normal pediatric electrocardiogram readings

Why are the indicators different?

ECG interpretation

P value

Interval P - Q

Complex Q, R, S

S-T interval

ECG normal

What do Roman numerals mean on an ECG?

How to determine pathologies in the heart

Myocardial infarction

Signs of myocardial hypertrophy

Zheludochkov

Atrial

Blockades

Right bundle branch block

Left bundle branch block

Normal values for adults