Normal human ecg. Description of the ecg norm

ECG interpretation plan - a general scheme for reading the results

• the position of the electrical axis of the heart;
• definition of correctness heart rate and conductivity of the electrical impulse (blockades, arrhythmias are detected);
• determination of the regularity of contractions of the heart muscle;
• determination of heart rate;
• identification of the source of the electrical impulse (determine whether the rhythm is sinus or not);
• analysis of the duration, depth and width of the atrial P wave and the P-Q interval;
• analysis of the duration, depth, width of the complex of teeth of the ventricles of the heart QRST;
• analysis of the parameters of the RS-T segment and the T wave;
• analysis of the parameters of the interval Q - T.

Based on all the studied parameters, the doctor writes a final conclusion on the electrocardiogram. The conclusion may look something like this: “Sinus rhythm with a heart rate of 65. Normal position of the electrical axis of the heart. No pathology has been identified. Or like this: “Sinus tachycardia with a heart rate of 100. A single supraventricular extrasystole. Incomplete blockade right leg bundle of His. Moderate metabolic changes in the myocardium.

• sinus rhythm or not;
• rhythm regularity;
• heart rate (HR);
• position of the electrical axis of the heart.

If any of the 4 pathological syndromes are identified, then indicate which ones - rhythm disturbance, conduction, overload of the ventricles or atria, and damage to the structure of the heart muscle (infarction, scar, dystrophy).

An example of decoding an electrocardiogram

Checking the regularity of heart beats

Calculation of heart rate (HR)

1. Belt speed is 50 mm/s - then HR is 600 divided by the number of squares.

2. The belt speed is 25 mm/s - then the heart rate is 300 divided by the number of squares.

Finding the Source of the Rhythm

ECG interpretation - rhythms

Identification of the pathology of the conduction of an electrical impulse in the structures of the heart

Electrical axis of the heart

Atrial P wave

• positive in I, II, aVF and chest leads (2, 3, 4, 5, 6);
• negative in aVR;
• biphasic (part of the tooth lies in the positive region, and part - in the negative) in III, aVL, V1.

The normal duration of P is no more than 0.1 seconds, and the amplitude is 1.5 - 2.5 mm.

1. High and sharp teeth in II, III, aVF leads appear with hypertrophy of the right atrium (" cor pulmonale»);

2. The P wave with two peaks with a large width in I, aVL, V5 and V6 leads indicates left atrial hypertrophy (for example, a defect mitral valve).

P–Q interval

• I degree: simple prolongation of the P-Q interval with the preservation of all other complexes and teeth.
• II degree: prolongation of the P-Q interval with partial loss of some QRS complexes.
• III degree: lack of communication between the P wave and QRS complexes. In this case, the atria work in their own rhythm, and the ventricles in their own.

Ventricular QRST complex

T wave

Q-T interval

ECG interpretation - norm indicators

5. Heart rate is 70 - 75 beats per minute.

6. sinus rhythm.

7. The electrical axis of the heart is located normally.

Deciphering the ECG in children and pregnant women

Deciphering an electrocardiogram in a heart attack

The most acute stage of myocardial infarction can last for 3 hours - 3 days from the moment of circulatory disorders. At this stage, the Q wave may be absent on the electrocardiogram. If it is present, then the R wave has a low amplitude, or is completely absent. In this case, there is a characteristic QS wave reflecting a transmural infarct. The second sign of an acute infarction is an increase in the S-T segment by at least 4 mm above the isoline, with the formation of one large T wave.

Deciphering the most common ECGs

Also, myocardial hypertrophy can be a consequence of myocardial infarction.

What is an ECG, how to decipher it yourself

From this article you will learn about such a diagnostic method as an ECG of the heart - what it is and what it shows. How is the registration of the electrocardiogram, and who can most accurately decipher it. And also you will learn to independently determine the signs of a normal ECG and the main heart diseases that can be diagnosed by this method.

What is an ECG (electrocardiogram)? This is one of the simplest, most accessible and informative methods for diagnosing heart diseases. It is based on the registration of electrical impulses that occur in the heart, and their graphic recording in the form of teeth on a special paper film.

Based on these data, one can judge not only the electrical activity of the heart, but also the structure of the myocardium. This means that with the help of an ECG, many different heart diseases can be diagnosed. Therefore, an independent interpretation of the ECG by a person who does not have special medical knowledge is impossible.

All that a simple person can do is only to roughly assess the individual parameters of the electrocardiogram, whether they correspond to the norm and what kind of pathology they can talk about. But the final conclusions on the conclusion of the ECG can only be made by a qualified specialist - a cardiologist, as well as a general practitioner or family doctor.

Method principle

The contractile activity and functioning of the heart is possible due to the fact that spontaneous electrical impulses (discharges) regularly occur in it. Normally, their source is located in the uppermost part of the organ (in the sinus node, located near the right atrium). The purpose of each impulse is to pass along the conductive nerve pathways through all departments of the myocardium, inducing their contraction. When an impulse arises and passes through the myocardium of the atria, and then the ventricles, their alternate contraction occurs - systole. During the period when there are no impulses, the heart relaxes - diastole.

ECG diagnostics (electrocardiography) is based on the registration of electrical impulses that occur in the heart. For this, a special device is used - an electrocardiograph. The principle of its work is to capture on the surface of the body the difference in bioelectric potentials (discharges) that occur in different parts of the heart at the time of contraction (in systole) and relaxation (in diastole). All these processes are recorded on a special heat-sensitive paper in the form of a graph consisting of pointed or hemispherical teeth and horizontal lines in the form of gaps between them.

What else is important to know about electrocardiography

Electrical discharges of the heart pass not only through this organ. Since the body has good electrical conductivity, the strength of the excitatory heart impulses is sufficient to pass through all the tissues of the body. Best of all, they spread to the chest in the region of the heart, as well as to the upper and lower limbs. This feature underlies the ECG and explains what it is.

In order to register the electrical activity of the heart, it is necessary to fix one electrode of the electrocardiograph on the arms and legs, as well as on the anterolateral surface of the left half of the chest. This allows you to catch all directions of propagation of electrical impulses through the body. The paths of the discharges between the areas of contraction and relaxation of the myocardium are called cardiac leads and are indicated on the cardiogram as follows:

1. Standard Leads:
   • I - the first;
   • II - second;
   • Ш - the third;
   • AVL (similar to the first);
   • AVF (analogue of the third);
   • AVR (mirror image of all leads).
2. Chest leads (different points on the left half of the chest, located in the region of the heart):

The significance of the leads is that each of them registers the passage of an electrical impulse through a certain part of the heart. Thanks to this, you can get information about:

What is an electrocardiogram

If the heart had the same structure of all its departments, nerve impulses would pass through them at the same time. As a result, on the ECG, each electrical discharge would correspond to only one tooth, which reflects the contraction. The period between contractions (pulses) on the EGC has the form of a flat horizontal line, which is called an isoline.

The human heart consists of the right and left halves, in which the upper section is distinguished - the atria, and the lower - the ventricles. Since they have different sizes, thicknesses and are separated by partitions, the excitatory impulse passes through them at different speeds. Therefore, different teeth are recorded on the ECG, corresponding to a specific section of the heart.

What do the teeth mean

The sequence of propagation of systolic excitation of the heart is as follows:

1. The origin of electropulse discharges occurs in the sinus node. Since it is located close to the right atrium, it is this section that contracts first. With a slight delay, almost simultaneously, the left atrium contracts. On the ECG, such a moment is reflected by the P wave, which is why it is called atrial. It is facing up.
2. From the atria, the discharge passes to the ventricles through the atrioventricular (atrioventricular) node (accumulation of modified myocardial nerve cells). They have good electrical conductivity, so there is normally no delay in the node. This is displayed on the ECG as a P-Q interval - a horizontal line between the corresponding teeth.
3. Excitation of the ventricles. This part of the heart has the thickest myocardium, so the electrical wave passes through them longer than through the atria. As a result, the highest tooth appears on the ECG - R (ventricular), facing up. It may be preceded by a small Q wave that points in the opposite direction.
4. After the completion of the ventricular systole, the myocardium begins to relax and restore energy potentials. On the ECG, it looks like an S wave (facing down) - a complete lack of excitability. After it comes a small T wave, facing up, preceded by a short horizontal line - the S-T segment. They say that the myocardium has fully recovered and is ready to make another contraction.

Because each electrode attached to limbs and chest(lead), corresponds to a certain section of the heart, the same teeth look different in different leads - in some they are more pronounced, and in others less.

How to decipher a cardiogram

Sequential ECG decoding in both adults and children involves measuring the size, length of the teeth and intervals, assessing their shape and direction. Your actions with decryption should be as follows:

• Unfold the paper with the recorded ECG. It can be either narrow (about 10 cm) or wide (about 20 cm). You will see several jagged lines running horizontally, parallel to each other. After a short gap, in which there are no teeth, after the recording is interrupted (1–2 cm), a line with several complexes of teeth begins again. Each such graph displays a lead, so it is preceded by a designation of which lead it is (for example, I, II, III, AVL, V1, etc.).
• In one of the standard leads (I, II, or III) that has the highest R wave (usually the second), measure the distance between three consecutive R waves (R-R-R interval) and determine the average value of the indicator (divide number of millimeters by 2). This is necessary to calculate the heart rate in one minute. Remember that such and other measurements can be made with a ruler with a millimeter scale or counting the distance on the ECG tape. Each large cell on paper corresponds to 5 mm, and each dot or small cell inside it corresponds to 1 mm.
• Evaluate the gaps between the R waves: they are the same or different. This is necessary in order to determine the regularity of the heart rate.
• Sequentially evaluate and measure each wave and interval on the ECG. Determine their compliance with normal indicators (table below).

Important to remember! Always pay attention to the speed of the tape - 25 or 50 mm per second. This is fundamentally important for calculating the heart rate (HR). Modern devices indicate the heart rate on the tape, and the calculation does not need to be carried out.

How to calculate the heart rate

There are several ways to count the number of heartbeats per minute:

1. Typically, an ECG is recorded at a speed of 50 mm/sec. In this case, you can calculate the heart rate (heart rate) using the following formulas:

What does an ECG look like in normal and pathological conditions?

What a normal ECG and wave complexes should look like, what deviations are most common and what they indicate, is described in the table.

How to decipher the ECG analysis, the norm and deviations, pathologies and the principle of diagnosis

Cardiovascular disease is the most common cause of death in post-industrial societies. Timely diagnosis and therapy of the organs of the cardiovascular system helps to reduce the risk of developing heart pathologies among the population.

An electrocardiogram (ECG) is one of the simplest and most informative methods for studying cardiac activity. The ECG records the electrical activity of the heart muscle and displays the information in the form of waves on a paper tape.

ECG results are used in cardiology to diagnose various diseases. It is not recommended to decipher the ECG of the heart on your own, it is better to consult a specialist. However, to get a general idea, it is worth knowing what the cardiogram shows.

Indications for an ECG

In clinical practice, there are several indications for electrocardiography:

With a planned examination, the ECG is a mandatory diagnostic method. There may be other indications, which are determined by the attending physician. If you have any other alarming symptoms, consult a doctor immediately to identify their cause.

How to decipher the cardiogram of the heart?

A strict ECG decoding plan consists of analyzing the resulting graph. In practice, only the total vector of the QRS complex is used. The work of the heart muscle is presented as a continuous line with marks and alphanumeric designations. Any person can decipher the ECG with some preparation, but only a doctor can make the correct diagnosis. ECG analysis requires knowledge of algebra, geometry and understanding of letter symbols.

ECG indicators to which you need to pay attention when deciphering the results:

There are strict indicators of the norm on the ECG, and any deviation is already a sign of abnormalities in the functioning of the heart muscle. Pathology can be excluded only by a qualified specialist - a cardiologist.

ECG analysis

ECG records cardiac activity in twelve leads: 6 limb leads (aVR, aVL, aVF, I, II, III) and six chest leads (V1-V6). The P wave represents the process of atrial excitation and relaxation. The Q,S waves show the phase of depolarization of the interventricular septum. R is a wave indicating depolarization of the lower chambers of the heart, and a T wave is relaxation of the myocardium.

The QRS complex shows the time of depolarization of the ventricles. The time it takes for an electrical impulse to travel from the SA node to the AV node is measured by the PR interval.

Computers built into most ECG devices are capable of measuring the time it takes for an electrical impulse to travel from the SA node to the ventricles. These measurements can help your doctor evaluate your heart rate and j,yfhe;bnm some types of heart block.

Computer programs can also interpret ECG results. And as artificial intelligence and programming improves, they are often more accurate. However, the interpretation of the ECG has a lot of subtleties, so the human factor is still an important part of the assessment.

In the electrocardiogram, there may be deviations from the norm that do not affect the quality of life of the patient. However, there are standards for normal cardiac performance that are accepted by the international cardiology community.

Based on these standards, a normal electrocardiogram in a healthy person is as follows:

• RR interval - 0.6-1.2 seconds;
• P-wave - 80 milliseconds;
• PR interval - milliseconds;
• PR segment - milliseconds;
• QRS complex - milliseconds;
• J-prong: absent;
• segment ST - milliseconds;
• T-prong - 160 milliseconds;
• ST interval - 320 milliseconds;
• the QT interval is 420 milliseconds or less if the heart rate is sixty beats per minute.
• ind. juice – 17.3.

Pathological ECG parameters

The ECG in normal and pathological conditions is significantly different. Therefore, it is necessary to carefully approach the decoding of the cardiogram of the heart.

QRS complex

Any abnormality in the electrical system of the heart causes a lengthening of the QRS complex. The ventricles have more muscle mass than the atria, so the QRS complex is significantly longer than the P wave. The duration, amplitude, and morphology of the QRS complex are useful in detecting cardiac arrhythmias, conduction abnormalities, ventricular hypertrophy, myocardial infarction, electrolyte abnormalities, and other disease states.

Q, R, T, P, U teeth

Pathological Q waves occur when an electrical signal travels through damaged heart muscle. They are considered markers of a previous myocardial infarction.

R-wave depression is usually also associated with myocardial infarction, but it can also be caused by left bundle branch block, WPW syndrome, or hypertrophy of the lower chambers of the heart muscle.

T-wave inversion is always considered abnormal on the ECG tape. Such a wave may be a sign of coronary ischemia, Wellens' syndrome, hypertrophy of the lower cardiac chambers, or a CNS disorder.

An enlarged P wave may indicate hypokalemia and right atrial hypertrophy. Conversely, a reduced P wave may indicate hyperkalemia.

U-waves are most commonly seen with hypokalemia but may also be present with hypercalcemia, thyrotoxicosis, or epinephrine, class 1A and class 3 antiarrhythmic drugs. They are not uncommon in congenital long QT syndrome and intracranial hemorrhage.

An inverted U-wave may indicate pathological changes in the myocardium. Another U-wave can sometimes be seen on the ECG in athletes.

QT, ST, PR intervals

QTc prolongation causes premature action potentials during the late phases of depolarization. This increases the risk of developing ventricular arrhythmias or fatal ventricular fibrillation. Higher rates of QTc elongation are observed in women, older patients, hypertensive patients and in people of small stature.

The most common causes of QT prolongation are hypertension and certain medications. The calculation of the duration of the interval is carried out according to the Bazett formula. With this sign, the interpretation of the electrocardiogram should be performed taking into account the history of the disease. Such a measure is necessary to exclude hereditary influence.

ST interval depression may indicate coronary artery ischemia, transmural myocardial infarction, or hypokalemia.

A prolonged PR interval (greater than 200 ms) may indicate first-degree heart block. Lengthening may be associated with hypokalemia, acute rheumatic fever, or Lyme disease. A short PR interval (less than 120 ms) may be associated with Wolff-Parkinson-White syndrome or Lown-Ganong-Levine syndrome. PR segment depression may indicate atrial injury or pericarditis.

Examples of heart rhythm description and ECG interpretation

Normal sinus rhythm

Sinus rhythm is any heart rhythm in which the excitation of the heart muscle starts from the sinus node. It is characterized by correctly oriented P waves on the ECG. By convention, the term "normal sinus rhythm" includes not only normal P waves, but all other ECG measurements.

ECG norm in adults:

1. heart rate from 55 to 90 beats per minute;
2. regular rhythm;
3. normal PR interval, QT and QRS complex;
4. The QRS complex is positive in almost all leads (I, II, AVF and V3-V6) and negative in aVR.

Sinus bradycardia

A heart rate less than 55 in sinus rhythm is called bradycardia. ECG decoding in adults should take into account all parameters: sports, smoking, medical history. Because in some cases, bradycardia is a variant of the norm, especially in athletes.

Pathological bradycardia occurs with weak sinus node syndrome and is recorded on the ECG at any time of the day. This condition is accompanied by constant fainting, pallor and hyperhidrosis. In extreme cases, with malignant bradycardia, pacemakers are prescribed.

Signs of pathological bradycardia:

1. heart rate less than 55 beats per minute;
2. sinus rhythm;
3. P waves are vertical, consistent, and normal in morphology and duration;
4. PR interval from 0.12 to 0.20 seconds;

Sinus tachycardia

The correct rhythm with a high heart rate (above 100 beats per minute) is called sinus tachycardia. Please note that normal heart rate varies with age, for example, in infants, the heart rate can reach 150 beats per minute, which is considered normal.

Advice! At home, with severe tachycardia, a strong cough or pressure on the eyeballs can help. These actions encourage nervus vagus, which activates the parasympathetic nervous system, causing the heart to beat more slowly.

Signs of pathological tachycardia:

1. Heart rate above 100 beats per minute
2. sinus rhythm;
3. P waves are vertical, consistent and normal in morphology;
4. the PR interval fluctuates between 0.12-0.20 seconds and decreases with increasing heart rate;
5. QRS complex less than 0.12 seconds.

Atrial fibrillation

Atrial fibrillation is an abnormal heart rhythm characterized by rapid and irregular atrial contraction. Most episodes are asymptomatic. Sometimes an attack is accompanied by the following symptoms: tachycardia, fainting, dizziness, shortness of breath, or chest pain. The disease is associated with an increased risk of heart failure, dementia, and stroke.

Signs of atrial fibrillation:

1. Heart rate unchanged or accelerated;
2. P waves absent;
3. electrical activity is chaotic;
4. RR intervals are irregular;
5. QRS complex less than 0.12 seconds (in rare cases, the QRS complex is lengthened).

Important! Despite the above explanations with the interpretation of the data, the conclusion on the ECG should be made only by a qualified specialist - a cardiologist or a general practitioner. Interpretation of the electrocardiogram and differential diagnosis requires higher medical education.

How to "read" myocardial infarction on an ECG?

For students beginning the study of cardiology, the question often arises, how to learn how to read a cardiogram correctly and identify myocardial infarction (MI)? You can “read” a heart attack on a paper tape by several signs:

• elevation of the ST segment;
• peaked T wave;
• deep Q wave or its absence.

In the analysis of the results of electrocardiography, these indicators are first of all identified, and then dealt with others. Sometimes the earliest sign of an acute myocardial infarction is only a peaked T-wave. In practice, this is quite rare, because it appears only 3-28 minutes after the onset of a heart attack.

Peaked T-waves should be distinguished from peak T-waves associated with hyperkalemia. In the first few hours, the ST segments usually rise. Abnormal Q waves may appear within a few hours or after 24 hours.

It is not uncommon to have long-term ECG changes, such as persistent Q waves (in 93% of cases) and peaked T-waves. Stable ST segment elevation is rare, with the exception of ventricular aneurysms.

There are widely researched clinical solutions, such as the TIMI score, which help predict and diagnose myocardial infarction based on clinical data. For example, TIMI scores are often used to predict the condition of patients with symptoms of MI. Based on symptoms and electrocardiographic findings, practitioners can distinguish between unstable angina and MI in the setting emergency care.

Deciphering the ECG in adults and children, the norms in the tables and other useful information

Pathology of the cardiovascular system is one of the most common problems affecting people of all ages. Timely treatment and diagnosis of the circulatory system can significantly reduce the risk of developing dangerous diseases.

To date, the most effective and easily accessible method of studying the work of the heart is an electrocardiogram.

Basic Rules

ECG analysis

Sinus rhythm of the heart

Source of excitation

What is postmyocardial cardiosclerosis and why is it dangerous? Is it possible to cure it quickly and effectively? Are you at risk? Find out everything!

The reasons for the development of cardiosclerosis of the heart and the main risk factors are discussed in detail in our next article.

You can read detailed and comprehensive information about the symptoms of cardiosclerosis of the heart here.

Conductivity

Electric axle

Teeth, segments and intervals

Norm in men and women

Healthy Childhood Outcomes

Dangerous diagnoses

Extrasystole

Arrhythmia

Bradycardia

Tachycardia

Conduction disorder

Learn all about recovery after a heart attack - how to live, what to eat and how to be treated to support your heart?

Is a disability group allowed after a heart attack and what to expect in terms of work? We will tell in our review.

A rare but accurate myocardial infarction of the posterior wall of the left ventricle - what is it and why is it dangerous?

Halter

Treadmill

Phonocardiography

Deciphering the ECG in adults: what do the indicators mean

An electrocardiogram is a diagnostic method that allows you to determine the functional state of the most important organ human body- hearts. Most people at least once in their lives have dealt with a similar procedure. But having received the ECG result in hand, not every person, unless he has a medical education, will be able to understand the terminology used in cardiograms.

What is cardiography

The essence of cardiography is the study of electrical currents that occur during the work of the heart muscle. The advantage of this method is its relative simplicity and availability. Strictly speaking, it is customary to call a cardiogram the result of measuring the electrical parameters of the heart, displayed in the form of a time graph.

Creation of electrocardiography in its modern form is associated with the name of the Dutch physiologist of the early 20th century, Willem Einthoven, who developed the basic methods of ECG and the terminology used by doctors to this day.

Thanks to the cardiogram, it is possible to obtain the following information about the heart muscle:

• Heart rate,
• Physical state of the heart
• The presence of arrhythmias
• The presence of acute or chronic damage to the myocardium,
• The presence of metabolic disorders in the heart muscle,
• The presence of violations of electrical conductivity,
• The position of the electrical axis of the heart.

Also, the electrocardiogram of the heart can be used to obtain information about some vascular diseases that are not related to the heart.

An ECG is usually performed in the following cases:

• Feeling an abnormal heartbeat;
• Attacks of shortness of breath, sudden weakness, fainting;
• Heartache;
• Murmurs in the heart;
• Deterioration of the condition of patients with cardiovascular diseases;
• Passage of medical examinations;
• Medical examination of people over 45 years old;
• Inspection before the operation.

• pregnancy;
• Endocrine pathologies;
• Nervous diseases;
• Changes in blood counts, especially with an increase in cholesterol;
• Over 40 years of age (once a year).

Where can I get a cardiogram?

If you suspect that something is wrong with your heart, you can contact a general practitioner or cardiologist to give you a referral for an ECG. Also, on a paid basis, a cardiogram can be done at any clinic or hospital.

Procedure procedure

The ECG recording is usually performed in the supine position. To take a cardiogram, a stationary or portable device is used - an electrocardiograph. Stationary devices are installed in medical institutions, and portable ones are used by emergency teams. The device receives information about the electrical potentials on the surface of the skin. For this, electrodes are used, attached to the chest and limbs.

These electrodes are called leads. On the chest and limbs, 6 leads are usually installed. The chest leads are designated V1-V6, the leads on the limbs are called the main (I, II, III) and enhanced (aVL, aVR, aVF). All leads give a slightly different pattern of fluctuations, however, summing up the information from all the electrodes, you can find out the details of the work of the heart as a whole. Sometimes additional leads (D, A, I) are used.

Usually, the cardiogram is displayed as a graph on paper containing millimeter markings. Each lead-electrode has its own schedule. The standard belt speed is 5 cm/s, other speeds can be applied. In the cardiogram displayed on the tape, the main parameters, norm indicators and the conclusion generated automatically can also be indicated. Also, data can be recorded in memory and on electronic media.

After the procedure, it is usually required to decipher the cardiogram by an experienced cardiologist.

Holter monitoring

In addition to stationary devices, there are also portable devices for daily (Holter) monitoring. They are attached to the patient's body along with electrodes and record all the information received over a long period of time (usually within a day). This method gives much more complete information about the processes in the heart compared to a conventional cardiogram. So, for example, when taking a cardiogram in stationary conditions, the patient must be at rest. Meanwhile, some deviations from the norm can manifest themselves during physical exertion, in sleep, etc. Holter monitoring provides information about such phenomena.

Other types of procedures

There are several other methods of carrying out the procedure. For example, this is monitoring with physical activity. Abnormalities are usually more pronounced on the exercise ECG. The most common way to provide the body with the necessary physical activity is a treadmill. This method is useful in cases where pathologies can manifest themselves only in case of increased work of the heart, for example, if coronary disease is suspected.

With phonocardiography, not only the electrical potentials of the heart are recorded, but also the sounds that arise in the heart. The procedure is prescribed when it is necessary to clarify the occurrence of heart murmurs. This method is often used for suspected heart defects.

The patient must be calm during the procedure. Between physical activity and the procedure must pass a certain period of time. It is also not recommended to undergo the procedure after eating, drinking alcohol, caffeinated drinks or cigarettes.

Causes that can affect the ECG:

• Times of Day,
• electromagnetic background,
• Physical exercise,
• food intake,
• The position of the electrodes.

Prong types

First, let's talk a little about how the heart works. It has 4 chambers - two atria and two ventricles (left and right). The electrical impulse, due to which it is reduced, is formed, as a rule, in the upper part of the myocardium - in the sinus pacemaker - the nerve sinoatrial (sinus) node. The impulse propagates down the heart, first affecting the atria and causing them to contract, then it passes through the atrioventricular ganglion and another ganglion - the bundle of His, and reaches the ventricles. The main burden of pumping blood is taken by the ventricles, especially the left one, which is involved in big circle circulation. This stage is called contraction of the heart or systole.

After the contraction of all parts of the heart, the time comes for their relaxation - diastole. Then the cycle repeats again and again - this process is called the heartbeat.

The state of the heart, in which there is no change in the propagation of impulses, is reflected on the ECG in the form of a straight horizontal line, called the isoline. The deviation of the graph from the isoline is called a tooth.

One heartbeat on an ECG contains six teeth: P, Q, R, S, T, U. The teeth can be directed both up and down. In the first case, they are considered positive, in the second - negative. The Q and S waves are always positive, and the R wave is always negative.

The teeth reflect the different phases of the contraction of the heart. P reflects the moment of contraction and relaxation of the atria, R - excitation of the ventricles, T - relaxation of the ventricles. Special designations are also used for segments (gaps between adjacent teeth) and intervals (sections of the graph, including segments and teeth), for example, PQ, QRST.

Correspondence of the stages of heart contraction and some elements of cardiograms:

• P - atrial contraction;
• PQ - horizontal line, the transition of the discharge from the atria through the atrioventricular node to the ventricles. The Q wave may be absent normally;
• QRS - ventricular complex, the element most often used in diagnostics;
• R - excitation of the ventricles;
• S - relaxation of the myocardium;
• T - relaxation of the ventricles;
• ST - horizontal line, myocardial recovery;
• U - may be absent in the norm. The reasons for the appearance of a tooth have not been clearly elucidated, however, the tooth is valuable for diagnosing certain diseases.

Below are some ECG abnormalities and their possible explanations. This information, of course, does not negate the fact that it is more expedient to entrust the decoding to a professional cardiologist who knows better all the nuances of deviations from the norms and related pathologies.

Deciphering ecg for dummies

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 in the early stages in order to take 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. Normal decryption The ECG provides that all indicators must be calculated to the 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 must have a constant shape, the distance between R-R indicators and R-R - be the same, and the number of contractions - 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 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 group of teeth under normal conditions is equal to s.
2. The Q-T wave group displays the duration of the ventricular contraction. Norm -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 instance, vertical position often found in thin people, and horizontal - in full.

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.

Basic Rules

When studying the results of a patient's examination, doctors pay attention to such components of the ECG as:

There are strict normal parameters for each line on the ECG tape, the slightest deviation from which may indicate a violation 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 determine by the highest 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.

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 duration of one mm by the length of the segment R-R, you can get the 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 nervous system hearts.

In some cases, other nodes (atrial, ventricular, atrioventricular) can take on the role of the pacemaker. You can determine this by examining the P wave - 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 axle

An indicator based on the process of excitation of the ventricles. Mathematical analysis of the Q, R, S waves in leads I and III makes it possible 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 is the process of excitation of the ventricles.
• T is 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 is the duration of ventricular contraction.
• ST is the time of full 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 identified by ECG readings when decrypting?

Extrasystole

This phenomenon is characterized by a failure of the heart rhythm. 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 by a change in frequency 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 beats per minute.

Tachycardia

The opposite phenomenon, characterized by an increase in heart rate of more than 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 are weakened, a person may feel weakness, dizziness caused by oppression 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 times of the 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.
• Eating. 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

A method of long-term study of the work of the heart, possible thanks to a portable compact tape recorder that can record the 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 physical activity. It is most commonly used for risk assessment. possible pathologies not detected on a standard ECG, as well as when prescribing a course of rehabilitation to patients who have had a heart attack.

Phonocardiography

Allows you to 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 you should follow the doctor's recommendations.

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”:

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?

• The conduction of the heart impulses is displayed here.
• From this diagram, you can evaluate the correctness and periodicity of cardiac oscillations.
• It contains information about the intensity of the processes of blood filling and heart contractions.
• According to the pattern of electrical impulses, it is possible to assess whether an increase in any of the sections of the heart has occurred.
• Also, according to the ECG, you can determine whether there have been heart lesions and evaluate not only their degree, but also the time when they occurred.

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 taking such medications.

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.

The diagnostic technique includes attaching four electrodes to the hands and ankles and placing 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 chronic illness like 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 itself attentive attitude. A reliable result occurs when the analysis is carried out accurately and reliably.

reading teeth

There are five various kinds teeth on the cardiogram. They are designated in Latin letters: S, P, T, Q and R. Each of them characterizes the work of one of the departments 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 usually amounts to contractions 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.

Normal indicators for adults:

• 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 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:

• One of the main ones is the inapplicability of such diagnostics for heart diseases that do not have their own stable picture. If the pains are temporary, and the cardiogram is not done at the moment when they occur, then it is not able to show anything.
• There are characteristics of cardiac activity that it does not diagnose. One example is the presence and characteristics of a heart murmur.
• Heart disease or the presence of a tumor in this place cannot be determined only on the basis of the use of an ECG. For such an analysis, it will be necessary to conduct an ultrasound diagnosis.
• In order for the use of an electrocardiogram to give a sufficiently reliable result, it is important to make a diagnosis also on the basis of clinical data.

This is due to the fact that a different clinical picture of the state of the human body can lead to similar changes in the activity of the heart, which were determined using an ECG.

Pathologies in the interpretation of the ECG can be determined according to the available descriptions various options cardiogram. 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. The price of an ECG with decoding is approximately 1,500 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.

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 the limits. in a 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 correcting 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. in a 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 internal organs and 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 functional diagnostics 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 the films of electrocardiography, on which medical conclusions are written. With their diversity, these records can bring to panic disorder even the most balanced, but ignorant person. 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

• When describing an ECG, as a rule, indicate the heart rate (HR). The norm is from 60 to 90 (for adults), for children (see table)
• Further, various intervals and teeth with Latin designations are indicated. (ECG with interpretation, see Fig.)

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 tops 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 prosperous 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 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 over 90 per minute - 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-term 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.

Received ventricular extrasystoles divided 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.

• Grade 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

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 in detecting ECG signs tachysystole of a permanent form of atrial fibrillation is a decrease in 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, syndrome of weakness of the sinus node, 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 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 may occur as functional disorders, but are more often the result of drugs or alcohol intoxication And organic diseases hearts. 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. From pathological conditions it is more characteristic of overloads of the right ventricle (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 violations of water and electrolyte balance (with vomiting or diarrhea), taking drugs (diuretics), 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). Distinctive feature such changes are reversible. 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 causes leading to the same type ECG changes, do not allow a non-specialist to interpret even the 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 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 equal to ms.

The duration of ventricular contraction can be determined by measuring the Q-T interval. The norm is 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 than 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 than 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 equal to 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.

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 age and general condition 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.

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. Such diagnostic method 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 surgical interventions, 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 pulse, 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. clinical picture does not give 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 one. 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 area of ​​necrosis is accompanied by changes complex Q-R-S, resulting in a deep Q wave;
• the damage zone is characterized by displacement (elevation) segment S-T, 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.

ECG - a method of functional study of the heart, based on graphical recording of changes in time of the potential difference of the electric field (biopotentials) that occur on the surface of the excitable heart tissue or in the surrounding conductive medium during the propagation of an excitation wave through the heart.

Electrocardiogram - graphic curve recorded during the ECG.

Elements of an electrocardiogram

Teeth P,Q,R,S,T,U. U wave is not always detected

Intervals: PQ, QT, RR, ST

Complex: QRST

Prong P- reflects depolarization and atrial excitation. Height 0.5-2.2 mm, duration 0.07-0.1.

PQ segment: at this time, both atria are completely covered by excitation and do not give a potential difference. Duration 0.12-0.2

ComplexQRS-reflects depolarization and excitation of the ventricles (ventricular complex). It is formed by one or more positive prongs, called R waves, and negative prongs, called Q and S. Duration 0.06–0.10 s. Amplitude in the leads from the extremities > 5 mm, in the chest leads - 8 mm, but less than 25 mm.

ST segment: during the period of complete coverage of the excitation of the ventricles, there is no potential difference and an isoelectric line is recorded on the ECG.

T wave associated with the third phase of ventricular repolarization. Height 6 mm, duration 0.10-0.25.

TR interval-isoelectric line, corresponds to the diastolic phase, when the entire heart is uniformly polarized and there is no potential difference.

QT interval– electrical ventricular systole = 0.35–0.44 s

U wave– the origin is still unknown. The presence of a pronounced U wave of increased amplitude indicates hypokalemia.

The founders of the ecg

August Waller- proved that there is a potential difference between the electrodes on the surface of the body

einthoven- recorded a classic ecg, sodao standard leads, gave names to the teeth.

Samoilo for the first time I took an ECG in Russia (Kazan). I organized an ECG room in Kazan.

wilson- proposed unipolar leads

Goldberger- modified the leads proposed by Wilson, made them reinforced.

88. Ecg leads (bipolar and unipolar): standard, reinforced from the limbs and chest

In 1913, Einthoven proposed to record an ECG 3 standard leads. These electrodes /2-pole/ register the potential difference between two points of the body. Standard leads are designated I, II, III:

I st. – right and left hands (red marking),

II Art. – right arm and left leg (yellow marking),

III Art. - left hand and leg (green marking).

Reinforced Leads

Proposed in 1942 by Goldberger. These are unipolar leads, they have an indifferent electrode whose potential is close to zero and an active electrode. The active electrode is connected to the positive pole of the galvanometer, and the indifferent one to the negative. The so-called. is used as a negative electrode. a combined electrode formed by connecting electrodes from two other limbs.

Three enhanced leads are used in electrocardiography. from limbs– leads aVR, aVl and aVF.

The designation comes from the first letters of English words: A (augmented) - reinforced; V (voltage) - voltage; R, L, F (right, left, foot) - right left, leg.

These are reinforced leads from right hand, left arm and left leg.

chest leads

The chest leads were proposed by Wilson in 1934 and register the potential difference between the active electrode placed on different parts of the chest and the combined electrode from three limbs, the combined potential of which is zero. The chest unipolar leads are denoted by the letter V, which reflects the physical symbol of tension. For the most part, 6 chest leads are recorded: from V1 to V6.

Lead V1 - the electrode is placed in the 4th intercostal space to the right of the sternum (red marking).

Lead V2 - the electrode is located in the 4th intercostal space to the left of the sternum (yellow marking).

Lead V3 is halfway between V2 and V4 (green marking).

Lead V4 is in the 5th intercostal space along the midclavicular line (brown marking).

Lead V5 - the electrode is located on the same horizontal line as the V4 electrode, but along the anterior axillary line (black marking).

Lead V6 - the electrode is located on the same horizontal line as V4, V5, but along the midaxillary line (purple marking).

89. Normal ECG: P wave formation mechanism; indicators characteristic of the P wave are normal. The P wave is a summary display of the passage of the sinus impulse through the conduction system of the atria with alternate excitation of the first right (ascending P wave knee) and then the left (descending P wave knee) atria. The atrial P wave should be: positive in I, II, aVF and chest leads (2, 3, 4, 5, 6); negative in aVR; biphasic (part of the tooth lies in the positive region, and part - in the negative) in III, aVL, V1. The normal duration of P is no more than 0.1 seconds, and the amplitude is 1.5 - 2.5 mm.

90. Normal ECG: mechanism of PQ interval formation; indicators characteristic of the PQ interval are normal. Simultaneously with excitation of the atria, the impulse leaving the sinus node is sent to the atrioventricular (atrioventricular) junction. In it, a physiological delay of the impulse occurs (slowing down the speed of its conduction). Passing through the atrioventricular junction, the electrical impulse does not cause excitation of the adjacent layers, therefore, excitation peaks are not recorded on the electrocardiogram. The recording electrode draws a straight line, called the isoelectric line.

It is possible to evaluate the passage of an impulse along the atrioventricular connection in time (for how many seconds the impulse passes this connection). This is the genesis of the P-Q interval.

The PQ interval has a normal duration of 0.12 to 0.2 seconds. An increase in the duration of the PQ interval is a reflection of atrioventricular block. 91. Normal ECG: mechanism of QRS complex formation; indicators characteristic of the QRS complex are normal. Continuing its path along the conduction system of the heart, the electrical impulse reaches the conduction pathways of the ventricles, represented by the His bundle system and Purkinje fibers. Passing through this system, the electrical impulse excites the ventricular myocardium. This process is displayed on the electrocardiogram by the formation (recording) of the ventricular QRS complex. It should be noted that the ventricles of the heart are excited in a certain sequence. First, the interventricular septum is excited for 0.03 s. The process of its excitation leads to the formation of a Q wave on the ECG curve. Then the apex of the heart and the areas adjacent to it are excited. So the R wave appears on the ECG. The excitation time of the apex is on average 0.05 s. Lastly, the base of the heart is excited. The consequence of this process is the registration of the S wave on the ECG. The duration of excitation of the base of the heart is about 0.02 s. Thus, the above Q, R and S waves form a single ventricular QRS complex, with a total duration of 0.10 s.

92. ECG is normal: the mechanism of formation of the ST segment; indicators characteristic of the ST segment are normal. Having engulfed the ventricles with excitation, the impulse that began its journey from the sinus node dies out, because the myocardial cells cannot remain excited for a long time. In them, the processes of restoring their original state, which was before excitation, begin.

The processes of extinction of excitation and restoration of the initial state of myocardiocytes are also recorded on the ECG.

The electrophysiological essence of these processes is very complex, here the rapid entry of chloride ions into an excited cell, the coordinated operation of the potassium-sodium pump are of great importance, there is a phase of rapid extinction of excitation and a phase of slow extinction of excitation, etc. All the complex mechanisms of this process are usually combined by one concept - repolarization processes. For us, the most important thing is that the processes of repolarization are displayed graphically on the ECG by the S-T segment and the T wave.

93. Normal ECG: mechanism of T wave formation; indicators characteristic of the T wave are normal.T wave- reflects the cycle of repolarization (recovery) of the ventricles of the heart muscle. It begins, as a rule, on the isoline, where the ST segment passes into it. The T wave is normally not serrated and positive, and its anterior part is flatter. The electrical axis of the T wave is usually the same direction as the axis of the QRS complex (the deviation is no more than 60 °). Therefore, in those leads where the QRS complex is represented by an R wave, the T wave is positive. In those leads where the S wave dominates, the T wave may be negative. 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.

Normally, the T wave is always positive in leads I, II, and usually in aVL, aVF (may be flattened or biphasic);

The T wave may be negative in enhanced lead aVL and standard lead III;

Normal T I > T III ;

The T wave is always negative in lead aVR;

T wave in chest lead V1 can normally be negative or flattened;

Normal T V6 >T V1.

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

Indications for an ECG

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

• The patient's complaints about high pressure, retrosternal pain and other symptoms indicating cardiac pathology;
• Deterioration of well-being of a patient with a previously diagnosed cardiovascular disease;
• Deviations in laboratory blood tests - high cholesterol, prothrombin;
• In the complex of preparation for the operation;
• Detection of endocrine pathology, diseases of the nervous system;
• After severe infections with a high risk of heart complications;
• For prophylactic purposes in pregnant women;
• Examination of the health status of drivers, pilots, etc.

ECG decoding - numbers and Latin letters

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

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

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

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

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

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

Sometimes a U impulse is registered behind the T wave, indicating the parameters of the electric charge carried away with the blood.

Interpretation of ECG indicators - the norm in adults

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

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

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

In the usual conduct of the study (recording speed - 50 mm / s), the decoding of the ECG in adults is performed according to the following calculations: 1 mm on paper when calculating the duration of the intervals corresponds to 0.02 sec.

Positive P wave (standard leads) and the next one normal complex QRS means normal sinus rhythm.

ECG norm in children, decoding

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

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

An example of an ECG with arrhythmias

According to deviations in the cardiogram, a qualified cardiologist can not only diagnose the nature of a heart disease, but also fix the location of the pathological focus.

Arrhythmias

Distinguish the following violations of cardiac rhythm:

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

EOS Position Deviation

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

When the EOS is shifted to the left (30-90º) and the pathological ratio of the height of the S and R teeth is diagnosed, left ventricular hypertrophy, blockade of the leg of the n. His. EOS deviation indicates a heart attack, pulmonary edema, COPD, but it also happens in the norm.

Conduction system disruption

The following pathologies are most often recorded:

• 1 degree atrioventricular (AV-) block - PQ distance more than 0.20 s. After each R, a QRS follows naturally;
• Atrioventricular blockade 2 tbsp. - a gradually lengthening PQ during the ECG sometimes displaces the QRS complex (Mobitz 1 deviation) or a complete prolapse of the QRS is recorded against the background of a PQ of equal length (Mobitz 2);
• Complete blockade of the AV node - atrial HR is higher than the ventricular FR. PP and RR are the same, PQ are different lengths.

Selected heart diseases

The results of the ECG decoding can provide information not only about what happened heart disease, but also pathologies of other organs:

1. Cardiomyopathy - atrial hypertrophy (usually left), low-amplitude teeth, partial blockade n. Gisa, atrial fibrillation or extrasystoles.
2. Mitral stenosis - the left atrium and right ventricle are enlarged, the EOS is rejected to the right, often atrial fibrillation.
3. Mitral valve prolapse - flattened/negative T wave, some QT prolongation, depressive ST segment. Various rhythm disturbances are possible.
4. Chronic obstruction of the lungs - EOS to the right of the norm, low-amplitude teeth, AV blockade.
5. CNS damage (including subarachnoid hemorrhage) - pathological Q, wide and high-amplitude (negative or positive) T wave, pronounced U, long QT duration of rhythm disturbance.
6. Hypothyroidism - long PQ, low QRS, flat T wave, bradycardia.

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

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

You should not sound the alarm if you found pathological changes in the ECG handed out. It should be remembered that some deviations from the norm occur in healthy people.

If the electrocardiogram revealed any pathological processes in the heart, you will definitely be assigned a consultation with a qualified cardiologist.