ECG norm and pathology interpretation. How to read an ECG? How to decipher an electrocardiogram yourself? What does the ECG show? Changes in electrocardiogram parameters while the patient is taking certain medications

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

Electrocardiography is a science that studies the rules of the procedure, ways to interpret the results obtained, and explains unclear points and situations. With the development of the Internet, you can even decipher an ECG yourself, using special knowledge.

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

Heart rate and heart rate are assessed. In a 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. Special formulas are used here.

The normal QT interval is 390 - 450 ms. If the interval is violated, if it lengthens, the diagnostician may suspect atherosclerosis, rheumatism or myocarditis, as well as coronary heart disease in the patient. Also, the interval may shorten, and this indicates the presence of hypercalcemia. These parameters are calculated using a specialized automatic program that provides reliable results.

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, an axis deviation is noticed, defects in the functioning 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 this interval shifts, it is customary to talk about a conduction defect, or it is also called bundle branch block. In case of incomplete blockade, RV or LV hypertrophy can be suspected depending on the location of the line on the ECG. The transcript describes ST particles, which reflect the time of restoration 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 asymmetrical and directed upward. It should be longer than the QRS complex.

Only doctors specially involved in this can correctly decipher ECG indicators, 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 diagnostic procedure describe various characteristics the work of the heart muscle, which is 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.
• P - description of the work of the atria. It may well indicate atrial hypertrophy. In a healthy person, the norm is 0.1 s.
• QRS - ventricular complex. In normal condition, 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 value should be no more than 0.45 s.
• RR - 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: interpretation and main diagnosed diseases

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

Atrial fibrillation is characterized by irregular contractions of the muscle, which can be completely different. This violation is dictated by the fact that the clock 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 are not fully filled with incoming blood, which causes oxygen starvation, which affects all organs in the human body.

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 (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, the ventricles (usually 200 per minute). This is atrial flutter, which often occurs already in the acute phase. But at the same time, the patient tolerates it more easily than flickering. Blood circulation 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. When a person is examined, fluttering 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 can also be the result of intoxications of various types (due to alcohol or taking medicines), as well as various diseases.

There are several types of disorders that a heart cardiogram shows. Deciphering these violations is possible based on 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 body.

Atrioventricular (AV block) - 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 degree, which means the blood flow defect 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 compression of the atria remains without compression of the ventricles;
• III degree(absolute transverse block) - the atria and ventricles are compressed independently of each other, which is clearly shown by deciphering the cardiogram.

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

Myocardial hypertrophy is clearly shown by a cardiac cardiogram. Interpretation on the electrocardiogram - this condition shows the thickening of individual areas of the heart muscle and stretching of the chambers of the heart. This happens with regular chronic overload of the body.

• Syndrome of early ventricular repolarization. Often this is the norm for professional athletes and people with congenitally large body weight. Clinical picture does not give and often goes away without any changes, so the interpretation of the ECG becomes more complicated.
• Various diffuse disorders in the myocardium. They indicate a myocardial nutritional disorder, as a consequence of dystrophy, inflammation or cardiosclerosis. The disorders are quite susceptible to treatment, and are often associated with a disorder of the body’s water-electrolyte balance, taking medical supplies, heavy physical activity.
• Non-individual changes in ST. A clear symptom of a myocardial supply disorder, without a bright oxygen starvation. Occurs during hormone imbalance and electrolyte imbalance.
• Distortion along the T wave, ST depression, low T. The cat's back on the ECG shows the state of ischemia (oxygen starvation of the myocardium).

In addition to the disorder itself, their position in the heart muscle is also described. Main feature such disorders is their reversibility. 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 yourself in this case. If a heart attack is suspected, additional studies are performed.

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

• Stage: acute, acute, subacute and cicatricial. Duration from 3 days to lifelong 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 heart rate description options

ECG results provide an opportunity to look at the state of a person’s heart. Exist different ways rhythm decoding.

Sinus- This is the most common signature on the electrocardiogram. If no other indicators are indicated besides heart rate, this is the most successful forecast, which means 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 existing defects and deviations from the norm. There is also atrial, ventricular or atrioventricular rhythm, which show which cells of specific parts of the heart set the rhythm.

Sinus arrhythmia- often normal in young adults and children. This rhythm is characterized by exit from the sinus node. However, the intervals between heart compressions are different. This is often associated with physiological disorders. Sinus arrhythmia should be carefully monitored by a cardiologist to avoid development serious illnesses. This is especially true for persons 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 compression 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. This rhythm can manifest itself in people who are professionally involved in sports. Their ECG waves are different from those of an ordinary person.

Persistent bradycardia can characterize weakness of the sinus node, manifested in such cases by more rare contractions at any time of the day and under any condition. If a person experiences pauses during contractions, then surgical intervention on installation of the stimulator.

Extarsystole. This is a rhythm defect, which is characterized by extraordinary compressions outside the sinus node, followed by ECG results show a pause of increased length, called compensatory. The patient feels the heartbeat as uneven, chaotic, too fast or too slow. Sometimes patients are bothered by pauses in heart rhythm. Often there is a feeling of tingling or unpleasant tremors behind the breastbone, 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 humans.

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

May occur after drinking alcoholic beverages, coffee, or energy drinks. In this case, the condition is temporary and goes away quite quickly. The pathological appearance of this condition is characterized by periodic heartbeats that bother a person at rest.

The causes of the pathological appearance may be increased body temperature, various infectious diseases, blood loss, being without water for a long time, anemia, etc. Doctors treat the underlying disease, and tachycardia is stopped only when the patient has a heart attack or acute coronary syndrome.

Paroxysmal tachycardia- in this condition, a person experiences cardiopalmus, 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 condition is a defect in the passage of electrical impulses in the conductive system. This pathology quite treatable.

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

• Holding your breath.
• Forced cough.
• Dive into cold water faces.

WPW syndrome- this is a subspecies of ventricular tachycardia. The main provocateur of an attack is an additional nerve bundle, which is located between the atria and ventricles. To eliminate this defect, surgery or drug treatment is required.

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

Atrial fibrillation - may be characterized by attacks or be permanent. The 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. ECG of the heart plays a very important role in the process of identifying abnormalities in the functioning of the heart, the most terrible of which is considered to be myocardial infarction. Necrotic zones of infarction can be diagnosed exclusively using electrocardiogram data. Electrocardiography also determines the depth of damage to the heart muscle.

ECG norms for a healthy person: men and women

ECG standards for children

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

Signs of myocardial infarction on an ECG include:

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

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

How to decipher a heart cardiogram yourself

Not everyone knows how to decipher a heart cardiogram on their own. However, with 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 heart rate indicators. 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 (faster rhythm) or bradycardia (slower rhythm).

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

1. Prolongation of the QT interval indicates development coronary disease heart disease, rheumatic disease, sclerotic disorders. A shortening of the interval indicates hypercalcemia.
2. An altered Q wave is a signal of myocardial dysfunction.
3. Sharpening and increased height of the R wave indicates right ventricular hypertrophy.
4. A split and widened P wave indicates left atrial hypertrophy.
5. An increase in the PQ interval and disruption of impulse conduction occurs with atrioventricular block.
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 acute heart attack; a decrease in the segment registers ischemia.

The cardiac ruler consists of divisions (scales) defining:

• 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 have for independently deciphering the ECG.

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

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

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

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

There are electronic sensors that can record ECG parameters on HDD system unit and, if necessary, display this data on the monitor or print it on the required paper sizes.

Decoding of the recorded electrocardiogram.

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

Normal ECG readings.

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

Electrocardiogram in case of myocardial infarction.

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

Heart rhythm disorder.

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

Hypertrophy of the heart.

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

Conclusion.

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

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Electrocardiography is considered the most simple method determining the quality of the heart, both in normal and pathological conditions. The essence of this method is to capture and record the electrical impulses of the heart that arise during its operation.

But in order to determine the degree of violation, it is necessary ECG interpretation heart, since the recording of these impulses is carried out using a specific graphic image for a certain time.

Indications for ECG:

1. For preventive purposes;
2. Directed determination of the frequency of contractions of the heart muscle and the rhythm of the organ;
3. Definition of acute and chronic failure hearts;
4. Revealing various violations conductivity inside the heart;
5. To determine the physical condition of the heart;
6. Diagnostics ;
7. Obtaining information about pathologies that occur outside the heart (for example, complete or partial).

Principles of ECG interpretation

The electrocardiogram schematically shows three main indicators:

1. Teeth are convexities with an acute angle, directed upward or downward and are designated P, Q, R, S, T;
2. Segments – are the distance between nearby teeth;
3. Interval – a gap that includes both a tooth and a segment.

Thanks to the above indicators, the cardiologist determines the level of contraction and recovery of the heart muscle. In addition to these indicators, during an electrocardiogram, the electrical axis of the heart can also be determined, which indicates the approximate location of the organ in chest cavity. The latter depends on the constitution of the human body and chronic pathology. The electrical axis of the heart can be: normal, vertical and horizontal.

Main indicators of ECG decoding

When deciphered, the norm indicators will be as follows:

1. The distance between the R and R waves should be even throughout the entire length of the cardiogram;
2. The intervals between PQRST should be from 120 to 200 m/s, graphically this is determined by 2-3 squares. This is an indicator of the passage of the impulse through all parts of the heart from the atria to the ventricles;
3. The interval between Q and S indicates the passage of the impulse through the ventricles (60-100 m/s);
4. The duration of ventricular contractility is determined using Q and T, normally 400-450 m/s;

At the slightest shift from these parameters, one can judge the onset or development of a pathological process in the heart muscle. Such parameters change especially pronouncedly in rheumatism.

It should also be noted that in some cases, ECG interpretation standards may change slightly due to the presence of certain disorders that are considered normal, since their presence does not affect the development of heart failure (for example, respiratory arrhythmia). It is important to note that for ECG decoding in adults, the norm can be presented in different tables describing the speed of passage between the elements of the cardiogram.

ECG decoding for adults norm in the table

ECG decoding norm table

Such tables are an official document for determining possible pathological changes in the heart muscle.

Video: ECG interpretation

With all kinds of pathologies of cardio-vascular system representatives of both sexes and in any age category face. Timely diagnosis greatly facilitates the selection of appropriate treatment and the process of stabilizing the condition of patients.

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

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

Basic elements of an ECG

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

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

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

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

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

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

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

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

Decryption plan

Decoding the cardiac cardiogram must include the following parameters:

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

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

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

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

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

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

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

Rhythm of contractions

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

Possible options electrocardiographic rhythms:

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

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

Repeating the rhythm multiple times

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

Heart rate

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

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

Total EMF vector

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

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

The table shows the ECG norm in adults

Basic criteria of the norm

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

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

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

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

Decryption stages

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

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

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

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

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

An ECG study consists of the following indicators:

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

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

How to decipher a cardiogram

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

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

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

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

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

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

Designations of chest leads:

Teeth, segments and intervals

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

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

How to count your heart rate

The heart rate calculation scheme looks like this:

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

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

Photo gallery

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

What is an abnormal ECG

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

Abnormal ECG results may indicate the following problems:

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

What does an ECG look like normally and with pathology?

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

What kind of cardiogram should a healthy person have?

Indications of a good cardiogram for an adult:

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

Indicators in adults

An example of a normal ECG in adults:

Indicators in children

Electrocardiogram parameters in children:

Rhythm disturbances during ECG interpretation

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

Arrhythmias

Heart rhythm disturbances can be:

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

Deviation of EOS position

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

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

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

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

Violation of the conduction system

The ECG conclusion may include the following conduction function pathologies:

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

Selected heart diseases

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

Video

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