Electrocardiograph with ecg interpretation. Decoding ECG cardiogram of the heart

Electrocardiography is a method for diagnosing the condition of the myocardium. This article will discuss ECG norms in children, adults and women during pregnancy. In addition, the reader will learn about what cardiography is, how an ECG is done, and what the interpretation of a cardiogram is.

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Electrocardiography is a method used to record electrical currents that occur during contractions and relaxations of the heart muscle. An electrocardiograph is used to conduct the study. Using this device, it is possible to record electrical impulses that come from the heart and convert them into a graphic drawing. This image is called an electrocardiogram.

Electrocardiography reveals disturbances in the functioning of the heart and disruptions in the functioning of the myocardium. In addition, after decoding the results of the electrocardiogram, some non-cardiac diseases can be detected.

How does an electrocardiograph work?

The electrocardiograph consists of a galvanometer, amplifiers and a recorder. Weak electrical impulses that arise in the heart are read by electrodes and then amplified. The galvanometer then receives data on the nature of the pulses and transmits them to the recorder. In the recorder, graphic images are printed on special paper. The graphs are called cardiograms.

How is an ECG done?

Electrocardiography is performed according to established rules. Below is the procedure for taking an ECG:

• The person removes metal jewelry, removes clothing from the legs and upper body, and then assumes a horizontal position.
• The doctor treats the contact points between the electrodes and the skin, and then places the electrodes in certain places on the body. Next, he fixes the electrodes on the body with clips, suction cups and bracelets.
• The doctor attaches the electrodes to the cardiograph, after which the impulses are recorded.
• A cardiogram is recorded, which is the result of electrocardiography.

Separately, it should be said about the leads used for ECG. The following leads are used:

• 3 standard leads: one of them is located between the right and left arms, the second – between the left leg and right arm, the third – between the left leg and left arm.
• 3 limb leads with enhanced character.
• 6 leads located on the chest.

In addition, additional leads can be used if necessary.

After the cardiogram is recorded, it is necessary to decipher it. This will be discussed further.

Decoding the cardiogram

Conclusions about diseases are made on the basis of heart parameters obtained after deciphering the cardiogram. Below is the procedure for deciphering the ECG:

1. The heart rhythm and myocardial conductivity are analyzed. To do this, the regularity of contractions of the heart muscle and the frequency of myocardial contractions are assessed, and the source of excitation is determined.
2. The regularity of heart contractions is determined as follows: the R-R intervals between successive cardiac cycles are measured. If the measured R-R intervals are the same, then a conclusion is made about the regularity of contractions of the heart muscle. If the duration of the R-R intervals is different, then a conclusion is drawn about the irregularity of heart contractions. If a person exhibits irregular contractions of the myocardium, then a conclusion is drawn about the presence of arrhythmia.
3. Heart rate is determined by a certain formula. If a person’s heart rate exceeds the norm, then a conclusion is drawn about the presence of tachycardia, but if a person’s heart rate is below normal, then a conclusion is drawn about the presence of bradycardia.
4. The point from which the excitation comes is determined as follows: the movement of contraction in the cavities of the atria is assessed and the relationship of the R waves to the ventricles is established (according to the QRS complex). The nature of the heart rhythm depends on the source that causes the excitation.

The following heart rhythm patterns are observed:

1. The sinusoidal nature of the heart rhythm, in which the P waves in the second lead are positive and are located in front of the ventricular QRS complex, and the P waves in the same lead have an indistinguishable shape.
2. Atrial rhythm of the heart, in which the P waves in the second and third leads are negative and are located in front of the unchanged QRS complexes.
3. The ventricular nature of the heart rhythm, in which there is deformation of the QRS complexes and loss of connection between the QRS (complex) and the P waves.

Cardiac conductivity is determined as follows:

1. Measurements of P wave length, PQ interval length, and QRS complex are assessed. Exceeding the normal duration of the PQ interval indicates that the conduction velocity in the corresponding cardiac conduction section is too low.
2. The rotations of the myocardium around the longitudinal, transverse, anterior and posterior axes are analyzed. To do this, the position of the electrical axis of the heart in the general plane is assessed, after which the presence of rotations of the heart along one or another axis is determined.
3. The atrial P wave is analyzed. To do this, the amplitude of the P wave is assessed and the duration of the P wave is measured. Afterwards, the shape and polarity of the P wave are determined.
4. The ventricular complex is analyzed. For this purpose, the QRS complex, RS-T segment, QT interval, T wave are assessed.

When assessing the QRS complex, the following is done: the characteristics of the Q, S and R waves are determined, the amplitude values ​​of the Q, S and R waves in a similar lead and the amplitude values ​​of the R/R waves in different leads are compared.

At the time of evaluation of the RS-T segment, the nature of the displacement of the RS-T segment is determined. The displacement can be horizontal, oblique and oblique.

During the period of analysis of the T wave, the nature of the polarity, amplitude and shape are determined. The QT interval is measured by the time from the beginning of the QRT complex to the end of the T wave. When assessing the QT interval, do the following: analyze the interval from the starting point of the QRS complex to the end point of the T wave. To calculate the QT interval, use the Bezzet formula: the QT interval is equal to the product of the R-R interval and a constant coefficient.

The coefficient for QT depends on gender. For men, the constant coefficient is 0.37, and for women – 0.4.

A conclusion is made and the results are summed up.

At the end of the ECG, the specialist draws conclusions about the frequency of contractile function of the myocardium and cardiac muscle, as well as the source of excitation and the nature of the heart rhythm and other indicators. In addition, an example is given of the description and characteristics of the P wave, QRS complex, RS-T segment, QT interval, T wave.

Based on the conclusion, a conclusion is made that the person has heart disease or other ailments of the internal organs.

Electrocardiogram norms

The table with ECG results has a visual appearance, consisting of rows and columns. In the 1st column, the rows list: heart rate, examples of contraction frequency, QT intervals, examples of axis displacement characteristics, P wave indicators, PQ indicators, examples of QRS indicator. ECG is performed in the same way in adults, children and pregnant women, but the norm is different.

The ECG norm for adults is presented below:

• heart rate in a healthy adult: sinus;
• P wave index in a healthy adult: 0.1;
• heart rate in a healthy adult: 60 beats per minute;
• QRS indicator in a healthy adult: from 0.06 to 0.1;
• QT score in a healthy adult: 0.4 or less;
• RR in a healthy adult: 0.6.

If deviations from the norm are observed in an adult, a conclusion is drawn about the presence of a disease.

The norms of cardiogram indicators in children are presented below:

• P wave index in a healthy child: 0.1 or less;
• heart rate in a healthy child: 110 or less beats per minute in children under 3 years of age, 100 or less beats per minute in children under 5 years of age, no more than 90 beats per minute in adolescent children;
• QRS indicator in all children: from 0.06 to 0.1;
• QT score in all children: 0.4 or less;
• the PQ indicator for all children: if the child is under 14 years old, then an example of the PQ indicator is 0.16, if the child is from 14 to 17 years old, then the PQ indicator is 0.18, after 17 years the normal PQ indicator is 0.2.

If any deviations from the norm are detected in children when interpreting the ECG, then treatment should not be started immediately. Some heart problems improve with age in children.

But in children, heart disease can also be congenital. It is possible to determine whether a newborn child will have a heart pathology at the stage of fetal development. For this purpose, electrocardiography is performed on women during pregnancy.

The normal electrocardiogram indicators in women during pregnancy are presented below:

• heart rate in a healthy adult child: sinus;
• P wave index in all healthy women during pregnancy: 0.1 or less;
• heart muscle contraction frequency in all healthy women during pregnancy: 110 or less beats per minute in children under 3 years of age, 100 or less beats per minute in children under 5 years of age, no more than 90 beats per minute in adolescent children;
• QRS indicator for all expectant mothers during pregnancy: from 0.06 to 0.1;
• QT index in all expectant mothers during pregnancy: 0.4 or less;
• PQ indicator for all expectant mothers during pregnancy: 0.2.

It is worth noting that during different periods of pregnancy, ECG readings may differ slightly. In addition, it should be noted that performing an ECG during pregnancy is safe for both the woman and the developing fetus.

Additionally

It is worth saying that under certain circumstances, electrocardiography can give an inaccurate picture of a person’s health status.

If, for example, a person subjected himself to heavy physical activity before an ECG, then when deciphering the cardiogram, an erroneous picture may be revealed.

This is explained by the fact that during physical activity the heart begins to work differently than at rest. During physical activity, the heart rate increases, and some changes in the rhythm of the myocardium may be observed, which is not observed at rest.

It is worth noting that the work of the myocardium is affected not only by physical stress, but also by emotional stress. Emotional stress, like physical stress, disrupts the normal course of myocardial function.

At rest, the heart rhythm normalizes and the heartbeat evens out, so before electrocardiography you must be at rest for at least 15 minutes.

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 because 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 posterior. To record a 12-lead ECG, special electrodes are attached to the patient’s body in specific places and in a certain sequence.

How to decipher a heart cardiogram: general principles

The main elements of the electrocardiographic curve are:

ECG analysis

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

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

Examples of electrocardiographic reports

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

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

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

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

Interpretation of ECG in children

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

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

Features of ECG during pregnancy

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

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

ECG interpretation, normal indicators

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

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

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

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

Numbers and Latin letters in ECG interpretation

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

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

QRS – (0.06-0.1s) -ventricular complex

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

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

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

Heart Rate Description Options

Sinus rhythm

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

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

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

Sinus tachycardia

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

Extarsystole

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

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

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

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

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

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

Paroxysmal tachycardia

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

• holding your breath
• increased forced cough
• immersing face in cold water

WPW syndrome

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

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

CLC – syndrome (Clerk-Levi-Christesco)

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

Atrial fibrillation

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

Atrial fibrillation

Atrial fibrillation

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

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

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

An attack of atrial fibrillation is difficult to miss.

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

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

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

Examples of recordings on ECG films:

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

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

Atrial flutter

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

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

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

Conduction disorders

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

Sinoatrial blockade

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

Atrioventricular block (AV block)

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

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

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

Impaired conduction within the ventricles

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

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

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

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

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

Myocardial hypertrophy

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

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

Changes in myocardial contractility and nutrition

Early ventricular repolarization syndrome

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

Moderate or severe diffuse changes in the myocardium

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

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

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

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

Advanced heart attack

It is usually described:

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

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

How to decipher ECG readings of the heart?

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

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

Principles of decoding

Each curve on the cardiogram graph has its own elements:

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

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

How are the results analyzed?

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

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

Normal values ​​for adults

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

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

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

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

What do the teeth mean?

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

• The Q wave is an indicator of excitation of the left cardiac septum. The norm is a quarter of the length of the R wave. If it is exceeded, there is a possibility of necrotic myocardial pathology;
• The S wave is an indicator of excitation of those partitions that are located in the basal layers of the ventricles. The norm in this case is 20 mm in height. If there are deviations, this indicates coronary artery disease.
• The R wave in the ECG indicates the activity of the walls of all ventricles of the heart. It is recorded in all ECG curves. If there is no activity somewhere, then it makes sense to suspect ventricular hypertrophy.
• The T wave appears in lines I and II, as directed upward. But in the VR curve it is always negative. When the T wave on the ECG is too high and sharp, the doctor suspects hyperkalemia. If it is long and flat, then there is a 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 children under 3 years old is about 110 pulsations per minute, and at the age of 3-5 years – 100 beats. This figure is already lower in adolescents - 60-90 pulsations.
2. The normal QRS reading is 0.6-0.1 s.
3. The P wave should normally not be longer than 0.1 s.
4. The electrical axis of the heart in children should remain without any changes.
5. The rhythm is sinus only.
6. On an ECG, the Q-T interval e may exceed 0.4 s, and the P-Q interval should be 0.2 s.

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

Why are the indicators different?

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

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

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

An electrocardiograph (ECG) is a device that allows you to evaluate cardiac activity, as well as diagnose the condition of this organ. During the examination, the doctor receives data in the form of a curve. How to read an ECG waveform? What types of teeth are there? What changes are visible on the ECG? Why do doctors need this diagnostic method? What does the ECG show? These are not all the questions that interest people who are faced with electrocardiography. First you need to know how the heart works.

The human heart consists of two atria and two ventricles. The left side of the heart is more developed than the right, as it bears a greater load. It is this ventricle that most often suffers. Despite the difference in size, both sides of the heart must work stably and harmoniously.

Learning to read an electrocardiogram on your own

How to read an ECG correctly? This is not as difficult to do as it might seem at first glance. First you should look at the cardiogram. It is printed on special paper that has cells, and two types of cells are clearly visible: large and small.

The ECG conclusion is read from these cells. teeth, cells? These are the main parameters of the cardiogram. Let's try to learn how to read an ECG from scratch.

The meaning of cells (cells)

There are two types of cells on the paper for printing the examination result: large and small. All of them consist of vertical and horizontal guides. The vertical ones are voltage, and the horizontal ones are time.

Large squares consist of 25 small cells. Each small cell is equal to 1 mm and corresponds to 0.04 seconds in the horizontal direction. Large squares equal 5 mm and 0.2 seconds. In the vertical direction, a centimeter of strip is equal to 1 mV of voltage.

Prongs

There are five teeth in total. Each of them displays the work of the heart on a graph.

1. P - ideally, this wave should be positive in the range from 0.12 to two seconds.
2. Q - negative wave, shows the condition of the interventricular septum.
3. R - displays the state of the ventricular myocardium.
4. S - negative wave, shows the completion of processes in the ventricles.
5. T - positive wave, indicates restoration of potential in the heart.

All ECG waves have their own reading characteristics.

P wave

All waves of the electrocardiogram have a certain significance for making the correct diagnosis.

The very first tooth of the graph is called P. It indicates the time between heartbeats. To measure it, it is best to isolate the beginning and end of the tooth and then count the number of small cells. Normally, the P wave should be between 0.12 and two seconds.

However, measuring this indicator in only one area will not give accurate results. To make sure that the heartbeat is even, it is necessary to determine the P wave interval in all parts of the electrocardiogram.

R wave

Knowing how to read an ECG in an easy way, you can understand whether there are heart pathologies. The next important peak on the chart is R. It is easy to find - it is the highest peak on the chart. This will be the positive tooth. Its highest part is marked on the cardiogram as R, and its lower parts as Q and S.

The QRS complex is called the ventricular or sinus complex. In a healthy person, the sinus rhythm on the ECG is narrow and high. The ECG R waves are clearly visible in the figure, they are the highest:

Between these peaks, the number of large squares indicates this indicator is calculated using the following formula:

300/number of large squares = heart rate.

For example, there are four full squares between the peaks, then the calculation will look like this:

300/4=75 heart beats per minute.

Sometimes the cardiogram shows a prolongation of the QRS complex by more than 0.12 s, which indicates a blockade of the His bundle.

PQ tooth spacing

PQ is the interval from the P wave to the Q wave. It corresponds to the time of excitation through the atria to the ventricular myocardium. The normal PQ interval varies at different ages. Usually it is 0.12-0.2 s.

With age, the interval increases. Thus, in children under 15 years of age, PQ can reach 0.16 s. Between the ages of 15 and 18 years, PQ increases to 0.18 s. In adults, this figure is equal to a fifth of a second (0.2).

When the interval lengthens to 0.22 s, they speak of bradycardia.

QT wave interval

If this complex is longer, then we can assume ischemic heart disease, myocarditis or rheumatism. With the shortened type, hypercalcemia may be observed.

ST interval

Normally, this indicator is located at the level of the midline, but can be two cells higher than it. This segment shows the process of restoring depolarization of the heart muscle.

In rare cases, the indicator may rise three cells above the midline.

Norm

The transcript of the cardiogram should normally look like this:

• The Q and S segments must always be below the midline, i.e. negative.
• The R and T waves should normally be located above the midline, i.e. they will be positive.
• The QRS complex should be no wider than 0.12 s.
• Heart rate should be between 60 and 85 beats per minute.
• There should be sinus rhythm on the ECG.
• The R should be higher than the S wave.

ECG for pathologies: sinus arrhythmia

How to read an ECG for various pathologies? One of the most common heart diseases is sinus rhythm disorder. It can be pathological and physiological. The latter type is usually diagnosed in people involved in sports and with neuroses.

With sinus arrhythmia, the cardiogram has the following form: sinus rhythms are preserved, fluctuations in the R-R intervals are observed, but during breath holding the graph is smooth.

With pathological arrhythmia, preservation of the sinus impulse is observed constantly, regardless of breath holding, while wave-like changes are observed at all R-R intervals.

Manifestation of a heart attack on an ECG

When myocardial infarction occurs, changes in the ECG are pronounced. Signs of pathology are:

• increase in heart rate;
• ST segment is elevated;
• there is a fairly persistent depression in the ST leads;
• The QRS complex increases.

In case of a heart attack, the main means of recognizing zones of necrosis of the heart muscle is a cardiogram. It can be used to determine the depth of organ damage.

During a heart attack, the ST segment will be elevated and the R wave will be depressed, giving the ST a cat's back shape. Sometimes, with pathology, changes in the Q wave can be observed.

Ischemia

When it occurs, you can see in which part it is located.

• The location of ischemia at the anterior wall of the left ventricle. Diagnosed with symmetrical pointed T-waves.
• Location at the epicardium of the left ventricle. The T-wave is pointed, symmetrical, and directed downward.
• Transmural type of left ventricular ischemia. T is pointed, negative, symmetrical.
• Ischemia of the left ventricular myocardium. T is smoothed, slightly raised upward.
• Heart damage is indicated by the state of the T wave.

Changes in the ventricles

ECG shows changes in the ventricles. Most often they appear in the left ventricle. This type of cardiogram occurs in people with long-term additional stress, for example, obesity. With this pathology, there is a deviation of the electrical axis to the left, against the background of which the S wave becomes higher than R.

Holter method

How can you learn to read an ECG if it is not always clear which waves are located and how they are located? In such cases, continuous recording of the cardiogram using a mobile device is prescribed. It continuously records ECG data on a special tape.

This examination method is necessary in cases where classical ECG fails to detect pathologies. During a Holter diagnosis, a detailed diary is necessarily kept, where the patient records all his actions: sleep, walks, sensations during activities, all activities, rest, symptoms of the disease.

Typically, data recording occurs within 24 hours. However, there are cases when it is necessary to take readings for up to three days.

ECG interpretation schemes

1. The conductivity and rhythm of the heart are analyzed. To do this, the regularity of heart contractions is assessed, the number of heart rates is calculated, and the conduction system is determined.
2. Axial rotations are detected: the position of the electric axis in the frontal plane is determined; around the transverse, longitudinal axis.
3. The R wave is analyzed.
4. QRS-T is analyzed. In this case, the state of the QRS complex, RS-T, T wave, as well as the Q-T interval are assessed.
5. A conclusion is made.

The duration of the R-R cycle indicates the regularity and normality of the heart rhythm. When assessing heart function, not just one R-R interval is assessed, but all of them. Normally, deviations within 10% of the norm are allowed. In other cases, an incorrect (pathological) rhythm is determined.

To establish pathology, the QRS complex and a certain period of time are taken. It counts the number of times a segment is repeated. Then the same period of time is taken, but further on the cardiogram, it is calculated again. If at equal periods of time the number of QRS is the same, then this is the norm. With different quantities, pathology is assumed, and they focus on the P waves. They must be positive and stand before the QRS complex. Throughout the entire graph, the shape of P should be the same. This option indicates a sinus rhythm of the heart.

With atrial rhythms, the P wave is negative. Behind it is the QRS segment. In some people, the P wave on the ECG may be absent, completely merging with the QRS, which indicates pathology of the atria and ventricles, which the impulse reaches simultaneously.

Ventricular rhythm is shown on the electrocardiogram as a deformed and widened QRS. In this case, the connection between P and QRS is not visible. There are large distances between the R waves.

Cardiac conduction

The ECG determines cardiac conduction. The P wave determines the atrial impulse; normally this indicator should be 0.1 s. The P-QRS interval reflects the overall conduction velocity through the atria. The norm of this indicator should be within 0.12 to 0.2 s.

The QRS segment shows conduction through the ventricles; the normal range is 0.08 to 0.09 s. As the intervals increase, cardiac conduction slows down.

Patients do not need to know what the ECG shows. A specialist should understand this. Only a doctor can correctly decipher the cardiogram and make the correct diagnosis, taking into account the degree of deformation of each individual tooth or segment.

Representatives of both sexes and in any age category face all kinds of pathologies of the cardiovascular system. Timely diagnosis greatly facilitates the selection of appropriate treatment and the process of stabilizing the condition of patients.

For many years, the electrocardiogram has remained the most accessible, but at the same time quite informative method of examining the heart. Performing this procedure involves recording cardiac electrical impulses and graphically recording them in the form of teeth on a special paper film. The data obtained make it possible not only to evaluate the transmission of electrical impulses in the heart, but also to diagnose problems in the structure of the heart muscle.

An ECG allows you to diagnose from minor to critical pathological conditions of the heart. However, without special professional training, a person will not be able to completely decipher the electrocardiogram. Although he can draw certain conclusions, knowing what a normal ECG looks like.

Basic elements of an ECG

The biopotentials of the heart are recorded by fixing the electrocardiograph electrodes on the upper and lower extremities, as well as on the left chest. Thus, it is possible to collect all directions of electrogenesis in the human body. Recording electrodes are placed on different parts of the body and this is what affects the leads. They are standard, single-pole and chest.

Interpretation of an ECG in adults is based on the study of all positive and negative peaks of the cardiogram, their duration, contiguity and other parameters. In the process, the following basic elements of the ECG are analyzed:

• the heart's response to contractions in the form of peaks (teeth);
• isolines between two adjacent teeth (segments);
• complex of teeth + segment (intervals).

After the passage of an electrical impulse through the conduction system of the heart, the rise and fall of the curve line are displayed on the cardiogram, which are designated in capital letters of the Latin alphabet - P, Q, R, S and T. The P wave occurs when the atria are excited, the QRS complex characterizes the excitation of the ventricles of the myocardium, the wave T indicates the process of extinction of excitation and restoration of the original state.

The interval on the electrocardiogram is measured in seconds. It indicates the passage of an impulse through certain parts of the heart. For diagnostic purposes, special attention is paid to the PQ interval (characterizes the time of excitation to the ventricles) and QT (does not have constant values ​​and depends on heart rate).

An ECG segment is a segment of an isoline located between two adjacent peaks. In making a diagnosis, the PQ segments (the time from the end of the P wave to the beginning of the Q wave) and ST segments (normally located on the isoelectric line or slightly deviates from it) are informative. The doctor’s report may also contain not only uppercase, but also lowercase letters of the Latin alphabet. They are also intended to indicate the main elements, but only when the peak does not exceed 5 mm in length.

If an ECG is recorded at a speed of 50 mm/sec, then each small cell (1 mm) on the tape equals 0.02 seconds.

To obtain more accurate information about the state of the myocardium, additional Neb leads can be used

Decryption plan

Decoding the cardiac cardiogram must include the following parameters:

• total direction of the electrical impulse;
• characteristics of heart rhythm and impulse propagation;
• frequency and regularity of heart contractions;
• definition of an electrical pulse generator;
• amplitude of the P wave, PQ interval and QRST complex;
• RST isoline and T wave parameters;
• QT interval parameters.

During the examination of people with problems with the heart and blood vessels, the following pathologies can be identified: bradycardia, tachycardia, arrhythmia, blockades, overload of the ventricles or atria, and damage to the myocardial structure itself.

The description of the ECG conclusion must indicate the following parameters:

• rhythm of heart contractions;
• estimation of distances between peaks;
• number of heart contractions per unit of time;
• EOS position (horizontal/vertical).

Example of a conclusion: “Sinus rhythm with 65 heartbeats per minute. The EOS is in a normal position. No pathological abnormalities were found." But maybe in conclusion, not everything is so smooth: “Sinus rhythm with pronounced tachycardia (100 contractions). Supraventricular untimely depolarization and contraction of the heart or its individual chambers. Incomplete blockade of PNPG. There is a moderate metabolic disorder in the myocardium.”

At the beginning of each electrocardiogram tape there must be a calibration signal, which, when applied to a standard voltage of 1 millivolt, should give a deviation of 10 mm. If it is missing, then the ECG recording is considered incorrect.

As a rule, on an ECG, each lead (12 pieces) is given a specific area

Rhythm of contractions

The main pacemaker of the first order is the sinus node or Keith-Fluck node. But in a number of pathological conditions, the sinus node loses its functionality and then underlying structures begin to replace it.

Possible options for electrocardiographic rhythms:

• With sinus rhythm on the cardiogram (electrode of the left leg (+) and electrode of the right hand (-), each QRS complex is preceded by a P wave going up from the isoline. The amplitude of all peaks is the same.
• Atrial rhythm occurs when the function of the sinus node weakens and impulses begin to emanate from the lower atrial centers. The P wave still occurs before each QRS complex, but in leads with electrodes connected to the left leg (+) and right arm (-) it goes down from the baseline.
• Rhythm of the atrioventricular connection. The impulses in this case propagate retrograde to the atria and antegrade to the ventricles. This rhythm is characterized by the complete absence of P waves on cardiograms or they appear after the QRS complex.
• Ventricular (indioventricular) rhythm is characterized by the presence of dilated and deformed QRS complexes. There is also no classical relationship between P waves and the QRS complex. In this case, the heart rate can be reduced to 40.

If any other structure becomes the pacemaker, then the electrical impulses of the heart, which are cyclical, become confused, and arrhythmia occurs against this background.

Repeating the rhythm multiple times

Heart rate repetition is an ECG indicator that is assessed by comparing the duration of the wave and segment complex (R-R) between several successive cycles. A regular rhythm on a heart cardiogram looks like this - throughout the entire recording, the peaks have the same amplitude and are evenly distributed one after another. The gap between two positive teeth of the complex is assessed by measuring any gaps between them. Electrocardiograph graph paper is very helpful for this.

Heart rate

Heart rate is calculated mathematically. On a tape with a cardiogram, large squares between the rises and falls of the curved line clearly catch the eye. They are counted and if the recording was made at a speed of 50 mm/s, then the number 600 is divided by their number. And if the speed was 25 mm/s, then 300 is substituted for 600.

If the heart rhythm is obviously incorrect, then it is necessary to calculate the minimum and maximum number of contractions of the heart muscle. To do this, the largest and smallest distance between the teeth that arise during excitation of the atria is taken as a basis.

Total EMF vector

On the ECG of the heart, the electrical axis is designated - ∠ α (alpha) and is the total vector of electromotive force (EMF) or ventricular depolarization. The total EMF vector may reflect a normal location, or may be located vertically (in thin patients) or horizontally (in stocky patients).

EOS within normal limits ranges from +30° to +69°, in a vertical position - from +70° to +90°, and in a horizontal position - from 0° to +29°. With a significant deviation of the axis to the right, indicators from +91° to +180° are observed. With a pronounced shift to the left - from 0° to -90°. A persistent increase in blood pressure will shift the total EMF vector to the right, and with heart blockades, both right- and left-sided shifts can be observed.

The table shows the ECG norm in adults

Basic criteria of the norm

If the ECG interpretation in adults is normal, then the conclusion may indicate the following:

• The interval from the beginning of the P wave to the beginning of the ventricular QRS complex is 0.12 seconds.
• The duration of intraventricular excitation (QRS complex) is 0.06 seconds.
• The distance from the beginning of the QRS complex to the end of the T wave is 0.31 seconds.
• The stable frequency of contractions of the heart muscle (RR interval) is 0.6.
• The heart beats at a rate of 75 beats in 60 seconds.
• Normal heart rhythm (the impulse is generated by the sinus node).
• Normogram (normal position of the EOS).

The ECG of a healthy person implies the following norms: sinus heart rate, heart rate above 60, but below 90 beats in 60 seconds, P peak is 0.1 second, PQ interval is in the range of 0.12–0.2 seconds, RS-T segment is on the isoline, the QT interval does not exceed 0.4 seconds.

ECG norms in children are practically no different from adults. However, in young patients, due to a physiological factor, the heart rate is higher than in older patients. In children under 3 years of age, the heart can beat up to 100–110 beats per minute, which is considered quite normal. And already at the age of 3 to 5 years this figure decreases by 10 units. As you get older, your heart rate decreases and in teenagers it is no different from adults.

Decryption stages

Such actions will help determine whether the ECG is normal or not. Expand the tape with the ECG recording and begin to carefully study the graphs. They represent several parallel horizontal lines with positive and negative teeth. In some places, at the moment the recording is interrupted, there are no teeth at some intervals.

The cardiogram is performed in different leads, so each new segment has its own designation (I, II, III, AVL, VI). It is necessary to find the lead in which the positive electrode is fixed on the left leg, and the minus electrode on the right hand and the highest peak in it, and then measure the intervals between them and derive the average value of the indicator. This figure will be useful in further calculation of heart rate in 60 seconds.

Calculations should be carried out taking into account the dimensions of the graph paper (1 large cell = 5 mm, 1 small cell or dot = 1 mm). To determine the characteristics of multiple repetitions of heart contractions, the gaps between the R waves (identical or very different) should be assessed. Then you should sequentially evaluate and measure all complexes of teeth and segments on the cardiogram.

And to understand whether they correspond to the norm, you can use special diagnostic tables. However, it should be remembered that a person without special education can only roughly evaluate the individual elements of the cardiogram and, using tables, check their compliance with the norm. But only a certified specialist in the field of cardiology can make final conclusions based on the ECG and prescribe adequate treatment.

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

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

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

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

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

Decoding of the recorded electrocardiogram.

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

Normal ECG readings.

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

Electrocardiogram in case of myocardial infarction.

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

Heart rhythm disorder.

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

Hypertrophy of the heart.

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

Conclusion.

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

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