Deviations in the ECG of the heart. What is a cardiac cardiogram (ECG). ECG: indications for performance

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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 an ECG, everyone can easily figure out whether their heart cardiogram is good or if there are some abnormalities.

Indications for an ECG

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

• The patient complains of high blood pressure, chest pain and other symptoms indicating cardiac pathology;
• Deterioration in the well-being of a patient with a previously diagnosed cardiovascular disease;
• Abnormalities in laboratory blood tests - increased cholesterol, prothrombin;
• In preparation for surgery;
• 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.

Decoding ECG - numbers and Latin letters

A full-scale interpretation of the cardiac cardiogram includes an assessment of the heart rhythm, the functioning of the conduction system and the condition 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.
• Strengthened: aVR - right wrist and combined left upper/lower limbs, aVL - left wrist and combined left ankle and right wrist, aVF - left ankle area and combined potential of both wrists.
• Thoracic (potential difference between the electrode with a suction cup located on the chest and the combined potentials of all extremities): 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-sided parasternal line, V4 - V intercostal space along the left 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 pectoralis 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;
• T wave - characterizes the extinction of electrical impulses in the ventricles;
• ST segment - describes the complete restoration of the original state of the myocardium.

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

Sometimes a U pulse is recorded behind the T wave, indicating the parameters of the electrical 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:

• Heart rate - normal heart rate is within 60-100/min. The distance from the tops of adjacent R waves is measured.
• EOS - the electrical axis of the heart is considered to be the direction of the total angle of the electrical force vector. The normal value is 40-70º. Deviations indicate rotation of the heart around its own axis.
• The P wave is positive (directed upward), negative only in lead aVR. Width (duration of excitation) - 0.7 - 0.11 s, vertical size - 0.5 - 2.0 mm.
• PQ interval - horizontal distance 0.12 - 0.20 s.
• The Q wave is negative (below the isoline). Duration 0.03 s, negative height value 0.36 - 0.61 mm (equal to ¼ of the vertical size of the R wave).
• The R wave is positive. What matters is its height - 5.5 -11.5 mm.
• S wave - 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 asymmetrical. Positive height 1.2 - 3.0 mm (equal to 1/8 - 2/3 of the R wave, negative in the aVR lead), duration 0.12 - 0.18 s (longer than the duration of the QRS complex).
• ST segment - passes 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 interpretation in adults and the norm in the table:

During normal research (recording speed - 50 mm/sec), ECG decoding in adults is carried out according to the following calculations: 1 mm on paper when calculating the duration of intervals corresponds to 0.02 sec.

A positive P wave (standard leads) followed by a normal QRS complex means normal sinus rhythm.

Normal ECG in children, interpretation

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

• 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;
• 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 - unstable parameters, negative values ​​in lead III are acceptable;
• P wave - always above the isoline (positive), the height in one lead may fluctuate;
• S wave - negative indicators of variable value;
• QT - no more than 0.4 s;
• The duration of the QRS and the T wave are equal, 0.35 - 0.40.

Example of an ECG with rhythm disturbance

Based on deviations in the cardiogram, a qualified cardiologist can not only diagnose the nature of the heart disease, but also record the location of the pathological focus.

Arrhythmias

The following cardiac rhythm disorders are distinguished:

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 teenagers - up to 200 per minute. The rhythm is correct. With sinus tachycardia, the P wave is slightly higher than normal, with ventricular tachycardia, the QRS length indicator is above 0.12 s.
4. Extrasystoles are extraordinary contractions of the heart. Single ones on a regular ECG (on a 24-hour 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 heart rate 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 of the next contraction is less than 0.09 s.
6. Atrial fibrillation is an irregular contraction of the atria with a frequency of 350-700 per minute, and of the ventricles - 100-180 per minute. There is no P wave, there are small-to-large undulating oscillations along the entire isoline.
7. Atrial flutter - up to 250-350 atrial contractions per minute and regular slow ventricular contractions. The rhythm may be correct; the ECG shows sawtooth atrial waves, especially pronounced in standard leads II - III and thoracic leads V1.

Deviation of EOS position

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

When the EOS is shifted to the left (30-90º) and there is a pathological ratio of the heights of the S and R waves, left ventricular hypertrophy and blockade of the bundle branch of His are diagnosed. Deviation of EOS indicates a heart attack, pulmonary edema, COPD, but it can also be normal.

Violation of the conduction system

The following pathologies are most often recorded:

• 1st degree of atrioventricular (AV) block - PQ distance more than 0.20 s. After each P, QRS naturally follows;
• Atrioventricular block, stage 2. - a gradually lengthening PQ throughout the ECG sometimes displaces the QRS complex (Mobitz 1 type deviation) or a complete loss of QRS is recorded against the background of a PQ of equal length (Mobitz 2);
• Complete block of the AV node - the atrial heart rate is higher than the ventricular heart rate. PP and RR are the same, PQ are different lengths.

Selected heart diseases

The results of ECG interpretation can provide information not only about the heart disease that has occurred, but also about the pathology of other organs:

1. Cardiomyopathy - atrial hypertrophy (usually the left one), low-amplitude waves, partial blockade of the His, atrial fibrillation or extrasystoles.
2. Mitral stenosis - the left atrium and right ventricle are enlarged, the EOS is deviated to the right, often atrial fibrillation.
3. Mitral valve prolapse - flattened/negative T wave, some QT prolongation, depressed ST segment. Various rhythm disturbances are possible.
4. Chronic pulmonary obstruction - EOS is to the right of normal, low-amplitude waves, AV block.
5. Damage to the central nervous system (including subarachnoid hemorrhage) - pathological Q, wide and high-amplitude (negative or positive) T wave, pronounced U, long duration of QT 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 - a pointed T with a sharp apex is recorded 30 minutes before the onset of necrosis of the heart muscle;
• stage of damage (changes are recorded in the first hours 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 - preservation of the dome-shaped ST and the transition of the T wave to negative values, decreased height of R, pathological Q;
• subacute stage (up to 3 months) - comparison of ST with the isoline, preservation of pathological Q and T;
• stage of scarring (several years) - pathological Q, negative R, smoothed T wave gradually comes to normal values.

There is no need to sound the alarm if you find pathological changes in the ECG issued to you. It should be remembered that some deviations from the norm occur in healthy people.

If an electrocardiogram reveals any pathological processes in the heart, you will definitely be scheduled for a consultation with a qualified cardiologist.

A cardiac cardiogram displays the activity of the biopotential of the heart muscle. With its help, you can identify abnormalities in the functioning of the organ and prescribe appropriate treatment in a timely manner. You can decipher the heart cardiogram yourself by familiarizing yourself with its designations and their meanings.

• P is an indicator of the passage of an electrical signal through the atria. Normally, the value is up to 2.5 mm in height.
• Q – indicates the condition of the upper lobe of the heart. Often instruments do not register it, or it is negative - this is the norm. If the indicator is strongly expressed, this indicates the presence of cardiac problems.
• R - reflects the activity of the outer part of the ventricles and the lower part of the heart. The interval norm is 0.03 s. If the value does not correspond to the specified value, the presence of myocardial hypertrophy is likely.
• S – reflects the completion of excitation processes in the ventricles of the heart. The normal value is up to 20 mm.
• The PR interval shows the speed with which excitation spreads from the atria to the ventricles. The natural indicator is 0.12-0.2 s.
• T - helps to diagnose ischemic diseases. The norm is from 0.16 to 0.24 s., positive. Indicates restoration of the biopotential of the heart muscle.
• TP – intermediate interval between contractions. Normal duration is 0.4 s.
• ST – indicates the activity of both ventricles. Permissible deviations: 0.5-1 mm down or up.
• QRS – reflects the work of the ventricles.

• Normal heart rate (heart rate) is 60-90 beats per minute. Deviations from the norm, in the absence of other signs, do not indicate the presence of pathology and may be a consequence of natural causes, for example, anxiety.
• The EOS (electrical axis of the heart) determines the location of the organ in the chest. It can be located normally, vertically, horizontally, with a deviation to the right or left. If the heart deviates to the left or is horizontal, hypertension can be assumed. The heart may deviate to the right in chronic lung diseases. The vertical position of the heart is found in asthenic people, while in obese people it is horizontal.
• A regular sinus rhythm indicates normal heart function. A non-sinus rhythm indicates cardiac pathology.
• Sinus arrhythmia, not related to breathing, is a sign of disease.

These are the main indicators; the list of possible deviations in the functioning of the heart muscle is quite large.

An electrocardiographic study is a fairly simple and effective diagnostic method used by cardiologists around the world to study the activity of the heart muscle. The results of the procedure in the form of graphs and numerical symbols, as a rule, are transferred to specialists for further data analysis. However, if, for example, the necessary doctor is not available, the patient has a desire to independently decipher his heart parameters.

Preliminary interpretation of an ECG requires knowledge of special basic data, which, due to its specificity, is not within the power of everyone. In order to make correct calculations of the ECG of the heart, a person who is not related to medicine needs to become familiar with the basic principles of processing, which are combined for convenience into appropriate blocks.

Introduction to the basic elements of a cardiogram

You should know that the interpretation of the ECG is carried out thanks to elementary, logical rules that can be understood even by the average person. For a more pleasant and calm perception of them, it is recommended to start familiarizing yourself first with the simplest principles of decoding, gradually moving to a more complex level of knowledge.

Tape marking

The paper on which data on the functioning of the heart muscle is reflected is a wide ribbon of a soft pink shade with a clear “square” marking. Larger quadrangles are formed from 25 small cells, and each of them, in turn, is equal to 1 mm. If a large cell is filled with only 16 dots, for convenience you can draw parallel lines along them and follow similar instructions.

The horizontal lines of the cells indicate the duration of the heartbeat (seconds), and the vertical lines indicate the voltage of individual ECG segments (mV). 1 mm is 1 second of time (in width) and 1 mV of voltage (in height)! This axiom must be kept in mind throughout the entire period of data analysis; later its importance will become obvious to everyone.

The paper used allows you to accurately analyze periods of time

Teeth and segments

Before moving on to the names of specific departments of the dentate graph, it is worth familiarizing yourself with the activity of the heart itself. The muscular organ consists of 4 compartments: the 2 upper ones are called atria, the 2 lower ones are called ventricles. Between the ventricle and the atrium in each half of the heart there is a valve - a valve responsible for accompanying the flow of blood in one direction: from top to bottom.

This activity is achieved thanks to electrical impulses that move through the heart according to a “biological schedule”. They are directed to specific segments of the hollow organ using a system of bundles and nodes, which are miniature muscle fibers.

The birth of the impulse occurs in the upper part of the right ventricle - the sinus node. Next, the signal passes to the left ventricle and excitation of the upper parts of the heart is observed, which is recorded by the P wave on the ECG: it looks like a flat inverted bowl.

After the electrical charge reaches the atrioventricular node (or AV node), located almost at the junction of all 4 pockets of the heart muscle, a small “point” appears on the cardiogram, directed downwards - this is the Q wave. Just below the AV node there is the following point the destination of the impulse is the His bundle, which is fixed by the highest R wave among others, which can be imagined as a peak or mountain.

Having overcome half the path, an important signal rushes to the lower part of the heart, through the so-called branches of the His bundle, which externally resemble long octopus tentacles that hug the ventricles. The conduction of the impulse along the branching processes of the bundle is reflected in the S wave - a shallow groove at the right foot of R. When the impulse spreads to the ventricles along the branches of the His bundle, their contraction occurs. The last hummocky T wave marks the recovery (rest) of the heart before the next cycle.

Not only cardiologists, but also other specialists can decipher diagnostic indicators

In front of the 5 main waves on the ECG you can see a rectangular protrusion; you should not be afraid of it, since it represents a calibration or control signal. Between the teeth there are horizontally directed sections - segments, for example, S-T (from S to T) or P-Q (from P to Q). To independently make an approximate diagnosis, you will need to remember such a concept as the QRS complex - the union of the Q, R and S waves, which records the work of the ventricles.

The teeth that rise above the isometric line are called positive, and those located below them are called negative. Therefore, all 5 teeth alternate one after another: P (positive), Q (negative), R (positive), S (negative) and T (positive).

Leads

You can often hear the question from people: why are all the graphs on the ECG different from each other? The answer is relatively simple. Each of the curved lines on the tape reflects heart parameters obtained from 10-12 colored electrodes, which are installed on the limbs and in the chest area. They read data on the cardiac impulse, located at different distances from the muscle pump, which is why the graphs on the thermal tape are often different from each other.

Only an experienced specialist can competently write an ECG report, but the patient has the opportunity to review general information about his health.

Normal cardiogram values

Now that it has become clear how to decipher the cardiogram of the heart, we should begin to directly diagnose normal readings. But before you get acquainted with them, you need to evaluate the ECG recording speed (50 mm/s or 25 mm/s), which, as a rule, is automatically printed on paper tape. Then, based on the result, you can view the norms for the duration of teeth and segments, which are listed in the table (calculations can be carried out using a ruler or checkered markings on a tape):

Among the most significant provisions for ECG interpretation are the following:

• Segments S-T and P-Q should “merge” with the isometric line without going beyond it.
• The depth of the Q wave cannot exceed ¼ of the height of the slenderest wave - R.
• The exact parameters of the S wave have not been approved, but it is known that it sometimes reaches a depth of 18–20 mm.
• The T wave should not be higher than R: its maximum value is ½ the height of R.

Control of heart rhythm is also important. It is necessary to pick up a ruler and measure the length of the segments between the vertices R: the results obtained must coincide with each other. To calculate heart rate (or heart rate), you should count the total number of small cells between the 3 vertices of R and divide the digital value by 2. Next, you need to apply one of 2 formulas:

• 60/X*0.02 (at a recording speed of 50 mm/sec).
• 60/X*0.04 (at a recording speed of 25 mm/sec).

If the number is in the range from 59–60 to 90 beats/min, then the heart rate is normal. An increase in this index implies tachycardia, and a clear decrease implies bradycardia. If for a mature person a heart rate of more than 95–100 beats/min is a rather dubious sign, then for children under 5–6 years old this is one of the varieties of the norm.

Each of the teeth and intervals indicates a certain period of time the heart muscle is working

What pathologies can be identified when decoding data?

Although the ECG is one of the extremely simple studies in structure, there are still no analogues for such a diagnosis of cardiac abnormalities. You can become familiar with the most “popular” diseases recognized by ECG by examining both the description of their characteristic indicators and detailed graphic examples.

This disease is often recorded in adults during ECG, but in children it manifests itself extremely rarely. Among the most common “catalysts” of the disease are the use of drugs and alcohol, chronic stress, hyperthyroidism, etc. PT is distinguished, first of all, by a frequent heartbeat, the indicators of which range from 138–140 to 240–250 beats/min.

Due to the occurrence of such attacks (or paroxysms), both ventricles of the heart do not have the opportunity to fill with blood in time, which weakens the overall blood flow and slows down the delivery of the next portion of oxygen to all parts of the body, including the brain. Tachycardia is characterized by the presence of a modified QRS complex, a weakly expressed T wave and, most importantly, the absence of a distance between T and P. In other words, groups of waves on the electrocardiogram are “glued” to each other.

The disease is one of the “invisible killers” and requires immediate attention to a number of specialists, since if left untreated it can lead to death

Bradycardia

If the previous anomaly implied the absence of the T-P segment, then bradycardia represents its antagonist. This disease is indicated by a significant prolongation of T-P, indicating weak conduction of the impulse or its incorrect accompaniment through the heart muscle. Patients with bradycardia have an extremely low heart rate index - less than 40–60 beats/min. If in people who give preference to regular physical activity, a mild manifestation of the disease is the norm, then in the vast majority of other cases we can talk about the onset of an extremely serious disease.

If obvious signs of bradycardia are detected, you should undergo a comprehensive examination as soon as possible.

Ischemia

Ischemia is called a harbinger of myocardial infarction; for this reason, early detection of an anomaly contributes to the relief of a fatal ailment and, as a result, a favorable outcome. It was previously mentioned that the S-T interval should “lie comfortably” on the isoline, but its descent in the 1st and AVL leads (up to 2.5 mm) signals precisely IHD. Sometimes coronary heart disease produces only the T wave. Normally, it should not exceed ½ the height of R, however, in this case it can either “grow” to the senior element or fall below the midline. The remaining teeth do not undergo significant changes.

Atrial flutter and fibrillation

Atrial fibrillation is an abnormal condition of the heart, expressed in the erratic, chaotic manifestation of electrical impulses in the upper chambers of the heart. It is sometimes not possible to make a qualitative superficial analysis in such a case. But knowing what you should pay attention to first, you can calmly decipher the ECG indicators. The QRS complexes are not of fundamental importance, since they are often stable, but the gaps between them are key indicators: when flickering, they resemble a series of notches on a handsaw.

Pathologies are clearly distinguishable on a cardiogram

Not so chaotic, large-sized waves between QRS already indicate atrial flutter, which, unlike flicker, is characterized by a slightly more pronounced heartbeat (up to 400 beats/min). Contractions and excitations of the atria are to a small extent subject to control.

Thickening of the atrial myocardium

Suspicious thickening and stretching of the muscle layer of the myocardium is accompanied by a significant problem with the internal blood flow. At the same time, the atria perform their main function with constant interruptions: the thickened left chamber “pushes” blood into the ventricle with greater force. When trying to read an ECG graph at home, you should focus your attention on the P wave, which reflects the condition of the upper parts of the heart.

If it is a kind of dome with two bulges, most likely the patient is suffering from the disease in question. Since thickening of the myocardium in the long-term absence of qualified medical intervention provokes a stroke or heart attack, it is necessary to make an appointment with a cardiologist as soon as possible, providing a detailed description of the uncomfortable symptoms, if any.

Extrasystole

It is possible to decipher an ECG with the “first signs” of extrasystole if you have knowledge about the special indicators of a particular manifestation of arrhythmia. By carefully examining such a graph, the patient may detect unusual abnormal surges that vaguely resemble QRS complexes - extrasystoles. They occur in any area of ​​the ECG, and are often followed by a compensatory pause, allowing the heart muscle to “rest” before starting a new cycle of excitations and contractions.

Extrasystole in medical practice is often diagnosed in healthy people. In the vast majority of cases, it does not affect the usual course of life and is not associated with serious illnesses. However, when arrhythmia is detected, you should play it safe by contacting specialists.

With atrioventricular heart block, an expansion of the gap between the P waves of the same name is observed, in addition, they can occur at the time of analysis of the ECG conclusion much more often than QRS complexes. Registration of such a pattern indicates low conductivity of the impulse from the upper chambers of the heart to the ventricles.

If the disease progresses, the electrocardiogram changes: now the QRS “falls out” of the general row of P waves in some intervals

Bundle branch block

Failure in the operation of such an element of the conduction system as the His bundle should in no case be ignored, since it is located in close proximity to the Myocardium. In advanced cases, the pathological focus tends to “spill over” to one of the most important areas of the heart. It is quite possible to decipher the ECG yourself in the presence of an extremely unpleasant disease; you just need to carefully examine the highest tooth on the thermal tape. If it does not form a “slender” letter L, but a deformed M, this means that the His bundle has been attacked.

Damage to its left leg, which transmits the impulse into the left ventricle, entails the complete disappearance of the S wave. And the place of contact of the two vertices of the split R will be located above the isoline. The cardiographic image of the weakening of the right bundle branch is similar to the previous one, only the connection point of the already designated peaks of the R wave is located under the midline. T is negative in both cases.

Myocardial infarction

The myocardium is a fragment of the densest and thickest layer of the heart muscle, which in recent years has been exposed to various ailments. The most dangerous among them is necrosis or myocardial infarction. When deciphering electrocardiography, it is sufficiently distinguishable from other types of diseases. If the P wave, which registers the good condition of the 2 atria, is not deformed, then the remaining ECG segments have undergone significant changes. Thus, a pointed Q wave can “pierce” the isoline plane, and a T wave can be transformed into a negative wave.

The most indicative sign of a heart attack is an unnatural elevation of R-T. There is a mnemonic rule that allows you to remember its exact appearance. If, when examining this area, one can imagine the left, ascending side of R in the form of a rack tilted to the right, on which a flag is flying, then we are really talking about myocardial necrosis.

The disease is diagnosed both in the acute phase and after the attack has subsided.

Ventricular fibrillation

Otherwise, an extremely serious illness is called atrial fibrillation. A distinctive feature of this pathological phenomenon is considered to be the destructive activity of conductive bundles and nodes, indicating uncontrolled contraction of all 4 chambers of the muscle pump. Reading the ECG results and recognizing ventricular fibrillation is not at all difficult: on a checkered tape it appears as a series of chaotic waves and valleys, the parameters of which cannot be correlated with classical indicators. In none of the segments is it possible to see at least one familiar complex.

If a patient with atrial fibrillation is not given early medical attention, he will soon die.

WPW syndrome

When, in the complex of classical pathways for conducting an electrical impulse, an abnormal bundle of Kent unexpectedly forms, located in the “comfortable cradle” of the left or right atrium, we can confidently speak about a pathology such as WPW syndrome. As soon as the impulses begin to move along the unnatural cardiac highway, the rhythm of the muscle is lost. The “correct” conducting fibers cannot fully supply the atria with blood, because the impulses prefer a shorter path to complete the functional cycle.

The ECG with SVC syndrome is characterized by the appearance of a microwave at the left foot of the R wave, a slight widening of the QRS complex and, of course, a significant reduction in the P-Q interval. Since deciphering the cardiogram of a heart that has undergone WPW is not always effective, the HM - Holter method of diagnosing the disease - comes to the aid of medical personnel. It involves wearing a compact device with sensors attached to the skin around the clock.

Long-term monitoring provides a better result with a reliable diagnosis. In order to timely “catch” an anomaly localized in the heart, it is recommended to visit the ECG room at least once a year. If regular medical monitoring of the treatment of cardiovascular disease is necessary, more frequent measurements of cardiac activity may be required.

Doctors obtain important information about the condition of the heart using ECG (electrocardiography). This simple test allows you to identify dangerous diseases of the cardiovascular system in adults and children and prevent their further development.

Electrocardiography provides detailed data on the condition of the heart

ECG - what is it?

Electrocardiography (cardiogram) is a determination of the electrical activity of the heart.

Using this procedure you can find out:

• heart rate and conductivity;
• presence of blockades;
• sizes of the ventricles and atria;
• level of blood supply to the heart muscle.

A cardiogram is the main study that can identify a number of dangerous diseases - myocardial infarction, heart defects, heart failure, arrhythmia.

A cardiogram helps identify abnormalities in the functioning of the heart.

Thanks to the ECG, it is possible to detect not only cardiac disorders, but also pathologies in the lungs, endocrine system (diabetes mellitus), blood vessels (high cholesterol, high blood pressure).

No special preparation is required to undergo a heart examination. In public hospitals, an ECG requires a referral from the attending physician; the procedure is free.

Private clinics do not require a referral, but here the study is paid:

• the price for registering a cardiogram without decoding is 520–580 rubles;
• the cost of decryption itself is from 430 rubles;
• ECG at home - from 1270 to 1900 rubles.

The cost of the procedure depends on the procedure and the level of qualification of the hospital.

ECG methods

For a comprehensive diagnosis of cardiac activity, there are several methods for conducting an electrocardiogram - a classic heart cardiogram, Holter ECG and stress ECG.

Classic cardiogram

The most common and simple way to study the strength and direction of electrical currents that appear during each impulse of the heart muscle. The duration of the procedure does not exceed 5 minutes.

During this time, specialists manage to:

• study the electrical conductivity of the heart;
• detect heart attack pericarditis;
• examine the chambers of the heart, identify thickening of their walls;
• determine the effectiveness of the prescribed therapy (how the heart works after taking certain medications).

A classic cardiogram is a simple and accessible method of studying the heart.

The disadvantage of this method is that it is carried out at rest. Therefore, pathologies that manifest themselves under stress (emotional, physical) or during sleep cannot be detected by this diagnostic method. In these cases, the doctor relies on the patient’s complaints, main signs and may prescribe other types of research.

The technique allows you to identify pathologies that do not appear in a calm state. The device records cardiac activity throughout the day and makes it possible to determine the moment of failure in the patient’s usual conditions (during physical activity, during stress, during sleep, while walking or running).

Thanks to the Holter study, it is possible to:

• determine at what moments an irregular heart rhythm appears and what provokes it;
• identify the source of the feeling of squeezing or burning in the chest, fainting or dizziness.

Heart rhythms using the Holter method are measured for at least 24 hours

Stress ECG is monitoring of heart function during exercise (exercises on a treadmill, exercise on an exercise bike). It is performed when the patient experiences periodic disturbances in cardiac activity that electrocardiography cannot detect at rest.

ECG with stress makes it possible to:

• identify factors that provoke deterioration of the condition during physical activity;
• find the cause of sudden surges in blood pressure or irregular heartbeat;
• monitor exercise after a heart attack or surgery.

The study allows you to select the most appropriate therapy and monitor the effect of medications.

Stress ECG is performed to study the work of the heart under stress.

Indications for electrocardiography

Typically, a cardiac cardiogram is prescribed based on the patient’s complaints and the presence of unpleasant symptoms:

• pressure surges, often upward;
• difficulty breathing, turning into shortness of breath even in a calm state;
• pain in the heart area;
• heart murmurs;
• diabetes;
• destruction of joints and muscles with damage to blood vessels and the heart (rheumatism);
• causeless pulse disturbance.

A cardiogram is always prescribed after a stroke, frequent fainting, and also before any surgical intervention.

If you have frequent pain in the heart, you need to do a cardiogram

Preparing for the study

Electrocardiography does not require special preparation. For more reliable indicators, experts recommend following simple rules on the eve of the study.

1. Rest. You need to get a good night's sleep, avoid emotional outbursts and stressful situations, and do not overstrain your body with physical activity.
2. Food. Do not overeat before the procedure. Doctors sometimes recommend fasting heart monitoring.
3. Drink. A few hours before the cardiogram, it is recommended to drink less fluid to reduce the load on the heart.
4. Meditation. Before the procedure itself, you need to calm down, take a deep breath, then exhale. Normalizing breathing has a positive effect on the functioning of the cardiovascular system.

Before performing an ECG, you need to get a good night's sleep.

How is an ECG performed?

Many have encountered a cardiac cardiogram and know that the procedure takes 5-7 minutes and consists of several stages.

1. The patient needs to expose the chest, forearms, wrists and lower legs. Lie down on the couch.
2. The specialist treats the areas where the electrodes will be adjacent with alcohol and a special gel, which promotes a better fit of the wires.
3. After securing the cuffs and suction cups, the cardiograph is turned on. Its operating principle is that it uses electrodes to read the rhythm of heart contractions and record any disturbances in the functioning of a vital organ in the form of graphic data.

The resulting cardiogram requires decoding, which is carried out by a cardiologist.

To measure heart rhythms, special suction cups are placed in the area of ​​the heart.

Contraindications for electrocardiography

A regular ECG does not harm the body. The equipment reads only cardiac currents and does not affect other organs. Therefore, it can be done during pregnancy, children and adults.

But electrocardiography with a load has serious contraindications:

• third stage hypertension;
• severe circulatory disorders;
• thrombophlebitis in exacerbation;
• myocardial infarction in the acute period;
• enlargement of the walls of the heart;
• severe infectious diseases.

You can’t do a cardiogram if you have thrombophlebitis

Decoding the results

Cardiograph data reflects the functioning of a vital organ and is the basis for making a diagnosis.

ECG analysis algorithm

The sequence of studying cardiac activity consists of several stages:

1. Assessment of the work of the heart muscle - rhythm and contraction of the organ. Study of intervals and identification of blockades.
2. Assessment of ST segments and identification of pathological Q waves.
3. Study of R waves.
4. Examination of the left and right ventricles to identify their hypertrophy.
5. Studying the location of the heart and determining its electrical axis.
6. Study of the T wave and other changes.

Electrocardiography analysis consists of 3 main indicators, which are schematically depicted on the cardiograph tape:

• serrations (prominences or depressions with sharp ends above a straight line);
• segments (segments connecting teeth);
• interval (a distance consisting of a tooth and a segment).

When decoding the cardiogram, the following parameters are taken into account:

• systolic indicator - the amount of blood that is ejected by the ventricle in 1 contraction;
• minute indicator - the volume of blood passed through the ventricle in 1 minute;
• Heart rate (HR) – the number of heart beats in 60 seconds.

After analyzing all the characteristics, you can see the general clinical picture of cardiac activity.

Normal ECG in adults

An inexperienced person will not be able to decipher the resulting diagram on his own, but it is still possible to have a general idea of ​​the state. To do this, it is necessary to understand the main characteristics of such monitoring within normal limits.

Table “Indicators of a good ECG”

What the main indicators of heart activity look like in a cardiogram is shown in the photo.

Normal cardiogram in children

Some ECG parameters in a child differ from adult parameters and depend on age:

1. Heart rate - from 135 (in a newborn baby) to 75–80 (in a teenager).
2. EOS (electrical axis of the heart) - normally, the total angle of the electrical force vector should not exceed 45–70 degrees. In a newborn, the heart is deviated to the right; in children under 14 years of age, the axis is vertical.
3. The heart rhythm is sinus.

The location and duration of the waves correspond to the normal cardiogram of an adult.

Normal cardiac parameters in a child

Any deviations from the norm in the interpretation of the cardiogram are a reason for a more detailed examination of the person.

There are several end results of an ECG:

• low-amplitude ECG - decreased wave height (QRS complex) in all leads - a common sign of myocardial dystrophy;
• borderline or atypical ECG - some parameters do not correspond to the norm, but do not belong to severe pathologies.
• pathological ECG - serious abnormalities in cardiac activity that require immediate medical intervention.

Cardiogram with deviations

Not all changes in the cardiogram should be taken as an indicator of serious heart problems. Rhythm disturbances or a reduction in the width of segments between the teeth in a healthy person can be a consequence of emotional overstrain, stress, or physical activity. In this case, it is better to go through the monitoring again and double-check the results.

Table “Pathological disorders of cardiac activity”

This interpretation of the ECG allows an inexperienced person to roughly navigate the general ECG scheme. It is important to remember that only a specialist can read electrocardiography and make appropriate conclusions. Therefore, there is no need to try to diagnose yourself.

Is it dangerous to perform an ECG?

A classic heart cardiogram simply reads heart impulses and transmits them to paper. The device does not affect the heart or other organs. Therefore, ECG does not pose a danger to children and adults. It can be safely done even for a newborn baby and women during pregnancy.

Monitoring cardiac activity using an ECG allows you to quickly and reliably obtain an analysis of the state of the heart. Thanks to this method, it is possible to quickly detect serious diseases of the cardiovascular system, check the effectiveness of drug treatment and identify diseases of other organs. Cardiography is completely safe for human health (only ECG with stress has contraindications).

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

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

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

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

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

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

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

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

ECG: indications for performance

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Myocardial dystrophy

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

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

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

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

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

Morphologically it is customary to distinguish three zones:

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

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

Dishormonal myocardial dystrophy

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

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

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

Changes in electrocardiogram parameters while the patient is taking certain medications

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

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

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

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

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

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

Early repolarization of the cardiac ventricles

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

Pericarditis

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

Myocarditis

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