What does a correct cardiogram look like? Description and interpretation of ECG for different conditions of the heart

An electrocardiogram is the first indicator of the state of the heart. It reflects all the problems of the human cardiovascular system, makes it possible to identify ailments at an early stage in order to take the necessary treatment. But in order to correctly diagnose, the cardiogram must be correctly interpreted.

What is a cardiogram

Deciphering an ECG requires a clear understanding of what this test is all about. An electrocardiogram schematically displays the electrical activity of the heart muscle on paper or electronic media. It is recorded on special calibrated paper. The length of the horizontal axis of the square (the smallest division) is 1 mm, in time it is 0.04 seconds, respectively, large blocks of 5 mm are equal to 0.2 seconds. The black marks at the top represent intervals of three seconds. A vertical line consisting of two blocks is equal to one millivolt - this is a unit of electrical voltage, a thousandth of a volt. To understand what is at stake, it is worth looking at the photo of the ECG transcript.

The cardiogram displays 12 leads: the first half comes from the limbs, and the second - chest. They depend on the location of the electrodes on the human body, so it is very important to place them correctly. These leads reflect the activity of different parts of the myocardium. The electrodes on the body are placed accordingly.

The propagation of an impulse through the heart on the cardiogram is displayed by intervals, segments and teeth. The latter are denoted in Latin letters: P, Q, R, S, T, U. The R wave is always negative, it displays indicators for the myocardium, Q and S are positive, they show the propagation of the impulse along the interventricular septum. As for the interpretation of the T and U waves, everything depends on their shape, amplitude and sign. The first reflects myocardial repolarization, and the value of the second for diagnosing does not play a special role. The normal interpretation of the ECG provides that all indicators must be calculated to a hundredth of a second, otherwise they can be misinterpreted.

What indicators are considered optimal

To effectively decipher the ECG, you need to study the indicators of the norm. First of all, you should pay attention to the heart rate. Normally, it should be sinus. This implies that the P waves should have a constant shape, the distance between the P-P and R-R indicators should be the same, and the number of contractions should be 60-80 per minute.

The electrical axis of the heart is a display of the ventricular excitation vector from an impulse, it is considered according to special medical tables, so deciphering an ECG for beginners may seem very difficult. EOS deviations are determined by the alpha angle. If the axis is in the normal position, the angle value is 50-70 degrees. It is worth paying attention: the R wave should be higher than the S. The intervals of the teeth show how the electrical impulse passes between the compartments of the heart. Each of them has specific indicators of the norm.

1. The width of the Q-R-S wave group under normal conditions is 60-100 ms.
2. The Q-T wave group displays the duration of the ventricular contraction. The norm is 390-450 ms.
3. For the Q wave, the optimal length is 0.04 s, and the depth is no more than 3 mm.
4. The S-tooth must not exceed a height of 20 mm.
5. The norm for the T wave is that in leads I and II it should go up, and in lead aVR it should have a negative indicator.

Identification of abnormalities and diseases

If you deal with the indicators of the norm, when deciphering the ECG, any pathology can be detected independently. Let's start with heart rate. If the electrical excitation does not start from the sinus node, this is an indicator of an arrhythmia. Depending on the branch of the heart in which depolarization begins, tachycardia (acceleration of the rhythm) or bradycardia (deceleration) is diagnosed. Another important indicator of deviations is abnormal teeth and intervals.

1. Prolongation of the interval between the Q and T waves indicates myocarditis, rheumatism, sclerosis, or coronary disease. When Q values ​​do not meet the norm, this signals myocardial pathologies.


2. If the R wave is not displayed in all leads, this indicates that ventricular hypertrophy is possible.
3. Deviations in the ST segment indicate myocardial ischemia.
4. A T wave that is out of range may indicate hypokalemia or hyperkalemia.
5. The expansion of the P wave, especially twice, indicates an atrioventricular block.
6. A sharp rise in the ST segment means that the patient is at risk of acute heart attack or pericarditis, and its descent indicates myocardial ischemia or that the person is taking cardiac glycosides.

This or that position of the electrical axis of the heart may indicate various diseases. When the EOS is horizontal or tilted to the left, we can talk about hypertension in the patient. If the axis deviates to the right, it is possible that the person has chronic lung disease. The doctor should be concerned if, within a short time, the electrical axis suddenly changed position. The peculiarity of the EOS is that its performance may depend on various factors. For example, the vertical position is often found in thin people, and the horizontal position is common in full people.

A cardiogram can indicate a number of diseases. But do not rush to diagnose yourself. It is very difficult to interpret the ECG for beginners, because not all indicators can be calculated independently. It is better to contact a professional who will interpret the cardiogram correctly and be able to make accurate diagnoses.

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Basic Rules

When examining the results of the examination of the patient, doctors pay attention to such components of the ECG as:

• teeth;
• intervals;
• Segments.

There are strict normal parameters for each line on the ECG tape, the slightest deviation from which may indicate violations in the work of the heart.

ECG analysis

The entire set of ECG lines is examined and measured mathematically, after which the doctor can determine some parameters of the work of the heart muscle and its conduction system: heart rate, heart rate, pacemaker, conduction, electrical axis of the heart.

To date, all these indicators are investigated by high-precision electrocardiographs.

Sinus rhythm of the heart

This is a parameter that reflects the rhythm of heart contractions that occur under the influence of the sinus node (normal). It shows the coherence of the work of all parts of the heart, the sequence of processes of tension and relaxation of the heart muscle.

The rhythm is very easy to identify by the tallest R waves: if the distance between them is the same throughout the entire recording or deviates by no more than 10%, then the patient does not suffer from arrhythmia.

heart rate

The number of beats per minute can be determined not only by counting the pulse, but also by the ECG. To do this, you need to know the speed at which the ECG was recorded (usually 25, 50 or 100mm / s), as well as the distance between the highest teeth (from one peak to another).

By multiplying the recording time of one mm by length of segment R-R you can get your heart rate. Normally, its performance ranges from 60 to 80 beats per minute.

Source of excitation

The autonomic nervous system of the heart is designed in such a way that the process of contraction depends on the accumulation of nerve cells in one of the zones of the heart. Normally, this is the sinus node, the impulses from which diverge throughout the nervous system of the heart.

In some cases, other nodes (atrial, ventricular, atrioventricular) can take on the role of the pacemaker. This can be determined by examining the P wave is inconspicuous, located just above the isoline.

Conductivity

This is a criterion showing the process of momentum transfer. Normally, impulses are transmitted sequentially from one pacemaker to another, without changing the order.

Electric axis

An indicator based on the process of excitation of the ventricles. Mathematical analysis of Q, R, S waves in leads I and III allows you to calculate a certain resulting vector of their excitation. This is necessary to establish the functioning of the branches of the His bundle.

The obtained angle of inclination of the axis of the heart is estimated by the value: 50-70° normal, 70-90° deviation to the right, 50-0° deviation to the left.

Teeth, segments and intervals

Teeth - ECG sections lying above the isoline, their meaning is as follows:

• P- reflects the processes of contraction and relaxation of the atria.
• Q, S- reflect the processes of excitation of the interventricular septum.
• R- the process of excitation of the ventricles.
• T- the process of relaxation of the ventricles.

Intervals are sections of the ECG lying on the isoline.

• PQ- reflects the propagation time of the impulse from the atria to the ventricles.

Segments - sections of the ECG, including an interval and a wave.

• QRST- the duration of the contraction of the ventricles.
• ST- the time of complete excitation of the ventricles.
• TP is the time of electrical diastole of the heart.

Norm in men and women

The decoding of the ECG of the heart and the norms of indicators in adults are presented in this table:

Healthy Childhood Outcomes

Deciphering the results of ECG measurements in children and their norm in this table:

Dangerous diagnoses

What dangerous conditions can be determined by the ECG readings during decoding?

Extrasystole

This phenomenon characterized by irregular heartbeat. A person feels a temporary increase in the frequency of contractions, followed by a pause. It is associated with the activation of other pacemakers, sending along with the sinus node an additional burst of impulses, which leads to an extraordinary contraction.

Arrhythmia

Characterized change in the frequency of sinus rhythm when pulses arrive at different frequencies. Only 30% of these arrhythmias require treatment, because can lead to more serious illnesses.

In other cases, this may be a manifestation of physical activity, a change in hormonal levels, the result of a fever and does not threaten health.

Bradycardia

It occurs when the sinus node is weakened, unable to generate impulses with the proper frequency, as a result of which the heart rate also slows down, up to 30-45 beats per minute.

Tachycardia

The opposite phenomenon, characterized by an increase in heart rate over 90 beats per minute. In some cases, temporary tachycardia occurs under the influence of strong physical exertion and emotional stress, as well as during illnesses associated with fever.

Conduction disorder

In addition to the sinus node, there are other underlying pacemakers of the second and third orders. Normally, they conduct impulses from the first-order pacemaker. But if their functions weaken, a person may feel weakness, dizziness caused by depression of the heart.

It is also possible to lower blood pressure, because. the ventricles will contract less frequently or arrhythmically.

Why there might be differences in performance

In some cases, when re-analyzing the ECG, deviations from previously obtained results are revealed. With what it can be connected?

• different time of day. Usually, an ECG is recommended to be done in the morning or afternoon, when the body has not yet had time to be influenced by stress factors.
• Loads. It is very important that the patient is calm while recording the ECG. The release of hormones can increase heart rate and distort performance. In addition, before the examination, it is also not recommended to engage in heavy physical labor.
• meal. Digestive processes affect blood circulation, and alcohol, tobacco and caffeine can affect heart rate and pressure.
• electrodes. Improper overlap or accidental shifting can seriously change the performance. Therefore, it is important not to move during the recording and degrease the skin in the area where the electrodes are applied (the use of creams and other skin products before the examination is highly undesirable).
• Background. Sometimes other devices can interfere with the operation of the electrocardiograph.

Additional examination methods

Halter

Method long-term study of the work of the heart, made possible by a portable compact tape recorder that is capable of recording results on magnetic tape. The method is especially good when it is necessary to investigate recurrent pathologies, their frequency and time of occurrence.

Treadmill

Unlike a conventional ECG recorded at rest, this method is based on the analysis of the results after exercise. Most often, this is used to assess the risk of possible pathologies not detected on a standard ECG, as well as when prescribing a course of rehabilitation for patients who have had a heart attack.

Phonocardiography

Allows analyze heart sounds and murmurs. Their duration, frequency and time of occurrence correlate with the phases of cardiac activity, which makes it possible to assess the functioning of the valves, the risks of developing endocarditis and rheumatic heart disease.

A standard ECG is a graphic representation of the work of all parts of the heart. Its accuracy can be affected by many factors, so doctor's advice should be followed.

The examination reveals most of the pathologies of the cardiovascular system, however, additional tests may be required for an accurate diagnosis.

Finally, we suggest watching a video course on decoding “ECG for everyone”:

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What is an ECG, how is the procedure

The principle of obtaining an ECG is very simple. We are talking about the fact that sensors are attached to the skin of the patient, which record the electrical impulses that accompany the beating of the heart. Recording is done on a sheet of paper. A competent doctor can tell a lot about the patient's health from this diagram.

It depicts cyclical changes in the corresponding electrical impulses. It is important to note that this diagnostic method is not absolutely accurate and exhaustive. It can be considered, rather, as a basis for the main conclusions.

What exactly is shown in the ECG?

Suppose you need to take an electrocardiogram. How to do it right? Do I need to be a specialist in order to carry out this procedure, or if all the necessary rules are carefully followed, even a non-specialist can carry out the procedure? Let's try to answer these questions.

Interestingly, the electrocardiogram is used not only in the treatment of cardiac patients, but also in a number of other cases:

• This takes place not only during various medical examinations, but also for the diagnosis of those diseases that are not directly related to the heart, but can create complications in it.
• Also, when using those medicines that have a strong effect on the body, the state of health of the cardiovascular system is often checked in this way in order to prevent possible consequences of taking such medicines.
  In such cases, it is customary to check not only before, but also after the therapeutic course is completed.

The procedure itself is not very complicated. Its total duration does not exceed ten minutes. The room temperature must not be too low. At the same time, the room must be ventilated. Compliance with this and similar rules is very important for such a procedure. This is due to the fact that any change in the patient's physical condition will be reflected in the electrocardiogram.

Here are some other requirements:

1. Before starting the procedure, the patient must be given rest. Its duration should be at least a quarter of an hour.
2. During the reading procedure, the patient should lie on his back.
3. During work, he should have even breathing.
4. You also need to take into account the time of eating. Everything should be done either on an empty stomach or not earlier than two hours after the last meal. This reception should not be plentiful.
5. Of course, on the day of the procedure, it is not allowed to take any sedative or tonic drugs. Also, do not drink coffee or tea or other similar drinks. If the patient smokes, then he should refrain from this habit for at least an hour before the procedure.

Diagnostic technique including
It includes the attachment of four electrodes to the hands and ankles and the installation of six suction cups on the patient's chest.

Do it in the following order. Each electrode has a specific color. Put a damp cloth under them. This is done both to increase conductivity and to improve the adhesion of the electrode to the skin surface.

When installing suction cups on the chest, the skin is usually disinfected with an alcohol solution. The diagram will display several types of teeth that have a different shape.

To carry out diagnostics, it is enough to record data for no longer than four consecutive cycles.

So, in what cases does it make sense to go to the doctor and do a cardiogram?

There are several main options:

• This should be done if you clearly feel discomfort in the chest.
• With shortness of breath, although it may look familiar, it makes sense to see a doctor for an ECG.
• If you are overweight, then you are undoubtedly at risk for heart disease. It is recommended to do an electrocardiogram regularly.
• The presence of chronic and severe stress in your life is a danger not only to your heart, but also to other systems of the human body. An ECG in such a case is a matter of vital importance.
• There is such a chronic disease as tachycardia. If you suffer from it, then the ECG should be done regularly.
• Hypertension is considered by many as a possible step towards a heart attack. If at this stage you regularly diagnose using an ECG, then your chances of recovering will increase dramatically.
• Before performing a surgical operation, it is important for the doctor to make sure. That your heart can handle it. An ECG may be done to check.

How often is it necessary to resort to such a procedure? This is usually determined by the attending physician. However, if you are over forty, then it makes sense to carry out this procedure annually. If you are much older, then you should do an ECG at least once a quarter.

What does the ECG show

Let's see what we can see on the electrocardiogram:

1. First of all, she will tell in detail about all the features of the rhythm of the heartbeat. In particular, this will allow you to track the increase in heart rate or weak heartbeat. The diagram shows in what rhythm and with what force the patient's heart beats.
2. Another important advantage is that the ECG is able to show various pathologies that are inherent in the heart. This is due to the fact that any, say, tissue necrosis will conduct electrical impulses differently than healthy tissue. Such features will also help to identify those who are not yet sick, but have a tendency to do so.
3. There is an ECG under stress. This is useful in cases where a relatively healthy person wants to assess the health of their heart.

Principles for decoding indicators

A cardiogram is not one, but several different graphs. Since several electrodes are attached to the patient, electrical impulses can in principle be measured between each pair of them. In practice, the ECG contains twelve graphs. The doctor evaluates the shape and frequency of the teeth, and also considers the ratio of electrical signals on various graphs.

Each disease corresponds to specific signs on the ECG graphs. If they are determined, then this makes it possible to make the correct diagnosis to the patient. The norm and violations in the interpretation of the ECG are very important. Each indicator requires the most careful attention. A reliable result occurs when the analysis is carried out accurately and reliably.

reading teeth

There are five different types of waveforms on an ECG. They are designated in Latin letters: S, P, T, Q and R. Each of them characterizes the work of one of the sections of the heart.

Different types of intervals and segments are also taken into account. They represent the distance between certain types of teeth and also have their own letter designations.

Also, the analysis considers the QRS complex (it is also called the QRS interval).

In more detail, the elements of the ECG are shown in the figure given here. This is a kind of ECG decoding table.
First, the heart rate is assessed. As you know, it is usually 60-80 cuts per second.

How the doctor analyzes the results

The study of the electrocardiogram occurs in several successive stages:

1. At this stage, the doctor must calculate and analyze the intervals. The doctor examines the QT - interval. If there is an elongation of this segment, then this indicates, in particular, coronary heart disease, if we are talking about shortening, then we can talk about hypercalcemia.
2. After that, an indicator such as the electrical axis of the heart (EOS) is determined. This is done using a calculation based on the height of the different types of waves on the electrocardiogram.
3. After that, the complex is considered. We are talking about a tooth of the R type and its nearest sections of the graph on both sides.
4. Next is the interval. It is believed that for a normal heart, it should be in the midline.
5. After that, based on the studied data, a final cardiological conclusion is given.

• P - normally should be positive, shows the presence of bioelectricity in the atria;
• The Q wave is normally negative, it refers to the interventricular septum;
• R - characterizes the electrical potential in the ventricular myocardium;
• The S wave - in a normal situation, it is negative, shows the final process of electricity in the ventricles, normally such a tooth will be lower than the R wave;
• T - must be positive, here we are talking about the recovery process of biopotential in the heart.
• The heart rate should be between 60 and 80 per minute. If it goes beyond these boundaries, then this indicates violations in the work of the heart.
• QT - the interval is normal for an adult is 390-450 milliseconds.
• The width of the QRS interval should be approximately 120 milliseconds.

Possible errors in the result

Despite its obvious advantages, this procedure also has certain disadvantages:

Pathologies in the interpretation of the ECG can be determined according to the available descriptions of various variants of cardiograms. There are detailed tables that will help determine the type of pathology detected. To increase the reliability of the result, the cardiogram should be combined with other diagnostic methods.

Cost of the procedure

If we talk about prices in Moscow, then they are approximately in the range from 650 to 2300 rubles. Let's not forget that, when receiving a cardiogram, its analysis by a qualified doctor and the quality of the medical equipment itself are of great importance.

In St. Petersburg, the average price is about the same as in Moscow. ECG price with decoding is approximately 1500 rubles for this procedure.

There is also a service to call such a specialist at home. In Moscow, this service can be provided for 1500 rubles, in Khabarovsk - for 900 rubles, and in Saratov it can be done for 750 rubles.

Conclusion

An ECG is an important means of diagnosing your cardiovascular system. She has a lot to say about her. It makes sense to regularly, at least once every two years, seek an ECG from a doctor.

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ECG interpretation

Any electrocardiogram displays the work of the heart (its electrical potential during contractions and relaxations) in 12 curves recorded in 12 leads. These curves differ from each other, as they show the passage of an electrical impulse through different parts of the heart, for example, the first is the anterior surface of the heart, the third is the back. To record an ECG in 12 leads, special electrodes are attached to the patient's body in specific places and in a certain sequence.

How to decipher the cardiogram of the heart: 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:

1. It determines whether the heart beats rhythmically, that is, whether the rhythm is correct. To do this, he measures the intervals between the R waves, they should be the same everywhere, if not, this is already the wrong rhythm.
2. Calculates the rate at which the heart beats (HR). This is easy to do, 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. per minute.
3. According to specific features (mainly by 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.
4. Assesses the conduction of the heart by the duration of the teeth and segments. For each of them there are indicators of the norm.
5. Determines the electrical axis of the heart (EOS). For very thin people, a more vertical position of the EOS is characteristic, for full people it is more horizontal. With pathology, the axis shifts sharply to the right or left.
6. 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 work of the doctor.
7. Gives a conclusion. It necessarily indicates the correctness of the rhythm, the source of excitation, heart rate, characterizes the EOS, and also highlights specific pathological syndromes (rhythm, conduction disturbances, the presence of overload of individual parts of the heart and myocardial damage), if any.

Examples of electrocardiographic findings

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

Also, for some people, sinus tachycardia (acceleration of heart rate) or bradycardia (slow heart rate) can be considered a normal option. 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 correction of the patient's nutrition, they mostly always disappear.

In addition, in conclusion, we can talk about a non-specific change in the ST-T interval. This means that the changes are not indicative and it is impossible to determine their cause only by the ECG. Another fairly common condition that can be diagnosed by 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 imbalances and other causes that the doctor will subsequently look for.

Prognostically unfavorable conclusions are considered, in which there is data on the presence of myocardial ischemia, hypertrophy of the heart, rhythm and conduction disturbances.

Deciphering the ECG in children

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

Also, sinus or respiratory arrhythmia (increased heart rate on inspiration and decrease on expiration) can be recorded in babies without any pathology. In addition, the characteristics of some teeth 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 leg of the bundle of His. All these features are taken into account by pediatric cardiologists when they make a conclusion on the ECG.

Features of the ECG during pregnancy

The body of a pregnant woman goes through various processes of adaptation to a new position. Certain changes also occur with the cardiovascular system, so the ECG of future 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 have a slight sinus tachycardia and signs of overload of individual parts of the heart. These changes are associated with an increase in blood volume in the body and usually disappear after childbirth. However, their discovery cannot be left without detailed consideration and a more in-depth examination of the woman.

Deciphering the ECG, the norm of indicators

Deciphering the ECG is the business of a knowledgeable doctor. With this method of functional diagnostics, the following is evaluated:

• heart rhythm - the state of the generators of electrical impulses and the state of the heart system that conducts these impulses
• the state of the heart muscle itself (myocardium). the presence or absence of its 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 records can bring even the most balanced, but ignorant person to a panic disorder. Indeed, often the patient does not know for certain how dangerous for life and health what is written on the back of the ECG film by the hand of a functional diagnostician, and there are still a few days before an appointment with a therapist or cardiologist.

To reduce the intensity of passions, we immediately warn readers that with no serious diagnosis (myocardial infarction, acute arrhythmias), the functional diagnostician of the patient will not let the patient out of the office, but at least send him for a consultation with a specialist colleague right there. About the rest of the "secrets of the Open" in this article. In all unclear cases of pathological changes on the ECG, ECG control, daily monitoring (Holter), ECHO cardioscopy (ultrasound of the heart) and stress tests (treadmill, bicycle ergometry) are prescribed.

Numbers and Latin letters in ECG decoding

PQ- (0.12-0.2 s) - time of atrioventricular conduction. 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. Can talk about 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 apexes of the ventricular complexes reflects the regularity of heart contractions and makes it possible to calculate the heart rate.

The decoding of the ECG in children is shown in Fig. 3

Options for describing the heart rate

Sinus rhythm

This is the most common inscription found on the ECG. And, if nothing else is added and the frequency (HR) is indicated from 60 to 90 beats per minute (for example, heart rate 68`) - this is the most successful 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, it can be atrial, atrioventricular or ventricular, indicating that the rhythm is set by the cells in these parts of the heart and is considered pathological.

This is a variant of the norm in young people and children. This is a rhythm in which impulses exit the sinus node, but the intervals between heartbeats are different. This may be due to physiological changes (respiratory arrhythmia, when heart contractions slow down on exhalation). Approximately 30% of sinus arrhythmias require observation by a cardiologist, as they are threatened by the development of 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 people with a 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. Also, bradycardia is often seen in professional athletes. Pathological bradycardia may indicate sick sinus syndrome. At the same time, 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 impaired oxygen supply to tissues and manifests itself, for example, by fainting, an operation is indicated to install a heart 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 in a short period of time after the cessation of the load. With pathological tachycardia, palpitations disturb the patient at rest. Its causes are temperature rises, infections, blood loss, dehydration, thyrotoxicosis, anemia, cardiomyopathy. Treat the underlying disease. Sinus tachycardia is stopped only with a heart attack or acute coronary syndrome.

Extrasystole

These are rhythm disturbances, in which foci outside the sinus rhythm give extraordinary heart contractions, after which there is a pause doubled in length, called a compensatory one. In general, heartbeats are perceived by the patient as uneven, rapid or slow, sometimes chaotic. Most of all, failures in the heart rhythm are disturbing. There may be discomfort in the chest in the form of jolts, tingling, feelings of fear and emptiness in the abdomen.

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 disruptions), organic (with IHD, heart defects, myocardial dystrophy or cardiopathy, myocarditis). They can also lead to intoxication and heart surgery. Depending on the place of occurrence, extrasystoles are divided into atrial, ventricular and antrioventricular (arising in a node on 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 the normal blood supply.
• Paired extrasystoles of two accompany a certain number of normal contractions. Such a rhythm disturbance often indicates pathology and requires additional examination (Holter monitoring).
• Allorhythmias are more complex types of extrasystoles. If every second contraction is an extrasystole, it is bigymenia, if every third is trigynemia, and every fourth is quadrihymenia.

It is customary to divide ventricular extrasystoles into five classes (according to Laun). They are evaluated during daily ECG monitoring, since the indicators of a conventional 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 grades 3 and 4 do not always require medical treatment. In general, if there are less than 200 ventricular extrasystoles per day, they should be classified as functional and not worry about them. With more frequent, ECHO of the COP is indicated, sometimes - MRI of the heart. They do not treat extrasystole, but the disease that leads to it.

Paroxysmal tachycardia

In general, paroxysm is an attack. Paroxysmal acceleration of the rhythm can last from several minutes to several days. In this case, the intervals between heartbeats 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. The basis of this pathology is the abnormal circulation of an electrical impulse in the conduction system of the heart. Such a pathology is subject to treatment. From home remedies to eliminate an attack:

• breath holding
• increased forced cough
• face immersion in cold water

WPW syndrome

Wolff-Parkinson-White syndrome is a type of paroxysmal supraventricular tachycardia. Named after the names of the authors who described it. At the heart of the appearance of tachycardia is the presence between the atria and ventricles of an additional nerve bundle, 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 (with ineffectiveness or intolerance of antiarrhythmic tablets, with episodes of atrial fibrillation, with concomitant heart defects).

CLC - Syndrome (Clerk-Levy-Christesco)

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

Atrial fibrillation

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

Atrial fibrillation

Atrial fibrillation

When the heart flickers, it contracts completely irregularly (intervals between contractions of very different durations). This is due to the fact that the rhythm is not set by the sinus node, but by other atrial cells.

It turns out a frequency of 350 to 700 beats per minute. There is simply no full-fledged atrial contraction; the contracting muscle fibers do not provide effective filling of the ventricles with blood.

As a result, the release of blood by the heart worsens 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 either be 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 heartbeat.
• It develops as a series of absolutely non-rhythmic 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 arousal.
• Sometimes there is a loss of consciousness.
• The attack ends with the normalization of the rhythm and the urge to urinate, in which a large amount of urine leaves.

To stop the attack, they use reflex methods, drugs in the form of tablets or injections, or resort to cardioversion (stimulation of 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 of patients and are felt only with 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 in '.
• Atrial fibrillation, normosystolic variant, heart rate 64 in '.

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

atrial flutter

These are frequent (more than 200 per minute) regular atrial contractions and the same regular, but more rare ventricular contractions. In general, flutter is more common in the acute form and is better tolerated than flicker, since circulatory disorders are less pronounced. Trembling develops when:

• organic heart disease (cardiomyopathies, heart failure)
• after heart surgery
• on the background of obstructive pulmonary disease
• it almost never occurs in healthy people.

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

Conduction disorders

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

Sinoatrial blockade

When the exit of the impulse from the sinus node is difficult. In fact, this leads to a syndrome of weakness of the sinus node, a decrease in 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 the Samoilov-Wenckebach syndrome.

Atrioventricular block (AV block)

This is a delay in excitation in the atrioventricular node of more 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.

• At the first delay allows each atrial contraction to maintain an adequate number of ventricular contractions.
• The second degree leaves part of the atrial contractions without ventricular contractions. It is described in terms of PQ prolongation and ventricular beat prolapse as Mobitz 1, 2, or 3.
• The third degree is also called a complete transverse block. The atria and ventricles begin to contract without interrelation.

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 be detected only with an ECG, then the second is already characterized by sensations of periodic cardiac arrest, weakness, fatigue. With complete blockades, cerebral symptoms (dizziness, flies in the eyes) are added to the manifestations. Morgagni-Adams-Stokes attacks may develop (when the ventricles escape from all pacemakers) with loss of consciousness and even convulsions.

Conduction disturbance within the ventricles

In the ventricles to the muscle cells, the electrical signal propagates through such elements of the conduction system as the trunk of the bundle of His, its legs (left and right) and the 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 covered by excitation at the same time, one of the ventricles is delayed, since the signal to it goes around the blocked area.

In addition to the place of origin, a complete or incomplete blockade is distinguished, as well as permanent and non-permanent. The causes of intraventricular blockades are similar to other conduction disorders (IHD, myo- and endocarditis, cardiomyopathies, heart defects, arterial hypertension, fibrosis, heart tumors). Also, the intake of antiarthmic drugs, an increase in potassium in the blood plasma, acidosis, and oxygen starvation also affect.

• The most common is the blockade of the anteroposterior branch of the left leg of the bundle of His (BPVLNPG).
• In second place is the blockade of the right leg (RBNB). This blockade is usually not accompanied by heart disease.
• Blockade of the left leg of the His bundle is more typical for myocardial lesions. At the same time, complete blockade (PBBBB) is worse than incomplete blockade (NBLBBB). It sometimes has to be distinguished from the WPW syndrome.
• The blockade of the posterior inferior branch of the left leg of the bundle of His can be in persons with a narrow and elongated or deformed chest. Of the pathological conditions, it is more characteristic of right ventricular overload (with pulmonary embolism or heart defects).

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

• Bailey's syndrome - two-beam blockade (of the right leg and posterior branch of the left leg of the bundle of His).

Myocardial hypertrophy

With chronic overloads (pressure, volume), the heart muscle in some areas begins to thicken, and the heart chambers 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 in normal athletes, obese patients and people engaged in heavy physical labor, there may be signs of LVH.
• Right ventricular hypertrophy is an undoubted sign of increased pressure in the pulmonary circulation system. Chronic cor pulmonale, obstructive pulmonary disease, cardiac defects (pulmonary stenosis, Fallot's tetralogy, ventricular septal defect) lead to HPZh.
• Left atrial hypertrophy (HLH) - 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 pulmonary embolism.
• Indirect signs of ventricular hypertrophy are the 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 LVH.
• 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

Syndrome of early repolarization of the ventricles

Most often, it is a variant of the norm, especially for athletes and people with congenitally 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 it does not give a clinic and most often remains without consequences.

Moderate or severe diffuse changes in the myocardium

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

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

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

This describes the reversible changes associated with oxygen starvation of the myocardium (ischemia). It 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, rapid troponin tests for myocardial damage or coronary angiography should be performed. Depending on the variant of coronary heart disease, anti-ischemic treatment is selected.

Developed heart attack

It is usually described as:

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

All the variety of syndromes and specific ECG changes, 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 a ready-made conclusion of a functional diagnostician. It is much more reasonable, having an 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 the ECG of the heart?

An electrocardiographic study is the simplest, but very informative method for studying the work 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. Deciphering 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 tells 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 the cardiogram of all 12 leads, electrodes are attached to the patient's body. The specialist does this sequentially, installing them in specific places.

Decryption principles

Each curve on the cardiogram graph has its own elements:

• Teeth, which are bulges directed down or up. All of them are denoted by Latin capital letters. "P" shows the work of the heart atria. "T" is the restorative capacity of the myocardium.
• Segments are the distance between several ascending or descending teeth in the neighborhood. Doctors are especially interested in 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 ECG element shows a certain process that occurs directly in the heart. According to their width, height and other parameters, the doctor has the ability to correctly decipher the data received.

How are the results analyzed?

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

1. The correct rhythm is determined by the intervals between the "R"-teeth. They must be equal. Otherwise, it can be concluded that the heart rhythm is incorrect.
2. With the help of an ECG, you can determine the 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.
3. The source of excitation in the heart muscle is determined by a number of specific features. This will be told, among other things, by the evaluation of the parameters of the “P” wave. The norm implies that the source is the sinus node. Therefore, a healthy person always has a sinus rhythm. If there is a ventricular, atrial or any other rhythm, then this indicates the presence of pathology.
4. The specialist evaluates the conduction of the heart. This happens according to the duration of each segment and tooth.
5. The electrical axis of the heart, if it shifts to the left or right sharply enough, may also indicate problems with the cardiovascular system.
6. Each tooth, interval and segment is analyzed individually and in detail. Modern ECG devices immediately automatically issue indicators of all measurements. This greatly simplifies the work of the doctor.
7. Finally, the specialist makes a conclusion. It indicates the decoding of the cardiogram. If any pathological syndromes were found, they must be indicated there.

Normal indicators of adults

The norm of all indicators of the cardiogram is determined by analyzing the position of the teeth. But the rhythm of the heart 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, it will no longer be the norm, which should be within 60-80 pulsations per minute. If sinus rhythm is more frequent, then the patient has tachycardia. On the contrary, a slow sinus rhythm indicates a disease called bradycardia.

The P-QRS-T intervals will tell you about the passage of the impulse directly through all the cardiac departments. 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, one 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 Q-T interval. The norm is 390-450 ms. If it is somewhat longer, a diagnosis can be made: rheumatism, ischemia, atherosclerosis. If the interval is shortened, we can talk about hypercalcemia.

What do teeth mean?

Without fail, when deciphering the ECG, it is necessary to monitor the height of all teeth. It can indicate the presence of serious pathologies of the heart:

• 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 pathology of the myocardium;
• The S wave is an indicator of the excitation of those partitions that are in the basal layers of the ventricles. The norm in this case is 20 mm in height. If there are deviations, then this indicates coronary disease.
• The R wave in the ECG tells about the activity of the walls of all the ventricles of the heart. It is fixed in all ECG curves. If there is no activity somewhere, then it makes sense to suspect ventricular hypertrophy.
• The T wave appears in the I and II lines, as directed upwards. 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 possibility of developing hypokalemia.

Normal pediatric electrocardiogram readings

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

1. The heart rate of babies under 3 years old is about 110 pulsations per minute, and at the age of 3-5 years - 100 beats. This indicator in adolescents is already lower - 60-90 pulsations.
2. The norm of QRS readings is 0.6-0.1 s.
3. The P wave should normally not be higher than 0.1 s.
4. The electrical axis of the heart in children should remain unchanged.
5. The rhythm is only sinus.
6. On the ECG, the Q-T interval e can exceed 0.4 s, and P-Q should be 0.2 s.

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

Why are the scores different?

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

1. Distortions in recording an ECG may be due to technical problems. For example, with incorrect gluing of results. And many Roman numerals look the same both upside down and upside down. It happens that the graph is cut incorrectly or the first or last tooth is lost.
2. Preliminary preparation for the procedure is important. On the day of the ECG, you should not have a hearty breakfast, it is even advisable to completely refuse it. You will have to stop drinking liquids, including coffee and tea. After all, they stimulate the heart rate. As a result, the results are skewed. It is best to take a shower beforehand, but you do not need to apply any body products. Finally, during the procedure you need to relax as much as possible.
3. The incorrect position of the electrodes cannot be ruled out.

It is best to check your heart on an electrocardiograph. He will help to carry out the procedure as accurately and accurately as possible. And in order to confirm the diagnosis indicated by the results of the ECG, the doctor will always prescribe additional studies.

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

Electrocardiography is a science in which the rules of the procedure are studied, how to decipher the results obtained and explains the unclear points and situations. With the development of the Internet, ECG decoding can even be done independently, using special knowledge.

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

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

Intervals are calculated that characterize the duration of the moment of contraction. This is where special formulas come into play.

The normal interval (QT) is 390 - 450 ms. If the interval is violated, if it lengthens, the diagnostician may suspect that the patient has atherosclerosis, rheumatism or myocarditis, as well as coronary artery disease. Also, the interval may be reduced, and this indicates the presence of hypercalcemia disease. These parameters are calculated by a specialized automatic program that provides a reliable result.

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

An indicator showing the activity of the ventricles, the QRS complex, is formed during the passage of electrical impulses to the heart. It is considered normal when there is no defective Q wave and the distance does not exceed 120 ms. When the specified interval is shifted, it is customary to speak of a conduction defect, or it is also called the blockade of the legs of the His bundle. With incomplete blockade, RV or LV hypertrophy can be suspected, depending on the location of the line on the ECG. The interpretation describes ST particles, which are reflectors of the recovery time of the initial position of the muscle relative to its complete depolarization. Under normal conditions, the segments should fall on the isoline, and the T wave, which characterizes the work of both ventricles, should be asymmetric and directed upwards. It must be longer than the QRS complex.

Correctly deciphering ECG indicators can only be done by doctors who are specially involved in this, but often an ambulance paramedic with extensive experience can easily recognize common heart defects. And this is extremely important in emergency situations.

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

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

Cardiogram of the heart: decoding and main diagnosed diseases

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

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

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

On the electrocardiogram, you can see frequent and constant contractions of the atria and less often of the ventricles (usually 200 per minute). This is atrial flutter, which often occurs already in the exacerbation phase. But at the same time, it is easier for the patient to tolerate than flicker. Circulatory defects in this case are less pronounced. Trembling can develop as a result of surgery, with various diseases, such as heart failure or cardiomyopathy. At the time of examination of a person, flutter can be detected due to rapid rhythmic heartbeats and pulses, swollen veins in the neck, increased sweating, general impotence and shortness of breath.

Conduction disorder - this type of heart disorder is called blockade. The occurrence is often associated with functional disorders, but it can also be the result of intoxications of a different nature (against the background of alcohol or taking medications), as well as various diseases.

There are several types of disorders that the cardiogram of the heart shows. Deciphering these violations is possible according to the results of the procedure.

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

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

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

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

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

Myocardial hypertrophy is well shown by the cardiogram of the heart. Decoding on an electrocardiogram - this condition shows a thickening of individual sections of the heart muscle and stretching of the chambers of the heart. This happens with regular chronic overload of the body.

• Syndrome of early repolarization of the ventricles. Often, it is the norm for professional athletes and people with congenital large body weight. It does not give a clinical picture and often passes without any changes, so the interpretation of the ECG becomes more complicated.
• Various diffuse disorders in the myocardium. They indicate a myocardial malnutrition, as a result of dystrophy, inflammation or cardiosclerosis. Disorders are quite susceptible to treatment, often associated with a disorder of the body's water and electrolyte balance, taking medications, and heavy physical activity.
• Non-individual ST changes. A clear symptom of myocardial supply disorder, without bright oxygen starvation. Occurs during hormonal imbalances and electrolyte imbalances.
• T wave distortion, ST depression, low T. Cat's back on the ECG shows the state of ischemia (oxygen starvation of the myocardium).

In addition to the disorder itself, they also describe their position in the heart muscle. The main feature of such disorders is their reversibility. The indicators, as a rule, are given for comparison with old studies in order to understand the patient's condition, since it is almost impossible to read the ECG on your own in this case. If a heart attack is suspected, additional studies are carried out.

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

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

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

ECG results and options for describing the heart rhythm

The results of the ECG provide an opportunity to look at the state of the work of the human heart. There are different ways to decipher the rhythm.

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

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

Sinus bradycardia- characterized by rhythmic contraction of the heart muscle with a frequency of about 50 beats. In a healthy person, this condition can often be observed in a state of sleep. Such a rhythm can manifest itself in people professionally involved in sports. They have ECG teeth that are different from the teeth of an ordinary person.

Constant bradycardia may characterize the weakness of the sinus node, manifested in such cases by more rare contractions at any time of the day and in any condition. If a person has pauses during contractions, then a surgical intervention is prescribed to install a stimulator.

Extrasystole. This is a rhythm defect that is characterized by extraordinary contractions outside the sinus node, followed by ECG results showing an extended pause, called a compensatory pause. The patient feels the heartbeat as uneven, chaotic, too fast or too slow. Sometimes patients are disturbed by pauses in the heart rhythm. Often there is a feeling of tingling or unpleasant jolts behind the sternum, as well as a feeling of fear and emptiness in the stomach. Often such conditions do not lead to complications and do not pose a threat to a person.

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

It can be observed after taking alcoholic beverages, coffee, energy drinks. In this case, the condition is temporary and passes quite quickly. The pathological type of this condition is characterized by periodic heartbeats that disturb a person at rest.

The causes of the pathological appearance can be elevated body temperature, various infectious diseases, blood loss, long periods without water, anemia, etc. Doctors are treating the underlying disease, and tachycardia is stopped only in case of a heart attack in a patient or an acute coronary syndrome.

Paroxysmal tachycardia- in this condition, a person has a rapid heartbeat, expressed in an attack lasting from several minutes to several days. The pulse may increase to 250 beats per minute. There are ventricular and supraventricular forms of such tachycardia. The main reason for this state is the defect in the passage of the electric pulse in the conducting system. This pathology is quite susceptible to treatment.

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

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

WPW syndrome It is a subspecies of supraventricular tachycardia. The main provocateur of an attack is an additional nerve bundle, which is located between the atria and ventricles. To eliminate this defect, surgical intervention or medication is required.

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

Atrial fibrillation May be episodic or permanent. A person feels pronounced atrial flutter.

ECG of a healthy person and signs of changes

The ECG of a healthy person includes many indicators by which a person's health is judged. The ECG of the heart plays a very important role in the process of detecting abnormalities in the work of the heart, the worst of which is myocardial infarction. Exclusively with the help of electrocardiogram data, it is possible to diagnose necrotic infarct zones. Electrocardiography also determines the depth of damage to the heart muscle.

ECG norms of a healthy person: men and women

ECG norms for children

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

ECG signs of myocardial infarction include:

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

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

How to decipher the cardiogram of the heart yourself

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

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

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

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

The cardio line consists of divisions (scales) that determine:

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

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

One of the leading causes of death among the population worldwide is cardiovascular disease. Over the past decades, this figure has declined significantly due to the emergence of more modern methods of examination, treatment, and, of course, new drugs.

Electrocardiography (ECG) is a method of recording the electrical activity of the heart, one of the first research methods, which for a long time remained practically the only one in this field of medicine. About a century ago, in 1924, Willem Einthoven received the Nobel Prize in Medicine, he designed the apparatus with which the ECG was recorded, named its teeth and determined the electrocardiographic signs of certain heart diseases.

Many research methods with the advent of more modern developments are losing their relevance, but this does not apply to electrocardiography. Even with the advent of imaging techniques (, CT, etc.), ECG for decades continues to be the most common, very informative, and in some places the only available method for examining the heart. Moreover, over the century of its existence, neither the device itself nor the method of its use has changed significantly.

Indications and contraindications

Electrocardiography is a unique examination method that helps to make a diagnosis or becomes the starting point for drawing up a plan for further examination of the patient. In any case, the diagnosis and treatment of any heart disease begins with an ECG.

ECG is an absolutely safe and painless method of examination for people of all ages; there are no contraindications to conventional electrocardiography. The study takes only a few minutes and does not require any special preparation.

But there are so many indications for electrocardiography that it is simply impossible to list them all. The main ones are the following:

• general examination during medical examination or medical commission;
• assessment of the state of the heart in various diseases (atherosclerosis, lung disease, etc.);
• differential diagnosis for retrosternal pain and (often have a non-cardiac cause);
• suspicion of, as well as control of the course of this disease;
• diagnosis of cardiac arrhythmias (24-hour Holter ECG monitoring);
• violation of electrolyte metabolism (hyper- or hypokalemia, etc.);
• drug overdose (for example, cardiac glycosides or antiarrhythmic drugs);
• diagnosis of non-cardiac diseases (pulmonary embolism), etc.

The main advantage of the ECG is that the study can be performed outside the hospital, many ambulances are equipped with electrocardiographs. This makes it possible for a doctor at home in a patient to detect myocardial infarction at its very beginning, when damage to the heart muscle is just beginning and is partially reversible. After all, treatment in such cases begins even during the transportation of the patient to the hospital.

Even in cases where the ambulance is not equipped with this device and the ambulance doctor does not have the opportunity to perform a study at the prehospital stage, the first diagnostic method in the emergency room of a medical institution will be an ECG.

Interpretation of the ECG in adults

In most cases, cardiologists, therapists, emergency doctors work with electrocardiograms, but a functional diagnostics doctor is a specialist in this field. Deciphering an ECG is not an easy task, which is beyond the power of a person who does not have the appropriate qualifications.

Usually, five waves can be distinguished on the ECG of a healthy person, recorded in a certain sequence: P, Q, R, S and T, sometimes a U wave is recorded (its nature is not known for sure today). Each of them reflects the electrical activity of the myocardium of different parts of the heart.

When registering an ECG, several complexes are usually recorded, corresponding to contractions of the heart. In a healthy person, all the teeth in these complexes are located at the same distance. The difference in the intervals between the complexes indicates .

In this case, in order to accurately establish the form of arrhythmia, Holter monitoring of the ECG may be necessary. Using a special small portable device, the cardiogram is recorded continuously for 1-7 days, after which the resulting record is processed using a computer program.

• The first P wave reflects the process of depolarization (excitation coverage) of the atria. According to its width, amplitude and shape, the doctor may suspect hypertrophy of these chambers of the heart, a violation of the conduction of an impulse through them, suggest that the patient has organ defects and other pathologies.
• The QRS complex reflects the process of excitation coverage of the ventricles of the heart. Deformation of the shape of the complex, a sharp decrease or increase in its amplitude, the disappearance of one of the teeth can indicate a variety of diseases: myocardial infarction (with the help of ECG it is possible to establish its localization and prescription), scars, conduction disorders (blockade of the bundle legs), etc.
• The last T wave is determined by ventricular repolarization (relatively speaking, relaxation), the deformation of this element can indicate electrolyte disturbances, ischemic changes and other pathologies of the heart.

The sections of the ECG connecting the various teeth are called "segments". Normally, they lie on the isoline, or their deviation is not significant. Between the teeth there are intervals (for example, PQ or QT), which reflect the time of passage of an electrical impulse through the heart, in a healthy person they have a certain duration. Lengthening or shortening of these intervals is also a significant diagnostic sign. Only a qualified doctor can see and evaluate all changes on the ECG.

In deciphering an ECG, every millimeter is important, sometimes even half a millimeter is decisive in choosing a treatment strategy. Very often, an experienced doctor can make an accurate diagnosis using an electrocardiogram without using additional research methods, and in some cases its information content exceeds the data of other types of research. In fact, this is a screening method of examination in cardiology, which allows to detect or at least suspect heart disease in the early stages. That is why the electrocardiogram will remain one of the most popular diagnostic methods in medicine for many years to come.

Which doctor to contact

For a referral to an ECG, you need to contact a general practitioner or cardiologist. The analysis of the cardiogram and the conclusion on it is given by the doctor of functional diagnostics. The ECG report itself is not a diagnosis and should be considered by the clinician in conjunction with other patient data.

Basics of electrocardiography in educational video:

Video course "ECG for everyone", lesson 1:

Video course "ECG for everyone", lesson 2.

Equipment for recording electrocardiogram

Electrocardiography - a method of graphic registration of changes in the potential difference of the heart that occur during the processes of myocardial excitation.

The first registration of an electrocardiosignal, a prototype of a modern ECG, was undertaken by W. Einthoven in 1912 . in Cambridge. After that, the ECG recording technique was intensively improved. Modern electrocardiographs allow both single-channel and multi-channel ECG recording.

In the latter case, several different electrocardiographic leads (from 2 to 6-8) are synchronously recorded, which significantly shortens the study period and makes it possible to obtain more accurate information about the electric field of the heart.

Electrocardiographs consist of an input device, a biopotential amplifier and a recording device. The potential difference that occurs on the surface of the body when the heart is excited is recorded using a system of electrodes attached to different parts of the body. Electrical vibrations are converted into mechanical displacements of the electromagnet armature and are recorded in one way or another on a special moving paper tape. Now they use directly both mechanical recording with a very light pen, to which ink is supplied, and thermal ECG recording with a pen, which, when heated, burns out the corresponding curve on a special thermal paper.

Finally, there are such capillary type electrocardiographs (mingographs), in which ECG recording is carried out using a thin jet of spraying ink.

A gain calibration of 1 mV, which causes a 10 mm deviation of the recording system, allows comparison of ECGs recorded from a patient at different times and / or different devices.

Tape drives in all modern electrocardiographs provide paper movement at different speeds: 25, 50, 100 mm s -1, etc. Most often in practical electrocardiology, the ECG registration rate is 25 or 50 mm s -1 (Fig. 1.1).

Rice. 1.1. ECG recorded at a speed of 50 mm·s -1 (a) and 25 mm·s -1 (b). Calibration signal is shown at the beginning of each curve

Electrocardiographs should be installed in a dry room at a temperature not lower than 10 and not higher than 30 °C. During operation, the electrocardiograph must be grounded

Electrocardiographic leads

Changes in the potential difference on the surface of the body that occur during the work of the heart are recorded using various ECG lead systems. Each lead registers the potential difference that exists between two specific points of the electric field of the heart, where the electrodes are installed. Thus, different electrocardiographic leads differ among themselves, first of all, in areas of the body on which the potential difference is measured.

Electrodes placed at each of the selected points on the body surface are connected to the galvanometer of the electrocardiograph. One of the electrodes is attached to the positive pole of the galvanometer (positive or active lead electrode), the second electrode is connected to its negative pole (negative lead electrode).

Today, in clinical practice, 12 ECG leads are most widely used, the recording of which is mandatory for each electrocardiographic examination of the patient: 3 standard leads, 3 enhanced unipolar limb leads, and 6 chest leads.

Standard leads

Three standard leads form an equilateral triangle (Einthoven's triangle), the vertices of which are the right and left arms, as well as the left leg with electrodes installed on them. The hypothetical line connecting the two electrodes involved in the formation of an electrocardiographic lead is called the lead axis. The axes of standard leads are the sides of Einthoven's triangle (Fig. 1. 2).

Rice. 1.2. Formation of three standard limb leads

Perpendiculars drawn from the geometric center of the heart to the axis of each standard lead divide each axis into two equal parts. The positive part faces the positive (active) lead electrode, and the negative part faces the negative electrode. If the electromotive force (EMF) of the heart at some point in the cardiac cycle is projected onto the positive part of the abduction axis, a positive deviation is recorded on the ECG (positive R, T, P waves), and if it is negative, negative deviations are recorded on the ECG (Q waves, S, sometimes negative T-waves or even P-waves). To record these leads, electrodes are placed on the right arm (red marking) and left (yellow marking), as well as the left leg (green marking). These electrodes are connected in pairs to the electrocardiograph to record each of the three standard leads. Standard limb leads are recorded in pairs by connecting electrodes:

Lead I - left (+) and right (-) hand;

Lead II - left leg (+) and right arm (-);

Lead III - left leg (+) and left arm (-);

The fourth electrode is installed on the right foot to connect the ground wire (black marking).

The signs "+" and "-" here indicate the corresponding connection of the electrodes to the positive or negative poles of the galvanometer, that is, the positive and negative poles of each lead are indicated.

Strengthened limb leads

Amplified limb leads were proposed by Goldberg in 1942 . They register the potential difference between one of the limbs on which the active positive electrode of this lead is installed (right arm, left arm or leg) and the average potential of the other two limbs. As a negative electrode in these leads, the so-called combined Goldberg electrode is used, which is formed when two limbs are connected through additional resistance. Thus, aVR is an enhanced lead from the right hand; aVL - enhanced abduction from the left hand; aVF - enhanced abduction from the left leg (Fig. 1.3).

The designation of enhanced limb leads comes from the first letters of the English words: “ a "- augmented (reinforced); "V" - voltage (potential); "R" - right (right); "L" - left (left); "F" - foot (leg).

Rice. 1.3. Formation of three reinforced unipolar limb leads. Below - Einthoven's triangle and the location of the axes of three reinforced unipolar limb leads

Six-axis coordinate system (according to BAYLEY)

Standard and enhanced unipolar limb leads make it possible to register changes in the EMF of the heart in the frontal plane, that is, in the one in which the Einthoven triangle is located. For a more accurate and visual determination of various deviations of the EMF of the heart in this frontal plane, in particular, to determine the position of the electrical axis of the heart, the so-called six-axis coordinate system was proposed (Bayley, 1943). It can be obtained by combining the axes of three standard and three enhanced leads from the limbs, conducted through the electrical center of the heart. The latter divides the axis of each lead into positive and negative parts, directed, respectively, to the positive (active) or negative electrodes (Fig. 1.4).

Rice. 1.4. Formation of a six-axis coordinate system (according to Bayley)

The direction of the axes is measured in degrees. The reference point (0 °) is conditionally taken as a radius drawn strictly horizontally from the electrical center of the heart to the left towards the active positive pole of standard lead I. The positive pole of standard lead II is at +60°, aVF is +90°, standard lead III is +120°, aVL is -30°, and aVR is -150°. The axis of lead aVL is perpendicular to the axis II of the standard lead, the axis I of the standard lead is perpendicular to the axis aVF, and the axis aVR is perpendicular to the axis III of the standard lead.

chest leads

Thoracic unipolar leads proposed by Wilson in 1934 ., register the potential difference between the active positive electrode installed at certain points on the surface of the chest and the negative combined Wilson electrode. This electrode is formed by connecting three limbs (right and left hands, as well as the left leg) through additional resistances, the combined potential of which is close to zero (about 0.2 mV). To record an ECG, 6 generally accepted positions of the active electrode are used on the anterior and lateral surfaces of the chest, which, in combination with the combined Wilson electrode, form 6 chest leads (Fig. 1.5):

lead V 1 - in the fourth intercostal space on the right edge of the sternum;

assignment V 2 — in the fourth intercostal space on the left edge of a breast;

assignment V 3 — between positions V 2 and V 4, approximately at the level of the fourth edge on the left parasternal line;

assignment V 4 - in the fifth intercostal space on the left mid-clavicular line;

assignment of V 5 — at the same level across, as V 4, on the left front axillary line;

Rice. 1.5. Location of chest electrodes

Thus, 12 electrocardiographic leads (3 standard, 3 reinforced unipolar limb leads, and 6 chest leads) are the most widely used.

Electrocardiographic deviations in each of them reflect the total EMF of the whole heart, that is, they are the result of simultaneous exposure to a given lead of a changing electrical potential in the left and right parts of the heart, in the anterior and posterior walls of the ventricles, in the apex and base of the heart.

Additional Leads

It is sometimes advisable to expand the diagnostic possibilities of an electrocardiographic study by using some additional leads. They are used in cases where the usual program for registering 12 generally accepted ECG leads does not allow one or another electrocardiographic pathology to be reliably diagnosed or requires some changes to be clarified.

The method of recording additional chest leads differs from the method of recording 6 conventional chest leads only by the localization of the active electrode on the surface of the chest. The combined Wilson electrode is used as the electrode connected to the negative pole of the cardiograph.

Rice. 1.6. Location of additional chest electrodes

Leads V7-V9. The active electrode is installed along the posterior axillary (V 7), scapular (V 8) and paravertebral (V 9) lines at the level of the horizontal, on which the electrodes V 4 -V 6 are located (Fig. 1.6). These leads are usually used for more accurate diagnosis of focal myocardial changes in the posterior basal LV.

Lead V 3R-V6R. The chest (active) electrode is placed on the right half of the chest in positions symmetrical to the usual points of the electrodes V 3 -V 6 . These leads are used to diagnose right heart hypertrophy.

Leads according to Neb. Bipolar chest leads, proposed in 1938 by Neb, fix the potential difference between two points located on the surface of the chest. To record three leads according to Nab, electrodes are used that are designed to record three standard leads from the limbs. The electrode, usually placed on the right hand (red marking), is placed in the second intercostal space along the right edge of the sternum. The electrode from the left leg (green marking) is moved to the position of the chest lead V 4 (at the apex of the heart), and the electrode located on the left arm (yellow marking) is placed at the same horizontal level as the green electrode, but along the posterior axillary line . With the electrocardiograph lead switch in position I of the standard lead, record the Dorsalis lead (D).

By moving the switch to the II and III standard leads, the Anterior (A) and Inferior (I) leads are recorded respectively. The Nab leads are used to diagnose focal myocardial changes in the posterior wall (lead D), the anterior lateral wall (lead A), and the upper sections of the anterior wall (lead I).

ECG recording technique

To obtain a high-quality ECG recording, it is necessary to adhere to some rules for its registration.

Conditions for conducting an electrocardiographic study

ECG is recorded in a special room, remote from possible sources of electrical interference: electric motors, physiotherapy and X-ray rooms, electrical distribution boards. The couch should be at least 1.5-2 m away from the mains wires.

It is advisable to shield the couch by placing a blanket under the patient with a sewn-in metal mesh, which must be grounded.

The study is carried out after a 10-15-minute rest and not earlier than 2 hours after eating. The patient must be undressed to the waist, the shins are also freed from clothing.

ECG recording is usually performed in the supine position, which allows for maximum muscle relaxation.

Application of electrodes

4 plate electrodes are applied to the inner surface of the legs and forearms in their lower third with the help of rubber bands, and one or more (for multi-channel recording) chest electrodes are placed on the chest using a rubber pear-suction cup. To improve the quality of the ECG and reduce the amount of inductive currents, good contact of the electrodes with the skin should be ensured. To do this, you must: 1) preliminarily degrease the skin with alcohol in the places where the electrodes are applied; 2) with significant hairiness of the skin, moisten the places where the electrodes are applied with soapy water; 3) use electrode paste or abundantly moisten the skin at the electrode sites with 5-10% sodium chloride solution.

Connecting wires to electrodes

Each electrode installed on the limbs or on the surface of the chest is connected to a wire coming from the electrocardiograph and marked with a certain color. The generally accepted marking of input wires is: right hand - red; left hand - yellow; left leg - green, right leg (patient grounding) - black; chest electrode is white. In the presence of a 6-channel electrocardiograph, which allows you to simultaneously register an ECG in 6 chest leads, a wire with a red color on the tip is connected to the V 1 electrode; to the electrode V 2 - yellow, V 3 - green, V 4 - brown, V 5 - black and V 6 - blue or purple. The marking of the remaining wires is the same as in single-channel electrocardiographs.

Choice of electrocardiograph gain

Before starting an ECG recording, it is necessary to set the same gain of the electrical signal on all channels of the electrocardiograph. To do this, each electrocardiograph provides the possibility of supplying a standard calibration voltage (1 mV) to the galvanometer. Typically, the gain of each channel is selected so that a voltage of 1 mV causes a deviation of the galvanometer and the recording system, equal to 10 mm . To do this, in the position of the lead switch "0", the gain of the electrocardiograph is adjusted and the calibration millivolt is recorded. If necessary, you can change the gain: reduce if the amplitude of the ECG waves is too large (1 mV = 5 mm) or increase if their amplitude is small (1 mV = 15 or 20 mm).

ECG recording

ECG recording is carried out with quiet breathing, as well as at the height of inspiration (in lead III). First, an ECG is recorded in standard leads (I, II, III), then in enhanced leads from the extremities (aVR, aVL and aVF) and chest (V 1 -V 6). At least 4 PQRST cycles are recorded in each lead. ECG is recorded, as a rule, at a paper speed of 50 mm·s -1 . A lower speed (25 mm·s -1) is used if a longer ECG recording is required, for example, for diagnosing arrhythmias.

Immediately after the end of the study, the last name, first name and patronymic of the patient, year of birth, date and time of the study are recorded on a paper tape.

Normal ECG

Prong R

The P wave reflects the process of depolarization of the right and left atria. Normally, in the frontal plane, the average resulting atrial depolarization vector (vector P) is located almost parallel to the standard lead axis II and is projected onto the positive parts of the lead axes II, aVF, I, and III. Therefore, in these leads, a positive P wave is usually recorded, which has a maximum amplitude in leads I and II.

In lead aVR, the P wave is always negative, since the P vector is projected onto the negative part of the axis of this lead. Since the axis of lead aVL is perpendicular to the direction of the mean resulting vector P, its projection onto the axis of this lead is close to zero, in most cases a biphasic or low-amplitude P wave is recorded on the ECG.

With a more vertical location of the heart in the chest (for example, in people with an asthenic physique), when the P vector is parallel to the aVF lead axis (Fig. 1.7), the P wave amplitude increases in leads III and aVF and decreases in leads I and aVL. The P wave in aVL may even become negative.

Rice. 1.7. P-wave formation in limb leads

On the contrary, with a more horizontal position of the heart in the chest (for example, in hypersthenics), the P vector is parallel to the I axis of the standard lead. At the same time, the amplitude of the P wave increases in leads I and aVL. P aVL becomes positive and decreases in leads III and aVF. In these cases, the projection of the P vector on the III axis of the standard lead is equal to zero or even has a negative value. Therefore, the P wave in lead III can be biphasic or negative (more often with left atrial hypertrophy).

Thus, in a healthy person, the P wave is always positive in leads I, II, and aVF; in leads III and aVL, it can be positive, biphasic, or (rarely) negative; and in lead aVR, the P wave is always negative.

In the horizontal plane, the average resulting vector P usually coincides with the direction of the axes of the chest leads V 4 -V 5 and is projected onto the positive parts of the axes of the leads V 2 -V 6, as shown in Fig. 1.8. Therefore, in a healthy person, the P wave in leads V 2 -V 6 is always positive.

Rice. 1.8. P wave formation in chest leads

The direction of the mean vector P is almost always perpendicular to the lead axis V 1 , while the direction of the two depolarization moment vectors is different. The first initial moment vector of atrial excitation is oriented forward, towards the positive lead electrode V 1 , and the second final moment vector (smaller) is turned back towards the negative pole of lead V 1 . Therefore, the P wave in V 1 is more often biphasic (+-).

The first positive phase of the P wave in V 1 , due to excitation of the right and partially left atria, is greater than the second negative phase of the P wave in V 1 , reflecting a relatively short period of final excitation of the left atrium only. Sometimes the second negative phase of the P wave in V 1 is weakly expressed and the P wave in V 1 is positive.

Thus, in a healthy person, a positive P wave is always recorded in chest leads V 2 -V 6, and in lead V 1 it can be biphasic or positive.

The amplitude of the P waves normally does not exceed 1.5-2.5 mm, and the duration is 0.1 s.

P interval‒ Q(R)

The P-Q(R) interval is measured from the beginning of the P wave to the beginning of the ventricular QRS complex (Q or R wave). It reflects the duration of AV conduction, that is, the time of propagation of excitation through the atria, AV node, bundle of His and its branches (Fig. 1.9). The P-Q(R) interval does not follow with the PQ(R) segment, which is measured from the end of the P wave to the beginning of Q or R

Rice. 1.9. P-Q(R) interval

The duration of the P-Q (R) interval ranges from 0.12 to 0.20 s and in a healthy person it depends mainly on the heart rate: the higher it is, the shorter the P-Q (R) interval.

Ventricular QRS complex T

The ventricular QRST complex reflects the complex process of propagation (QRS complex) and extinction (RS-T segment and T wave) of excitation through the ventricular myocardium. If the amplitude of the QRS complex teeth is large enough and exceeds 5 mm , they are denoted by capital letters of the Latin alphabet Q, R, S, if small (less than 5 mm ) - lowercase q, r, s.

The R wave denotes any positive wave that is part of the QRS complex. If there are several such positive teeth, they are designated as R, Rj, Rjj, etc., respectively. The negative wave of the QRS complex immediately preceding the R wave is denoted by the letter Q (q), and the negative wave immediately following the R wave is called S (s).

If only a negative deviation is recorded on the ECG, and there is no R wave at all, the ventricular complex is designated as QS. The formation of individual teeth of the QRS complex in different leads can be explained by the existence of three moment vectors of ventricular depolarization and their different projections on the axes of the ECG leads.

Q wave

In most ECG leads, the formation of the Q wave is due to the initial moment vector of depolarization between the ventricular septum, lasting up to 0.03 s. Normally, the Q wave can be registered in all standard and enhanced unipolar limb leads and in the chest leads V 4 -V 6 . The amplitude of the normal Q wave in all leads, except for aVR, does not exceed 1/4 of the height of the R wave, and its duration is 0.03 s. In lead aVR, a healthy person may have a deep and wide Q wave or even a QS complex.

R wave

The R wave in all leads, with the exception of the right chest leads (V 1 , V 2) and lead aVR, is due to the projection of the second (middle) QRS moment vector, or conditionally vector 0.04 s, on the lead axis. The 0.04 s vector reflects the process of further spread of excitation through the RV and LV myocardium. But, since the LV is a more powerful part of the heart, the R vector is oriented to the left and down, that is, towards the LV. On fig. 1.10a it can be seen that in the frontal plane the 0.04 s vector is projected onto the positive parts of the lead axes I, II, III, aVL and aVF and onto the negative part of the lead axis aVR. Therefore, in all leads from the extremities, with the exception of aVR, high R waves are formed, and with a normal anatomical position of the heart in the chest, the R wave in lead II has a maximum amplitude. In the aVR lead, as mentioned above, a negative deviation always predominates - the S, Q or QS wave, due to the projection of the 0.04 s vector onto the negative part of the axis of this lead.

With a vertical position of the heart in the chest, the R wave becomes maximum in leads aVF and II, and with a horizontal position of the heart - in standard lead I. In the horizontal plane, the 0.04 s vector usually coincides with the direction of the V 4 lead axis. Therefore, the R wave in V 4 exceeds the R wave in the other chest leads in amplitude, as shown in Fig. 1.10b. Thus, in the left chest leads (V 4 -V 6) the R wave is formed as a result of the projection of the main moment vector of 0.04 s onto the positive parts of these leads.

Rice. 1.10. R wave formation in limb leads

The axes of the right chest leads (V 1 , V 2) are usually perpendicular to the direction of the main moment vector of 0.04 s, so the latter has almost no effect on these leads. The R wave in leads V 1 and V 2, as shown above, is formed as a result of the projection on the axis of these leads of the initial moment of choice (0.02 s) and reflects the spread of excitation along the interventricular septum.

Normally, the amplitude of the R wave gradually increases from lead V 1 to lead V 4, and then again slightly decreases in leads V 5 and V 6. The height of the R wave in the limb leads usually does not exceed 20 mm, and in the chest leads - 25 mm. Sometimes in healthy people, the r wave in V 1 is so weakly expressed that the ventricular complex in lead V 1 takes the form of QS.

For a comparative characteristic of the propagation time of the excitation wave from the endocardium to the epicardium of the RV and LV, it is customary to determine the so-called interval of internal deviation (intrinsical defl ection), respectively, in the right (V 1, V 2) and left (V 5, V 6) chest leads. It is measured from the beginning of the ventricular complex (the Q or R wave) to the top of the R wave in the appropriate lead, as shown in Figure 1. 1.11.

Rice. 1.11. Measuring the interval of internal deviation

In the presence of R wave splits (RSRj or qRsrj complexes), the interval is measured from the beginning of the QRS complex to the top of the last R wave.

Normally, the interval of internal deviation in the right chest lead (V 1) does not exceed 0.03 s, and in the left chest lead V 6 -0.05 s.

S wave

In a healthy person, the amplitude of the S wave in different ECG leads varies widely, not exceeding 20 mm.

In the normal position of the heart in the chest, the S amplitude in the limb leads is small, except for the aVR lead. In the chest leads, the S wave gradually decreases from V 1, V 2 to V 4, and in the leads V 5, V 6 has a small amplitude or is absent.

The equality of the R and S waves in the chest leads (transitional zone) is usually recorded in the lead V 3 or (less often) between V 2 and V 3 or V 3 and V 4 .

The maximum duration of the ventricular complex does not exceed 0.10 s (usually 0.07-0.09 s).

The amplitude and ratio of positive (R) and negative teeth (Q and S) in various leads largely depend on the rotation of the axis of the heart around its three axes: anteroposterior, longitudinal and sagittal.

RS-T segment

The RS-T segment is a segment from the end of the QRS complex (the end of the R or S wave) to the beginning of the T wave. It corresponds to the period of complete excitation coverage of both ventricles, when the potential difference between different parts of the heart muscle is absent or small. Therefore, in normal standard and enhanced unipolar leads from the limbs, the electrodes of which are located at a great distance from the heart, the RS-T segment is located on the isoline and its displacement up or down does not exceed 0.5 mm . In the chest leads (V 1 -V 3), even in a healthy person, a slight shift of the RS-T segment upwards from the isoline is often noted (no more 2 mm).

In the left chest leads, the RS-T segment is more often recorded at the level of the isoline, the same as in the standard leads (± 0.5 mm).

The point of transition of the QRS complex to the RS-T segment is designated as j. Deviations of point j from the isoline are often used to quantify the displacement of the RS-T segment.

T wave

The T wave reflects the process of rapid final repolarization of the ventricular myocardium (phase 3 of the transmembrane PD). Normally, the total resulting ventricular repolarization vector (T vector) usually has almost the same direction as the average ventricular depolarization vector (0.04 s). Therefore, in most leads where a high R wave is recorded, the T wave has a positive value, projecting onto the positive parts of the electrocardiographic lead axes (Fig. 1.12). In this case, the largest R wave corresponds to the largest T wave in amplitude, and vice versa.

Rice. 1.12. T wave formation in limb leads

In lead aVR, the T wave is always negative.

In the normal position of the heart in the chest, the direction of the T vector is sometimes perpendicular to the III axis of the standard lead, and therefore a biphasic (+/-) or low-amplitude (smoothed) T wave in III can sometimes be recorded in this lead.

With a horizontal location of the heart, the T vector can even be projected onto the negative part of the III axis, and a negative T wave in III is recorded on the ECG. However, in lead aVF, the T wave remains positive.

With a vertical location of the heart in the chest, the T vector is projected onto the negative part of the aVL lead axis, and a negative T wave in aVL is recorded on the ECG.

In chest leads, the T wave usually has a maximum amplitude in lead V 4 or V 3 . The height of the T wave in the chest leads usually increases from V 1 to V 4, and then decreases slightly in V 5 -V 6 . In lead V 1, the T wave can be biphasic or even negative. Normally, T in V 6 is always greater than T in V 1.

The amplitude of the T wave in the limb leads in a healthy person does not exceed 5-6 mm, and in the chest leads - 15-17 mm. The duration of the T wave ranges from 0.16 to 0.24 s.

Q-T Interval (QRST)

The Q-T interval (QRST) is measured from the beginning of the QRS complex (Q or R wave) to the end of the T wave. The Q-T interval (QRST) is called ventricular electrical systole. During electrical systole, all parts of the ventricles of the heart are excited. The duration of the Q-T interval primarily depends on the heart rate. The higher the rhythm rate, the shorter the proper QT interval. The normal duration of the Q-T interval is determined by the formula Q-T \u003d K√R-R, where K is a coefficient equal to 0.37 for men and 0.40 for women; R-R is the duration of one cardiac cycle. Since the duration of the Q-T interval depends on the heart rate (lengthening when it slows down), it must be corrected relative to the heart rate to evaluate it, so the Bazett formula is used for calculations: QTc \u003d Q-T / √R-R.

Sometimes on the ECG, especially in the right chest leads, immediately after the T wave, a small positive U wave is recorded, the origin of which is still unknown. There are suggestions that the U wave corresponds to a period of short-term increase in the excitability of the ventricular myocardium (exaltation phase), which occurs after the end of the LV electrical systole.

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

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 electrical potentials that are formed in a beating heart. The removal of indicators and their display is carried out by means of special devices - electrocardiographs, which are constantly being improved.

As a rule, during the study, 5 teeth are fixed: P, Q, R, S, T. At some points, it is possible to fix an inconspicuous U wave.

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

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

Note:when used in parallel with a cardiophone, the electrocardiograph provides the ability to remotely determine some acute heart diseases (presence 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. "load tests".

In isolation or in combination with other diagnostic methods, ECG is often used in the study of cognitive (mental) processes.

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

ECG: indications for holding

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

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

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

With left ventricular hypertrophy, the R wave is pronounced in the left chest leads and its depth is increased in leads V1-V2. The electrical axis is either horizontal or deviated to the left, but it can often correspond to the norm. The QRS complex in lead V6 has 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 rather significant increase in the P wave (up to 0.11-0.14 s). It acquires a "double-humped" shape in the left chest leads and leads I and II. In rare clinical cases, there is some flattening of the tooth, and the duration of the internal deviation of P exceeds 0.06 s in leads I, II, V6. Among the most prognostic 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 some shift to the right.

Combined atrial hypertrophy is characterized by a parallel expansion of the P wave and an increase in its amplitude. In some clinical cases, changes such as sharpness 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 fetal development, a significant increase in the amplitude of the P wave in leads V1-V3 is more characteristic.

In patients with severe chronic cor pulmonale with emphysematous lung disease, as a rule, an S-type ECG is determined.

Important:combined hypertrophy of two ventricles at once is rarely determined by electrocardiography, especially if the hypertrophy is uniform. In this case, pathological signs tend to be mutually compensated, as it were.

With "syndrome of premature excitation of the ventricles" on the ECG, the width of the QRS complex increases and the R-R 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 sections of the heart muscle of the ventricles.

Blockades are caused by the termination of the conduction of an electrical impulse in one of the sections.

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

Important:sinoatrial blockade 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, the evaluation of electrocardiography data is carried out on the basis of analysis and comparison of intervals (inter- and intra-cycle) for 10-20 seconds or even longer.

An important diagnostic value in the diagnosis of arrhythmias is the direction and shape of the P wave, as well as the QRS complex.

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 some 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 pectoris, then a noticeable decrease (depression) in RST is recorded on the electrocardiogram, and in some cases, inversion of T. These changes on 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:transient elevation of the RST segment is a characteristic feature of the pathology known as Prinzmetal's angina.

Approximately 50% of patients in the intervals between angina attacks, changes in the ECG may not be recorded at all.

In this life-threatening condition, an electrocardiogram makes it possible to obtain information about the extent of the lesion, its exact location and depth. In addition, the ECG allows you to track the pathological process in dynamics.

Morphologically, it is customary to distinguish three zones:

• central (zone of necrotic changes in myocardial tissue);
• the zone of the expressed dystrophy of a cardiac muscle surrounding the center;
• peripheral zone of pronounced ischemic changes.

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

Dishormonal myocardial dystrophy

Myocardial dystrophy, caused by a sharp change in the hormonal background of the patient, as a rule, is 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 over time may vary. Pathological changes recorded on the ECG are only in rare cases associated with such clinical symptoms as pain in the chest area.

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

Changes in the electrocardiogram parameters against the background of the patient taking certain medications

Changes in the ECG picture can give the reception of the following drugs:

• drugs from the group of diuretics;
• agents related to cardiac glycosides;
• amiodarone;
• Quinidine.

In particular, if the patient takes digitalis preparations (glycosides) in the recommended doses, then the relief of tachycardia (rapid heartbeat) and a decrease in the QT interval are determined. "Smoothing" of the RST segment and shortening of T is also not excluded. An overdose of glycosides is manifested by such serious changes as arrhythmia (ventricular extrasystoles), AV blockade, and even a life-threatening condition - ventricular fibrillation (requires immediate resuscitation measures).

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 thromboembolism of the pulmonary arteries, blockade of the branches of the bundle of His is not uncommon.

On the ECG, the rise of the RST segment is recorded in parallel in leads III (sometimes in aVF and V1.2). There is an inversion of T in leads III, aVF, V1-V3.

Negative dynamics is growing rapidly (a matter of minutes pass), and progression is noted within 24 hours. With positive dynamics, the characteristic symptoms gradually stop 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 feature is the presence of a specific transition wave on the R or S waves. These changes on the electrocardiogram are not yet associated with any myocardial pathology, therefore they are considered a physiological norm.

Pericarditis

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

Myocarditis

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